Fuel Pump no Power
October 5th, 2020, 11:34 AM
#1
Fuel Pump no Power
I have a Stroker I built and put in my 86 S10 on to have a lot of problems keeping the car cool here in Texas. Headers just to close to floor boards. It was like 130 degrees in car on a hot day. I just put that stroker in my 1994 C1500 4.3. No longer TBI running a Holly 750. Once complete my in tank fuel pump no longer excites. No power going to the pump. I read somewhere that the damn ecm completes the ground to the pump. Where am I losing my signal to the ecm, is it the fuel pressure reg that sends a signal to the ecm to excite the fuel pump ground?? Need Help!!!
October 5th, 2020, 12:18 PM
#2
CF Veteran
The PCM in the 94 will prime the fuel pump for 2 seconds at key on, but before it continues to run the pump it needs to receive reference pulses from the ICM which would’ve been mounted in the distributor.
If you’re running a carb set up, the PCM is pretty much worthless to you. You’ll have to wire the fuel pump relay to run constantly with the key on. You’ll probably also need to install an inline FPR for your carb as the pumps for these trucks run about 10 PSI and the carb probably only needs 6 or 7.
As for transmission control, there’s plenty of standalone controllers available if you search.
If you’re running a carb set up, the PCM is pretty much worthless to you. You’ll have to wire the fuel pump relay to run constantly with the key on. You’ll probably also need to install an inline FPR for your carb as the pumps for these trucks run about 10 PSI and the carb probably only needs 6 or 7.
As for transmission control, there’s plenty of standalone controllers available if you search.
October 5th, 2020, 1:58 PM
#3
CF Monarch
The PCM in the 94 will prime the fuel pump for 2 seconds at key on, but before it continues to run the pump it needs to receive reference pulses from the ICM which would’ve been mounted in the distributor.
If you’re running a carb set up, the PCM is pretty much worthless to you. You’ll have to wire the fuel pump relay to run constantly with the key on. You’ll probably also need to install an inline FPR for your carb as the pumps for these trucks run about 10 PSI and the carb probably only needs 6 or 7.
As for transmission control, there’s plenty of standalone controllers available if you search.
If you’re running a carb set up, the PCM is pretty much worthless to you. You’ll have to wire the fuel pump relay to run constantly with the key on. You’ll probably also need to install an inline FPR for your carb as the pumps for these trucks run about 10 PSI and the carb probably only needs 6 or 7.
As for transmission control, there’s plenty of standalone controllers available if you search.
October 5th, 2020, 3:33 PM
#4
THX Grumby... A few months ago when I started having problems with my 4.3 TBI with 252 K miles on it my fuel pressure dropped to low for the TBI and I said to myself i'll be damned if I am going to pull the bed off for a fuel pump so I already hooked up a Holly external inline. That gave me five more months till the weather cooled and I could throw my stroker in. It is running right now but having lots of problems with the Tranny I felt that maybe the same ground that the PCM excites could be reaking Havic with me with my install of TPC on my Holly. I will create another post on that issue with pics...I look at the bright side Fuel gauge would not work when both internal fuel pump and external Fuel pump were hooked up together and now tha gas gauge works again.
October 5th, 2020, 3:44 PM
#5
THX Kevin I have a nice Regulator on her already. Ran my Fuel lines while engine was out using original line set up with the return line as well. 5 PSI on Holly right now.
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