Car shuts off under throttle, idles fine. Looking for some pointers.

rmarcotte

New Member
Jul 8, 2023
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Good day, Friends!

I'm new here, so please forgive me if I am doing something wrong. English is my native tongue, and I am not on mobile...spelling mistakes are my own, so I cannot blame the phone.

I'm hoping I can get some pointers in to what to try with my 2000 GT, 5spd. I've gone over many post, but don't seem to see one with what seems like the same issue as mine, and it has me stumped.

It starts and idles without issue, no surging or wandering RPM, but the idle does seem a wee bit lower than normal. If you give it any throttle, it will bog down, and likely shut off. It will do this with everything turned off in the car, turning on things inside the car (AC/Heat) changes nothing. It's similar to a cold carbed engine running without choke.

So far, I've tried:

1) Cleaned all sensors I could with carb cleaner, nothing looked dirty or broken. Connectors were cleaned with electrical contact cleaner. Nothing looked corroded or out of place.
2) Went over the vacuum hoses, they all seem fine/clean.
3) Replaced plugs/wires. Cleaning the coils and adding dielectric grease to the boots. There was a noticeable difference in how it ran by unplugging one coil at a time.
4) Removed and cleaned IAC (the gasket looks a little brittle, so I temporarily added some gasket maker to see if anything changed, it did not). Going to replace it this afternoon.
5) Replaced the fuel filter.
6) Checked all ground wires in the engine compartment, which look ok.
7) Removed and cleaned each injector. With no other way to test, other than listening for them clicking, the seemed clean and in good shape.

Things to note so far, that I've noticed, but may not mean a thing to a trained pro.

1) It has new gas in it, and I only ever use high octane. I've owned it for 7 years, during which it is very well maintained, and never driven very hard (135k on the odometer).
2) I suspected the fuel pump at first, so I bought myself a gauge to test the pressure, and when I attach the gauge, I notice that if I turn the key position to ON to prime, it will get to about 20psi, if I cycle the key again, without starting, it will jump to about 40psi. The car will show between 40-50psi while idling. I am unsure about the pressure while driving, as I cannot use it with the way this gauge is setup (hood won't close).
3) If I am driving and push the throttle more to make it bog down and shutoff, it will not start again until I turn the key position to off, then back on, which tells me it could be something electrical, maybe?
4) The check engine light is not on, and my code reader shows no codes present. (Test ID $53 will show misfires, but general misfires, not under any specific cylinder).
5) Voltage from the alternator is fine.

If you would like more information, and want me to try certain things, please ask/post away. I am very familiar with using a multi-meter, so don't hesitate to ask for readings off anything, I will do anything you suggest, as I am the one here asking for help and appreciate anything you have to add here.

Thank you, very much, for reading, and thanks in advance for any and all suggestions/contributions.

Rick
 
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If it idle without miss then it seems fuel related....my bet is fuel pump since there is no codes....also check the fuel lines from front to back...make sure nothing is damaged.....could be computer but try the pump first...

ED
Thank you, I am going to replace it this weekend, as that is my suspect part as well, everything else seems to be operational and within spec. I will report back.

Rick
 
Also chech MAF meter... unplug and see if it idles and can rev....if it does plug back in and try again...
After I replace the pump, a friend has offered to loan his spare to test, if it wasn't it. I thought the pump was going to give issues soon anyway, as it's made a few odd noises over the last few weeks. It's not a loss if this doesn't sort it (And a great chance to show my son how to do it...win win).

Thanks again for the pointers.

Rick
 
Reporting back...Sorry I took so long to respond, I've been dealing with Napa and wrong part deliveries. I am happy to report that it was indeed the fuel pump. I replaced the pump and it fired right up, with no cutting out or loosing power.
 
Update #2.

It seemed to work, but I notice the pump is still making noise, and on my way home last evening, it bogged down and shut off again. I suspect the pump driver module, and am going to replace that in about an hour. I will report back with my findings.

When it bogged down and shut off, I checked the fuel pressure at the rail, and there as none whatsoever.

Wish me luck ;)
 
Doesn't sound fun brother.... please let us know if this works.... there is also a fuel cutoff switch or reset in the trunk on the DS behind the light area... check to make sure this switch is working or tripping.... I haven't really had any issues like your describing before so knowing the issue and fix will help others with future reference...