90 454 dualie engine problem

[Mudstud]

Posting for a friend.
1990 Standard cab 454 TBI Auto Tranny 2wd with about 300,000 miles.

Problem- starts fine but stalls if foot isn't on the gas. Give it gas and runs normal. Just won't stay running unless you give it gas.

• He has put in a new distributer, points/condenser, button and cap.
• Has replaced both the electronic deals on the passenger side of the throttle body.
• Has replaced vacuum lines and hoses and has tightened down the TB.

Says he's made sure fuel is getting to engine. Obviously cuz it will run.

Any thoughts on what to check next?

Thanks.

 

[dyeager535]

ECM temp sender, ensure no vacuum leaks, and that the plugs/wires are in good shape.

 

[Mudstud]

thanks. I'll talk to him tonight about it.

 

[Mudstud]

Didn;t talk to him last night but another guy said it could be the Accelerator Control module. Wasn't sure of the exact name. Thoughts? Where is it located?

 

[dyeager535]

No such thing as an accelerator control module on that truck AFAIK. Perhaps he meant flux capacitor?

Maybe he meant TPS, but the systems aren't so dumb as to not try and keep the vehicle running if possible, and TPS isn't necessary for the thing to keep running.

 

[Stomis]

Dont just randomly replace things. Get a cheapo multi meter and some paper clips and check that the sensors are putting out the right resistance. Did he check the fuel pressure regulator? Just because its getting fuel doesnt mean its getting the right amount.

 

[Mudstud]

Just because its getting fuel doesnt mean its getting the right amount.

What would/could cause it to not get the correct amount at idle- The regulator?

 

[blazinzuk]

I have had a bad fuel filter cause this problem before, on a totally different truck. pull the air cleaner and watch the spray out of the injectors.

 

[static1]

Id have to second the fuel filter. Also maybe pump issues? Is it the original fuel pump? Maybe check the volume that the pump is putting out. Or if you have a preasure guage to hook into the line at the filter. just some ideas.

 

[Mudstud]

FYI- talked to dude last night and he showed me the timing gear. It was WORE out. It had or was about to jump timing. He was wrong on the milage on this engine. It is over 400k. He's puttin it back together now. Guess who helped him diagnose the problem . . . come on guess; a guy at Auto Zone. Told him some tricks to test if that was it and sure enough was right on the money.