I do have a good bit of experience with old car/truck, and motorcycle 4 stroke engines, but none at all with 2 strokers. How to Make a Car Backfire. If your Briggs & Stratton engine has a spark but won't run, then it is most likely a problem with the gas or air intake in the engine. I am getting good fuel flow beyond the fuel filter to the carburetor, so it isnt the fuel filter. Note: Backfire and afterfire through the carburetor will not harm the engine at all! Find out the most common causes and possible fixes for engine backfire and afterfire. This problem has a relatively simple cure. Re: Engine backfires but won't start. Just a thought. In other words it needs "enriching". That is, you put in a dry spark plug, try to start the engine, and end up with a spark plug dripping with gas. It backfires when trying to start. Remember, the tensile strength of steel is greater than wood. Whether performing maintenance or complete engine overhaul to the 35hp engine, this downloadable 35hp repair manual covers it all. com TexasNissans. air, float seems to be working fine. it wont start it turns over but does not start. If you can crank the engine but it won't start, go HERE. but you are supposed to turn the key to the first on position, let it stay there for 5 seconds. It shut off in the middle of cutting and that was that. Once the engine is warmed up, opening the choke will return the engine to normal operation. Maybe it's a old machine your trying to bring back to life, or a dependable engine that never lets you down. Diagnosing the cause is the first step to making the necessary repair. 4: Backfires in Exhaust Note: It is normal for many high performance exhaust systems to moderately backfire or pop when the throttle is closed from mid-to-high rpm. If fuel and electrical is all good/correct it is often the case in these symptoms that motor cycle spark plugs that although looking good and firing outside of the engine are breaking down and will not fire under compression pressures on a power stroke but will fire unburned fuel on the. This would be especially true with bikes that are not used much. So you're getting fuel, spark, you're at top dead center and your rotor is pointing at the #1 post and still the thing won't start. Leave it for about 10 minutes for fuel to evaporate before attempting a re-start. My 79 f150 started backfiring & now wont start 6 Answers. Most common cause to why a small 2-stroke engine won't start and bog down Weedeater featherlite 2 cycle gas trimmer won't start diagnosis How to fix a small two stroke engine that bogs. Dear friends, I would be really thankful if you could help me. Backfires and loud explosion-like sounds are common when an antilag system is present and active. I'd change the spark plug first. The engine cuts out under hard braking (normally from 55+ mph) with the clutch pedal fully depressed. I have a hard time starting my 1999 Merc 2-stroke 25HP and can't figure it out. I've never had any of my 2 Strokes backfire before. The problem is my engine will not fire up. I need some help on my 2-Stroke, Polaris 250. There are a number of reasons a mower won't start. When that was done, I syphoned all the old fuel out, and replaced it with fresh 91. So you should check your plug often. 9 HP repair manual, also known as a service manual or workshop manual, is a book of instructions designed to aid a mechanic in the action of fixing or mending an outboard boat motor. Whether your machine is running a Mikuni, Keihin or Lectron carb, the basic principle is the same. I'm new to jet skis and my brother in laws recently purchased 1997 kawasaki sts 750 won't start. Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires. 5 kohler engine. I can get it to start but it backfires then shuts off it looks like fuel is getting to it. It has spark and fuel. It could be you are not in Park or Neutral or have the clutch down, too. replaced fuel filter, ran a week then again no start. It backfires when trying to start. When i tried to turn it back on, it turned but there was no response. air, float seems to be working fine. This chart is to be used as a guideline for troubleshooting engine problems. Backfiring through the carb is one symptom of valve trouble. Your engine could be low by just 3-4 quarts causing a hard start. , while the engine is running or while shutting down. If you fill the tank all the way to the top, then gas will leak out as the engine moves around. Report back with more information (year, hp of the motor) and results of your attempts. Cutting the throttle to idle will sometimes keep the engine running, wait 15 sec and then take it up to full load, will run 5-10 minutes and then repeats the stumble. But it still pops, even when I speed up the notor. Scared the shit out of me but I've had backfires before so I gave it a few seconds and went to start it again, nothing. For a four stroke the fuel efficiency is poor and motor is loud with the Yamaha 2. A backfire results in a temporary loss of power and forward