1988 E150 Conversion Fuel Pressure Issues
 

I have a 1988 E150 (with a 302 EFI V8) that has been a thorn in my side for several months, now. It's sound except for what I believe to be a fuel system problem.

When the engine actually gets fuel, it turns over and runs (briefly). Unfortunately, it doesn't appear that fuel is getting there on a consistent basis.

I popped a fuel pressure gauge on the rail and and get 0 PSI after full pressure release and ignition off (as it should be). When I key the ignition on, I get a consistent 10 PSI (and it stays that way after cranking, removing the key, etc.

As stated, the truck is a conversion, and it has dual tanks. I believe the symptoms above are the same regardless of which tank is selected. That tells me that both of the in-tank pumps are functioning.

Here's the questions:
- What pressure do the in-tank pumps provide and what does the inline (on the driver's-side chassis rail next to the fuel filter) pump provide. The aggregate is supposed to be 30-45 PSI but I don't know how that breaks down with the multi-pump setup.

- If the issue is the inline pump, how can I verify that it's getting power (i.e. bad pump relay... where is it)?

- I purchased a new pressure regulator, since they're cheap, but how can I tell if the old one is bad or not. I wouldn't mind saving the 20 bucks if a replacement isn't needed.

Thanks.
Dan

87-91 or even 92's use a low pressure sysytem.. max output is somewhere around 35 - 40 psi
The tank pumps are LOW pressure @ 8-10 psi.

If you have dual tanks I am going to say with very good probability that the manual tank selector valve is bad. This is VERY common on 87 - 91 vans & trucks with dual tanks. my 91 351 dual tank did the same thing run for a few seconds and go dead.

I totally disconnected & bipassed my front tank and have had no problems since. The selector valve is only available through FORD, my cost was over $110.00

Oddly, though, I'm getting a constant 10PSI when the system has power, which would lead me to believe that the low-pressure pumps (or at least one of them) is getting fuel through.

I've thought about bypassing the tank multiplexer thing, but the ford lines have those little proprietary plastic clamp on them, and I don't have female-female adapter.

That seems like a lot of work to do, though, if nothing's wrong with it. I'd like to eliminate the pressure regulator and relay as problems. (oh, and I already replaced the TFI module). The relay is under the passenger kick-panel, yes? Any distinguishing marks, or do I need to trace the wires down to the fuel pump.

Also, silly question, but do all three pumps get power from that relay? If so, then I might not need to test it. If at least one of the pumps actuates correctly, then the relay is probably fine (assuming they share it).

Dan

OK, This is what happened to me... First my front tank started to overflow during warm weather after a fillup (both tanks) on a trip while running off of the rear tank. What was and is happening is that the selector valve is malfunctioning,

Some months later i drove about 3 miles, turned the engine off. restarted the engine and started down the road, i had went less than 1/2 a mile when the engine started acting like it was running out of gas...... It finally died, i restarted it and put it in gear, started rolling , before i could get up to speed it started missing again, went dead... well, it did this for the next 2 1/2 miles..... when i finally got home where i could work on it, it would start and run for only a few secounds.... I replaced ALL 3 pumps!!! x( the TFI, and the engine temp sensor... nothing worked, UNTIL, i removed the tank selector valve and completly bipassed the front tank. :-X22

take a small saw and cut the fittings off the tank selector valve and use regular gas line and 4 clamps and connect the fuel lines. Connect only the rear tank, and see what happens.

Other than this you will have to buy the manual selector valve from FORD. Oo.

I too had the "one tank filling from the other tank" problem with the valve. I found the selector valve unit had a damaged o-ring and it kept the valve from switching. it was repairable after I found a source for the oring. Ford offered only the bottom half back then and it was only about $60. I would not be surprised if you had to buy the whole thing now.

I got the impression that the valve was completely mechanical, no electrical wiring. It relied on the fuel pressure to cause the switch between sources. the toggle switch only changes the pumps on/off.

and I now have a dead front tank pump. I'll be back in there again and I'll double check it.

You're right about the valve being completely mechanical. That's the reason for the low-presure in-tank pumps (to provide a pressure source for the mechanical valves).

