94 gmc 454 fuel issue??

i have a 94 gmc 3500 c&c 454 4x4, engine dies on throttle, revs great with no load but when put in gear she dies, lack of power. new fuel pump, tank, fuel filter, tbi unit, tps sensor idle air sensor, ecm temp sensor, ecm, exhaust, but still no luck. she seems like it running lean on fuel but fuel pressure is good. any ideas?? and of course it is obd1!

Check the vacuum line going to the MAP sensor, the MAP needs to hold a vacuum. Even though it is OBD-I, it can still be scanned to see what all the sensors are reading and what the fuel trims are at.

//2000CAYukon

checked and replaced map sensor already, checked for pluged fuel return and vent lines. have taken truck to a few shops and no one can find out what the problem is. any other suggestions?

It dies when put into gear? Or it dies when you give it throttle?

When you say exhaust, that include the cat as being replaced?

Have you checked timing chain yet? Remove #1 plug, get piston at TDC on compression stroke and then make sure both valves are closed (valve cover off).

//2000CAYukon

timing is good, there is no cat (1 ton in canada dont come factory with cats) i have converted to dual fuel since the problem started and runs great on propane. it dies on throttle but if you put the gas to the floor it runs like it is at 1/4 throttle. although it will run good sometimes then starts bucking; turn the key off and on and it runs great for a few minutes (make me think sensor or broken wire but which one)

Make sure both injectors are spraying fuel, remove the air cleaner of course put some load on it and see, ( 2 people required here of course). LOL

already checked spray and have replaced the tbi unit.

Did you replace the sock/tank filter, have you checked fuel pressure under load?

yes sock filter was changed, fuel pressure underload is good, i am starting to think maybe a bad ground somewhere. just for giggles i unpluged the map sensor (been replaced too) and it runs without bucking and dying but lacks power.

sorry but could you tell me what is tha cat?

Catylytic convertor.

:) Catylytic convertor.

thanks for your answer, I have the same problem right now my truck is a 1998 gmc sierra 5.0 8 cil. 305 and it turns on fine but when I want to accelerate it turns off, I have checked the fuel pump and it's working fine and it has only 1 week new and I changed also the distributor cap and the rotor, do I have to change the module inside the distributor cap? and I change the pressure valve under the intake because it was smoking a lot but that was fixed when I changed the valve,

hope you have some time to help me.....

Regards.

Get a gage on the fuel rail you need 60-65 psi, also how is the inline fuel filter, new?

Get a gage on the fuel rail you need 60-65 psi, also how is the inline fuel filter, new?

Maxwedge, this is a 94 so it should be a TBI. Pressure should be 9 to 13 PSI even for the 454. Also, no fuel rail test port, a special tool is required.

//2000CAYukon

hi again yes I checked the psi and it's fine, and the filter you mean the one under the driver? yes I put it new...