motion along with a loud popping noise. Tried it again, this time running the throttle all the way up and it sputtered for a bit longer. If an engine with spark won't start with it, it'll never run! A couple of 2 stroke facts for you guys. Learn how to diagnose and solve an engine backfiring problem… in case it is a problem. Went out and finally managed to get my exhaust fitted to my downpipes using a gasket I made from a can of Macaroni Cheese Anyway, tried to start my bike after it and it wouldn't start, it was turning over but just wouldn't fire up, then it sounded like it was backfiring Battery got drained so I just fully charged it and same is happening - turning over but not firing up!. A small price to pay for keeping your engine cooler and as any operator of a 2 stroke Detroit Diesel knows, it won't be long until the level will be back to the normal level. If still you have a no start engine condition then probably it's best to consult with a qualified engine mechanic as somewhere in the trouble shooting process something has been over looked. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit. A download outboard repair manual is a book of instructions for learning how to maintain, service, troubleshoot, and overhaul the engine to factory specifications, including procedures for engine wont or will not idle. As its a been 20 years since i last messed with a 2 stroke. I'm about out of options, we pulled the engine out and re-tested for air leaks and found none although I checked the backplate screws and got about a 16th of a turn on them. MerCruiser Cranks but Wont Start or Hard to Start 5. What causes backfiring on a 2 stroke ATV? but a lot of people put 2 stroke engines in it because it's relatively easy A 2 stroke will require oil & gas mix while a 4 stroke will not. If the engine is flooded put the throttle control to full throttle (making sure that you do not put the control into the choke detent if the unit has the choke and throttle on the same control) and crank the engine over. But it still pops, even when I speed up the notor. Below is a chart of common Engine problems and some easy troubleshooting to fix the problem you may be experiencing. They both start but as soon as they get hot they die. I checked and recheck the timing going from 10 degrees which didn't start, 8 to 7 degrees which starts but backfires then shuts off and now 5 degrees and still backfires, it won't run. Read on to learn how to diagnose your oil burning F250 or F350. 1 these two stroke engines is that fixing an issue like this is pretty easy, it just takes a little. My mini chopper wont start upWhat causes a 49. I have plenty of gas going to the carb and the solenoid on the bottom is working fine. This chart is to be used as a guideline for troubleshooting engine problems. It's running now! But there are a few questions I still have, let me know if I should just start a new thread 1) Why won't it start with my battery alone? It sounds like it's trying to start when I use the electric start, but it won't fire. Starting in cold weather could also be a disadvantage if one doesn't have a "current bush" handy to plug the coolant heater into. Fuel level: Fill gas tank to just below the fill neck so there is room for the gas to expand. I'm trying to help out a kid who recently acquired an air-cooled 2-stroke trials bike and then ran it without any oil. Turn fuel to off position and try starting engine with. I bought an '09 Polaris Dragon 600 SP this summer and I'm having some issues. Although there are many problems that can cause the intake system to backfire, the overall effect is the same. Top 25 Reasons Your Boat's Engine Wont Start Even the mood created by this idyllic scene can be ruined by a hard to start marine engine. Outdoor Gasoline and Electric Powered Equipment and Small Engines - Engine wont start and backfires through carb - Its a Briggs Model 31P777 Type 0296-E1. When you then try to start the engine the oil blocks the jets in the carb. If compression. How to Fix a Lawn Mower That Won't Start. If your engine still wont start, it probably has a fuel clog or water in the fuel. At the end of the second day right engine started to just shut off randomly but start right up again. Now the motor runs for 1 or 2 seconds and cuts out with a huge backfire loud from both manifold and exhaust. Engine cranks real good but after about 15 secs of cranking, it backfires. After putting those two parts in I went to start my car and all it would do was crank and crank, but wouldn't start. The following problems are common with the Yamaha snowmobile, download a repair manual instantly to get the remedy on how to fix the issue. Honda has pulled the cover off of the long-rumored and much-anticipated 2021 CBR1000RR-R Fireblade SP. We turned it off and maybe 5 minutes later when we wanted to ride again we tried to start it but it wouldn't start. It just cranks and cranks. Greeting esteemed mower owners, I have a 15 year old Craftsman tractor with a 17HP OHV Briggs and Stratton engine that won't start but occasionlly backfires. If your Briggs & Stratton engine has a spark but won't run, then it is most likely a problem with the gas or air intake in the engine. This INSTANT REPAIR MANUAL DOWNLOAD for the Mercury-Mariner, Johnson-Evinrude, Suzuki, Honda, Yamaha 70HP outboard engines were designed primarily for factory service 70HP outboard technicians in a properly equipped shop. Download a 35 hp manual straight your computer in seconds and fix your problems now. I then attempted to start the engine and it spun over quickly but did not start. 