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Car Forum / Ford / Ford Trucks / December 2008fuel delivery problems with 1990 F-250, 5.8 L engine, dual tanks & Fuel Delivery module
Had a problem with my F-250. The rear tank rusted out. I tried to siphon the fuel out of the rear tank and run off the front tank, but the front tank fuel pump didn't seem to work. But the truck ran fine off the rear tank when the tank switch was set to "Rear", and the engine almost died when set to "Front" - I couldn't hear the front pump whir at all when I turned the key when the switch was set at "front" but could hear it whir when set to "rear". So I pulled the rear tank out, took out the fuel pump, tagged the lines, and bagged the pump till I could put a new tank in. That took a while due to some family health issues, and when I put it back in, I added almost 5 gallons of fuel and the truck started right up. It ran for a bit last night, and then this morning it was hard if not impossible to start. It felt like it was out of gas. So I added more from a gas can, and it finally started up. I went into the house to get my wallet (to take the truck up to a gas station to fill it up) and when I got outside it stalled again and won't catch. I wondered if there is a problem with the dual tank selector switch, and I checked to see if there was a some sort of regulator or in line valving, but there is none. It is possible that I got the fuel lines reversed when hooking up the tank? The truck ran good for a while, but felt like it ran out of gas. When I added a bit more, it ran OK but ran for a much shorter time. If I reversed the fuel lines at the fuel pump on the rear tank, could this allow the truck to run until it pumped fuel through the fuel injector rail and then into the front tank? Could the truck run without the front pump working at all? There is no three or six-way valving, so I assume that each tank has a Fuel Delivery Module in it. So do both fuel pumps need to work in order to run the vehicle, or did something happen to just the rear pump which isn't running even though it is whirring when I turn the key but don't start the vehicle? > Had a problem with my F-250. The rear tank rusted out. I tried to siphon > the fuel out of the rear tank and run off the front tank, but the front [quoted text clipped - 28 lines] > something happen to just the rear pump which isn't running even though it > is whirring when I turn the key but don't start the vehicle? if the rear tank has been emptied into the front tank it is possible the front pump is bad and leaking through the pump into the tank. >> Had a problem with my F-250. The rear tank rusted out. I tried to siphon >> the fuel out of the rear tank and run off the front tank, but the front [quoted text clipped - 31 lines] > if the rear tank has been emptied into the front tank it is possible the > front pump is bad and leaking through the pump into the tank. The front pump doesn't work at all - there is no whirring noise when the switch is set to "front". So I take it that there is some electrically-operated valve in the fuel pump that shuts off when there is no power applied to the pump, and that keeps fuel moving out of and back into the fuel pump that is working? So if the rear tank pump is working properly, but the front fuel pump is corroded and/or not working, the fuel will take the path of least resistance and go into the front tank? > >> Had a problem with my F-250. The rear tank rusted out. I tried to siphon > >> the fuel out of the rear tank and run off the front tank, but the front [quoted text clipped - 40 lines] > working, the fuel will take the path of least resistance and go into the > front tank? I think that is what Mike K. is suggesting. Perhaps if you seal off the unused pump/fuel line that would prevent it from going where you don't want it to go. The first thing I think I would do in your situation is to check the fuel pressure at the rail. It should probably be above 30 psi if I remember correctly. Another thing I would do is to check the fuel pump relay which is probably in a large fuse box under the hood. On Explorers there is another relay that can be switched temporaily to test the relay. By switch I mean remove the two relays and put them in each other's place. You didn't mention anything about checking/replacing the fuel filter (or I missed what you said) so with a rusty tank I would think that would be a high priority. >>>> Had a problem with my F-250. The rear tank rusted out. I tried to > siphon [quoted text clipped - 60 lines] > unused pump/fuel line that would prevent it from going where you don't want > it to go. Not quite sure how to do that - I would need some way to remove the two "Y" connectors and replace them with two connectors that remove the front tank from the loop. > The first thing I think I would do in your situation is to check the fuel > pressure at the rail. It should probably be above 30 psi if I remember > correctly. The pump is pumping fuel down the fuel inlet line into the new fuel filter (which I still don't see what that has to do with pumping fuel into the front tank from the rear) - it's just not returning to the rear tank. SO I fail to understand what fuel pressure has to do with anything. > Another thing I would do is to check the fuel pump relay which is probably > in a large fuse box under the hood. On Explorers there is another relay > that can be switched temporaily to test the relay. By switch I mean remove > the two relays and put them in each other's place. This is a 1990 truck and according to the wiring diagrams for the 1990 F-250, there is only one fuel pump relay and the power from that goes to the Intertial Switch, then from there to the Fuel tank Select Switch, then to the tanks. There is no whirring noise when the switch is set to the front tank, but there is a whirring noise when the switch is set to the rear tank. There appears to be only ONE fuel pump relay. What I am wondering (and no one seems to be able to tell me) is if there is some sort of a valve in the pump that is turned off that prevents fuel from being pumped into a tank that is not being drawn from. If that is the case, the fuel is just being pumped into the tank with the least resistance. I assume that since the front pump doesn't "whir" when power is applied to it, that this means it might be so corroded from not being used for several years (since the locking gas cap jammed up and I didn't want to screw with it - and just used the rear tank) and I assume therefore that this corroded pump is the culprit. Or could the pump in the rear tank have developed problems over the summer while it was removed and put into storage (covered in a plastic bag and kept from having anything press up against it) and therefore some valving in the rear pump be a problem here as well? After I started the truck up earlier during the week, the fuel pump did seem to be making a much louder noise than before. Could this have been a symptom of something wrong with the rear pump even though the engine started and it ran (for a while) with plenty of power before it ran the rear tank out of gas? > You didn't mention anything about checking/replacing the fuel filter (or I > missed what you said) so with a rusty tank I would think that would be a > high priority. Not really sure why the fuel filter which filters fuel from the pump down to the engine would have anything to do with why the wrong tank is being filled, but it was replaced. >>>>> Had a problem with my F-250. The rear tank rusted out. I tried to >> siphon [quoted text clipped - 124 lines] > down to the engine would have anything to do with why the wrong tank is > being filled, but it was replaced. And I should also mention that when I siphoned fuel out of the front tank (which was almost empty before I started to pull the rear tank in June) - there was almost as much fuel in the front tank as I had put in the rear tank. I dropped the rear tank today to make sure I didn't cross the lines, and that tank was almost empty. And the lines were connected to the correct fuel pump port. So unless there is a problem with the rear pump that is clogging the return to the rear pump, or the front pump is just open and the gas is taking the path of least resistance, I don't see what fuel pressure or a new fuel filter would have to do with anything. >>>>>> Had a problem with my F-250. The rear tank rusted out. I tried to >>> siphon >>>>>> the fuel out of the rear tank and run off the front tank, but the >>>>>> front >>>>>> tank fuel pump didn't seem to work. But the truck ran fine off the There should be a shuttle valve (looks like a big can) that switches between the tanks depending on which in-tank pump is energized. Those can get clogged up and not switch back and forth. Search the alt.trucks.ford newsgroup, there was a discussion on this topic a couple of weeks ago. >>>>>>> Had a problem with my F-250. The rear tank rusted out. I tried to >>>> siphon [quoted text clipped - 7 lines] > alt.trucks.ford newsgroup, there was a discussion on this topic a couple > of weeks ago. For 1990 trucks there is no such shuttle valve on the frame of the truck - this is all done inside the fuel pump. That is why I am asking if any of you know how the fuel pumps control the valving of the gasoline returning to the tank. There are at least three separate systems for switching dual tanks. One is for carbed vehicles that