1987 Blazer, Fuel Injected, 350 V8

When I first start the engine, theRPM's jump up over 2000 and stays there until you put it in gear. Then, when you stop at a light, it doesn't go below 1000...then when you put it back in park, it goes back up over 2000? This is a new development...it didn't do that when we bought it. Any ideas why it would suddenly do this?

 

Sounds like you have a vacuum leak. If you have a regular propane plumbing torch, turn on the gas, but leave it unlit. Trace around the intake and all vacuum lines with it. If you hear the idle increase, then you've found your leak. Be especially critical of the throttle body gasket as these engines have problems in that area.

 

I have this same problem so you are not alone

I cleaned all the sensors with electracal cleaner and that fixed it for a couple of days...then it returned.

So I am going to check for a vacuum leak this time...You can try cleaning up the MAP sensor...

 

First, thank you very much for your response, it's really appreciated! Second, I don't have a torch, are there any other ways to determine if is a vaccuum leak for sure?

 

You can get some carb cleaner and spray it on the various components on the intake, but be careful and do this only with a cold engine. But carb cleaner won't be kind to old rubber parts in the long run. Spraying it around the base of the throttle body shouldn't hurt anything.

You can generally pick up a cheap propane torch for $15-20 at Walmart... I'm not talking about the cutting steel type torch, just the hand held plumber's type torch. I have two, one cheapy that I use as a fire starter in my burn barrel or fireplace. My other one is my MAP gas torch I purchased for doing the plumbing in my house, but it now gets used in the garage for heating bolts, etc.

 

Yea just a Bernzomatic type....wont be more then $15-$20