My 1996 f150 has a problem starting, and it doesn't matter if the engine is warmed up or not.

It will crank and then it will begin to run real rough at 500 rpm and hitting the accelerator doesn't afftect anything, sometime it will die and I'll have to try again.

After a few seconds of running like crap the rpm's will rise and it will idle normally.

The other night the engine started to run like crap on my way home from work. It felt like a couple of cylinders were not firing and it had no acceleration, the rpms were bouncing around so at least one cylinder was not firing. I pulled to the side of the road, shut it down and started back up and it ran fine the rest of the way home.

I'm stumped, I've changed the fuel filter and MAF sensor, the plugs and wires are new. By the way this is a 4.9 6cyl with a 5 speed.

 

Sounds like the TPS to me. If you have a code reader, you can pull your codes. Or Autozone can do it for free.

 

Is you check engine light on? Also check your vac. hoses going towards your IAC valve. These hoses gets dry rotted or if gets real soft and pinches close your truck will run rough. If it has a hole in Your IAC hose your truck won't idle but will run at high rpm only. IAC(Idle air control)

 

Fuel filter maybe?

 

I changed the fuel filter and it didn't do anything. The check engine light is on so something must be wrong. It idles fine, just not right at start up. it will crank and it sits there and runs real rough at 500 rpm for a few seconds and either dies or jumps up to 1000 rpm and begines to idle fine. It almost seems like for the first few seconds it's not running on all cylinders.

 

I am having a very similiar problem on my 90' F-150, and my code is reading that the tps is bad, I am planning on replacing it within the next week or so, so ill let you know if it does anything for me.

 

How much does a TPS cost? I might as well just change even if it's not the cause of the problem, it's probably the original one anyway.

 

How about fuel pump on its way out? Do you have dual tanks? Try switching front to rear.

 

tps somewhere around 50 to 100 bucks for 95 5.0
4.9 should be around there somewhere

Try distributor cap and rotor maybe. Tps or fuel pumps
Tps Around 50 to 100 bucks
Fuel pump from napa is 234 bucks plus tax
Cap and rotor 30 bucks

 

The TPS has been changed and that did nothing. Last night on my way home I was driving on the highway and all of a sudden the truck just lost power and began to barely run. I shut it down and restarted it about 20 times and nothing changed. I had to rev it up and slip the clutch to make it all the way off the exit ramp and toward the bottom, the truck just began to run normal again and I took off and made it home.


The codes coming back are reffereing to a Lean Bank 1. whatever that means.

While the truck was running like crap I switched tanks and it did not do anything. Do these trucks have one pump for both tanks? how does that work?

 

Mikemustang,

I am having the same problem with my 1991 f350.

Mine will also crank and then it will begin to run real rough at 500 rpm, But I can give it gas to bring the idle up. When I do this it runs rough for 10 to 15 seconds then usually smooths out. Mine will also sometime die and I'll have to try again. It is acting like it is flooded. Sometimes I will have to floor it to start it.

This weekend I am going to attempt to resolve the issue. I am leaning toward the TPS and the fuel pressure regulator. I will let you know the outcome.

 

im having similar problems with mine,96 300,5 spd,hope you figure it out,im lost

 

i unpluged the tps,seems to work fine now except for high idle when shifting gears,gonna pick up a new tps this week and see if that works

 

Well, I worked on my truck this weekend and it works great now. I changed the fuel pressure regulator. It was about $30 and took about a half an hour to change. Hope this will work for you guys as well.