I have a '94 that keeps running out of fuel - but it is not because there isn't any in it! It seems to be random. It acts as if it simply runs out of fuel, dies, and when I crank it over - nothing. If I drain the fuel filter using the seperator, and pump it up via the lift pump - it will start and run again. I thought it as water/freezing as it first happened in -40 weather a few weeks ago, but yesterday it was nearly zero and it happened again - twice.

I put on a new lift pump less than 2000kms ago, new fuel filter, during the cold spell a few weeks ago. I cleaned the pre-screen filter both times. The most recent check -it was clean of debris.

When I pump the lift pump I can hear a noise like air leaking from some where once the filter is filled. Is this normal?

Any ideas?

 

I've never had this happen to me, but it sounds like symptoms of fuel gelling.

 

First, yes, when you hear the hissing sound like squeezing air thru your front teeth, it is the overflow valve at the IP working, means you now have fuel all the way to the IP.

Now, what could be causing it to lose fuel, gotta be an air leak somewhere in the primary, start at the top of the fuel tank and work your way back to the lift pump...............

 

As Pat said, you have an air leak. Very common for leaks to suck air without leaking fuel. Often just looking won't find the leak.

The answer is here> http://www.cumminsforum.com/forum/94...m-writeup.html

 

maybe I should read the whole post before I hit reply

 

Have you deleted your fuel heater, and checked the hoses around there? I know I had a huge air leak there, but because of the way its set up, you'll never see fuel dripping out. If you haven't, get rid of the fuel preheater, and check your rubber feed line going from the lp to the preheater. They're known for cracking and going bad.

 

Thanks for the replies - I will check closer for the air leaks. I appreciate knowing about the overflow valve. I have read oter posts about removing the preheat and was pondering this move too. Maybe it is time.

As of lately there is a vaccuum when I open the fuel cap. Would this cause my symptoms? I was wondering if the lack of breathability could somehow be causing a resistance to flow? I have been opening the tank each time I stop and I have not had the issue repeat itself. This may be coincidence but I hauled heavy loads of hay yesterday and she purred like a kitten the entire day - up mountains and had lots of power.

This may be completely unrelated. Any thoughts on why I have that issue - is it just a matter of a bad cap? The truck has a 12' deck on it so the filler tube had been very slightly moved to a bit further back -but using the same hose.
Thanks- Derrick

 

A vacuum locked tank will definitely cause those symptoms. It's probably not a real good idea on a hay hauler, or if you drive gravel, but I would leave the cap a bit loose next time and see what happens. If it don't happen again, you've found the culprit. On my truck the cap is attached and in behind the filler door, so I wouldn't have to worry about loosing it. Not sure about your deck truck though.... Also, my truck always has a wee bit of vacuum whenever I remove the cap to fuel up, so I'd say a bit of vacuum is normal but if there's a lot......

 

The tank is vented by two means, the cap and a vent on top of the tank.
Only problem I heard coming from both vents plugged is a collapsed fuel tank and an impossible to remove fuel cap.
Wouldn't hurt to check it out but both vents are designed to hold 3 psi pressure and vacuum, just a little hiss when removing the cap is of no concern.