Initially I thought I was having problems with the gas guage or the tank selector switch but it turns out that gas from the rear tank is flowing into the front tank. That explains why (regardless of which tank I'm running on) the gas guage for the front tank always shows it to be full until the rear tank is empty.
So, what do I need to do to determine what's causing this? The rig runs great -- no stalling or starting problems.
I've talked with a few folks about this and they say it may be the fuel selector valve. Some say it's one of the low pressure pumps in one of the tanks.
Can someone tell me how to go about determining what's causing this to happen so I can fix it?
It would have to be the valve. Your efi has a return fuel system. Besides switching the main fuel supply from one tank to another, it also has to switch the return lines also. Apparently it's not switching the return lines to the correct tank.
After relieving the pressure in the fuel line and turning out the four bolts on the rail (2 that hold the valve and two of the three remaining bolts to the cover plate), I then disconnected the three return lines and the line to the fuel pump that sits on rail.
The surprise came when I disconnected the two supply lines from the tanks. No pressure per se but still lots of gas running out of them. Pretty regular streams too...so much that after realizing it wasn't going to stop until the tanks empltied, I reconnected them to stop the flow.
Two questions about this....is this normal? Even though the tanks are full and the lines are lower than both tanks, should the in-tank pumps be letting gas to flow by them? BTW: there's no power going to the in-tank pumps as I've disconnected the negative terminatal at the battery. And there's no pressure in the tanks as I've loosened the gas caps. It seems like this is gravity fed. Should this be happening or is there something wrong with the two pumps?
Second question: If I proceed down the same path and replace the value, I think I've found the part at silverstatefordparts.com. P/n F1UZ9B263B for $144.87. Anyone done business with this company? The price is the best I can find for new FORD valve. I could of course install one of those generic GM units but that would require converting all six fuel lines. I don't think I want to do that...or is it easier than I think it is? (The only good news about that approach is that I would not have to mess around "converting" an electrical connector as the value I'm replacing is totally mechanical.)
I have the same valve in my 1986 and you can't get it at the regular parts stores--it was only used on a few trucks. I had to pay $225 to a Ford dealer and wait for it to be shipped. However, I recently got the new LMC catalog and they have one for $114.95, part # 40-1986--it's at the bottom of page 111 of their current print catalog. They are at Truck Parts and Truck Accessories for Chevy, GMC, Ford and Dodge Trucks from LMCTruck.com or 1-800-LMC-Truck.
I've had the same fuel draining problem you had with the lines disconnected. Also be forewarned, the fuel filter is in the bottom of this and the o-ring that seals it is a pain to get in place so that it doesn't leak. A new one should have a filter in place, but if you have to replace it, it won't be fun. The o-ring never seems to be the right size. Heating (such as holding between you hands) or cooling the o-ring can help.
If the lines are rubber and not plastic, vise grips can be handy in stopping the flow of fuel. If they are plastic, take the line off and then fold the line back on top of itself and then wrap some tape around it to keep it folded, and that will usually stop the flow till you are done installing the new valve.
Thanks for the info on the part from LMC -- that looks like the part -- I'll chat with them Tuesday.
Also good to hear that it's not uncommon for the supply lines to be passing fuel when they're unattached from the valve. Not too excited about dropping the tanks to replace the low pressure pumps.
I sure would like to know how to plug those lines temporarily so I can pull the valve to take a look inside. It might be something pretty easy to fix (and save me some bucks in the meantime). I wish I had kept that old inline fuel filter I changed a few months ago...would have hooked a supply line to either side of the old filter...that may have worked.
And about the filter inside the lower portion of the value being a problem child....ran into that a few months ago when I replaced that fuel filter too. Hopefully the new valve comes with a filter already installed.
It looks like mine. It has 4 inlets and 2 outlets. I don't think there were many variations of this part--just the single and dual tank variation. I'd say you found the right one relatively cheap, but I have had no dealings with that company so I can't attest to quality.
I spoke with my local ford dealer and he said that the f1uz-9b263b is the three port while the p/n for the 6 port appears to be e5tz-0189b.
Does that sound correct?-------------------------------------------------------------------------------------------------------------------------------------------------------9
Almost, I think you posted a typo....
E5TZ-9189-B VALVE & SOLENOID ASY Marked E57B 97271-BA or E67B 9F271-AA Contains 6 ports for dual fuel line system; Fits numerous vehicles including 85/86 F150/350 all 6 & 8 cyl I believe over 8500# GVW
Ed Olson www.partsguyed.com can get this, MSRP $290.77 Ed's price $209.35
F1UZ-9B263-B replaces F1UZ-9B263-A KIT-FUEL SYSTEM SERV Marked F1UA 9B263-AA Frame mounted, does not contain filter; Fits 88/89 F150/350 w/EFI dual tanks, 87/89 F150/350 & F(SuperDuty) with dual tanks - all engines
MSRP $273.29 Ed will sell you this for $147.58