Okay Need Some Help

harmony37659 · December 15, 2008

New here so I hope I'm putting this in the right spot. I have a 89 GMC Suburban R2500 with a 454 eng and a 400 trans. Now what is going on is it has lost it's power. I have check the timing and fuel pressure it is good. When I first start it up and run a 1/4 mile up the road it does good but after that it loses it's power and seems it me like it's loading up. I do hear some noise from under it. I think it may be the trans or exhaust. Any help would be thanksful.

Jason

Mike G · December 16, 2008

When it feels like it loading up, is the motor still operating fine or is it actually the motor (that would rule out tranny). hen was the last tune-up done. Check to see if your wires are arching each other. After that, could be a plugged cat converter.

--Mike (not an expert).

harmony37659 · December 16, 2008

When it feels like it loading up, is the motor still operating fine or is it actually the motor (that would rule out tranny). hen was the last tune-up done. Check to see if your wires are arching each other. After that, could be a plugged cat converter.
--Mike (not an expert).

I have done changed the wires, cap and stuff. Motor seems not to change when it does it. Converter was what I was thinking about next but didn't really know if that would make this happen. Thanks for the help.

Impalacat · December 16, 2008

I've never had a G.M. converter plug up on me, but I used to drive a ford f-350 460 gas at work and one day it couldn't even do 45 mph no matter what, took it to the fleet mechanic,and they had to put a new cat on, ran fine then, that could be your problem.

Mike G · December 17, 2008

...... Motor seems not to change when it does it. Converter was what I was thinking about next but didn't really know if that would make this happen. Thanks for the help.

If the motor does not change, but you are losing power to the wheels, could be something slipping in the trans. If th emotor still revs, i would lean towards trans. Pull the dipstick and look at the fluid. You could also pull the pan and see if you have any metal.

--Mike

harmony37659 · December 18, 2008

yea that's two things I have planed for this weekend pulling the conv. off and the trans pan off. What is killing me is it runs good the first 1/4 mile. Thanks for the help guys. One other thing, when this happen at first I heard a loud pop like hitting a mail box. One thing I found was the fly wheel bolts had came loose and one of them had fell out. I'm hope that was the loud pop I heard. Thanks again.

harmony37659 · December 21, 2008

Well it was the converter.

Alljackedup408 · December 21, 2008

I've never had a G.M. converter plug up on me, but I used to drive a ford f-350 460 gas at work and one day it couldn't even do 45 mph no matter what, took it to the fleet mechanic,and they had to put a new cat on, ran fine then, that could be your problem.

Then you must have never owned or worked on 2000 range grand prix's... lol Them cats are notorious for clogging. Customer comes in and says its slow and wont do over 30-35 lol. I replace one at least once a month