Idling at a mail box, the truck acted as if it was running out of gas, spit & sputtered, raced slightly, dropped rpms, then a gradual dead engine stop. Impossible to start engine. Let it sit with the tank selector set to the new side fuel tank position for 45 minutes. Truck started and was able to make my driveway when it stopped again (same scenario).

Inertia switch was not blown. Removed wiring connector from switch, jumped switch, no change.

Jumped fuel lead of DLC to ground... should have heard main electric fuel pump. Heard nothing except a slight electrical sparking.

Installed new Fuel Pump relay on general principles. Still could not hear the main electrical fuel pump. I'm pretty sure I can hear the side tank pump but not sure about the rear tank.

Inertia switch... disconnected wiring connector. Hooked a volt meter up to the connector's brown (12v) lead (meter red to lead, black to ground). Turned key on, voltage jumped to 12v but only for a second then dropped to 8v. (Is This Normal?)

Jumped wires at inertia wiring connector with a paper clip. Again hooked up a volt meter to the paper clip (meter red to clip, black to ground). Turned key on, voltage jumped to 12v again for only a second after which it dropped to 0 (zero) volts this time. Plugged inertia wiring connector back on the switch. (Is This Normal?)

Turned key to the start position and the truck started, BUT I cannot hear the main electric fuel pump whirling which leaves me wondering if it is safe to drive or not.

Is it possible to wire the pump directly at the pump to see if it works or not?

 

Just a thought...

Since you have dual tanks, you have 3 fuel pumps. Low pressure pumps in the tanks to feed the high pressure pump on the frame rail. I would check to see what type of fuel pressure you have at the fuel rail. It's possibe that your high pressure pump has gone on you. The low pressure pump could provide enough pressure to start the engine and run it for a short period, but will not provide enough pressure to keep the engine running.

 

I have to qualify what I state so let's hope it is correct.
The info I have states Ford made 4 systems for fuel delivery and control in those years.
The F Series doesn't show a high pressure in line pump with dual tanks as shown for Econoline and Ranger.The in tank pumps are supposed to be hi pressure for F series with dual tanks.
I suspect there is a connection problem , either a poor ground or poor voltage supply to the pumps, both of them.
Since both pumps are involved there could be a poor ground that both tank pumps share or the power coming from the fuse/fusible link to the fuel pump relay, through it on to the pumps themselves.
This is one of those situations where checking with a voltmeter without doing voltage drop testing will not reveal the problem. If you are going to check the supply to the pump you need something like a headlamp sealed beam to really load that circuit .
If there is any kind of supply problem with that load, the sealed beam will not glow with full light brilliance. When time and possible corrosion can get into the picture it gets kinda muddy.
Another consideration is "aftermarket" pumps do not have a good reputation .

 

Common Sense... Your explnation of the three (3) pump setup having dual tanks, and the possibility of having the main high pressure electric pump fail has been foremost in my mind, hence I have been thinking of wiring it direct for just a second or two while I'm close to it.

Hanky... I'm glad to hear that you find that Ford has four (4) different type fuel feed setups. My "Haynes 1988-1996 F150" manual shows just two, neither of which apply to my 1988 F150 when it comes to describing (or pics) of the fuel and EEC relay assemblies.

I didn't mention previously that about a week before this present complete shut down, the side tank removed and running on the rear tank, while running errarnds, The truck acted as if it was running out of gas but I made it to a gas station and filled the tank. After the fill up, all was well again. Shortly thereafter, I installed the side tank.

On this total shut down problem, although I've been checking everything, the only component I replaced was the Fuel Pump Relay and the engine has been running fine ever since. I assume that the "running out of gas" problem encountered as per the previous paragraph was due to the Fuel Pump Relay starting to fail.

This morning, needing to know for sure if a main electric fuel pump existed or not, I put the truck up on ramps and slid under there. I found it just ahead of the Dual Function Reservoir, pictured exactly as in the manual.

Now, as I turned the key to the RUN position, of course the loud Warning Gong blaring away 5 times was foremost in my ears BUT I could definitely hear a separate whirling sound in the background for one second. I did this for three or four times and although that whirling sound (electric pump) is very low as compared to the gonging, it is there.

