I have a 1987 Ford F150 4X4 with the inline 6 cylinder, with duel tanks (using the front tank). I just bought it and I'm having some problems with what I'm thinking is in the fuel system. It will start and idle great. But after 15-20 minutes of idling it will dye, like it's running out of gas. Also when driving down the highway you can only go a mile or so and it dies (like its running out of gas) but you can coast to a stop and sit a second and it will fire right up and run good, until you get about a mile or so down the road and it will dye again. It's almost like clock work every time. I have put a new fuel relay in it and it still does it. Gonna put a new EEC relay in it in the morning.

Previous owner says he thinks it's bad gas, but I think it runs too good (when its running) to be bad gas. Any help is greatly appreciated!

 

You need to find out what the fuel pressure is when it dies, or if it has fuel pressure at all.

Have you tried switching tanks when this happens? Seems to me a bad selector switch could be the cause, if it's corroded or not making solid contact within the switch itself.

 

how would I find out the fuel pressure when it almost instantly starts working right?
And I cant switch tanks because the bank tank has a hole in it. It hasn't been used in quite some time.

 

You may have several problems. Could be the injectors, or it could be the filter. I'd change out the filter to see if this gets more gas to your truck while running. If your filter is clogged, then you may get enough gas to the injectors but once the fuel in the line is used up to the filter it will die. Because the filter is blocking fuel from traveling fast enough to supply the engines need.

Just my .02$

 

thats kinda what i was thinking too. havent gotten to crawl around on it (the truck) much. just got it. Does it have the inline fuel filter under the cab? or some one said this year model is in the tank?

 

Update: put a new filter on it, ran better but still didn't fix it. I also bought a new EEC relay put it on it won't do anything. Took it back got another one, same thing, nothing. So I put the old one back on it. Fuel pump maybe? Running out of ideas.

 

Update: I have put a new fuel relay, fuel filter, fuel pump (on the frame), gas, and EEC relays (which didn't even work at all). But still doing the same thing only getting worse. Could it possibly be the fuel pump in the tank is weak? It will sit and idle great (most of the time) but as soon as you go to drive it (specifically on the highway) it will die out, as if out of gas... Any Idea's are greatly needed

 

My 88 5.0 is doing the same thing. I' going to put a clear filter on my truck to see if the fuel is making to motor or not. I have replaced and cleaned all the usual things, and still it acts like its running out of gas. Could it be water in fuel? Good gas then bad gas? Who knows with all the additives nowadays.

 

That's what the previous owner said it was (water in the gas). But I ran my truck outta gas and then put premium in it and its ran worse. We have done some messing with it today and now we are thinking it's the fuel pump in the tank. So we are gonna mess with it this afternoon and hopefully have more info by morning.

 

I found out it was the pick up tube in the tank was bad. I ran a line from the filter, pump to the tank from the outside where you put gas into tank, and the truck runs fine now! So, now I need to find another tank and hopefully that pickup tube isn't bad or any suggestions?

 

Sounds like the newer type fuel has dissolved the hose from the pump to the stand pipe.
Could also be a bad in-tank pump.

Can be seen in the photo below.


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The fuel pump on the frame should be self priming. Try running a fuel line from that pump into a gas can (put it in the bed if you want to try to drive it). If it runs fine, then your issue is in the tank (pump, "sock", pick-up).

 

The pick up hose in the tank was alot of my problems too. You can put a new hose in side and possibly not have to buy anything else. Just take the old one off (its about 2 inches long) and put a slightly longer new one on it. Mine had swallen over the years and was only part of the way on. Although on my truck I had more than one problem (frame pump, rear tank pump, rear tank had hole in it, fuel selector valve) but after i changed the hose in the front tank it ran good for a day or two, until everything else finally messed up.