00 Now: $169. The spark on the spark plug ignites the gas in the. Spark plug cap not in good contact with spark plug. 4L 4cyl that will crank all day long but will not start, bought it off of a friend thinking it was a sensor, when she had it it developed a long crank then eventually start now it wont start at all, I have replaced Crankshaft position sensor and both Camshaft position sensors, all 4 coils and plugs. My Nissan 5hp 2-stroke starts on the first or second pull after sitting on the dock for a week. I drained the gas tank, and put 2 or 3 gallons of fresh fuel. Or, it would be, if you hadn't seen this video on basic troubleshooting when your outboards won't start. Whether the bike is a two- or four-stroke, it's almost always easiest to check the fuel supply first. In other words it needs "enriching". Pam - There are many areas to check. I would start looking at ignition timing or I've done this before, left a rag in the intake and mounted carbs, started it and had the same problem, no revs but did idle just fine. when i initially turn the key on i would always hear a short hum or buzz. 2 Stroke Engine tuning is about getting all the core components working together in symmetry. won't start. This will help locate the system that is having a problem and needs repair. The reason the engine kicks back is because the blade has hit something solid which caused the engine to come to a sudden stop and break the flywheel key. The backfire is produced when unburned fuel. Engine cranks but won't start. Engines need air, fuel and spark. A Mercury 9. Engine Won't Start: 1: Carburetor choke: If engine is cold, ensure that the choke lever is up. Got a new fuel pump, got the injector nozzles cleaned and it still won’t accelate. This is an old OS FS-120 Serpass I have had for about three years and tonight was the first time I ran the motor. Any dirt bike, whether it be a 2 stroke or 4 stroke, MUST have these 4 prerequisites to start and run:. An E 3 spark plug is always a good start, Stabil (fuel stabilizer)in the fuel or better yet run it dry when stored, the float/fuel bowl etc can be varnished by gunk if not properly stored. Now it wont start at all cranks but wont turn over seems likes it backfiring through carb. It also won't take long for that out-of-balance prop to cause serious if not catastrophic consequences to your motor. It won't take long for the out-of-balance condition to tear the fan apart. Give it a rest. 5cc 4 stroke engine to backfire when starting? If your engine backfires when trying to start and the valve timing is correct, then it could be. 9 HP repair manual, also known as a service manual or workshop manual, is a book of instructions designed to aid a mechanic in the action of fixing or mending an outboard boat motor. Tips To Prevent Backfire. As the engine runs leaner or if there is less time for the fuel to burn in the combustion chamber, there is a tendency for incomplete combustion. Do you think I need to do a valve job? I am going to start by measuring the clearances. Don't hold the choke on for 15 seconds then release it, that will almost certainly flood the motor. Possible causes: Fuel tank is empty or shutoff valve is closed, or fuel line or fuel tank cap vent is clogged. In fact, one should expect a well-tuned high performance engine to "pop" and "crackle" when the throttle is closed at high rpm. Or, maybe you can't even get to the job site at all. If the valves are operating properly and the compression is still low, worn rings or bore are best fixed by installing a rebuild kit, shortblock or complete replacement engine. I checked and recheck the timing going from 10 degrees which didn't start, 8 to 7 degrees which starts but backfires then shuts off and now 5 degrees and still backfires, it won't run. In almost all cases, whether it is a 2 cycle or 4 cycle engine, golf cart backfiring is caused by the accelerator cable being out of adjustment at the throttle plate of the carburetor. The backfire is produced when unburned fuel. Try rocking the engine back and forth to listen for fuel sloshing. When it doesn't, there is an interruption in the engine's operation. As the engine runs leaner or if there is less time for the fuel to burn in the combustion chamber, there is a tendency for incomplete combustion. it wont start it turns over but does not start. If you jump the two larger terminals and it cranks OK it means your starter is OK and your slave solenoid is bad. The way I got the engine started was by taking off the air filter and spraying alot of starter fluid in it. Yes the oil level. 