have a fuel pump mounted on the engine - they obviously don't need gas to return into the tank. The earlier fuel injected engines did need such valving going both ways into and out of the tank - and that valving was outside of the tanks. Later EFI dual-tank set-ups didn't have that separate valving outside of the tanks - they only switched power from one pump to the other, and the valving was inside the fuel pump itself. That is the system I have and that is what I am asking about. So please do not confuse the systems - I am asking specifically about the later EFI dual tank system with a check valve inside the pump itself. >>>>>>>> Had a problem with my F-250. The rear tank rusted out. I tried to >>>>> siphon [quoted text clipped - 25 lines] > am asking specifically about the later EFI dual tank system with a check > valve inside the pump itself. I found a repair manual, the pump in the tank is not a simple pump but a fuel control module. When the fuel pump is shut off, it is suppose to close the fuel return line to the tank. I would figure the shut off valve in the front tank is not closing or the valve in the rear tank is not opening. The reason to check fuel pressure is to make sure the pressure regulator is allowing fuel to the return line or if the pressure is too high which might force the fuel through the front pump into the tank. > >>>> Had a problem with my F-250. The rear tank rusted out. I tried to > > siphon [quoted text clipped - 103 lines] > After I started the truck up earlier during the week, the fuel pump did > seem to be making a much louder noise than before. Could this have been > a symptom of something wrong with the rear pump even though the engine > started and it ran (for a while) with plenty of power before it ran the [quoted text clipped - 7 lines] > down to the engine would have anything to do with why the wrong tank is > being filled, but it was replaced. I guess I misunderstood what you were asking. I thought you said the engine would die after a short time from lack of fuel. Determining if you have enough pressure going the the intake manifold might be a clue as to what is wrong. I did not realize that you were SURE it was going into the other tank instead of to the intake. > This is a 1990 truck and according to the wiring diagrams for the 1990 > F-250, there is only one fuel pump relay and the power from that goes to > the Intertial Switch, then from there to the Fuel tank Select Switch, > then to the tanks. There is no whirring noise when the switch is set to > the front tank, but there is a whirring noise when the switch is set to > the rear tank. There appears to be only ONE fuel pump relay. That would work (one relay). The switch probably just switches between the two electric pumps. > What I am wondering (and no one seems to be able to tell me) is if there > is some sort of a valve in the pump that is turned off that prevents [quoted text clipped - 5 lines] > up and I didn't want to screw with it - and just used the rear tank) and > I assume therefore that this corroded pump is the culprit. There is probably a check valve built into the fuel pump if it's anything like the '91 Explorer pump, which it probably is. It's just a one-way valve. It doesn't get "turned off" it simply allows fuel to pass one way only. Unless it's busted. >Had a problem with my F-250. The rear tank rusted out. I tried to >siphon the fuel out of the rear tank and run off the front tank, but the [quoted text clipped - 29 lines] >something happen to just the rear pump which isn't running even though >it is whirring when I turn the key but don't start the vehicle? i THINK , you have three fuel pumps - one in each tank ( low pressure ) and one high pressure pump which pressurizes the injectors. the front/back switch changes only the power ( through a relay ) to the pump in the tank selected. the low pressure from the pump in the tank selected moves a valve ( where all four fuel lines are together ) to have both the feed and return lines in use for that selected tank. there is no electrically move valve has the fuel filter been replaced? >> Had a problem with my F-250. The rear tank rusted out. I tried to >> siphon the fuel out of the rear tank and run off the front tank, but the [quoted text clipped - 41 lines] > selected tank. there is no electrically move valve > has the fuel filter been replaced? Read the rest of the thread. The fuel filter was replaced, and there is no valving in line between the tanks and the engine. There is just the fuel pump relay, then the front/rear tank switch - there are supposed to be a check valve in the tank mounted pump itself. There si no other fuel pump on the engine. There might have been for older