1990 7.3 Fuel filters keep needing changed ever 20 miles

[zukgod]

The last few months my truck is going through filters every 20-50 miles. I can't drive the truck for fear of it dying and needing to install a new filter on the side of the highway. I've pulled fuel out of the tank and it looks clear, and I've drained the filters into a clear glass and it doesn't look dirty either. I can't figure out what's going on, but I'll be driving along and the filter light comes on and I have a couple miles before the truck will die and need the filter changed. It does this on both tanks, not sure if I should drain both tanks which are full and put in new fuel. I did fill both tanks at the same gas station, so I could have gotten bad fuel. I've run fuel cleaner through it to see if that helps, but it is still doing it. I've gone through 5 filters in the last month and less than 50 miles. I don't drive the truck much because it's my farm truck, but I do need it now for the summer months.

If I do drain all the fuel out of both tanks, what could it be used for? That's a waste of a lot of fuel, but if it fixed the truck I'll deal with it. I really just need some idea's on how to fix this soon, because we're moving out of state and I have to drive the truck 400 miles and can't be breaking down on the highway pulling my trailer full of animals. Thanks for the help everyone.

The truck is a 1990 7.3 IDI non turbo 5pd 4x4 truck.

 

[Thewespaul]

Put a clear cheap inline filter in the soft line just before the lift pump, this will catch any large debris if that is your issue, more than likely you have a tank pressurizing issue, a lift pump issue or just rust in the tanks. Cut the next filter apart and see if its actually clogged in the pleats.

 

[zukgod]

Ok I'll try that, and thank you very much. I have looked pretty close at all the filters I've pulled out and they looked clean. I also notice when I'm pushing the truck kind of harder it seems to want to eat the filters fast, or maybe like you say it's not getting enough lift from the lift pump? If I need to replace the lift pump should I just use a stock one or go with something better?

 

[Thewespaul]

Stock one is fine, many convert to an electric lift pump for easier priming.

 

[IDIBRONCO]

The "better" part seems to be in debate. A lot of people have switched to electric pumps. Some have issues while others seem to have no trouble at all. as for me, I'm sticking with thee stock style mechanical lift pump.

 

[steve phillips]

Are you buying your fuel from the same place? I know this sounds hard to believe, before I retired in 2010 I bought fuel for my co truck from same small convience store.Their fuel had black tar looking particles suspended in it .Stopped up fuel filter on a 6.0 liter 550 in 1 week. Lots of bad fuel and dirty tanks out there. Another thought fuel fill neck and flexible hose going to tank. I have seen these loose or broken and cause a lot of head scratching. Hope this helps, Steve

 

[chillman88]

I had a partially stuck tank selector valve causing a similar problem. I would try the lift pump first, but something to look at if you get to pulling your hair out.

 

[Shadetreemechanic]

I had a partially stuck tank selector valve causing a similar problem. I would try the lift pump first, but something to look at if you get to pulling your hair out.

I have had a lift pump give your symptoms, but also the half stuck selector valve. That one was harder to figure out.
If you suspect that, try tapping it with a hammer while someone else switches it back and forth. Sometimes they get junk in them that jams them up,
If it is the lift pump, eventually it will get worse and will be easy to diagnose.

 

[zukgod]

I have been getting fuel from the same small gas station, so there is a chance that the fuel is indeed the problem. As for the tank selector switch I don't think that's the problem because it started giving me the filter problems without me ever switching the tanks. In fact I hardly ever switch tanks, but just keep the second tank full in case I don't have time to get fuel. I only switched the tanks to see if the problem would change, but it continued to give the same problems on both tanks, but both tanks have been filled at the same station.
When I purchased the truck 10 years ago the person that owned it had been running bio diesel, and I had to change the filter a few times due to it clogging up, but after a couple filter changes it didn't due it again until just recently. This truck has been dead reliable with the exception of this new issue. I am now starting to get a bit of blue smoke all the time, so my valve guide seals may be getting tired, but I don't think that would do anything to the filter.
How would I go about testing the lift pump? Or should I just switch it out? Thank you everyone for trying to help out with this, I really do appreciate it.

 

[YJMike92]

A fuel pressure gauge before the filter would tell you something about the lift pump pressure. You could also try a fuel volume test. There should be a specification for that somewhere.

 

[austin92]

What is it doing when you decide to change the filter? Bucking, dying, filter light? You could try running the feed and return lines in a 5gal can and see if it stops.


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[zukgod]

The filter light comes on, and then in a couple of minutes it starts bucking and then dies, and won't restart until I change the filter out. So do you mean to bypass the filter with the feed and return lines? I guess that would tell me if it's indeed the filter correct? If it ran fine when doing the lines into a loop without the filter, then it should mean it's the filter?

 

[steve phillips]

Another thought, is your filter full of fuel when your truck quits? The other fellow is telling you to connect suction side of lift pump into 5 gallon bucket, and dump return fuel into same bucket. This will elimintate tank,pump and FSV. Have you ever changed the olives in your truck. Just thinking out loud here if you have had hard fuel lines loose, you may now have an air leak also. If you have old filters cut them open and see if you truly have a dirt problem. If your still using filter with drain bowl, check to make sure fuel isn t leaking from drain. I hope this helps, Steve

 

[zukgod]

Steve,
Ok that makes sense I'll give that a shot, thanks for the explanation. I'm not sure what the olives are, but I haven't had any fuel lines loose on the truck in a couple of years. The only time I had any fuel lines loose was when I changed out the little O rings because I had a bit of a leak on the plastic caps, but it ran fine after doing that and bleeding the system. I'm still using the filter with the drain bowl on the bottom, but don't seem to have any leaks on the drain or anyplace else that I can see.

This place is very helpful, and I can't say I've ever met a group of people so helpful and it's truly appreciated. Hopefully one day I will be able to pay it forward here, but that would assume I actually knew what I was talking about lol. Thanks again everyone.

Zuk

 

[austin92]

It definitely sounds like air intrusion, not a clogged filter. Do you have any fuel leaks at all? What he meant by olives is the 2 o rings on each injector that seal the return lines. If they’re old and dry, they leak fuel when pressurized and suck air when the engine is off. Usually causes hard starts not so much bucking while driving. The filter light coming on means it’s pulling a vacuum at the filter head so I’m thinking lift pump or blockage at the fsv, lines, or shower head. Does your oil smell like diesel fuel or raise on the dipstick? If it doesn’t, the test with the external fuel jug could help narrow it down for us.


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