ATV Help & Brand Specific Topics

I had a similar problem on my 350, but if it runs on choke the pump must be working, since the fueltank is lower than the carb. Maybe you have a clogged carburettor? When I crank the 350 for a split second the pump starts and build preassure then it stops. I do this everytime i start it to "prime" the fuel lines so i dont have to crank it so long. Inside the fuelpump is a preassure switch to that cuts the power to the pump when there is enought preassure in the line, The fuel relay somehow works with the rpm of the machine. I hate this setup, almost thought of putting a gastank from a 300 trx on it 😃

I thought you might have already done that, just thought i would mention it. This is a tough one. You may be right about the fan controller, i would check all the connections very carefully at the controller and CDI for good contact. Is there any other problems going on other than fuel pump?

Agreed! None of these problems should cause it to only run for a few seconds and quit.

It had the problem before the overhaul, so it's probably not blow by or bad rings. You'd have to fit the wrong size rings, or break a top ring, to get enough blow-by to cause the filter housing to get oil in it. And, if it starts easily, it's got enough compression. So.. blow-by, by itself, shouldn't be a problem once/if you get the engine running. Neither blow-by, nor oil in the filter housing should cause the engine to stop after only a few seconds. If the air-filter was so full of oil that it choked the engine, then it probably wouldn't start easy, and it wouldn't start easily after the oily filter had flooded it of fouled the plug. If the oil in the filter housing, and the cutting out, are related, it will be fuel in the oil. There is a chance though that the two are not related. If you have a timing light you could connect that up and watch it to see if you are loosing spark. If you don't have a timing light you can fit a plug to the plug lead, and then rest that against the fitted spark plug so that the spark has to jump the first gap to fire the second plug. If the spark is good it will do that jump and the bike will run, and if the spark dies you can see it on the first/external plug.

Thank you for this info. The Quad is at my holiday home, so cannot check oil levels etc at the moment. It was not overfilled as the bike was not using oil and therefore had not been topped up in a while. However, it is possible that fuel got into the oil and I will check this. I have just done the top end so it is possible that the rings are not yet seated properly. If this is the case, I am not sure how to fix this as the bike will only run for a minute or two before dying. I will check the breather pipes for blockages etc.

Yeh, I have fitted a new relay and rectifier. If I cant find a wiring fault I can only think either the CDI or the fan actuator may be to blame.

That's brilliant, I will have another go at it this morning!! Thank you!!

Cdi coils should have almost no resistance on their primary windings. 0.6 Ohm would be about right. Coils for switched 12v have resistance.

Photo has been removed, what part are you referring to.

That sounds like piston ring blowby, how long since you did your top end job. If you are using synthetic oil it takes longer for the new rings to seat.

Sounds like a bad relay did you replace it and still wont work.

You have been busy, sparlplug coil sounds weak, should be between 6 and 10 OHMs, what does the book say about that. . Do you get a good spark at the plug.

Update: Correction, I did check valve clearance it is 0.00. This Rotax 650 uses the shim type. So not as easy to adjust. After some the recommendations about testing electrical components I decided to just follow the service manual. I've now check the rectifier for voltage at 5500RPMs = 15Volts=OK. Manual states it should not to exceed 15volts. Checked and measure the resistance between the Stator wire leads AC-1 and AC-2 = 0.6 Ohms. Should be 0.3 Ohms. Checked continuity between Stator coils AC-1 to ground, AC-2 to ground. There was no continuity=OK. Measured voltage across 2 of the Stator coils while turning over the engine, they each measure with the 4-6 Voltage AC range=OK. Measured resistance on the Trigger Coil and it read 243 Ohms=OK. Measure Sparkplug coil and it measured 0.6 Ohms. Not sure if this ok? I hooked up separate gravity feed fuel tank and running it but still runs the same way. Tps out at 20MPH. Using an external tachometer, if it is set correctly, I only reached 5500 RPMs. FYI, I did make vides and load them to Youtube, so I know what I've done because my memory isn't the best. I have not yet checked for breather hoses for vacuum leaks or this below. I have it on blocks so once I get it off blocks I can try this.

I think these will be right.. The manual is for 86-89. If it's not right it probably means your bike is the previous model, up to 86. 86wiring.pdf 86 fuelpump.pdf

Check the oil level first as the other post said if over filled or if fuel leaks into the bottom end this can happen. from my own experience with my kfx700 after I did a big bore kit hi performance cams and a rev box this problem all of a sudden showed up. This was due to excessive air movement inside the cylinder bottom end and there was not a breather box to catch any excess oil that will blow out with the moving air. to fix this problem I got a breather box from a Yamaha raptor and installed this in line with the breather hose then it also has a drain and I had to use a extra unused port on the other cylinder for the oil to drain back to the lower end.