3 cranks but wont start. Presuming its kick start or the E start is working and the engine is turning over, the first thing to do when diagnosing why any dirt bike won't start, is to ensure the 4 basic necessities listed below are met. I have a 2013 50cc Bintelli Taizhou Zhongneng Motorcycle Co. replaced fuel pump. 9 HP repair manual, also known as a service manual or workshop manual, is a book of instructions designed to aid a mechanic in the action of fixing or mending an outboard boat motor. After investigating I found the rotary valve shaft got a free play 1/4 -1/2 of an inch (approx 5-6mm movement). I turned up the idle screw a bit and it stopped backfiring, unless you tried to choke it, then it would backfire. The bore and stroke of the Sebring are the same as Suzuki's 250cc street twin. The sizing of the orifice to the engine can be checked for accuracy by energizing the SV valve separate from the starting circuit. So your 2 stroke engine won't start. Motorcycle Forum > Motorcycle. A backfire in a lawnmower engine can damage both the engine and the exhaust as burning fuel explodes. smallengines) submitted 1 month ago by -AmTeC-Im ready to throw in the towel. Things were looking up: I replaced the spark plug, cleaned out the exhaust, adjusted the idle / fuel screws, and even replaced the brakes (I can stop now!). I'm an auto-mechanic by trade, and I've had 2 stroke bikes and jetski's throughout my younger years. When engine starts, move throttle to 1/2 throttle and then remove glow driver. However, a two-stroke engine uses more gasoline and burns lots of oil, so it is far more polluting. Here's my history: If you go to the engine. A squirt of fuel directly into the air intake can help; if the engine fires on that small shot of fuel but won't start without it, the fuel system's the problem. 50cc 2 stroke Wont Start? ScootDawg's Scooter Forum a. Try this, Remove the valve covers and turning the engine by hand, watch the rockers, in order, and when that cylinder is on the compression stroke, (no movement of either rocker) loosen the adjusting nuts until you feel a LITTLE rocker to valve clearance, like in a solid lifter engine. Posted on July 31, 2014 by Rosy Maria Most of the Tecumseh engines that are used as small vehicles such as lawn mowers, snow blowers, carburetors, generators, etc. Features may include: ENGINE Robust 90cc Engine The 90cc four-stroke SOHC engine is tuned to develop excellent low- to-mid-range performance, just where it’s needed. Improper timing. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit. but it would be at the top of the exhaust stroke. The engine may. It runs kinda rough when you first crank it and then it backfires like a cannon when you try to engage the blades. If engine won't start, try more throttle until it does. But there are also plenty of details to. Re: Honda Clone generator backfires out the carb, any idea? Try another spark plug. Common causes of backfires are: Wankel rotary engines are known for leaking oil into the exhaust system which causes backfire. Backfiring, won't start now. has a reed valve, check that the carb needle valve is working as it should, then drain the cylinder and crank of fuel check the plug sparks, leave the carb off and put a small amount of petrol in it, try and start it if it fires once or twice, then it should start with the carb on it, if not. 95% of starting problems are caused by the same group of things and don't require a mechanic. If it is cranking too slow the engine will not start. Engine Cranks But Won't Start. Check for DTCs codes, even if you haven't seen the check engine light come on. It could have been a backfire. So I'm lost. if you say you are getting fuel and it is cranking hard. 0L MPI 350 MAG MPI MX 6. Start each needle at 1 1/2 turns out and work from there. What could be the likely issues please. Yes, a two-stroke is a little stiff at -34 degrees but they WILL start. It's a frustrating thing to have a snowblower and not be able to use it. This stops the flow of fuel to the carburetor causing the engine to stall. If still you have a no start engine condition then probably it's best to consult with a qualified engine mechanic as somewhere in the trouble shooting process something has been over looked. It has spark and fuel. Snowblower Start-up Maintenance Check for Bad Gas - Many people don't add stabilizer at the end of the season and the gas goes stale / collects moisture. Engine backfires can be produced by a vacuum leak, bad timing, problems in the ignition system, a faulty sensor, an exhaust leak, or some other system fault. While it's not dangerous, it can be a symptom of other problems, and should be addressed. However, if by opening the throttle it will start in a turn or two, the orifice is satisfactory. I have 252 Club car carryall that will not turn over. Generally, a two-stroke engine produces a lot of power for its size because there are twice as many combustion cycles occurring per rotation. 