Hello all, newbie here with a problem. My '94 F150 302 auto won't start. Turns over fine, got good spark. I put in a new front gas tank and new fuel filter on the frame rail. Both tanks have gas in them and both fuel pumps run when you turn the key just never fires. The only thing I notice is that there seems to be no pressure in the fuel rail when you depress the schrader valve. What provides the pressure? It is just from the fuel pump in the tank? Thanks for any help.

 

The fuel pumps in the tanks.
YES

Does the fuel pumps run all the time the key is on with the engine not running?

 

No only when you first turn the key on.

 

You may not be pushing the inter pin in the valve on the fuel rail (manifold) down far enough.
You should put a fuel pressure gauge on the fuel manifold and ground pin #6 of the self-test connector and turn on the key.
The gauge should read about 42 PSI and the pumps will be running with pin #6 grounded.

 

I will have to go buy a fuel pressure guage and check it. Does the fact that the pump shuts off mean that it is coming up to pressure? I did reuse the old pump and sending unit when the tank was replaced. It did run for a while after the tank was swapped but always started hard. Seemed to get a little better after changing the filter.

 

No it does not. The PCM will turn off the fuel pump in one second if it does not see a PIP pulse in the one second time out. Has nothing to do with pressure.

I would say you have a bad fuel pump in the tank(s).

 

If I swap to the rear tank shouldn't it start and run from that tank?

 

If the front is bad and the rear has a good Fuel Delivery Module (FDM) it may or may not depending on what is all wrong with the front FDM.

If the rear pump is free pumping into the front tank with no head pressure then there may not be enough pressure to start and run the engine.
That is where the fuel pressure gauge comes in, you have to know what you have so you know how to go at the problem.

There is an outside chance if you do not use the rear pump the rear FDM may be bad also or it may be why the front is not pumping the pressure up.

 

Your Fuel System:
http://i54.photobucket.com/albums/g9...FuelSystem.jpg

The FDM:
http://i54.photobucket.com/albums/g9...yAssembly2.gif

The FPR:
http://i54.photobucket.com/albums/g9...eRegulator.jpg

Fuel Pressure Gauge:
http://i54.photobucket.com/albums/g9...P0L_SS500_.jpg

http://i54.photobucket.com/albums/g9...ssureGauge.jpg
/

 

I got the pressure guage. Where do I find the self-test connector and is pin 6 labeled? Can you post a picture? Before I put the pressure guage on the truck I tried starting it and it started right up and ran. I drove it out of the garage and to the end of my private road and turned around and drove it back and backed back in the garage. It ran fine no skipping or anything ran smooth. After backing in the garage I revved the gas slightly and it responded fine so I tried turning off the Ignition and restarting the truck. No luck! It won't restart. Can this still be fuel pressure. Thanks for all the help.

 

Do you have spark when it does not start?
Does the fuel pump run all the time with the key on when it does not start?
Also find out if you have fuel pressure when it does not start.
Let us know what you find out.

Here is a diagram of the self-test connector and with pin 6 labeled.

 

Labeled Diagnostic Self Test Plugs in the diagram below.
The location of the self-test plug:

 

Is the self test connector located under the hood? Is it labeled EEC Test?
Yes I have spark when it won't start and no the fuel pump does not run longer than a second or 2. Once I locate the self-test connector I will measure the pressure and post the results. Without grounding pin 6 it reads zero pressure.

 

Yes see above diagram.
YES

 

Thanks. I posted before I saw your second diagrahm. OK I found the connector and pin 6 and did the pressure test. Unfortunetly it doesn't read any pressure 0. Never moves the needle in the gauge. Just so you know I bought the exact gauge you sent in the picture. Does that mean the pump is shot? Why did it start earlier? Does the rear tank pump into the front tank? I got zero pressure on either tank.