Hi all,

I've been working on a friend's F150 for several days, rehabbing it for a graduation present. Ran into a situation that's driving me up the wall !

From a cold start, fires right up. If you literally start it, shut down & try to restart, it just cranks over with no attempt to fire up. The only way to restart, is to floor the accelerator, & crank for several seconds til it starts.

Prior to me, someone has replaced the TPS, & IAC valve. I've checked both, & they are working properly. ( Proper voltage, resistance, etc) .

Has anyone run into this on these early fuel injected models ?

 

Always pull the codes first when working on a fuel injected engine. They may lead you in the right direction.

What you are doing by flooring the accelerator and cranking it is turning the fuel injectors off. You are putting it in "clear flooded engine" mode.(TPS signal wide open, engine rpm less than a certain rpm).

Does it puff black smoke when it finally starts, like it really was flooded? Does the fuel pressure stay up when you turn the engine off or does it leak down, like some injectors may be leaking? Also check the fuel regulator vacuum line. Make sure it does not have fuel in the vacuum line going to it.

 

Always pull the codes first when working on a fuel injected engine. They may lead you in the right direction.

What you are doing by flooring the accelerator and cranking it is turning the fuel injectors off. You are putting it in "clear flooded engine" mode.(TPS signal wide open, engine rpm less than a certain rpm).

Does it puff black smoke when it finally starts, like it really was flooded? Does the fuel pressure stay up when you turn the engine off or does it leak down, like some injectors may be leaking? Also check the fuel regulator vacuum line. Make sure it does not have fuel in the vacuum line going to it.

 

I have the same problem with my 85. It happens when the engine gets warm and has run for a while, 30 minutes or so. Almost as if it cannot get fuel. I have changed same as you. looking for a answer as well!!

 

Ahhh...That makes more & more sense ! I thought about scanning it, but I'm afraid it would come back like a bingo card ! There's "several " bypassed pollution controls, & other goodies.

Checked the vacuum line, no fuel, but it does have a strong fuel odor on the restart. So, obviously, it's getting flooded out. I'll have to see if I can borrow a fuel pressure tester. I suspect the pressure is ok, as the cold start, & after the final restart it runs smoothly.

So, odds are the fuel pressure regulator is the culprit, I presume ?

 

I have the heavy gas smell as well. Please let me know how it works out!

 

I too have the same probem ('86 f250 efi 5.0). Starts OK when cold but very hard to start after being driven for an little as 5 minutes. Did changing the fuel pressure regular fix it?

 

Sounds like the fuel pressure regulator to me. I have had several go out on my Ford vehicles and they would do what you are describing and once I changed the regulator they started right up and even got a little better fuel economy.

 

Thanks --- I've checked around for pricing and the part doesn't seem too expensive. Are they easy to replace and would you happen to know where its located on my 1986 f250 5.0l efi? Can't seem to fnd any reference to a fuel pressure regular in my shop manual.

 

Gentlemen,

Thank you all for weighing in on this nighmare ! It indeed was the fuel pressure regulator causing the problem. Weird thing was I had checked the pressure & it appeared to be ok. In talking to a friend who worked at a dealer back then, he went right to it a week ago.

Thanks again !

Ritchie