Fuel pump not working - low pressure

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check if the ECM/BATT fuse no.9 20amp is blown, this the one that powers the fuel pump relay and then transfer power thru the gray wire to the fuel pump.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JIMMY95
  • MEMBER
  • 5 POSTS
I did that before installing the new fuel pump. Is kind of weird, I hate this kind of problems, is not usual.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The old pump works but new pump don't think! For a moment here-When you hook up the new fuel pump there were sparks! You probably fried it-put the old one on-did it come on.

The fuel pump relay powers the pump for 2 secs to prime the system when it fires up the fuel pump and oil sending unit powers it from there.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
ARELLDBLU
  • MEMBER
  • 4 POSTS
  • 1993 GMC JIMMY
  • 194,000 MILES
I was having trouble with a cold start in the morning. I was having to spray starting fluid in it to get it started when it was cold. But only when the temp was below like 60 degrees. It kept getting worse until it got so bad I had to do something. I started replacing sensors, iac, tps, aits and connectors. I replaced the fuel pump and filter. After that I checked the poppets for fuel flow and was getting none. Assuming the pressure was good due to the new pump and filter (duh me), I replaced the spider injector assembly. I had come to my last straw as was considering replacing the ecm when I decided to recheck the fuel pressure today. Lo and behold, I got real low pressure. What is my major malfunction not including my personal traits.
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Is the fuel pressure at the rail within the manufacturer's spec? It sounds like a bad regulator or something as simple as a fuel filter being plugged.
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-1
Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)
Tiny
ARELLDBLU
  • MEMBER
  • 4 POSTS
NEW fuel pump, NEW fuel filter, NEW fuel injector assembly which came with a new fuel pressure regulator attached. And actually, I had already replaced the regulator before buying the injector assembly not knowing I was going to replace the inj assem, or that it would come complete with regulator. So it's my guess that either I'm not getting enough voltage to my fuel pump or, something I find unlikely, which is your "wild guess" that the filter is clogged, maybe had some gunk in the tank that came loose when I replaced the pump and restabbed the tank. I think my first order of business is to hook up my fuel pressure gauge to the fuel line before the filter, if I have the right fittings. If no problem there, I move on to testing the voltage on the pump. Or vice versa. I'm real sorry to have to say, but your so called "expert" advice just doesn't seem very good. I really don't know squat about working on vehicles post the fuel injection, computer controlled era and really wasn't that good on the old school rides either. And it appears to me like my searching Google for answers has given me more knowledge than coming here and asking my question. Or is it just that unless someone actually PAYS for an answer they really don't get SQUAT for help or advice?
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Tuesday, June 23rd, 2020 AT 1:42 PM (Merged)

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