i recently bought an 88 f150 that had been sitting for approximately 3 years. when i got it, it wouldn't even start. changed the battery, then changed the distributor, then the starter went out of it so i had to replace it. then i had it running in the driveway one day and after about 15 minutes it died. if i waited a while it would run again for a few minutes then die, it acted like it was out of gas but i knew it wasn't. next day it did the same thing, ran for almost exactly 15 minutes then died. we put a fuel pressure gauge on it and when it was running it has about 32 psi then when the time comes, it drops to about 10 psi. it has 2 tanks and i checked with a test light to make sure it was switching electrically between the 2 tanks and it was. since switching tanks didn't change anything and i had found that it was in fact switching power between the pumps, i decided that it wasn't the in tank fuel pumps. so first i replaced the filter, i knew it couldn't possbilby be something that simple but for 7 bucks it was worth a try, didn't fix it. then i decided it had to be the external fuel pump on the framerail, so i replaced it, again, no change. then i changed the fuel pressure regulator and the fuel pump relay (green one) and still nothing changed. then i noticed the oxygen sensor wire was broke off, right at the sensor, so i decided to replace it, which of course didn't help. next day we bypassed the other relay (for the computer i believe, not sure, it was the brown one) that made it run for 20-30 minutes before it died. the other difference is now when you turn the key on the fuel pump doesn't run. you can hear something click that i believe to be the fuel pump relay but the pump doesn't run unless you crank the engine or when it is running. and when it dies, it sounds like the pump is still running for about one second after the engine dies. i don't know what else it could possibly be, i've changed about everything in the fuel system and nothing has helped. and all of this without ever even having it licensed or leaving the driveway. oh and i also bypassed the inertia switch which didn't help either, i didn't think it would but it was easy to try. and it had been in a crash before it sat for 3 years if that makes a difference. it was on the passenger side front fender, the whole fender was crushed and had been removed when i bought the truck. i had to ground the starter solenoid to get it to start then i got a fender and put on it. so if anyone has any idea what else it could possibly be, please let me know, thanks.

 

What kind of oil pressure does it have just before it dies? I dont know what years had the oil pressure sensor.

There was / is a sensor that if your oil pressure droped out or got to low it would shut off your fuel pump. I dont know if the crash sensor replaced that or not. It was kind of for the same thing. Maybe someone that knows more about that will chime in.

Is the motor all stock? I had a old 76 390 that did the same thing. the Magnet on the pickup coil was cracked. I have not looked inside a newer dist. I dont know if the pickup is about the same or not? that might be worth a look!

My 76 I could drive it for a bit. 15 maybe 20 min and it would just cut out. let it sit for a few min and it would fire right up.

Have you tryed to pull codes?

 

Ground pin #6 of the DLC (VIP/TEST) connector and see if it keeps running.
DLC/VIP/TEST connector:
http://i54.photobucket.com/albums/g9...taLinkConn.jpg

 

ford farm my truck does the same thing, let it sit for 10 mins and starts right back, i watch my gauges too i dont see anything wrong when it dies, only dies in heat or heavy humid or uhh moisture, i have replaced so much starting to get a little **** lol. When i move the throttle slightly(1/2 inch) i can hear a bit of a high pitch noise comming from back of the engine, so i checked vaccums line near oil filter no cracks , followed thoes line to the canister all over no cracks or breaks, only other thing behind that engine is the fuel line. I dont know a god darn thing about any of that.

 

Check the dual function resevoir, it sits on the frame rail ~3' back of the HP pump, it has an internal filter and is part of the tank selector.

I have the same issue as you and will be tearing mine apart in the AM, pretty sure it's the internal filter on that thing that's causing the problems. Post your results please, I will do the same.

Thanks!!

 

I had the same problem on my 88. It ended up being the in tank pump. I did the same thing starting with the filter,changed frame mounted pump then ended up changing internal pump and sending unit so the gauge would work.

