I have a 1991 F150 that was running great until a few days ago. As I was driving up the road it just died on me. No warning signs at all. I tried to start it and it started then died immediately. I had it towed home and replaced the fuel filter along with checking codes. The fuel pump runs with the key on motor off and It answers from the engine compartment. It still will not stay running but I did get a code on the tps. Went ahead and replaced this since it was still the original one but did not solve the problem. Have run and cleared codes a number of times now and the only code I get is 334. Not sure what to start looking at and wonder if anyone could point me in the right drection to start looking?

 

Code 334, EVP voltage above closed limit. EVP being the Egr Valve Position Sensor, mounted on top of the EGR valve. Possible causes the valve may not be completely seated closed, possible carbon under the valve. Vacuum applied to valve during the test, holding the valve open. Faulty valve, sensor, wiring, PCM. Start by removing the green vacuum line from the valve itself, plug the line and retest. If the valve is opening at the wrong time, or staying open it will cause the engine to die.

 

Ok. I will try cleaning out valve when I get home. I have nothing but trouble with the egr system on this truck. I just put a new valve on a couple of months ago...I had thought I was just getting that code due to the motor not being at operating temp. Thanks

 

Are you saying that when it will not start and when you turn on the key the selected fuel pump runs all the time and does not time out and stop running after one second.

 

The truck will pretty much start right up, it just stalls out almost right away. When I turn the ignition on motor off the feul pump will run in each tank and I hear the clicking response from under the hood on each tank also.

 

How long does the pump run in each tank when you turn on the key with the motor off?

 

The fuel pump will run for a couple seconds and then stop...thats when the clicking response comes from under the hood..I noticed today that it will start good on the first start up after sitting for a whil and run rough...go up to about 1500 rpm run and kinda drop off on rpm and then die. If I try to start it right away it will turn over and not catch. When I let it sit for a couple minutes it will start and run rough. I can rev the rpms while holding down the gas pedal but it still cuts out real quick. Holding the throttle seems to make no difference at all. Went through the EGR system and found no faults. Dont mean that I didnt miss something but am starting to lean towards a fuel issue...I dont know...

 

My guess would be the Ignition system. More than likely the ICM (TFI) is bad. But could also be the PIP sensor or the Ignition coil.

 

I have already pulled the ignition module and took it to advance and had it checked...the guy checked it 13 times and it passed each time. I will check the coil when I get home and what is the PIP?

 

First off they can not test a Ignition module as a bad one will show good as they do not apply any heat to it.

The PIP sensor and the Ignition module is the same as the points was to the point type ignition system.
The PIP sensor is mounted on the stator inside the distributor.

PIP = Profile Ignition Pickup. A "hall effect" vane switch that furnishes crankshaft position data to the EEC-IV processor and a pulse train for the Ignition module.

 

Well I did all of the tests I could preform solo last night and at this point can rule out the coil. Am waiting on help to arrive this afternoon so I can do some voltage testing on the module and pip

 

Ok, I just did all the voltage tests and according to the haynes manual if all the tests pass then by default the icm is bad. So I guess I need a new control module...