My issue is that there are still a couple things that 'could' be the problem. I'd like to try BlueMule's idea about simply bypassing the valve as a test (since I know that at least one if the tanks is full), but I don't want to have to cut/destroy any expensive parts to troubleshoot if it turns out to be something else.

I know that the plastic "coupling" systems that ford uses on these vans is somewhat modular. Anyone know of where I might find an adapter to try out the bypass idea without having to cut anything?

Dan

OH, Here is what to do, take the 2 lines off of the front tank, and take a short peice of hose and run the small return line fitting back to the main supply line fittingon the selector valve.

I just took the cup off the bottom of my valve. Don't.

the oring I found sealing the cup is too big for the surface, so it doesn't sit flat. it has a "hump" in it when you reinstall it. I had to use black rtv to make a seal when I put the cup back on.

However, I also found a small oring in the bottom of the selector valve cup. same as the last time when it screwed up. Looks like maybe I only need a new selector valve, or maybe try again to fix this one. I think I'll remove it and see what'sup inside. If like the last time, the valve body is hung up, blocking the front tank fuel, and the oring is the cause.

OK. pictures and theory on how the valve works are here.
http://www.stangler.com/motorsports/...alve/index.htm

to test, just unplug your rear fuel tanks lines from the valve, and switch the ignition switch to on. fuel will pump from the tank to the ground.

Both my pumps work. My valve was broke. My front tank return line and feed lines are blocked internally inside the valve body. I forced the valves and heard something snap, then they finally moved. Looks like I'll be buying a new valve as I couldn't repair this one. but I did disassemble it for an autopsy

Selector valve assy, p/n F1UZ-9B263-B $ 77.99 plus shipping from www.fordpartsnetwork.com for my 89 E-150

Thanks 5.0 for the info... I AM sure it will help other Ford efi truck & Van owners.

Thanks from me, too! Mine ain't broke yet, but I'm saving this thread for when it does.

1991 E 150 problems
 

After reading some of the posts, you guys (and gals) seem to know the score.

So I will try and describe the problems i'm having and see what i can find out.

My van is a 1991 E 150 with i believe a 302, i have no idea what tranny, and it has dual tanks. 60,000 origional, i just bought it from the neighbor.

problem 1. fuel guag doesnt work in either position most of the time, but sometimes, yes sometimes it shows a quantity, and it only seems to feed off the rear tank, i cannot hear the intank fuel pumps running with the key in the run position. It hesitates pretty bad from a stop but seems ok at speed.


problem 2. the tranny doesnt seem to want to shift to 2nd or 3rd gear without lifting off the accelerator first, and then it will only stay in 3rd if im doing like 45. forget cruising the neighborhood at 25, it wants to shift from 2nd to 1st and back constantly

also, when i put it in reverse, it kills the motor unless i really gas it, which is a problem when trying to finesse it into my small driveway.

where can i start checking? fuel filter is new.


thanks for any help you can give this new e150 owner

Transmissions I take to a shop. No help here.

does it have the switch for the dual tanks? is the gauge inop in either position? will it run off either tank?

Put a gauge on the fuel rail. It should be about 45 pounds of pressure.

Might also check the regular maintenance items (plugs, air filter, wires, etc)

Siginificant Progress
 

So, after some helpful advice from my local NAPA, I pulled the supply/return hoses from the dual-tank valve and stuck them into a portable gas can. Sure enough, after cranking a few turns, the van started up. PSI at the rail was ~37

I dropped the rear tank (since it had much less fuel in it) and took it to my local radiator shop for cleaning. The sock filter in there was a nice shade of yellow (about the color of laquer).

I'd like to bypass the combo-tank valve and just run the rear-tank once I get it back, at least till I have time to drop the center tank and clean it. I don't want to troubleshoot the multi-tank valve till I know both tanks are clean (no use re-doing things).

Any suggestions on connecting the female hose-with-clip fittings together that will hold pressure for running the van around town, but which I can easily take out later? It would need to basically be a male-male extension whose ends look like the male ends of the major fuel system components?

Dan