At the present, I am 81 and my hearing is somewhat lacking I know but not bad, and even wearing two hearing aids does nothing more than make the Gonging louder. What I am going to do isn't listed in any manual but I'm going to hook up a mike to a amplifier with the mike being close to the electric pump(s) to amplify the whriling noise only to ease my mind.

The rear tank needs to be dropped due to a bad sender or float. I can check that in tank pump during that process. Yes, I know better than to run it dry. I'll let you know how the amplifier thing turns out.

Thanks for the replies and advice fellows, I do appreciate it.

 

Something that may even be easier would be to have somebody put their ear to the fuel filler with the cap off to see If they hear the pump run each time cycleing the key. Do this to each tank filler. Then have the same person put their hand on the high pressure pump to see if they can feel the pump run.

This may not be your problem, but another thing to look for (had this issue with my 88 Ranger S/C 4X4. It had the same set-up as your F-150. Ford used a canister filter in the reservoir and a filter for the high pressure pump. However, they phased out the canister filter that went in the reservoir in 1987, so in 1988 there was non. I had issues with the engine running and in checking, I found that my 1988 came with a canister filter and it was crudded all up, thus was having trouble feeding fuel to the high pressure pump.

 

Joe,
do you have access to a fuel pressure gauge?

 

Common Sense... I'll call in a neighbor to give me a hand pertaining to hearing the pump(s) running. I'll also take a look at that reservoir filter.

Hanky... No, unfortunately I don't have access to a pressure gauge and have never used one. I assume the Haynes manual shows that but I just never got to that part. I will check around to see if I can borrow one.

 

The truck has been running on both tanks okay since replacing that relay, depending of course on what tank I have the switch pressed to. However, I ran the rear tank out of fuel so that I could drop it to install a new float, then immediately after the engine started to fail, I switched to the side tank... that never took effect and I had to call AAA to tow me home.

I have since made sure that I have a proper amount of fuel in both fuel tanks.

When shorting out the terminal to manually apply electrical power to the pumps (all 3), I can hear the pumps run but apparently I am not getting fuel to the engine. If I let the truck sit for a few hours, it seems that fuel is siphoning from a tank down to the main electric pump and the engine starts and runs for a few minutes until it runs out of gas again.

When turning the key on, the pump(s) run for about a second then shut down.

Question (couldn't find answer in Haynes manual)... does the pump(s) come on intermittently when the engine is running, coming on due to a change in fuel pressure?

Sometime today I will be removing fuel lines from the 6 hose reservoir to see if the in tank pumps do indeed pump 6oz of fuel in 5 seconds as per the manual, and will also check to see if the reservoir is switching tanks properly.

Even though the engine runs for a few minutes after sitting, is it possible that the main pump has failed, or is failing even though it is running, at least when the terminal is shorted or for that normal one second period when the key is turned on.?

 

The selector valve that Ford uses (If my memory service me right) uses +12vdc to move the valve to the rear tank when the rear tank is selected and spring return to the front tank when the front tank is selected. The spring gets tired and will "HANG" in between the front and rear ports causing fuel starvation/shut down. I know that POLLOCK makes a 6-Port selector valve that uses +12vdc for both directions to elinimate any HANG-UPS.

 

Common Sense... The fuel selector valve (reservoir) on my 1988 F150 is not electrical, it is the manual switch type that has a diaphragm which is controlled by the low pressure in tank pump(s). However what you've had to say has me leaning towards that selector being faulty. It would make sense that a slow leakage/siphoning from the tank(s) would allow fuel to seep by over a days time which in turn would allow the engine to run for a short time, then run out of fuel.

I've unexpectly been under the weather and haven't been able to scoot under the vehicle but will be back at it shortly. At that time, I'll double check the in tank pump output and the switching passageways of that six port selector reservoir. The tank switching setup seems to me to be vastly overdesigned.

[EDIT 09/17/13] Both in tank pump pressure and fuel flow were up to specifications. Nothing flowing thru 6 port fuel reservoir. New reservoir ordered, being shipped today. Will update when I get it all back together.