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Junior Charter Member
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Discussion Starter #1
I have been doing a lot of lurking and reading and have solved a lot of problems by reading this forum, but this is my first post.

I am looking for some thoughts with respect to what I might want to check next to fix an engine stalling problem. Here are the issues, and what I have tried.

Engine - 1988 302 speed density, no PS, no A/C, using stock engine computer and harness

The engine will start although not reliably. When it does start, it will run briefly, and then stall out. I can get the engine to run by disconnecting the vacuum tube to the MAP sensor and closing it off so there is no vacuum leak, which causes the engine to idle rough, and run rich since the computer is dumping full fuel. As soon as I reconnect the vacuum line to the MAP sensor the idle smooths out, the engine runs for a few seconds, and then stalls out. It is like the idle is just set too low, but I have played with the idle screw and it does not help. I have also tried different idle air motors and they have not helped.

If I blip the throttle during this process the engine does not rev instantly, but does eventually surge.

There is no valve on the fuel rail to check fuel pressure, but I am assuming it is good, since I can get it to run ok if i let it run rich.

I have checked the engine for vacuum leaks with an air compressor and it holds plenty of pressure. I have also replaced the MAP sensor thinking it was bad. I have replaced the fuel pressure regulator and the intake air temp sensor as well. I have checked the voltage on the harness side of the TPS and it also seems within spec.

Spark plugs are properly gapped and the wires are run correctly. Timing is set correctly. The Salt and Pepper shakers seem to be in good condition.

I have done a lot of reading on fordfuelinjection.com and feel like I Have tried everything.

Anyone else have issues like this or any thoughts on what else to check?

Thanks,

Brian
 

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Official OLD GUY
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3,843 Posts
Codes?

If you have access to a code reader, that will help point you in the right direction. Codes will help you diagnose any issues with your sensors. Also, make sure your TPS is set correctly to .95 to .96 volts. Do a search for how to properly set the idle speed and check timing. All of these, if not set right, will prevent you from getting it to idle or run.

HTH

Doc :beerchug:
 

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Junior Charter Member
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2 Posts
Discussion Starter #3
There is no valve on the fuel rail to check fuel pressure, but I am assuming it is good, since I can get it to run ok if i let it run rich.
Turns out this assumption was where I went wrong. Have a buddy with the hardware to hook up a pressure tap between the rail and the supply line, and was finally able to check fuel pressure. Old fuel pump was only putting out 5 PSI of pressure. Apparently this is enough pressure to allow the engine to run rich at idle. Swapped in a new pump, 40 PSI, and the car runs great. Just need to put some clean plugs in the car since the old ones are so badly fouled.

Really happy I left myself access holes to the fuel pump and level sender when i put the trunk sheet metal in!
 
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