2 Models these procedures apply to: 1994 350 mercruiser engine won't start;. 2) Big vacuum leak on engine somewhere. Real backfiring means the engine is not properly timed and the fuel/air mix is getting a spark and ignition at the wrong time (when the intake valve is open). Backfiring, won't start now. Check magneto Rotor for being on. yes i put in fresh fuel. Engine backfires when cranking, but won't start? My cj7 has sat for the last year, it ran when I left it but after a year of neglect its taking its revenge. I have a Stihl HS 45 hedge trimmer with a 2 cycle engine that won’t start. Re: 115 Yamaha 4 Stroke won't start PS, Not sure if your is the same as mine as i have a 2003. If engine is hot, ensure that the choke lever is down. ) and stored it in my basement. gx390 backfires, wont start On a four stroke engine, (intake, compression, power, exhaust), the engine makes two complete revolutions to accomplish this cycle. I'm new to jet skis and my brother in laws recently purchased 1997 kawasaki sts 750 won't start. 4 Stroke KTMs - 2005. How to Repair a Four Stroke Lawn Mower. In order for an engine to start running, the carburetor must have a supply of fuel. If it won't fire on the compression stroke, it will fire at the end of the exhaust stroke and ignite the intake charge on valve overlap. Did the same thing again. 3 cranks but wont start. If the engine cranks but won't start, check for spark and fuel pressure. 3hp 2 Stroke. There are a variety of possible causes for a no start, but one of the most common with the 3800 engine is a bad crankshaft position (CKP) sensor or a bad ignition control module (ICM). it is normal for most if not all of the small pre-mixed and some of the oil injected engines. Cranks but no start, backfiring through intake. When you then try to start the engine the oil blocks the jets in the carb. It has spark and fuel. But it still pops, even when I speed up the notor. A clogged or dirty carburetor is a very common reason for backfiring. While outboards have become more and more complex, they still operate on much the same principles as they did before the current wave of EFI/DFI and four-stroke technology. ! If this is your first visit to 3WHeeLeR WoRLD, please take a moment and look around. 5 kohler engine. driving me nuts! i've. ) No spark; weak spark: Spark plug fouled, broken, or misgapped. This chart is to be used as a guideline for troubleshooting engine problems. While this is usually something you'll want to avoid, an explosion in the exhaust or air. , while the engine is running or while shutting down. 3 cranks but wont start. Its color right away will tell you if your running lean or rich. After putting those two parts in I went to start my car and all it would do was crank and crank, but wouldn't start. How to Repair a Four Stroke Lawn Mower. Replace or rebuild the carburetor and correctly set idle speed adjustment. Anyhoo Bike ran fine when I demo'd it before buying, but when I got it off the back of my pickup truck, it would barely start, and then it wouldn't idle without playing with the choke, and then it would backfire through the carb. Engine Won't Start: 1: Carburetor choke: If engine is cold, ensure that the choke lever is up. Backfiring, is extremely rare these days with electronic ignitions and the high reliability of engines. 3 cranks but wont start. There are a number of reasons a mower won't start. Johnson - Evinrude Service Manual Application: Outboard & Sea Drive (Sea Drives) For 48 50 55 60 65 70 75 85 88 90 100 110 115 120 135 140 150 175 185 200 225 & 235 HP (Horsepower - Horse Power) Outboard & Sea Drive Marine Engine Johnson/Evinrude 2Stroke 2-Stroke Two Stroke & 4Stroke 4-Stroke Four Stroke models. This is a guide about troubleshooting a riding lawn mower that won't start. (I always assumed this was the electronic fuel pump. Lack of fuel. Porsche 911 Engine is backfiring Inspection costs between $80 and $90 on average. Float valve worn or stuck open. The engine may. We turned it off and maybe 5 minutes later when we wanted to ride again we tried to start it but it wouldn't start. A two stroke engine needs fuel, air, ignition, and compression to work. In many cases with small engines, there will appear to be gas when in actuality none is getting to the engine. My engine cranks but will not start and the shifter is locked in park, I have to use the shift lock next to the gear shift to get it into neutral. Luckily for you 2 stroke engine troubleshooting is relatively simple. If an engine with spark won't start with it, it'll never run! A couple of 2 stroke facts for you guys. But I've been doing it this way for over 20 years. Its color right away will tell you if your running lean or rich. I pulled the shroud and pull start off and am using a drill to crank the engine as pull start was killing my arm. 9 HP repair manual, also known as a service manual or workshop manual, is a book of instructions designed to aid a mechanic in the action of fixing or mending an outboard boat motor. You’ll be. I am new to this group, and new to 2 stroke engines. The mower started after that and ran fine while I cut the grass. When I stop the car the engine idles very fast so then I have to push the choke in again until I start out again and have to pull it out so it doesnt backfire. Compression. 