Have you replaced fuel pressre regulator? Its cheap, I thought there was a recall on them at one point. My truck would only run using alot of throttle when this was bad. Wont idle when this is bad, but will run ok with High RPMs

 

Hmmm. Interesting. Tell me about this. My Old yeller is a 5.0 FI 1996.
No, I have not replaced this part.In case the IAC doesnt do the job, I would need to know where to start next. Where is this part located?

 

See what happens with the IAC first. There is a lot of different parts that can cause the problem. If you are not getting codes it doesnt mean that you cannot check things the old fashion way. It takes longer but with the cost of parts it can get out of hand. Sometimes when poking around you may discover the problem.

 

Note that the IAC is just a bypass around the throttle plates so if you have problems with you foot on the gas peddle it is not the IAC.

Pull the vacuum line off the Fuel Pressure Regulator (FPR) with it running and see if gas comes out of the FPR.

You should also have higher fuel pressure with this hose off and your finger over the end of the hose. It may idle a little better at this point and if so you may have a fuel problem.

Check the fuel pressure with a gauge at the fuel rail with the hose off, running and the hose plugged, it should be 45 psi.

Be careful of spilled gas and a fire while doing this, use rags around fuel connections when removing fuel connections. Make all fuel connections with the engine not running and cold if possible.

The FPR (Fuel Pressure Regulator):
http://i54.photobucket.com/albums/g9...d/Fuel/FPR.jpg

 

I took my truck to local garage and they got all kinds of bad codes from the computer. Changed alot of parts that still didnt fix it. After paying the bill the owner mentioned something about fuel pressure. Went and bought one from Advance. Solved everything. Its located at the firewall side of intake manifold, Drivers side. 3 allen screws hold it on. Works on a vacum, not electrical. Just because the code comes up on part doesnt meen its bad, that part was just sensing high fuel pressure/flooding past injectors.

 

[QUOTE=subford]Note that the IAC is just a bypass around the throttle plates so if you have problems with you foot on the gas peddle it is not the IAC.

Pull the vacuum line off the Fuel Pressure Regulator (FPR) with it running and see if gas comes out of the FPR.

You should also have higher fuel pressure with this hose off and your finger over the end of the hose. It may idle a little better at this point and if so you may have a fuel problem.

Check the fuel pressure with a gauge at the fuel rail with the hose off, running and the hose plugged, it should be 45 psi.

Be careful of spilled gas and a fire while doing this, use rags around fuel connections when removing fuel connections. Make all fuel connections with the engine not running and cold if possible.

The FPR (Fuel Pressure Regulator):
http://i54.photobucket.com/albums/g91/subford/Fuel/FPR.jpg[/QUOTE]

Thanks. I will try this as well. Great picture. Helps alot..

 

It looks like only two allen head screws holding it on. They are about $45 or so. About what I paid for the new IAC valve.

 

Ok everyone. Got the Idle Air Control valve in today. Changed it with no problems. Also found the FPR and took the vaccumn hose off and no gas came out so the diaphram does not seem to be broken. Now for the bad news.. Started the truck and it is the same as before. It cranked up second try and ran for about 1 to 2 seconds. I gave it good throttle and it reved up and then died. Still seems as if it is not getting gas. If it runs, then it is not ignition or major mechanical. Just starts up and dies. I lubricated the throttle linkage. It works fine, no binding. I am waiting on my fuel filter disconnect tool. I tried to pry off the fuel hose on one end of the filter gently but no go. Didn't want to break anything so I stopped. Figure the tool will do it right. Have the new filter. I don't have high hopes that a clogged filter is the problem but the filter looks old, rust on one end, so it needs to be changed anyway.
What next, the fuel pressure regulator?
There is one accessible pressure relief valve ( like a tire valve stem end ) on the fuel rail on drivers side. I removed the cap and pushed down the stem, only a little gas came out. Very little. Of course the engine is not running, as it doesn't idle. Any significance to this? I am stll thinking that it just is not getting fuel for it to die right after it starts up.
Help...

 

Have you visually inspected all the sensor connections to make sure they are all tight and free of corrosion? I'm really surprised that there are no codes with the engine running the way you describe it. That makes me wonder if there is possibly something wrong with the computer. It's pretty unlikely and I do NOT suggest just replacing it for kicks. One thing you can try for practically free is to clean the mass air meter. This usually would be a slow process of getting dirty, but cleaning it won't hurt anything if you are careful. You can clean the thin wires inside the meter with a q-tip and rubbing alcohol. Be very gentle, as these wires are very small and easily broken if you are not careful. Also check the connection on the engine temperature sensor. I accidentally left the one unplugged on my truck after swapping thermostats and the truck would not idle or start without throttle input from my right foot. I suggest getting a repair manual and then going through the sensor diagnostics until you find something out of whack, whether it is in the wiring or in a sensor itself.

 

Sounds like you fuel pressure regulator is more than likely a good one.
I would go ahead and check the fuel pressure as I describe above.

 

Well, Im all guessed out. Let us know what it is when you find it.

 

That would be OK but I can't keep it running, it won't idle, just dies so it would be hard to check the pressure regulator that way. I do think that if the pressure regulator is stuck closed, not allowing enough fuel to get to the fuel rails and injector nozzles, it would act just like it is.
Don't you think??
I think the one part, other that the fuel filter, that I could "throw" at this problem is the FPR. Thanks to a picture here I know where it is and just two allen head screws to change. About $45 though. I guess I will order this part and see what happens then. One thing for sure, if I do end up having to take it to the Ford service department, it won't be one of these parts. I will change the filter first and then try to run the truck. Then if no go, the Fuel Pressure Regulator. In this way, if it runs and solves the problem, I would be able to report exactly which part was the culprit. To everyone's benefit.
So, I will order a new FPR and let you guys know what the result is.
Thanks for the help and let me know of any new ideas..

 

I was looking at everything carefully while I changed the IAC valve. Nothing looks loose or off. Not much corrosion anywhere. Some on exposed aluminum parts as is expected. Pretty clean for a 96 5.0 with 145K.
I expect at least 200K from the motor though. Runs great before this wierd problem. I do need to replace the front tank pump/sending unit to get the guage working again. Pricey part and lots of work to get to it..Not been necessary for now.
Anyway, while changing these next two parts, the filter and the FPR, I will check connections again..

 

Thanks for all the help. Keep thinking on it and if you come up with something else, let me know..

 

By the way, after I installed the IAC, just for the heck of it, I plugged up the computer reader and, yup, you guessed it, code "0".
No codes. There are on this 96 of course, only 6 pins to read anyway. But still nothing coming from the computer..