Won't idle

Propane, Butane, LPG, GPL, C3H8, C4H10
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Sopp
Posts: 3
Joined: Thu Aug 24, 2023 4:07 pm

Won't idle

Post by Sopp »

I'm new to propane and IMPCO products ( also this forum ). IMPCO 425 on a slightly built up Ford 302. Starts great but jumps up to about 3000rpms immediately. All 4 butterflies are closed properly. Has not been started in about 2 years, stored indoors, and ran great last time I started it. Searched this forum for answers to this problem but did not find anything directly addressing this issue. I'm betting it's something real easy that I'm just not seeing.
Any and all help will be greatly appreciated.

Sopp

Sopp
Posts: 3
Joined: Thu Aug 24, 2023 4:07 pm

Re: Won't idle

Post by Sopp »

Come on guys ( and gals ), 33 views and no responses. Someone out there must have an idea of what my problem is. If I push the button on the top of the mixer, it will slow and then kill the engine. Can't figure where the air is coming from to make the engine rev like that. All 4 venturis are closed, pcv valve is working properly, and I'm baffled.

Is propane different than gas as far as the amount of air needed to make it rev up like that? I started it several times and it did the same thing each time. Is there other info that you need to help solve this?

Sopp

Tom68
Posts: 74
Joined: Mon Jun 18, 2018 2:46 am
Location: Australia

Re: Won't idle

Post by Tom68 »

Brake booster line and booster diaphragm OK ?

Sopp
Posts: 3
Joined: Thu Aug 24, 2023 4:07 pm

Re: Won't idle

Post by Sopp »

Thanks for the suggestion, Tom. I disconnected the line and plugged it and started it again-----------------right up to 3000rpms. Checked all the other ports on the carb and all are capped off.
I will recheck everything again tomorrow for any leaks.

Sopp

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