95 Chevy Suburban won't run very good

[btroy]

Hi guys, so I am trying to help my friend on his 95 Chevy Suburban.
5.7
TBI
200k

No lights on the dash like check engine soon or any other diag lite.

Issue: Trunk starts ok but then when you get up to aronud 1200-1500 rpm it starts cutting off. Runs better cold then warm.

We thought this was an electrical issue so he started throwing money at it. .

The following has been replaced: distrib cap,rotor, ignition module, primary and secondary coil. Plugs and wires. fuel filter has been replaced. Timing mark is set to 0 and when a light is on it he sees it start jumping around alittle then back to 0.

Now I am thinking it might be fuel issue. Maybe a bad fuel pump. Not real sure. Anyway is there a test for fuel pump for the correct presure?

Any suggestion would be greatly appreciated.

[tempfixit]

Here is a thread with a very good fuel pressure testing procedure by MT 2500, read post # 10:

http://www.automotiveforums.com/vbul...+pressure+test

Hope this helps

[Elbert]

I would check the fuel pressure as suggested. Still no codes? Did you guys check the base timing? 0 degrees with the wire unplugged? Set at zero with wire unplugged. Turn truck off, reconnect wire....disconnect battery for about 5 min to clear codes, start engine.

I'm betting its the fuel pump. This issue just started out of the blue with no other repairs or issues?

[jdmccright]

This may sound strange, but I had similar probs with my truck (same engine and mileage). When cold it would pull good at any rpm. But as it warmed up, it would bog down and nearly stall if I tried to accelerate from 1500-2000 rpm. The IP engine temp gauge would also swing wildly from 160-230 degrees. Once the truck got good and up to "normal" temps the symptoms would die down but not go away completely. Temp gauge would still give wide-ranging readings as the thermostat(?) open/closed.

I replaced the engine coolant temp (ECT) sensor, thermostat, and heater core, but this did not help. However, when doing this I had to drain the coolant and it was very dark and rusty (not my doing...bought it as a project truck). So, I installed a flushing tee and gave it a GOOD flush. Then I refilled with water and added 2 jugs of Prestone Super Cleaner (need 2 since 1 only treats up to 12-qt capacity). You can run it for 3-6 hours over several days to let it work. I've yet to drain it again, but the temp fluctuations have stopped and the bogging down during acceleration has gone away.

I also notice some oily sheen on top of the drained coolant and my oil is down since I changed it (though not milky thank god!), so I have a new radiator coming. That along with changing the intake manifold gaskets should finish it up.

Not sure if everything applies to you, but it's a different possibility I've recently experienced.