Caburator Problem, Fast Idle When Warm

rightrev · Post by **rightrev** » Fri Jun 09, 2006 5:37 pm

O.K., I have a 1976 Fiat 124 Spider (California). Stock carburetor.

When I start the car it idles properly (850-1000 RPM.) When it gets warm the idle increases to 20,000 and then to 30,000.

The accelerator cable looks fine and is not sticking. Iâ€™ve tried spraying the linkage with carburetor cleaner and the problem corrects itself. However, after about 45-60 minutes of run time the idle starts to creep up again.

Any ideas?

-The Right Rev

jacksplace · Post by **jacksplace** » Fri Jun 09, 2006 7:54 pm

Looks like you've found the problem but haven't yet conquered it. Look closely at that cable and the linkage and find out what is either sticky or kinked. (probably dry and sticky).

So Cal Mark · Post by **So Cal Mark** » Sat Jun 10, 2006 3:12 am

if you think it's the cable or linkage, disconnect it and see what the idle speed is. Then check the fast idle cam, make sure it drops off when the choke opens (it does open doesn't it?)

Jim DeShon · Post by **Jim DeShon** » Sat Jun 10, 2006 1:26 pm

I have not seen this on Fiat but on some other makes where air leaks develop as the engine warms up and things expand. I have a Porsche 914 in my shop right now that was doing this badly before we tore the engine down. We'll see what happens when we get it back on the road. Sometimes this is around the throttle shafts if the carb is worn. Sometimes in the intake track somewhere. For this to happen, some kind of enrichment must also be present (in the 914, Bosch D Jetronic enriches on low vacuum). Just something to look into. ...J.D.

So Cal Mark · Post by **So Cal Mark** » Sat Jun 10, 2006 2:37 pm

Jim makes some good points-you may have a huge air leak but the choke may be limiting the amt of air until it opens up. How does it run cold?

rightrev · Post by **rightrev** » Mon Jun 12, 2006 4:28 pm

It runs fine cold. However, here is another interesting item that may help troubleshooting.

I'll be experiencing the fast idle problem, and then take it on the freeway. Then, when I come off the off ramp and down shift to 4th gear and slow down almost to a stop, it idles at the normal speed. Then, as soon as I start going again the idle goes back up to around 20.

So Cal Mark · Post by **So Cal Mark** » Mon Jun 12, 2006 6:56 pm

have you checked for looseness in the throttle shaft?

Caburator Problem, Fast Idle When Warm

Caburator Problem, Fast Idle When Warm

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