[jmrylands]

Thanks in advance for any help. I've been on a bunch of blazer forums with no help. I just acquired a 99 Jimmy. It has a rough idle and check engine light on. Checked some things out, plugs and wires are good, cap and rotor could be replaced. Oil was good, no water in it. Got the codes pulled off of it, they were, p0301 and p0452. I am sure the spider injector is working fine as you can smell the unburnt gas and the plug has gas on it when you pull it. Did a compression test on it and cylinder one had about 40psi and the rest had around 150psi. Is this more than likely a bad head gasket, or burnt valve. Is there an easy way to find out which it is, or does the head have to come off to find that out. I'm trying to spend as little as possible on this as I need to sell it for a wood hauler. Thanks again for any help.

 

[bobfig]

if i remember right in that cylinder put some oil in it and re-due the compression test. if it bumps up pressure it would be the rings giving problems. if its the same then the problem lies in the head some where.

 

[jmrylands]

Thanks for the reply, I had read to do that but forgot. Is that common issue with these motors. I'm not familiar with them. I was expecting the spider injector to be bad to be bad, not really low compression.

 

[bobfig]

well you need to check the fuel pressure and possibly bleed off of the fuel. but with having 1 cylinder that low on compression i would head that way first.