About a month or so ago, I acquired a 1988 Ford F150. The engine had been rebuilt less than 10,000 miles ago, but the pickup hadn't ran in just over four years. I cleaned both tanks and put new pumps in each tank. I also installed a new high pressure pump on the frame rail. The pickup ran great for about 1200 miles. Then, it started dying for no apparent reason. If it would sit for sometimes a couple of hours to sometimes taking days, it would start. However, it would then die sometimes if driven as few as two miles. I put a new idle bypass on it. I've put a new distributor cap and rotor. I've put a new coil on it. I've put new relays on it. I thought I had the problem mastered and took it for a drive yesterday. The first three miles were great, then it started to chug like it was running out of fuel and then died. I switched tanks and it fired right up only to die about a quarter of a mile down the road. I towed it home. It started. I sat there revving it up for like 20 minutes because I thought something was getting hot. It ran great. Then I started out driving it and it died. I've ruled out something getting hot, but I think I must have a loose wire somewhere. Anybody have any ideas as I'm running extremely short on patience and ideas?

 

Have you replaced the fuel filter? Whats your fuel pressure?

 

Yes, the fuel filter is new. I don't have a gauge to measure the fuel pressure, but when I hooked a jumper wire to the high pressure pump it shoots quite a bit of fuel. I have for the most part ruled out a fuel problem as I can sit there and hold the accelerator down where I'm running 2000+ rpm for several minutes with the vehicle sitting and not have a problem. When I tried to load the vehicle on a trailer, it died three times at an idle when I engaged it into gear and started moving. I'm guessing I have a loose wire. What I don't know is where to start and what safety measures an 88' 351 efi engine would have that would just kill the engine. As said before, everything fuel related is new from tank pumps, screens on the tank pumps, fuel filter, and high pressure pump. I'm to the point where I've thrown a lot of new parts at the problem, but nothing is working. There are times when it dies even when the vehicle has cooled off that it won't start. I even put a new ignition module on it. It seems everytime I think I've got it fixed and take it for a test drive, it leaves me stranded. It ran great for 1,200 miles.

 

You need to clean or replace the Fuel Tank Selector Valve.

 

If it was the fuel tank selector valve, wouldn't it die when I rev the engine and hold it to around 2000 rpm for several minutes? It only seems to die when I'm driving it which has been on country roads for my test drive. Sometimes when it dies, it gives a warning of chugging. Other times, it just dies without warning. Then, it won't restart until it has sat for a while. Sometimes, it has to set a couple of days before it goes again.

 

Well if is not that and if it is Ignition then it is either the ICM or the PIP sensor. As either one can do that also.

 

Where are those sensors located? The other reason I don't think it's fuel related is the fact that at the times it won't start I have give it a snort of ether and it won't even hit at all on the ether. You're probably right with those two sensors you mentioned, but I don't know where they are located. Do you have any type of diagram? I have already put a new ignition modulator on it. Is this the ICM?

 

Yes the TFI ignition module is a type of ICM.

The PIP sensor in mounted on the Stator and the Stator is inside the Distributor.