Rug_Trucker

Did you change the O-rings in the pick up? Pick up and return lines are different sizes.

edwinsmith

I replaced both the angle fittings on the top of the tank. They both had new o-rings. Is this what you mean? Yes the supply is 3/8 and the return is 5/16.

When I had the assembly out of the tank I found trash on the pickup screen which I cleaned off. Everything else looked OK but I didn't want to monkey with it to much because old plastic stuff gets fragile.

Edwin

Rug_Trucker

There is an O ring in the tank on mine. You have a 89 so I have no idea what yours looks like. My fittings on the top of the tank are plastic. I replaced the O rings there too. Still losing prime.

edwinsmith

Today I pulled the fuel pickup assembly out of the tank and I replaced the rubber hose running from the pickup screen to the top of the assembly. I found no cracks or holes in the existing hose but I replaced it anyway. I'll have to wait until my tank gets lower to see if it fixed the problem. I doubt it will fix it so my next fix is to replace the entire fuel line from the top of the tank to the engine.

Edwin

Rug_Trucker

Ever think about pressurizing the tank with 10lbs of air and look for leaks?

oliver foster

I recommended he pressurize his tank a year or two ago when he started having this problem.
IIRC he tried it and didn't find a wet spot at any connections.


I would NOT use that much PSI though. Bursting a pretty full fuel tank would be REALLY messy.
1, maybe 2 PSI should be plenty. He is trying to find a pin hole leak, not split the tank wide open.

10 PSI [Per Square INCH], over a surface area that large, on a plastic 30 year old tank would scare me.
I only run 7-8 PSI in my 39 inch Super Swampers tires on my '72 PowerWagon when wheelin' and that is not a very light rig.

edwinsmith

I did that. I used less than 10 psi because I didn't want to push the seal out of the VE again. I had a fuel pump putting out 35 psi plus did that on the riverside freeway. A poor motorcyclist with fuel oil mixture had to let me know about that. After replacing the seal and installing the proper fuel pump the troubles started. IMHO the tank should withstand 10 psi and a lot more but don't try it on my say so. I set the regulator to 10 psi on my compressor and hooked it up. IDK how accurate the little gauge on the compressor is down that low. Could be +/- 5 psi. Most of the air came out of the vent on top of the tank anyway.

Stay tuned.

Edwin

oliver foster

Ed....

I thought we where talking about putting a little air PSI into the fuel tank though the filler neck to look for leaks in the fuel lines and system in general.

Not FUEL pressure PSI into the injection pump from a Lift Pump.

I think we are now talking about separate issues.

edwinsmith

No. I would think the pressure in the tank would go right through the piston pump and into the VE and push the seal out. If I am wrong please correct me. The valves are one way check valves in the lift pumps are they not?

Yes. I put pressure through a fuel cap which I put a quick air connector in to the tank.

Edwin

oliver foster

I doubt adding a little air pressure to the fuel tank gets much fuel pressure all the way up through the injection pump. I would assume a closed FSS would stop fuel pressure from going through it and therefore making much fuel pressure on the front VE seal.

If you do split a fuel tank wide open with 10-15 PSI, rest assured I have a spare OEM one.

If it was me I would use 1 PSI, as you are trying to find a small leak, not make a large one.

edwinsmith

I forgot about the FSS being closed. Anyway. I had no problems tank wise But again I didn't put a decent gauge on it to see what the actual pressure was. I just barely cracked the regulator on the compressor until the gauge started to move. The face of the gauge is about 1 inch across and goes up to 200 psi. I'm sure you've seen the type and my eyesight isn't as good as it once was.

edwinsmith

A few days back I replaced the entire fuel line from the tank to the lift pump with a 3/8 inch rubber diesel rated hose. I had to wait until I had used enough fuel to get down to 3/8 of a tank. The truck starts fine and I consider it fixed.

We are heading out tomorrow morning on our trip out of Commiefornia to Okiehoma. I'll post back when we're set up at our new residence.

Edwin

edwinsmith

Not Fixed!

Stopped in Kingman AZ for overnight. Got fuel and after fueling the truck spun for a minute until it finally got going on enough cylinders to run on it's own.

I'm at my wits end. Just have to stop more often for fuel (and to pee).

KRB

Bummer.

So what's left? What's not new or upgraded??? I didn't go back and reread yet but what about from the IP to the lift?

And I remember the day I used to plan peeing & eating around a fuel stop too. Now I plan fueling and eating around pee stops...

Rug_Trucker

Wish I had an answer for you.