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95 suburban not running under load


elbuego
10-31-2005, 03:53 PM
I have a 95 Suburban that starts fine, idles fine,but when I put a load on the engine it acks like it is not getting enough fuel. It misses and runs terible. I've replaced the fuel pump, map sensor,fuel filter,fuel screen in the tank,plugs &wires. I've also tried a different distributer and no improvement. thought maybe timming had jumped a tooth but have 19lbs of vacuum at idle and timing is right on. Any ideas would be greatly appreciated...

Ryan685
11-01-2005, 01:15 AM
If the engine misfires as you state. The check engine light had to have come on. Have you had the codes read? 1995 has the ODB2 computer so any misfires would be stored in memory and can be read with a code reader. How many miles does the engine have? Have you ever replaced the O2 sensors? If it has dual Cat converters, it will have 4 O2 sensors. More then 60K miles O2 sensors should be replaced for best economy.

elbuego
11-01-2005, 11:20 AM
If the engine misfires as you state. The check engine light had to have come on. Have you had the codes read? 1995 has the ODB2 computer so any misfires would be stored in memory and can be read with a code reader. How many miles does the engine have? Have you ever replaced the O2 sensors? If it has dual Cat converters, it will have 4 O2 sensors. More then 60K miles O2 sensors should be replaced for best economy.
I have not replaced the o/2 sensor,the rig has 160,000 miles. I have had the codes read and no codes,no check engine light, I replaced the map sensor because while using a reader I noticed the map was only reading 7lbs. After testing with a vacuum testing gauge it has 18-19lbs. It only has 1 cat converter, I also have cut open my exhaust thinking the exhaust was plugged. Do the injectors plug very easely,I can see they seem to be dumping a lot of fuel.Have not checked for base gasket leak yet. Don't think it is intake gasket ,when changed plugs they all looked pretty good alittle warn but not to black and not white. Thanks....

Ryan685
11-02-2005, 01:23 AM
I hate to keep guessing at someone elses expense. All anyone can do without "hands on" is give you as best information without knowing exactly what condition the vehicle is in.

I do know that antifreeze affects cat converters. It clogs them up, turns the ceramic into a solid lump. Something people have noticed when replacing the intake gaskets on these Vortec engines is an oil coking buildup under the intake manifold. With 160K miles, if the intake gasket hasn't been replaced, this could very well be your trouble. As for injectors. It is possible to clean them yourself. I use a 9 Volt battery and a injector plug off an old wire harness (salvage yard item) Never use 12 volts to open an injector, it will damage the coil inside them. Anyway I use a spray carb cleaner and spray backwards through the injector onto a white sheet of paper to see what comes out. The battery with a plug connected too it powers the injector and holds the pintle open. Spray carb cleaner into the tip of the injector to flush it out. You can use compressed air afterwards or not. Work quickly as the battery will not last long to do all eight injectors. A very fine screen is inside the inlet end of the injector and it can clog up with particles. This is actually what clogs an injector (the screen)

MashBill
11-02-2005, 07:43 PM
My '95 Suburban did the same thing. I replaced the plugs, plug wires, distributor cap and rotor, and coil. It started much quicker but still would not accelerate or run over 40 MPH. Next I had Jiffy Lube do a fuel system clean. It now runs like a bat out of hell.

fromcgee
11-09-2005, 08:53 AM
i have a 95 suburban as well that seems to be sluggish under a load or even if it is going up a hill it just seems to have very little pulling power and i wanted to know what the problem is also i have changed my o2 sensor with in the last few months and that helped but still did not solve the problem. i some times think that at speeds going up a hill my truck does not down shift as soon as it should but i have not had any trans problems

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