# 68 GTO Engine racing when starting up



## mwatson1647 (Feb 27, 2012)

Hello, Have another question about our 68 GTO. When we start it up, the engine RPM is way up and doesn't drop down when I pump the accelerator even after it's been running for minute or more. If I turn off the ignition, and then restart it back up again right away, it starts up fine at the correct RPM around 750. Does anyone have a suggestion if there's something on carb that should be replaced or cleaned that would be causing this? Thanks.


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## jmt455 (Mar 26, 2012)

Sounds like the choke is sticking, keeping the carb on the high-speed idle setting.

OR, the idle stop solenoid that is not adjusted properly or mis-wired.


What carb is on this engine?
Does it have an electric choke?
Is there an idle stop solenoid?


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## mwatson1647 (Feb 27, 2012)

The carb is a Rochester 4MV Quadrajet. The engine is a 350hp, 400ci, Manual Trans, no A/C, no power brakes, no power steering. I quickly looked into the Service Manual, and didn't see anything about an electric choke or an idle stop solenoid for that carb, but I could have missed that or there no related procedures for either of them. My wife is the original owner and there was no special options on the engine other than what was standard for the GTO The only special option on the car is it's a convertible. Anyway, I'll post a reply what I find out. Thanks again for all your help. It's really appreciated


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## eeyore (Oct 23, 2014)

Check the choke pull-off operation.


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## Matthew (Feb 11, 2011)

The choke and high idle cam should come off after a few minutes, but depending on the temp, that could be 5 minutes or more. It sounds to me like the high idle cam and choke are not stuck, because you say if you shut it off and restart, it runs around 750 rpm. What you describe sounds normal to me unless after 5 plus minutes the high idle cam does not step down. Matt


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## mwatson1647 (Feb 27, 2012)

Matt, Thanks for the reply. When I first start it, the idle seems to be much higher than I would expect even with it being cold. I understand what you are saying, but at the speed it's running I would think it would be warm enough to settle down before I have to stop and restart it. After it has run for a while (e.g. a minute or two), even if I quickly pump the accelerator, it doesn't back down, sometimes seems to make it run faster. The speed isn't dropping down on it's own while it runs, only when I stop and immediately restart after it has run for a few minutes is it down to the proper idle RPM. Thanks.


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## Matthew (Feb 11, 2011)

The choke thermostat and fast idle cam work in harmony, so if it is not working properly, it is right in that area of the carburetor. As JMT said, it could be the choke is sticking. Use carburetor cleaner on the linkage area (right side). Matt


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## mwatson1647 (Feb 27, 2012)

Thanks Matt, I'll give it a try.


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## geeteeohguy (Feb 2, 2008)

Check the fast idle cam for binding. Check the pull-off, too. Not uncommon.


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