94 s10 blazer, what now?

[tmay11]

I have a 1994 s10 blazer with a 4.3 liter v6, it hesitates a little uppon acceleration.
I have already replaced the EGR, CPI, O2, FUEL FILTER, AIR FILTER, PLUGS, WIRES, IGNITION COIL, ALL VACUUM HOSES, PCV VALVE, DIST. CAP, AND ROTOR. Each part that I have replaced has made it's own difference. The truck is running alot better than when I started. The CPI was the last thing replaced, and right after I replaced it the truck ran like a brand new one for about ten minutes. I did pull the upper plenum back off to make sure all the injectors remained in place, and they were still in place. Oh, the timing is correct also.
The fuel pump does prime and run, but does anyone know if these pumps gets weak over time? I am pretty sure my problems is to little fuel or to little air. I will be testing the fuel pressure one day this weak.
I would like to hear any helpful input that anyone may have. THANKS!!!

[Fractured1]

yes the pump could slowley loose it's pressure...the pressure for the CMFI is 58 to 64 psi with key on not running and drop 3 to 10 psi when running...good luck

[sholcombe]

Try the CMPI wiring it's a tricky devil

[sholcombe]

I too have the exact problem and here is my two cents ($1300 dollars) worth:

I ALSO have a 1994 s10 blazer with a 4.3 liter v6, it hesitates a little uppon acceleration.
I ALSO have already replaced the EGR, CPI, O2, FUEL FILTER, AIR FILTER, PLUGS, WIRES, IGNITION COIL, ALL VACUUM HOSES, PCV VALVE, DIST. CAP, AND ROTOR.
In addition I have replaced the fuel pump (in tank), fuel filter, TPS, MAPS, Catalytic convertor, muffler...... I was graspng at straws as everything had been replaced twice. Dealer was stumped too after a nice donation$$$

I finally fixed it by flexing the wires to the CMPI in the plennum. I will need to replace the wire b y removing the upper half and replacing the plug and part of the wiring.

You should measure the fuel pressure ( Mine was pretty steady at 60psi)to eliminate the fuel pump or regulator (part of the CPI). It cost me $40 to get a tester but kept me from dropping the tank again. I have replaced many parts twice and this is hard to cure.

Please let me know if you fix yours and email me if ou have questions.

Steve

[tmay11]

Originally Posted by sholcombe

I too have the exact problem and here is my two cents ($1300 dollars) worth:

I ALSO have a 1994 s10 blazer with a 4.3 liter v6, it hesitates a little uppon acceleration.
I ALSO have already replaced the EGR, CPI, O2, FUEL FILTER, AIR FILTER, PLUGS, WIRES, IGNITION COIL, ALL VACUUM HOSES, PCV VALVE, DIST. CAP, AND ROTOR.
In addition I have replaced the fuel pump (in tank), fuel filter, TPS, MAPS, Catalytic convertor, muffler...... I was graspng at straws as everything had been replaced twice. Dealer was stumped too after a nice donation$$$

I finally fixed it by flexing the wires to the CMPI in the plennum. I will need to replace the wire b y removing the upper half and replacing the plug and part of the wiring.

You should measure the fuel pressure ( Mine was pretty steady at 60psi)to eliminate the fuel pump or regulator (part of the CPI). It cost me $40 to get a tester but kept me from dropping the tank again. I have replaced many parts twice and this is hard to cure.

Please let me know if you fix yours and email me if ou have questions.

Steve

"UPDATE"---pulled all the plugs back out and one of them was coated with carbon, so i went ahead and replaced all plugs, and dumped a cleaning agent into the fuel system, now the thing runs like brand new

[Joequin]

Originally Posted by tmay11

"UPDATE"---pulled all the plugs back out and one of them was coated with carbon, so i went ahead and replaced all plugs, and dumped a cleaning agent into the fuel system, now the thing runs like brand new

I have a 94 jimmy with the vortech and I have replaced everything on your list and mine still runs like a piece of junk if it runs at all.What is flexing the wire mean..I am just about out of ideas and patience with this thing.I replaced the cpi,fuel pump,filter,nut kit,cat converter,plugs,wires,rotor and everthing else I could think of and the truck ran great for the first 10 minutes and then it went back to idling like trash and now it hardly runs at all.

[Skeeter6755]

Originally Posted by Joequin

I have a 94 jimmy with the vortech and I have replaced everything on your list and mine still runs like a piece of junk if it runs at all.What is flexing the wire mean..I am just about out of ideas and patience with this thing.I replaced the cpi,fuel pump,filter,nut kit,cat converter,plugs,wires,rotor and everthing else I could think of and the truck ran great for the first 10 minutes and then it went back to idling like trash and now it hardly runs at all.

Have you tried cleaning the EGR valve? You want to make sure the spindle moves freely. Mine was covered up in Carbon deposits and after I cleaned it out, you couldn't even tell the engine is started it ran so smooth. BTW, mine is a 1994 4X4

[tmay11]

Originally Posted by Joequin

I have a 94 jimmy with the vortech and I have replaced everything on your list and mine still runs like a piece of junk if it runs at all.What is flexing the wire mean..I am just about out of ideas and patience with this thing.I replaced the cpi,fuel pump,filter,nut kit,cat converter,plugs,wires,rotor and everthing else I could think of and the truck ran great for the first 10 minutes and then it went back to idling like trash and now it hardly runs at all.

pull out your plugs and look at them, i think what happens, is when your injectors are spraying proberly for the first time in a long time, so the plugs get coated with the build up from the valves and cylinder walls. my truck also ran great for ten mins, went to crap, i checked the plugs, 1 of them was full of carbon, went ahead changed all of them, runs great now, also when it is dark, run your engine and look for any sparks from your wires and your coil

[gbic1]

Were these flooding 3 cylinders?

[BlazerLT]

You should also remove the timing wire from the PCM and time the engine with a timing gun.

The timing goes out after time and is considered mormal maintanence.

[Joequin]

Originally Posted by tmay11

pull out your plugs and look at them, i think what happens, is when your injectors are spraying proberly for the first time in a long time, so the plugs get coated with the build up from the valves and cylinder walls. my truck also ran great for ten mins, went to crap, i checked the plugs, 1 of them was full of carbon, went ahead changed all of them, runs great now, also when it is dark, run your engine and look for any sparks from your wires and your coil

thank you I will try this also I am just about out of ideas on this thing.My wife has a new car and I have a newer vehicle I just wanted this truck as a back up but its not working out this way at all.I will try this and also blazer mentioned the timing I will give this a try also.. thanks

[BlazerLT]

Good luck and let us know

[dragonsfury711]

i have a 1994 chevy blazer 4.3 vortec v-6 and i cant find the fuel filter i looked but no luck help me out somehow ???

[gbic1]

On the drivers side frame rail under car.

[BlazerLT]

Yip, inside drivers side fram half way back.