 

I checked the dual function resevoir and everything seemed good however the internal filter that the Haynes manual mentioned did not exist, not sure where they got there info, it was a neat thing to take apart (excluding gas vapors) to see how it works, after reassembly I took it for a ride and pulled new codes and 95 came up, "Fuel Pump Seconday Circuit Failure" which coincides nicely with how it's acting, shuts down when you turn left or right, My guess is someting in the tank is lose and sloshing around with the gas, will look at that next.

 

i had the same thing happen to my 89 150. i changed the pump in the tank and it never did it again. high pressure pump on the frame will not supply enough fuel or pull from the tanks.

 

If you jumpered pin 6 as instructed, that will cause a 95 to show up. That is a latching fault. If the EEC cannot switch the pump off as well as switch it on (bypassed ouput), it will throw a code. This sounds to me like you probably have some dirty socks. I'm not talking about the ones on your feet either. The in-tank pumps will have socks on them to filter out rust, etc. If it's been sitting for 3 years, chances are, they're caked with varnish and crud from the fuel that was left in it. I had a 1/4" fuel line get completely plugged on my VW when it sat for a while. I had to clear it by running a piece of steel wire through it. The socks are a bit easier, but if I was going to go through the trouble of dropping the tanks, a new pump will come with new sock, and really isn't that expensive as compared to the time it takes to drop that tank out. Try this on for size. Disconnect the line from the selected tank between the tank and the multifunction reservoir. Drop the line in a catch can, and then jumper the fuel pump at the DLC. Turn on the key, and see how long you have fuel flow. Just watch out for sparks etc, while you have that much gasoline vapor around. Even if the socks aren't completely plugged, the amount of sludge that can form in a tank in 3 years is incredible. The inside of my tank when I changed my pump was bright and shiny. The pump, though, was about the color of a brick (Should be white). Needless to say, what we buy at the pump ain't always gasoline.

 

Very good info hope the "Thread Poster " is making way on his problem, as far as the 95 code I'm sure I cleared the fault codes before I test drove and got the code "again" I will repeat the test drive with codes clear to see what happens.

I suspect you are right about the dirty sox

Thanks

 

i guess that could be it but i was thinking it would have to be something outside of the tank because if it dies and you switch tanks it still won't run, i checked the wires with a test light and the power is switching so i would think it would have to be something external. i checked the oil pressure situation today, first i checked the oil and it was down 2 quarts, (i don't think i had checked it since i bought it and it leaks a little around the valve cover) so i put some in and started it and it seemed to run ok but the gauge showed no oil pressure. if the gauge was right and it didn't have oil pressure or if the sensor was wrong would that make it die when it warmed up or just not run to begin with? because i would think that if it saw no oil pressure it would kill it quicker but i don't know, it sounds like the external pump continues to run for about a second after it dies. i'm just about tired of messing with it but i hate to take it somewhere now, and the way it sits now i probably couldn't sell it for what i have in it....

 

Oil pressure is not checked by the EEC computer and will not kill your engine.
Put a fuel pressure gauge on the fuel rail (manifold) and see what the fuel pressure is when it dies, it may not be a fuel problem.
If you have fuel when it dies check for spark, it may me a bad TIF module or the pick up unit in the distributor.
It is normal for the fuel pump to run for one second after the engine dies.

 

it has about 32 psi when its running and 10 psi ish when it dies, it acts a lot like when you run out of gas but its obviously not out of gas.

 

32 psi is normal for an 8 cyl at idle, taking the vacuum hose off the fuel pressure regulator while idling the pressure should go up to about 45 psi. Make sure you put your finger over the end of the hose when you take it off.

 

my truck will run for about 20-30 mins then start spitting and sputtering, then one day we put the fuel pressure guage on it and when it started choking up it was reading 20 psi, we have put, hp fuel pump, fp relay, FPR, fuel filter. And last week we switched to the rear tank, keep in mind the front tank had half. Then when we switched back to the front tank today and it had an 8th of a tank so we know the selector valve is trash but it doesn't explain the sudden loss of fuel pressure after 20 minutes of driving. I'm stumped, got any ideas?