95 Chevy Silverado low power, bogging down.

Asked by Feb 07, 2017 at 06:52 PM

Question type: Maintenance & Repair

I've got a 95 Silverado 2500, 250k miles. Runs like
crap. Does great when idling, rpms wrap up and
sounds good. However, when driving it won't run
well at all. It bogs down like the engine is choking
or not getting gas. Even when flooring it, it just
slowly gets up to speed, spitting and sputtering the
whole time. Even when it's at cruising speed it'll
suddenly lose all power to the motor like the gas
got cut off. I have to floor the accelerator and hold
it down until it gets going normally again. It does
this quite frequently.

Despite it seemingly being a fuel delivery problem,
the fuel pressure test checked out. As well as the
compression test. I've rebuilt the whole TBI and
replaced a lot of crap. The egr valve and solenoid,
map sensor, iac valve, tps, coolant temp sensor,
thermostat, o2 sensor, knock sensor, I've replaced
every vacuum hose including the brake booster. I
bought a brand new hei distributor with new cap
and rotor and replaced all plugs, wires and ignition
coil. I even replaced the entire exhaust system for
whatever reason (it does sound really good idling
now though). Most recently I put new timing chain
and gears in it. Still doing the same crap. I'm at my
wits end here, I think I'll go crazy if I can't get this
fixed soon.

Any help or suggestions would be greatly
appreciated. Thanks.

12 Answers

73,035

Have you checked the compression? And what is it.

74,135

Check the catalytic converter.

73,035

And what was the fuel pressure? Was the fuel filter changed?

7,155

If fuel pressure tested ok, check the catalytic converter

73,035

Also, have you looked at the injectors to see how they are spraying at an idle, and revving it up a little? There should be a nice cone shape spray coming out without any drips at all.

I had a friend of mine who has the fuel pressure and compression kits do the tests. He didn't tell me exactly what they were he just said they were okay. Yes, the fuel filter was one if the many things I changed when this started happening, sorry I didn't mention it before, just forgot. The catalytic converter is brand new, just put on within the last week along with new pipes and muffler. Before that the cat had been cut off by the previous owner some years before I owned it (luckily inspection is pretty lax where I go).

I don't know if it's relevant but I also put on a new torque converter and rebuilt the transmission a little over a year ago.

I will look at the injectors tomorrow to see if they look like they're spraying well. Maybe fuel pressure regulator? I never did check them because I just assumed since my friend told me the fuel pressure to the tbi was fine, it wouldn't be a fuel problem and started looking elsewhere.

73,035

Need to know what the fuel spray looks like coming out of the injectors. A nice cone shape, with NO drips at all.

73,035

You said you rebuilt the TBI so I assume the regulator got rebuilt since it is in the TBI. Was the fuel pressure checked after the TBI rebuild? Fuel pressure needs to be 9 to 13 lbs.

The rebuild was done last year around June or July. The problem started around October which is when I had the fuel pressure checked. I'll take a look at the spray tomorrow when I get a chance. I remember looking at it before but I wasn't paying attention to what the spray actually looked like. I just looked to see if it was spraying and didn't give it any other thought.

73,035

I'll be here, These things I ask is because I don't know unless you tell me. These things are important for proper diagnosis. Remember that we are not there to see. You may want to borrow that fuel pressure gauge again for some further test. The fuel delivery could be a cause of your problem so we have to eliminate it.

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