I have a 1995 F150 with a 4.9L engine and it has 196,000 plus miles on it. The problem I am having is my truck is after I crank it up it will sit and idle perfectly fine. After I put the tranny in drive or reverse the engine will hesitate and then stall out. I can keep it running sometimes by pressing the accelerator to idle it up. Sometimes after driving I come to a stop and put it in reverse it will shut off as soon as put it in reverse. Also, if I stop to abruptly at a stop light it will stall out no matter what I do.

I have removed the throttle body and IAC and cleaned the carbon out of them. It seemed to help for a couple of days with the sudden stopping in drive but it did nothing with the reversing problem.


The question I have is does anyone think it is a sensor, torque converter or is the transmission going bad?

Any help will be greatly appreciated.

Thanks

 

Are there any vacuum leaks?

 

I wouldn't suspect the transmission itself. If the torque converter clutch (TCC) were locking up, giving it a little gas with it still in gear probably wouldn't save it. That is, the TCC would stall out the motor even if you gave it a lot of gas while stopped. A sanity check is, does the truck surge forward as it dies out? The TCC would cause that.

The IAC is likely. Here's the test. If you pull to the stop using your left foot on the brake and it starts to die, can you just crack the throttle and the truck act normal? If so, the IAC isn't doing its job. Cleaning them is rarely helpful. It could still be the TPS so have it checked too. Or if you replace the IAC and that doesn't do it, then try the TPS.

 

CHECK FUEL PRESSURE! Should be 60 psi on the 4.9. The shrader valve is behind the plenum on the pass side by the firewall. It looks like a tire fill valve and may have a black cap screwed onto it. Sounds like you got a bad pump. Also, the 4.9 has a tendency to dirty up fuel injectors. If the pressure is ok(check it while driving also, route the gauge through the hood and tape to the windshield) then I would recommend a thorough fuel injector flush, check all filters and have the codes read.

Robbie

 

bigbronc, I'm here to learn about Fords. What is his description was your cue for fuel pressure?

 

cliles55,

I have checked all the vacuum lines on the truck I can find and there are no vacuum leaks.

cantrma,

The truck does try to surge forward as it dies out. In fact when I press the brake it tries to stall but when I let up off the brake with it in drive it will move forward a little and most of the time level out. Going into reverse it will stall out most of the time no matter what I do.

bigbronc,

I will have to check the fuel pressure and the codes read.


Thanks for the replies and if you think of anything else to check please let me know.

 

Just to be sure, a lean surge feels like you tapped the gas, i.e., the engine speed exceeds the pull in the seat of the pants. A TCC surge might fell more like the engine is pulled down from the surge.

Respond again, but it really might be a TCC lockup problem. I'm playing along but bigbronc is a real Ford tech. Hope he weighs back in for you.

 

yawr250f,

The surge I have been feeling is like the engine is pulled down from the surge.


I think it is the TCC but I am not sure.

One other question: the truck has two gas tanks on it. The front tank is not working because of bad fuel pump so I just use the back one. The question I have is there is old gas coming out of the front tank whenever it gets hot outside. The gas will overflow out of the tank due the pressure built up in the tank.
Does anyone think this is contributing to my problem and what should I do to stop the overflow?


Thanks