Are you thinking the timing chain jumped? What psi should I get on a compression tester? Thanks

 

Anything is possible.

Every engine is different, but it should be somewhere north of 150psi.

 

Thanks I'll try to give it a check tomorrow. Do I need to check all cylinders or if the timing is out will it show by checking one? Thanks again

 

and they should all be within 8% of each other.


so that tells you right there that all cylinders need to be tested.

be sure to disconnect your coil wire when you do the compression testing.

 

Yes, test them all and compare them. Could reveal something else. At the least, it will give you an indication of the health of your motor.

 

Ok I've been really busy at work and haven't had any time to work on the truck. I did take a few minutes before it got dark and quickly checked one cylinder. The number 5 cylinder was about 160psi. I know checking only one cylinder doesn't mean much, but I thought I would let you guys know.

Also what really concerns me is noticing something else. Before the test I got it to start for a minute and all it would do is the usual 200 - 1000 rpm surge and wouldn't rev at all. When I took the air intake off the throttle body with it running it sounded like the engine would suck and then push air back through the throttle body! I'm not sure if it's just because of the surge that makes it sound that way but, it's pretty loud. It sounds like it will suck air and start to rev and then push it back out and almost stall, and then cycle over again.

Any thoughts?

 

I would expect all kinds of weird things to happen if you remove the intake duct work with the engine running. When you remove the duct work, the MAF can no longer read all of the air flow going through the throttle body. If you disconnect the MAF sensor and then remove the duct work, there should be no adverse effects.

 

I did unplug the MAF before I pulled the intake off the throttle body.

 

I have a 98 GMC Sierra 2500 with a 5.7 Vortec. One day while driving home the radio quit and the truck drops into 2nd gear and was stuck at 1800 RPM. I had no control over the throttle but was able to limp home.
I shut it off and tries restarting it but all it did was crank over. I called my machanic buddy and he said it was a bad alt. and my battery wasn't strong enough to let the computer fire it up.
I tried jumping it and all it would do is start and die. So I replaced the alt. and jumped it again and everything was good.
Long story short make sure you're battery is strong and that it's not a fault in the elc. system. Worth a quick check.