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Engine fuel cut when reved above idle
Topic Started: Nov 5 2016, 11:23 AM (661 Views)
houdini0118
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So I have been working on one of the verts that i have yet to get running properly due to a loss of another car( i will post pics of that later). I still cant figure out what is going on though. The engine fires right up and runs fairly well at idle but when i open the throttle it pulses at about 2 second intervals. So it revs up and dies down continuously. looking in the throttle body it looks like when it dies down that it is cutting off the fuel entirely. Any idea what could cause this? It has good fuel pressure(40 psi)
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freegeo
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houdini0118
Nov 5 2016, 11:23 AM
So I have been working on one of the verts that i have yet to get running properly due to a loss of another car( i will post pics of that later). I still cant figure out what is going on though. The engine fires right up and runs fairly well at idle but when i open the throttle it pulses at about 2 second intervals. So it revs up and dies down continuously. looking in the throttle body it looks like when it dies down that it is cutting off the fuel entirely. Any idea what could cause this? It has good fuel pressure(40 psi)
Check the tps to see if it needs adjusted. Don't make any adjustments unless voltage readings indicate it.

Since you have a 94 do you know if you have standard emissions or upgraded? That may make a difference how to check it.

Upgraded emissions would look like this. The black thing (ISC) behind the throttle body.

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Metromightymouse
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Powdercoat Wizard

He said it was one of the verts, so I don't think it's the car in his profile, or a 94.
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freegeo
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Metromightymouse
Nov 5 2016, 12:06 PM
He said it was one of the verts, so I don't think it's the car in his profile, or a 94.
Thanks MMM. I'm brain dead today and didn't catch it.
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houdini0118
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Yea this one is a 91 vert not sure if it is any different i did measure the resistance across the tps and it changes like it should. unplugging the tps seems to have no effect.
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freegeo
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I can post the procedure later for how to check it.
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houdini0118
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Would that cause this issue i had the tps off when i switched throttle bodies but the other tps had different connector so i kept the old one and lined the marks back up
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Metromightymouse
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freegeo
Nov 5 2016, 12:32 PM
Metromightymouse
Nov 5 2016, 12:06 PM
He said it was one of the verts, so I don't think it's the car in his profile, or a 94.
Thanks MMM. I'm brain dead today and didn't catch it.


:thumb kinda figured

houdini0118
Nov 5 2016, 01:33 PM
Would that cause this issue i had the tps off when i switched throttle bodies but the other tps had different connector so i kept the old one and lined the marks back up


Yes, absolutely, sounds like a likely cause, etc.
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freegeo
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40 psi is too high. How are you checking the fuel pressure?
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houdini0118
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Harbor freight fuel injector test gauge T fitted into the fuel supply line.
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freegeo
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houdini0118
Nov 5 2016, 10:39 PM
Harbor freight fuel injector test gauge T fitted into the fuel supply line.
Was that with the engine running or with the key in the on position and engine off?
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houdini0118
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Key in the on position engine not running. I think it was bouncing around 30ish with it running but i am not sure about that.
Edited by houdini0118, Nov 7 2016, 10:52 AM.
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freegeo
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houdini0118
Nov 7 2016, 10:52 AM
Key in the on position engine not running. I think it was bouncing around 30ish with it running but i am not sure about that.
That's to high. Either the gauge is off or your fuel pressure is actually too high.

That shouldn't cause the surging your engine is doing.
Edited by freegeo, Nov 7 2016, 01:16 PM.
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freegeo
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Is your car a manual or auto trans? Once I know I can post the procedure for checking the tps.
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houdini0118
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auto. Its a brand new gauge and it seemed to move freely and it leaked down over several hours to 20 psi before i stopped working on it for the day.
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