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I bought an 1988 Z24 2.8L last year previous owners says it had 20000 miles. Looks real clean might be possible. Anyway I've tried looking for a solution to my problem but not having much luck. If I let the car sit a day or two , when I start it up it starts, then stumbles and sometimes stalls. When it recovers it idles high for a second or two then comes down. I have checked the fuel pressure, when I turn the key on I can hear the pump and the pressure is about 42lbs after it runs it's about 37/38 lbs. Also sometimes for the first 20 minutes there is a slight hesitation when I press the gas then seems to go away. I also checked the IAC valve and replaced the air temp sensor in the air filter canister. Any ideas?
 

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Hello, have you checked for any possible vacuum leaks any wear? being 30+ years old they usually crumble. You wont always hear the leaks, but I've used carb cleaner and sprayed carefully around the top of he engine. It would idle high fast when ya spray carb cleaner, finding your leak. ( if you knew or not)

possible plenum gasket...from what ya posted, does not seem to me a fuel issue. :guns:
 

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My 1989 with 70k is left at vacation house for summer use. It was running rough after starting, and then stalled. Seems like it wants to run, but will sometimes start and then will stall out after a few seconds of running.
Towed to shop to diagnose. They have replaced the engine temp sensor, plugs, wires, fuel filter..( good pressure at fuel rail)
Car still stalls and they are having trouble keeping it running....

Vacuum leak is a possibility from the info above posts?
Need help.
Thanks,
 

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well...The shop you took it too seemed to have thought of the basics, of issues causing your problems. Years ago when I bought my 1989 z24, It would start and die right after. maybe 2 seconds run time. I bought fuel pump ,tune up ,temp sensor, etc..( I was 24 and learning still). A friend of mine who was just smart in general said to test the resistance on my fuel injectors. well I found 2 that the resistance was bad. suppose to be around 11-12....and I had one at 4.9 and another at 6.0 ... replaced and the car ran great.....

other problem I was told....ignition control modules.....I know they commonly go...But was told by a guy who had a 87 z24.....oem ( gm) modules are best...he had trouble with a few aftermarket ones....gm are around $350 though at dealer :guns:
 
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