trucks, but not for the 1990 model. >>> Had a problem with my F-250. The rear tank rusted out. I tried to >>> siphon the fuel out of the rear tank and run off the front tank, but the [quoted text clipped - 51 lines] >There si no other fuel pump on the engine. There might have been for >older trucks, but not for the 1990 model. if you know all this why are you asking questions in here? >>>> Had a problem with my F-250. The rear tank rusted out. I tried to >>>> siphon the fuel out of the rear tank and run off the front tank, but the [quoted text clipped - 53 lines] > > if you know all this why are you asking questions in here? I was asking people if they had similar problems with the specific model and if it was caused by a valve in the fuel pump or something else - why would a front tank pump that wasn't working allow gas from the rear pump to full the front tank? I find it hard to believe that one half the pump in the rear could work yet totally have a valve in the back (the other half of the pump) not work and pump gas into non-working tank - makes no sense to me at all. So I was asking if anyone had similar problems with the same model and year truck - and all I got was "have you checked for this?" - most of which wasn't even applicable for my truck. The most bizarre one was the fuel filter - which makes no sense whatsoever. The engine was getting fuel because the pump was pumping gas from the rear tank to the fuel injection rail and through the fuel pump. The fuel was not getting back to the rear tank - it was going into the front tank for some reason I can't figure out. That is why I wanted to know if anyone had specific information about the 1990 pumps and check valves in them. "Usenet Newsreader" <usenet247reader@earthlink.net> wrote in message > So I was asking if anyone had similar problems with the same model and > year truck - and all I got was "have you checked for this?" - most of > which wasn't even applicable for my truck. The most bizarre one was the [quoted text clipped - 4 lines] > can't figure out. That is why I wanted to know if anyone had specific > information about the 1990 pumps and check valves in them. I'm saying that the check valve in the front(inop) pump is bad. Replace the front pump and all your problems should be solved.  SignatureOld Crow '82 FLTC 'Pearl' '87 FLTC 'Fugly' '61 F-100 BS#133, SENS, TOMKAT, SLOB#13, MAMBM > "Usenet Newsreader" <usenet247reader@earthlink.net> wrote in message > > So I was asking if anyone had similar problems with the same model and [quoted text clipped - 10 lines] > I'm saying that the check valve in the front(inop) pump is bad. Replace > the front pump and all your problems should be solved. Why is the check valve in the front pump all of a sudden bad when there was no problem with it for YEARS? Doesn't the valve stay shut unless the pump itself is working? There was a recall on these trucks for the check valve and pumps. Check with Ford to see if your truck was one of them and if it was ever serviced. If not, you should be able to get it done for free. NHTSA93V125000 - Check valve malfunction 93S68 - Fuel tank cross-flow condition 01M05 - Fuel cross-flow extended coverage > Had a problem with my F-250. The rear tank rusted out. I tried to > siphon the fuel out of the rear tank and run off the front tank, but the [quoted text clipped - 29 lines] > something happen to just the rear pump which isn't running even though > it is whirring when I turn the key but don't start the vehicle? Nope. I have a 1993, dual tank, F-150. Went to the dealer and discussed this, plus found the TSBs about the "Fuel Crossover" safety recall on the websearch in google for Ford TSBs and F-150 TSBs. On the EFI trucks, the pump and fuel guage selected by the dash switch is the one that pumps. The recall involved the return line over filling the tank tht was NOT selected by the dash switch, and the installation in BOTH pump output lines (the smaller, high pressure line on each pump) of a redundant anti-back flow valve ($85.00, each!). I found my preventer valves in the wrecking yard. Not knowing what they were, I only was charged a buck each. One was from a 1992 F-250. The TSB covers 1989 through 1993 trucks. Ford had extended this voluntary recall for 12 years or 150,000 miles, but, many owners evidently failed to comply! Link: http://www.ford-trucks.com/recalls/recall.php/m-FORD/d-F150/y-1993/t-49803 The tools were $7.99 at Harbor Freight Tools. Part Number is P38732 and includes 3 tools, for all Air Conditioner and fuel lines on most Ford, GM, and Chrysler vehicles. Please relieve the system pressure and Negative Battery Cable, before disconnecting any lines! |
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