Fuel Supply Problem - Please Help

[AzAtti2d]

I have a 96 F250, 2WD that I am having fuel issues with. I might be able to work through this myself if I could find a diagram of the fuel line system somewhere... what lines go where, etc. Maybe you will be able to give me some ideas to keep me from lighting a match under this thing. When I purchased the truck a couple years ago, it had a homegrown veggie oil system installed on it. Basically the front tank was preheated and then the fuel(oil) was routed through a heat exchanger, elec. fuel pump, an add on oil filter and then back into the original system just behind the switching valve. When it worked it was wonderful. When it didn't it was pure frustration. So I removed all of the in-line stuff and just ran diesel in both tanks. I don't know if this has anything to do with my problem, but thought I should include that info up front. So here is my problem... It started as a fuel filter issue. Fuel Filter light would illuminate, and about 3 miles later I'm dead on the side of the road. Replace the filter, drive for anywhere from 10 - 50 miles and repeat. When I take the filter out, the bowl would be empty and the filter would appear brand new, no sign of anything to clog it. I would change it anyway. So I drain both tanks, and then use fresh fuel. Now I no longer get the fuel filter light, or any other warning, it just loses power and dies, although occasionally when it is barely hanging on it will all of a sudden pick back up like it just got some good fuel and then quickly revert back to barely running again. When it finally dies, the only way to get it running again is to fill the filter bowl up with fuel and then start it. But it wont last long... maybe 5-8 minutes idling. When I open the filter housing, the bowl will be nearly full with the level just below the opening into the pressure regulator. I pulled the regulator yesterday and the screens were really gummed up so I cleaned it all out. still have the same issue. Also when I top off the fuel bowl and start it, the pressure at the schrader valve fitting reads about 20 In. Hg.(I know, but it was the only guage I had handy) which I'm not sure how that converts to PSI but I know it is a decent amount of pressure. After the truck idles for about 1 minute that pressure begins dropping to about 5 in/hg. a minute later and its at 1/2" hg and soon starts running rough and dies. I've even tried dropping the fuel line into a jerry can of clean fuel, tapped in where it goes into the switching valve, no difference. Not sure about the switching valve, but i can hear it "click" like it is switching when i flip the tank1/tank2 switch. Any ideas? I'm beginning to think it might make for good target practice on my next trip to the desert...lo l

[14psd]

Azatti2d welcome to fte. Let me get this strait. You removed all of the veggie oil stuff, correct? Now you are back to all stock correct? Have you checked ALL of the lines that the veggie oil ran threw? That stuff will break down the rubber lines. Ask me how I know. I had to replace ALL of the rubber lines on my truck cuz I didn't switch them over to other kind of line. I forgot the name of the line. Anyway I blew a high pressure line and two of my small rubber lines failed. That's my 0.02. I hope that helps some.

[Cuda_jim]

Fuel pump is going bad.
BTW: 20 in. hg = 10 psi
You need 50 psi for it to run.

[14psd]

Originally Posted by Cuda_jim

Fuel pump is going bad.
BTW: 20 in. hg = 10 psi

thanks jim for that info I did not know that.

[AzAtti2d]

I'm really hoping that the fuel pump going bad is not the case... I thought that mechanical pumps either work or they don't, but that they usually don't exhibit a "going bad" behavior. It wouldn't really surprise me though, as I replaced it about a year ago with a "life time warranty" pump from checker auto. Wouldn't be the first time those rebuilt suckers were garbage. It is just such a MF to replace... God I hate my life sometimes.

Can anyone tell me about the fuel routing on these trucks... from the tank through the system and back to the tank? Also anyone know about the fuel bowl elimination kits?

[rodneywar]

get a new carter pump i just put one in It blew a hole in my bowl. My bowl had a weak spot from corrosion I put in a new one from ford the whole bowl assembly including everything for the bowl cost me 275. they originally quoted me 560. woot woot

[pjwoolw]

Here is a link to a pdf file that has a pretty good explanation.

Going to an electric system would be the the best thing to do but is costly. Dieselsite and Beans have kits. Or a DIY system.

If not you may need a new bowl and FPR if yours isn't rebuildable. Plus a new pump.

The latter is cheaper but you can look forward to doing it again down the road. But if you use good quality o rings and change filters regularly it may last quite a while. But if the pump is getting junk through it from the tanks it will likely fail fairly quickly.

SAE 30r9 is the rubber hose to use.

A good kit can be found here to replace the stock pump and good o rings for the bowl and FPR.

Good luck to you and welcome to the forum!

[Cuda_jim]

Originally Posted by AzAtti2d

I'm really hoping that the fuel pump going bad is not the case... I thought that mechanical pumps either work or they don't, but that they usually don't exhibit a "going bad" behavior. It wouldn't really surprise me though, as I replaced it about a year ago with a "life time warranty" pump from checker auto. Wouldn't be the first time those rebuilt suckers were garbage. It is just such a MF to replace... God I hate my life sometimes.

Can anyone tell me about the fuel routing on these trucks... from the tank through the system and back to the tank? Also anyone know about the fuel bowl elimination kits?

The FP is a 2 stage pump. It sucks fuel from the tank(s) then pressurizes it for the injectors (60-80 psi).
Before you replace it be sure it can draw fuel through the lines. As Todd (14psd) already stated, the WVO system
might have damaged any of the rubber lines involved in the system.

Here's a fuel flow diagram:
.
.
.

[AzAtti2d]

Thanks alot for the help... especially the links and diagram... exactly what I needed(well, short of a free mechanic that is... anyone?... lol). If I'm not too giddy with excitement when I figure this out, I'll try to remember to let you all know what the results are. Thanks again!

[helifixer]

Originally Posted by AzAtti2d

Thanks alot for the help... especially the links and diagram... exactly what I needed(well, short of a free mechanic that is... anyone?... lol). If I'm not too giddy with excitement when I figure this out, I'll try to remember to let you all know what the results are. Thanks again!

Where in Arizona are you?
if Northern Az I have a shop, if in the Valley I know a good one down there. keep us updated and if need be I can help hook you up locally.
on a side note drop by the Arizona chapter and say hi to the locos! uh I meant locals

[AzAtti2d]

I'm in the Valley of the Slum... lol... but I do appreciate the offer. That is very kind of you. I go north fairly often though, draggin the ol' 5th wheel camper up the mtn so you never know, I might run into you(figuratively speaking, of course) sometime.

It appears that the mystery has been solved. It was indeed the supply line from the tank. All of the fuel lines were in really bad shape from the WVO, so I replaced them and cleaned everything out, and it seems to be running pretty good. I'll take it out for a lengthy trial run tomorrow when there is daylight... just in case. What kinda gets my goat is that when I called the "friend" that I bought the truck from and mentioned the info about the WVO destroying the factory lines, his response was that he had heard that too but doesn't believe it to be true... "HELLO? Is there anyone home?"... sure would have been nice if he had passed that info on sooner... "Thanks, Buddy!"

So thank you to everyone again, and I will stop in here later tomorrow and let you know how my test drive went. Wish me luck!

[kawa]

I've been studying the fuel system diagram posted above and for the life of me.....where is the "Fuel Strainer" located? Is this in reference to a "Sock" on the fuel pick up stand pipe inside the fuel tank (s)?

Rog

[95_Dually]

I thought the FPR was ahead of the injectors. The diagram shows it after the injectors. I guess I am stuck in the carburetor days, LOL.

[AzAtti2d]

Yep... that's my guess... thats the only possible explanation I could come up with

[95_Dually]

Thank you for the diagram Jim. REPS SENT!