5cc 4 stroke engine to backfire when starting? If your engine backfires when trying to start and the valve timing is correct, then it could be. I've taken off the top of the engine block and fitted a fresh seal ontop of the cylinder. I thought about pulling the carb and doing a rebuild, since that's fairly easy to do but I'm at a loss as to why this saw ran fine one day, then two weeks later wouldn't even sputter. For a two-stroke engine, having a fresh spark plug is incredibly important. 0 Power Stroke Engine, it is just a matter of time before it fails. First, let's look at the obvious: the battery. If an engine with spark won't start with it, it'll never run! A couple of 2 stroke facts for you guys. It could explain the poor starting and then the clouds of smoke. Engine stumbled when new once or twice a weekend, but wouldn't die. Check magneto Rotor for being on. I have a 2013 50cc Bintelli Taizhou Zhongneng Motorcycle Co. Is your 2-stroke BACKFIRING? This could help Over the last month or so while everyone is getting their carts dialed in for the season, I have noticed an above-average number of posts asking about backfiring issues with Marathons, so I thought I'd throw this post together so there's a searchable solution for those with questions. Electric Power Tool Parts 101 This article defines the basic parts of most power tools, explains how they work, and what to look for when they stop working. They will tick over for a while longer but as soon as I touch the throttle they die. Greeting esteemed mower owners, I have a 15 year old Craftsman tractor with a 17HP OHV Briggs and Stratton engine that won't start but occasionlly backfires. It could be you are not in Park or Neutral or have the clutch down, too. On 2 cycle engines like this one, backfires through the carburetor often indicate a plugged muffler which causes a backpressure and pushes some of the burning fuel back out the intake. It sounds like it wants to start but it just won't turn over. Don't know for a fact on the 2. So I'm back home from uni for afew days during summer. Then consider registering so that you may make posts, and view the additional content available. Why it wont start??. The motor starts easily and will run but it pops throuhg the exhaust. it is normal for most if not all of the small pre-mixed and some of the oil injected engines. 4 Stroke KTMs - 2005. If after several attempts at starting, nothing happens, the engine may have flooded. I got it for so cheap it didn't matter if it worked or not. The rapid burn that occurs while the exhaust valve is open causes a backfire. Mowing the grass is one of the rites of summer, but now your mower won't start. I recently bought an old Yamaha 2 stroke golf cart, early 1980s vintage. Also had a Honda 2 HP 4. This will help locate the system that is having a problem and needs repair. Went to start my Preddy to go riding Sat. 5hp OHV - Won't Run [ 8 Answers ] I have a yard machine mower that was running great. Start cranking with the choke on for 2-3 seconds, then release it for 2 seconds, and repeat. 5 won't start, cranks hard, and backfires. Engine Won't Start: 1: Carburetor choke: If engine is cold, ensure that the choke lever is up. When engine starts, move throttle to 1/2 throttle and then remove glow driver. A two stroke engine needs fuel, air, ignition, and compression to work. I was told years ago that with a pre-mix 2 stroke the oil can separate and go to the bottom of the fuel tank. Backfiring is a small explosion. Now it wont start at all cranks but wont turn over seems likes it backfiring through carb. I have a 2006 Accord EX K24 motor 2. Engine backfires can be produced by a vacuum leak, bad timing, problems in the ignition system, a faulty sensor, an exhaust leak, or some other system fault. The list of electronics is long: adjustable traction control, wheelie control, quickshifter for both up and downshifts, and, something you won't find on other bikes in this class, cruise control. I have found them hard to restart when they are hot. Farmall Cub won't start. Setting 2-stroke ignition timing is fairly simple. Leave it for about 10 minutes for fuel to evaporate before attempting a re-start. Why should an engine that has everything right still refuse to start. Engine Cranks But Won't Start. What is making my 25 hp johnson backfire through the exhaust. But if I go sailing, it won't start for many pulls when I want to get back to the dock. Engine backfires when cranking, but won't start? My cj7 has sat for the last year, it ran when I left it but after a year of neglect its taking its revenge.