Wont rev past 2500

Magiarn · #1 03-03-2006, 12:26 AM

95 GM 350 TBI. Coasting to a toll booth, clutch in, engine stalls so I dump the clutch and jump start it. 3 minutes later I realize it starts to chug and wont rev higher than about 2500, coincidence I think not. I thought the converter was plugged/blown out because it had done that same thing before. Last night I took out they-pipe to find NOTHING inside the cat. Took off the muffler to see if the insides were blown into that and it was clean. Checked ignition timing with ect off and its at 0 (supposed to be, but I have a timing adjuster in the vehicle also). The only engine code I get is "ect short or disconnect at engine run" which is obviously from when I checked the timing. It only does it when it warms up; I adjusted roller rockers again that I installed a month or two ago, took off and it was fine for three blocks, then nothing after about 2000-2500. I unhooked the MSD box and reconnected the stock ignition, same thing. Anyone got any ideas what else could cause this?

maxwedge · #2 03-03-2006, 05:02 PM

How about fuel pressure? Both injectors spraying?

Magiarn · #3 03-04-2006, 05:10 PM

I dont have a way to measure the fuel pressure, but both were spraying. I swapped out the TBI with a holley 670 TBI I had and it made the problem less significant. It revs higher but still seems to struggle a bit. I'm thinking fuel pump and/or vacuum leaks.

horse482 · #4 03-04-2006, 06:38 PM

Have you checked to see if your egr valve is stuck open? When was the last time you changed the fuel filter?

Magiarn · #5 03-05-2006, 04:26 AM

As a matter of fact, I just got a new filter today and before installing it I was going to turn the key on with the old filter off with a hose attached to the line to flush it out. A buddy of mine has a Yukon and the line behind the filter was full of crap, causing similar problems. I'll check the EGR too, its about the only thing I've never replaced since I've owned it!

Magiarn · #6 03-07-2006, 06:14 AM

Changed the fuel filter AND the EGR valve, no change. Fuel pump?

maxwedge · #7 03-07-2006, 07:19 AM

Still haven't done the basics, checked the fuel pressure?

Magiarn · #8 03-07-2006, 10:35 AM

What do I need specifically to check it? Whatever it is, its one of the tools I have never used. Is there a gauge that can be stuck where the filter is to test it?

Magiarn · #9 03-10-2006, 10:22 PM

OK, so I found a pressure tester and it DOES connect where the filter is. The pressure KOEO is about 10psi and when the engine is running its about 14 psi. If I let it sit, it goes to 5psi in a few minutes...

2000CAYukon · #10 03-11-2006, 12:59 AM

I had a late 70s Celica in college that blew a converter into the muffler. It was never the same and had to replace the muffler.

You should take the muffler off and drive to see if that is your problem.

You posted that you adjusted the valves. Where they adjusted before when the problem started?

I think you either jumped a tooth on the timing chain or you have an ignition problem. Pickup coil, ignition coil or ignition module.

I recently did the chain on my 90 K1500 (115K Miles) and the chain was very loose. You do need a harmonic balance puller/installer to do the job; otherwise, not a hard job.

//2000CAYukon

Magiarn · #11 03-11-2006, 05:08 AM

Drove with only the Y-pipe and had the same problem.

The valves were adjusted when the rockers were put on, and it was running fine, even though one had a slight tap.

I have a gear drive, so I dont think it skipped. I have a new MSD coil and box, which were working fine before. I swapped back to the stock components and had the same problem.

2000CAYukon · #12 03-11-2006, 02:45 PM

Quote:

Originally Posted by Magiarn

Drove with only the Y-pipe and had the same problem.

The valves were adjusted when the rockers were put on, and it was running fine, even though one had a slight tap.

I have a gear drive, so I dont think it skipped. I have a new MSD coil and box, which were working fine before. I swapped back to the stock components and had the same problem.

The pickup coil is inside the dist and performs a similar job that points did and they are known to go bad.

The fuel pressure looks good but did you what the pressure while the problem was happening?

Have you run a compression check?

//2000CAYukon

Magiarn · #13 03-11-2006, 03:22 PM

Quote:

Originally Posted by 2000CAYukon

The pickup coil is inside the dist and performs a similar job that points did and they are known to go bad.

The fuel pressure looks good but did you what the pressure while the problem was happening?

Have you run a compression check?

//2000CAYukon

Compression is 180 on all 8.

Those are the pressures I was reading and was having the problem, still do.

I will check about the pickup coil, but I would think that if it was that the problem it would be all the time, not just after running awhile.

Thanks.

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