1993 Saturn SL1 Fuel Pump Won't Run

BONZ0921

MEMBER
1993 SATURN SL1
4 CYL
FWD
AUTOMATIC
200,000 MILES

To make a long story shorter, All has been tested from the PCM to the pump. If the PCM is unplugged and I put 12 volts to the signal wire (green w/ white stripe) the fuel pump will run. When the PCM is plugged in, there is no voltage on that wire with the ignition on. I have tried two other PCM's. They all did the same. Is there something else that could possibly be telling the PCM not to turn on the fuel pump? I dont have much hair left, and this has stummed a former saturn mechanic.

Wednesday, February 25th, 2009 AT 6:49 PM

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Check fuse I/P BATT 30amp and fuse no.12 10amp if okay test the fuel pump relay. Relay test okay check the fuel pump control relay circuit dark green and white going back to the computer

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Thursday, February 26th, 2009 AT 12:24 AM

BONZ0921

MEMBER
2 POSTS

That is where it all dies. I get no signal out the PCM. If I unplg the PCM and put 12 volts to the green and white wire the fuel pump will turn on. But with the PCM connected and the ignition on I do not get 12 volts at the green and white wire. I have tried a total of 3 PCM's and I dont believe all three are bad for the same reason. But I will double check the fuse under the hood. I know the 30 amp maxi fuse is good, but will double check the other. Is there anything else that tells the PCM to turn on the fuel pump? Maybe some sensor on the engine that could be bad? Like I said, when I apply 12 volts to the control wire, the pump does turn on. Thank You for your responce.

Well come to find out there were 2 PCM fuses and one was missing. Problem solved.

Thank You

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Thursday, February 26th, 2009 AT 4:17 AM