edwinsmith

Here's the thread you need.

https://www.dieseltruckresource.com/...-lines-235374/

I tried that because I have the same problem but there is a vent in my 89 tank pickup assembly which negates the idea. NJTman found his problem was an o-ring in the fuel pickup allowing air to get in the line.

Rug_Trucker

I dropped the tank 2 years ago. No algae in the 6 or 7 year old fuel. Pumped all of the fuel out of it. Replaced the O-rings. Ran brand new flexible fuel lines to the lift pump, and the return rated for biodiesel. Still have the same problem.

Don't have the heater plate. The previous owner evidently deleted it. It will probably be next Saturday before I can do this as it is wet and nasty today. I'm really tired of paying insurance, and tag renewal on it and it not running right. I can barely get it to run 55mph. Filter is fine. Lift pump hasn't got any use on it. I changed the fuel pin last summer to a THD, and did the 3200 spring. I know that wouldn't help it.


You never figured out your problem did you?

NJTman

I'll bet you dollars to donuts You're losing prime in the reservoir, and you'll never see this with the air pressure test, as it's inside the tank.

It took me a decade to figure this out. I was tired of breaking down on the side of the road, which is why I continued to press forwards. 30 year old O-rings are the issue. Answered on the last page.

I've posted my results here. air entering fuel system

NJTman

Sorry, I missed this post. You replaced ALL O-rings ????

or just ones you can see without disassembling the reservoir completely ?

NJTman

Today, I ordered a new bottom quarter panel to repair my good fender's hole. Couldn't find anyone who had one used, nor locally in the boneyards, as all these trucks are gone. I heard some dude up in VT is buying them all up.

Sherman Parts SHE326-36R Sherman Fender Patches | Summit Racing

Post photos when I do the repair.

Rug_Trucker

Completely tore it down. New Viton O-rings. Bought a box of various sixes from Harbor Freight. They should have been right.

I was wondering about getting a gasoline fuel pump assembly and trying to use it. It would have to be regulated way down if at all. Found this today. It's a pump for our 1st gens. $870 fwiggen wiggen bucks! https://puredieselpower.com/new-arri...e-pf-cumm-9198


They have a non pump model https://puredieselpower.com/new-arri...e-pf-cumm-9198

Rug_Trucker

the pump

edwinsmith

Sounds like a pricey fix for this problem.

I haven't been driving my truck much since cold weather set in. I keep dreaming about all the stuff that needs fixing. This problem is #2 on the list after installing the D.E exhaust.

TMan: My pickup assembly is an 89 and looks different than yours. I replaced the swirley line (what the heck is it for?) last time I was into it at the same time I replaced the entire line to the lift pump. I had it all apart and stripped one of the screw into the plastic at the top which I plan to fix next time. That may be the cause. There aren't o-rings inside nor are there the quick connect to the pickup line. I did find the filter sock on the pickup was clogged with crap which I cleaned but it made no difference.

I did find a couple of flat rubber washers that appeared to be used as gaskets for the lines but they appeared to be OK. Next time those will be dealt with.

Oliver: Will a newer pickup assembly work with the 89 tank? If so I may need to buy one from you.

Edwin

oliver foster

The '91-'93 "sending unit" in the tank will not even attach to the '89-'90 fuel tank as one screws in and the other clamps on..
So no those will not interchange.

NJTman

Well, that sucks. I'm sorry to hear that. My issue, which was periodic sitting on the side of the road, was caused by the orings in the squirrley line that ran from the pickup up to the bottom of the reservoir top. They were toast. I've run this thing down about a dozen times, and it's as if I never had the issue to begin with. The truck would pretty much die if I was below 1/2 tank, and driving on the highway, which is why I kept it filled constantly to avoid being pizzed off.

Looks expensive, but I guess you gotta do what you gotta do.

NJTman

Could he not buy an entire tank assembly ?

thrashingcows

Sure could...would be cheaper than that after market fuel tank sending unit kit.

Rug_Trucker

My mad scientist friend and I got on Rock Auto. The thing I posted above Is pertnear $900. Look at all the models it fits. It fits a '98. We found one on RA that is a factory unit that may fit off the '98 models. Less than $200. We can't be the first to look into this.

edwinsmith

Good suggestion but I'm waiting on warmer weather to get back to working on it. Right now we're waiting for it to start snowing here in NEO. Looks like it may snow for 24 hours. I hope we don't get more than a couple inches and they clear it quickly. Tman, you could drive down and help now that you got your fuel issue fixed. I'd be glad to buy you a cup.

Rug_Trucker

I wonder if the '89 gassers have the same sized tanks? Might end up with an electric pump. My '79 Maxivan has a 36.

My Cummins fuel tank has a vent that will have to be plugged for the test.