First the truck is VERY hard to start. had my 10 year old key it over while spraying starting fluid in the throttle body (yes, parking brake was on). finally got it going. It only idles at like 500rpm. I can only tack it up to around 3000 rpm before it dies out. it seems like it is backfiring through the intake. I also know it sounds like the general area of the problem is in between the rear of the motor and the firewall. My mechanic already checked the fuel pump, ignition, and timing. Even when i tack it up as far as I can get it, when I put it in drive it just dies out. No, I didn't search through the archives. I'm on 12 hour days with a hours drive to and from work. Just not enough time to do that, sorry in advance. Any and all help is greatly appreciated. Also, thanks in advance. Don't know if this is related to the problem but yes, the rear fuel tank leaks and that pump is bad. I just don't put fuel in it.

 

Spray starting fluid around intake gasket at rear of engine with it running...sounds like a gasket leak/hose cracked to me...

 

how would I be able to tell if it's a burnt valve or a vac leak?

 

Ford Fuel Injection » How To Run a Self-Test Here is a link on how to check for any trouble codes that might be there, might be worth doing even if no light is on.
If you can keep it running at a steady idle and spray starting fluid as stated, you will hear the engine change note if some of the fluid is sucked in through the vacuum leak.
Ask your mechanic what fuel pressure readings he got.
Also check for a restricted exhaust (plugged cat).

 

vacuum gauge. if all stock and no vacuum loss it should be around 20 hg. How to Use and Interpret a Vacuum Gauge this link was given to me by another member. it has helped me and gave me some insight on vacuum

 

My mechanic now says it's not a vacuum leak. now he is saying that the injectors are not working properly. what could cause this to happen? would it be a module or a computer problem? he told me he cranked the hell out of the thing and the plugs were not even a little wet. but the fuel pressure is good.

 

A bad PIP can cause the injectors to not fire. The PIP signal triggers the ICM to fire the plugs and injectors via the PCM. The signal can be weak enough to trigger the spark, but not enough to fire the injectors. And yes it can be very thermal in nature.

It is very easy to check for the injector trigger signal by using a noid light on an injector or two. If it flashes when you crank the engine then you know the PIP is good, if it is does not then you know what you are working with.

One caveat to be aware of. If the TPS signal indicates wide-open throttle when starting the vehicle, the PCM will not fire the injectors. It's a feature built into the PCM to allow the user to clear a "flooded" condition. Simply unplugging the TPS connector will eliminate that possibility. Verifying the output signal with a DVM would also work.

 

thanks rla2005. I'll have my mechanic check that out. he does not have a clue right now what it is. he is thinking a module or the computer.