Hey everyone:

I've been having some fuel pump problems on my '86 Fourtrax 350. From what I've read on-line, that's not uncommon. My fuel-cut relay and pump both test fine, according to the test procedures in the manual. The pump can deliver the specified amount of fuel per minute, and the pressure stays steady at about 1.5 psi, however, my problem is an intermittent one: sometimes it works great, other times it stalls and won't re-start. I was thinking the pump was getting weak and it would intermittently fail. But I've noticed the pattern is that when the fuel gets below 1/4 tank is when I get a problem. What happens is that it loses its ability to suck fuel when the tank is low. I know this because I put a clear section of fuel line between the pump and the carb, and when the bike won't run, I can see that there's no fuel in the line, however, the relay is triggering the pump and the pump is running, it just can't suck up any fuel. So either the pump is weak and it can't suck up the fuel when the tank is low, or there is some sort of problem inside the tank, like a hole in the pick-up tube, part way up. I know the tank has some rust on the bottom, but is it commom for pick-up tubes to rust out? I've had every section of fuel hose off the machine and there are no obstructions, I took the petcock off and it is clear, too. What else would cause this? Just wondering if anyone else has any suggestions. Thanks a lot and sorry for the long post.

 

Sounds like IMO.the metal fuel line inside of tank is blocked off some or partially closed..May need to take fuel tank out of atv an take to an radiator shop an have it vatted out an reseal to treat the rust problem you have now...If pump is running an not pumping then I would guess fuel is gettin restricted some how an pump cannot pick the fuel up..since you said you have some rust in bottom of tank then my guess the metal pipes inside tank is corroded also..

 

Thanks for the reply Papa Hogg Scoot. I would have replied sooner, but the flu has gone through our family one by one for the past week, plus frigid temperatures (well I am in Canada) and a massive storm system the past few days. About the fuel pump problem, it seems like there must be a restriction somewhere, but I have had every inch of fuel line off, including the pump, carb, pet ****, filter, and the tank. I've blown through each peice with a blowgun and my mouth. Can't quite figure this out. I've also noticed fuel drains out of the fuel line from the carb, back through the pump, lines filter, right back into the tank if the bike sits for more than 3-4 days. And of course, once the fuel drains out, the bike won't start because the pump loses it's prime or it just can't suck it up out of the tank. Once I prime the pump, everything works great, until the tank gets low, or if it sits for days again. I've started to turn the pet **** to the "off" position when I'm done riding so fuel can't drain back into the tank. Hopefully this will help with my problem. I'll keep you posted.

 

Just an update: since I've been turning the petcock to the "off" position after I'm done riding, I haven't had any starting issues. I also figured out a fairly easy way to bypass the fuel pump if one should quit on you if you're in the middle of nowhere: you can take a fuel primer bulb, like those used in an outboard motor fuel line, and hook it between the tank and the carb, all it needs is a couple of squeezes a minute to keep the motor running. Don't forget to unplug your fuel pump so you don't burn it out. Not a perfect fix, but it may certainly get you out of trouble one day. Plus it only costs $10 and takes less than 5 minutes to install. It might also make sense to plumb one in permanently to save yourself the trouble of doing it during a breakdown. Just a thought.

 

80's Honda,

That is a good idea about the primer bulb. Can you send some pictures on where you put that bulb? I want to put one in but am slightly worried that if I route the bulb somewhere easily accessed that it might make the fuel pump struggle to stay primed or to move the required fuel. Thanks!

 

I don't actually leave the primer bulb hooked up at all times, I just carry it with me in case I ever need it - an emergency back-up really. The fuel pump hasn't given me any more trouble now that I turn the petcock to "off" after I'm done riding.