Not sure anymore...

[94GMCK1500]

1994 GMC Sierra K1500... When I start the truck and put in gear I can power brake with spinning the tires... Drive it down the road and stop, take off and it bogs... Power brake it, it bogs... Shut the truck off, start it again and repeat process with same outcome... I've replaced the ignition switch, PCM, intake gasket, transmission rebuild, transfer case rebuild, radiator, plugs, wires, rotor button and cap...It shifts at first start up and every other time I start it... Transmission shop states the transmission is fine... Is it haunted ?

 

[RichLo]

Thats an impressive parts cannon!!

How about the fuel filer? Thinking maybe it loosens a clog enough when the pressure drops when you shut it off, then re-clogs as you drive it.

 

[1997]

don't see an 02 sensor in the list ... how old is it?
any codes?
think it's time for a scanner .... 94, TBI 5.7, 4L60E?

 

[Schurkey]

don't see an 02 sensor in the list ... how old is it?
any codes?
think it's time for a scanner .... 94, TBI 5.7, 4L60E?

Thanks. You saved me a bunch of typing.

Verify fuel pressure.
Connect a scan tool, view the data stream. Verify all sensors and computer outputs--spark advance, EGR, etc.
Have you ever checked the initial timing? Cranking compression pressures? Exhaust restriction due to failed catalysts or other damage?

 

[94GMCK1500]

Thats an impressive parts cannon!!

How about the fuel filer? Thinking maybe it loosens a clog enough when the pressure drops when you shut it off, then re-clogs as you drive it.

Fuel filter was changed last November of 2022...I pulled it off and checked...

 

[94GMCK1500]

Thanks. You saved me a bunch of typing.

Verify fuel pressure.
Connect a scan tool, view the data stream. Verify all sensors and computer outputs--spark advance, EGR, etc.
Have you ever checked the initial timing? Cranking compression pressures? Exhaust restriction due to failed catalysts or other damage?

Fuel pressure checked before new pump and also after.. Pressure reads 10 to 12 PSI... While running, its the same... When revving the motor, fuel pressure remains the same with no movement... I've set the timing in 3 different settings... Unplugging the timing connection wire each time.... First set at 4' degrees BTDC. Then 6' degrees, 2'degrees next time and finally 0' degree and it runs best there...Converter is 7 months old but also checked it with a thermo gun and temp is same at the beginning and middle and end of converter and at the flange about foot down was little cooler... New EGR, PCV, hoses.... Transmission shop states it's an electrical demon somewhere like a broken, pinched or something along those lines... It's obd1 an no shops have one around here or so I'm told when I inquire about one... No codes pop up on dash...

 

[94GMCK1500]

don't see an 02 sensor in the list ... how old is it?
any codes?
think it's time for a scanner .... 94, TBI 5.7, 4L60E?

02 sensor is less than a year old and no codes... Correct on 94, TBI 5.7, 4L60E... Transmission shop states its a bad wiring issue... Test drove it and said transmission is fine, that I need to have a shop that specializes in electrical cause nobody really likes chasing a electrical demon...lol

 

[TexasRebel]

Maybe take it to a different transmission shop and see what they think. I've seen some kinda shady trans shops down here give customers the runaround when there is an issue so that they don't have to do warranty work or admit that they may have done something wrong.

 

[94GMCK1500]

Maybe take it to a different transmission shop and see what they think. I've seen some kinda shady trans shops down here give customers the runaround when there is an issue so that they don't have to do warranty work or admit that they may have done something wrong.

I thought the same thing and had 3 different shops check it out... All 3 made the same call... Lot of the parts I replaced needed replaced... Like the tune up... Radiator was leaking coolant into the transmission cooler line tank... Transmission needed rebuilt due to fried clutch plates, transfer case had re-sealed with new chain since it was out... Intake had a leak on driver side rear section...I replaced the ignition switch and PCM out of curiosity... I do get parts pretty cheap at my local parts store cause I do lot of business with them.... I did have someone ask if I changed out the ignition control module under dist cap... Yes I did but its an auto zone part and I didn't buy it....

 

[Komet]

Datalog that captures the engine bogging might lead to some results.

There could be a crispy wire somewhere that stops working when hot. All electrical work is resolved the same way and to quote a guy from another place, its eeeezzzyyy you just have to physically check all the wires.

One of your new parts may be working incorrectly, or installed incorrectly, or physically fits but is wrong for the vehicle. All cheap junk parts are suspect.