Hi all, I have a 1992 E150 VIN 1FDEE14N3MHB14774 with dual fuel tanks. The rear tank does not pass fuel. The switch tests fine. Since I dont have an electrical schematic for this vehicle, I dont pretend to understand the circuits to the tanks. Altho, I isolated the guage circuits at the switch and hence at the rear tank too. On the other circuit (valve or in-tank pump??) I get 13 volts when the engine is running and switched to the rear tank... Is there a pump inside the tanks on this year/model?? Is there multiple fuel pumps on this van?
Also, on this same van, it runs pretty good for about 20 miles and then when pushed fairly hard (65 mph) it starts misfiring as tho it isnt getting fuel. It also heats up to the high end of the temp guage. I feel like it is starving for fuel and heating as a result, however, it could be the other way around. I have had this problem to 3 different mechanics. they replaced egr, and some sensors. One told me the computer was the problem. I took the computer out and apart and YES there was corrosion on the PC board from salt water entering it... I installed a rebuilt computer. it seemed to run fine and now (200 miles later) is back to its old tricks... any ideas on this subject? maybe I am looking at ONE problem that manifests itself in 2 ways... any help would be appreciated..
Larry Brandon

 

megapicker here, have a f250 90 with simular problem.
rear pump no good, fuel filter on frame rail just ahead of rearwheel driver side
may need changing, air filter may need changing, you may need to check fuel pressure
and volume off pump, these are high pressure pumps guage needs to be capable of 100 psi, not sure of volum output, thats what i need to know right now.
none of codes reflect the problems we are experiencing. but, do the filter thing
you might get lucky, and they are reasonable . hope this helps

 

My van with dual tanks has one fuel pump per tank. Also, my van heated up according to the gauge. Turned out to be a defective guage. The trick is to verify you are actually overheating.

Like megapicker said, check that fuel filter.

 

OK, I just got back inside. The mechanics chkd fuel pump pressure and flow, also new filters (air & fuel). they said pump ok, but it always reminded me of starving for fuel... The rear tank was leaking so I took it down anyway. GUESS WHAT!!! Internal pump, seized tight... I disassembled it, as in ripped outer can apart, and found impeller (nylon) welded itself to housing. apparently this happened from running the pump with no fuel in tank... the fuel flows right thru the pump including the motor and therefore cools it too. It was getting dark so I quit for today and have to take the van back to my wife tomorrow running on just one tank since this one cant be fixed by me (too many holes after I sand blasted it)... I will probably find a junker tank for it this coming week or so. ANYWAY, I will be you dollars to donuts (probably not a good bet anymore) that the pump in the front tank is the same way. I would say this internal pump is simply a volume pump since it is very simply made without much to the impeller or housing. I think it must supply the initial volume to the high pressure pump up along the frame. (this is the pump everyone was checking and it tested ok) but I suspect it does not provide enough sucktion to move the fuel from the tank properly. Also on a 2 tank system, there is some type of valving that switches from tank to tank. It has 4 hoses coming into it and 2 hoses leaving. I would say that is 2-tank outlets + 2-tank returns on the input side and 1-tank supply to hi pressure pump + 1-return on the other side. I suspect this device NEEDS the internal pumps to force it to SWITCH FULLY TO that tank that is supposed to be providing fuel since there are no other connections, electrical or vacuum. Anyway, thx for your advice. I hope my predicament might indicate to you what to check also. I couldnt get to the wiring for the front tank but the rear tank I could get to nicely. Knowing what I know now, the ORANGE wire and the BLK wire directly next to it are the 12 volt feed for the internal pump. If you were to put 12 volts to them (orange = positive) with the connector disconnected and all systems off, you certainly should be able to hear this pump running inside the tank....
and you are correct too that I never got a code of any kind that indicates this kind of fault. Just goes to show, the computer can tell you a lot of things, but it cant tell you the fuel pump INSIDE a tank is malfunctioning.
Larry
thx again