I have a 91 ford f150 with a 4.9 efi 8cyl eng. Dual tanks was running fine, now suddenly it sputters and bucks then dies when put in gear. After this it will not restart till it sits for at least an hour. Any one have any ideas, would appreciate your help.
I am new to this site I hope I posted this in the right place on here, thanks

 

Did you replace your fuel filter? It could be plugged up, put a new one on and see how it goes. If the problem goes away then comes back then you also may have garbage in the tank that is blocking the fuel pickup. That wouuld necessitate dropping the tanks and cleaning them. Also, check your rubber fuel lines to see if any of them look rotted or failing, they could be collapsing if they are rotting from the inside out.
Good Luck
Brian

 

seems to be good pressure from the tank, although I did just now (per the last Post) replace the fuel filter and blow the lines, it still does the same thing, pops right on initially, then you put it in gear and it acts as though it running out of fuel, then dies. It will then not restart for a good fifteen minutes or so. I also made a mistake in my first post it is a 5.8 EFI v-8

 

does a '91 still have a mechanical fuel pump??? did you check your fuel pressure at the manifold? could be you have a bad pump and the load of having it in gear is just enough to make it stall.....

 

has an electric pump and yes the pressure is adequate at the manifold

 

hmmmmm this is a hell of a head scratcher

 

I know what you mean, I have no clue.

 

is there a fuel pump/pressure regulator somewhere in your system?

 

The pressure is fine at the rail, this just has me confused as all heck.

 

could be somthing shortingout when it gets wram that could cause a problem i mean renmember the old days when you had points and condenser a truck would strat fine and then dies remember it was the condensir when it got warm so it could be somthing to that effect

 

Has this truck been your daily driver? Are you SURE the gas is good? Water in the gas will do this in boat motors. I see it every year in at least one of my friends motors. They'll fire up and idle for a bit but will not run.

Good Luck

 

Is the truck an automatic? I don't know much at all about autos, except there are a lot of vacuum lines etc - you should visually inspect all your hoses etc for cracking or disconnection...if the fuel is bad, there are water-absorbing products you can try at least as a temp fix...

I remember reading of a fuel starvation issue that turned out to be the fuel line getting pinched shut, so it didn't deliver enough fuel at peak load - the fuel pump might still be delivering adequately under test (if it's an electric pump at the tank, then it should show as bad, but if it's a mechanical one at the engine, it might work fine until peak demand causes cavitation.

I'd also look at the emission control valves etc, anything that might partially fail under load....also read your computer - if it's a '91 you'll have an EEC-IV test terminal under the hood on the driver's side firewall, you can buy a Ford code reader for around CDN$50 - might help you narrow it down.

My '92 has an emergency fuel shut-off that can trip at times by mistake, the owner's manual should tell you where yours is and how to reset it if it's somehow faulty...worth a look too.

One last thought, does it misbehave running on either tank??