NO POWER AT FUEL PUMP

BOB WILSON

MEMBER
CHEVROLET

I HAVE A 96' SUBURBAN 5.7 143000MI
THE FUEL PUMP QUIT SO I REPLACED IT. THE NEW RAN FOR FIVE MINUTES AND QUIT. UPON REMOVING THE NEW, I RAN HOT AND GROUND DIRECT TO PUMP OUT OF TANK AND THE PUMP WORKED. ALSO THE PREVIOUS PUMP WORKED THIS WAY. MY CENTER PRONG WIRE AT THE PUMP READS 8.4V AND NO VOLTAGE AT THE GRAY. MY HAYNES MANUAL DIAGRAM SHOWS ORANGE FROM THE RELAY TO AN OIL PRESSURE SWITCH, THEN GRAY TO PUMP. I CAN'T FIND SWITCH TO FIND THE GRAY WIRE AND THE VOLTAGE LOSS.
OR COULD IT BE SOMETHING ELSE. FUSE IS GOOD AND NEW RELAY INSTALLED. MY CODE READER SHOWS MAV CIRCUIT LOW?

4 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

I'm not sure what years, but some of the GM trucks in that period had a bad connector that went to the pump. The stealer may be able to provide you with that info, where you would have to buy it anyways.
Good luck.

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Saturday, December 30th, 2006 AT 11:00 PM

2CARPRO JACK

MECHANIC
11,533 POSTS

Definitly go to the dealer and get the revised connector for the pump. They had big problems with them. Also replace the fuel pump relay any time you do a pump, its cheap insurance that the circuit is ok. The code MAV? Was it MAF. 96 should be a CPI engine. Most likely needs a new MAF sensor. Seeing more and more of them failing these days.

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Sunday, December 31st, 2006 AT 8:04 AM

BOB WILSON

MEMBER
13 POSTS

THANKS FOR THE HELP,
WHICH CONNECTOR? IS IT THE ONE TO THE FUEL PUMP IN FRONT OF TANK, OR THE ONE TO PUMP INSIDE OF TANK. MY MANUAL SHOWS A MASS AIR VOLUME SENSOR, NOT A MAF. PLEASE DON'T SAY THE ONE IN THE TANK, I'VE DROPPED AND INSTALLED IT TWICE ALREADY WITH 3/4 TANK OF GAS. DO YOU KNOW WHERE TO FIND THE OIL PRESSURE/FUEL PUMP SWITH? LAST QUESTION, WOULD THE MAV SENSOR, WHICH IS GETTING 12V, ACTUALLY STOP THE FUEL DELIVERY?
THANKS AGAIN

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Sunday, December 31st, 2006 AT 9:13 PM

2CARPRO JACK