Hi , if you go on to the E-Ton site you can download a parts and workshop manual.

Ok, Finally found out it's a 1986 TRX350 Fourtrax. I have power from the battery to the relay but nothing at the pump. I have continuity on both pump wires from the relay but the pump is not energising on the starter or when the engine is running so it cant rev. cheers!!

You could try riding it in low gear till you hit the revs you do at 20 in high gear. If it keeps going past those revs then it says it's not a rev limiter. Then if you rode it down a hill so it had no load on it, and it still wouldn't go over 20, then it really looks like being a speed limiter. It's possible it has a speed(or rev) limit by design, that you've triggered by accident, either in the wiring or the ecu repair. If you figure which limit it is, )if it is not a load limit), then it might be a lead where to investigate.

Valve clearance is rather concerning, was the valve adjusting screw loose, it should not have changed that much in 650 miles.Unless previous owner adjusted it I would reset the valve clearances to spec and see if that helps. That would definately affect compression because clearances could actually be less than zero. Not really sure how you fixed the computer or what was wrong but that could also be limiting your revs electronically. Never had much luck at fixing computers, when something goes out it could actually take out another sector then it hard to diagnose.

I'll check for a decompressor. It does start and idle fine. Valve Clearance is suppose to be 0.015. Powers up 20 to no problem, maybe not full power compared to a Honda 500 I had. No power or throttle left after it hits 20mph. Speed is always the same. It's a CVT transmission so I can't change gears only shift to high or low. It could be limited at certain revs or throttle. I can try and see if my RPM meter works on this type of coil. I have not tried doing a tune. I blew out air filter. I also ran engine without air filter and ran the same. I've tried new sparkplug. I have not checked fuel flow from the tank, valves, coil and cap for correct resistance and breather hoses for vacuum leaks. I've got some things to check, Thank You, Ben

Yup.. What Gw says.. What is this fouling like ? Wet or dry, oily or powdery, baked hard or fluffy ? And how does the bike run ? When did it last get a tune ? Is the fuel fresh ? Have you inspected the air-filter ? Is the plug the right one for the bike ?

I think that will have a decompressor and so that low compression is probably normal. If it starts and idles ok I wouldn't worry about the compression. The valves should have some clearance. Check the manual. You don't really describe the riding and it's topping out at 20 very well.. Does the power just slowly taper off till it won't go any faster, or does it pull to that speed and then abruptly limit itself, and is the limit absolute or can you coax it a little higher by manipulating the throttle, or going down a slope ? Is that speed always the same? If you use a lower or higher gear will it go faster, or in a lower gear does it limit at a lower speed ? Are you sure it's the speed it's limiting at, and not perhaps at certain revs, or throttle opening ? Have you tried doing a tune ? Checked the air-filter, fuel flow from the tank, valves, new spark-plug, checked the coil and and cap for the correct resistance, inspected the breather hoses and checked for vacuum leaks..

I did a compression test on my 2005 Bombardier Traxter 650 CVT and it's 75 PSI. Service manual only talks about leak down test. No specification for engine compression the manual. What does 75 PSI tell me? Thank in advance. A little history of this machine. 640 miles. Picked it up about 2 years ago, not running. Probably the computer. Tested all circuits and confirm it was the computer. Long story short, I watched a Youtube video and fixed the computer. ATV now started and runs. BUT, it tops out 20 MPH. I cleaned the carb 3 times also using a Mikuni carb kit after the second time. Slide in carb is going up and down. Only adjustment for fuel is at 1.5 turns out. NGK Sparkplug had soot on main part but brown on the electrode. Champion sparkplug is brown. I check CVT clutches and they both appear to engage like they suppose to. Checked valve clearance it's 0.00, I can't get any feeler gauges in-between. I check timing chain I believe it's in the correct position and hasn't skipped. I removed muffler plug and drilled into muffler to try and make sure it wasn't plugged.

Many things could cause this. If it is oil fouling maybe rings or valve guides, hope its not that. If it is dry powdery fowling it probably flooding. I know its fuel injected, the only thing i can think of there is replace the injector, but before doing that i would run some fuel injector cleaner through it and see if that helps. The other question would be how does it run, good, sluggish acceleration, jerky accelertion. What im getting at is to properly diagnose i need a little more information on how its running. There may be other electronics involoved that control the fuel injector.

Hi All I have a 2012 Coleman 500 Outfitter that keeps fouling out the plug within 10-15 minutes not sure where to start