Hey everyone, i could really use some help here. Local mechanic suggested a new fuel pump for my dads blazer so me and him cut a access panel in it and replaced the pump and put fresh gas in.

After the pump replacement thats when the issues started. Truck will crank for days and has no problem with it. No start. So of course i dug in the forums for days and im stumpt.

We used a delphi pump and didn’t cheap out with it. The fuel gauge will go from full to E while cranking. Otherwise with key on its pretty erratic its jumps from full to above full. I do not hear the pump prime at all but i do hear the relay click. The last odd symptom im having is every time i hook up a code reader to it it wont establish communication.

any ideas?

 

Did you have to replace the fuel pump connector? Did you get all the wires hooked up in the right places? How about the ground wire on the frame rail? How is it? They can get corroded and break internally, even though they look good.

 

i did have to replace the connector but i made sure i wired it the way its listed in the manual that came with the connector. The ground im pretty sure is good I clean some metal off and sent a clean bolt through the eyelet. What caught my attention was the copper braided strap was really corroded. Not broken anywhere but from my understanding thats to ground the filler cap.

Should I cut the old ground eyelet out and replace it just to be safe? And what is the likely hood that the pump i put in is bad? Sorry just not used to doing electrical repairs

 

Do you know how to test voltage and resistance with a multimeter?


George

 

Honestly not really. I know the ground needs to be less than 6 ohms and grey wire should be 12V but do i test that by sticking pos side of meter into grey pin connector or am I missing something?

 

Anytime a sensor or load (fuel pump) is malfunctioning, the wiring/connectors/power/grounds need to be checked before condemning the sensor or load and then verified once fixed. What matters is the net voltage at the load (fuel pump) under a full load. The battery voltage can sag and the ground can lift if the wiring is defective. Here are two primers for you:

https://blazerforum.com/forum/2nd-ge...59/#post732668

https://blazerforum.com/forum/2nd-ge...29/#post731395

Let me know if you still need help after you read this stuff.


George

 

On the vehicle side of the connector, the factory grey wire is the power from the relay to the fuel pump. Black is the ground. Check to make sure it is wired this way. See attachment.

If the relay is clicking, then check the 20A ECM B fuse in the underhood relay center.

Good luck and best wishes for a successful repair.

 

Hi all, still having issues, took apart the new connector and im only getting .7 volts to the pump with key in on position. I have a charger hooked up to the battery but the battery is pretty old. Is it worth swapping the battery out or could this be a vcm issue?

 

What is the battery voltage with the ignition key on and the truck not started? Same question when the truck is running.


George

 

So far I cannot get the truck running bc I cannot get the fuel pump to turn on. .8VDC was the most i got with the relay clicked over. I grabbed a new battery because the old one was at 3V testing now.