fuel pump not working - low pressure

Check and test the fuel pump fuse, fuel pump relay and the fuel pump and oil pressure sending unit-also test for voltage drop problem

They have a known problem with the contacts in the plug at the tank.

I did just find that the oil sending unit was unplugged. How would the oil pressure sending unit affect the fuel pump? How can I tell if the fuel pump relay is bad?

The oil pressure sender is a redundant power supply to the fuel pump. The truck can run with either/or working properly but if it loses both, it will not run so there is a good chance you have a problem with the relay. When running on the oil pressure switch only, you will have a long crank before starting because you aren't getting the 2 second prime supplied by the relay.

The car stood for 3 months with 1/4 tank of petrol. Initially the car started after this period, but then stop working after a week. Initially, I thought that it could be the battery as the indicator was white but after replacing the battery the problem still persisted. When the carburette cover was removed and petrol was poured into it then the car started. What could be the solution if the petrol pump works?

First, we need to make sure the pump is producing enough pressure to run the engine. Here is a how to for checking pressure.

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Let me know what you find.

Engine Mechanical problem
1998 GMC Jimmy 4 cyl Four Wheel Drive Automatic

not getting any gas..fuel pump is not running.i replaced fuel pump already.why is fuel pump not running not running?

Hi, did you check for voltage and ground at the pump connector, engine cranking? Gray wire is voltage, black wire is ground. Without voltage and ground, the pump won't do anything. Next, I check voltage circuits at the fuel pump relay, use a dmm to check for voltage. I'd also check fuses.

engine is cranking good.and fuses are good..

You need to check for voltage at some of the circuits I mentioned.

fuses are good..relay is good..pump only works first time i turn the key..if i unplug it and plug it back in it only works the first time

ok i was driving on the higjway, so the trucks just shut off, towed back home, so no fuel pressure at all, i replaced the relay, nothing, put a new fuel pump, nothing, no pressure, fuel pump just wont kick on, i use a hot wire to power the fuel pump in the harness right there on the top of the fuel tank, but nothing, a faulty sending unit can be possible, dont let power the fuel pump???? do this truck has a shut off valve or switch, thanks.

Power the fuel pump connector gray wire from the battery positive post did it come on if not check the black ground wire to it. If okay think! fuel pump again

i tested the old fuel pump, i power it and it works!!!! that means the fuel pump wasnt the problem.

Where are you checking the fuel pressure? Is this the spider Vortec fuel system come on back

it say vortex, but is not the spider one, this is a 95, i put my gauge at the fuel rail, pump is not kicking on at any time, check the fuse, but is ok, i put a new fuel pump relay, fuel filter was replaced a month ago, i didnt check the black ground wire, i put the hot wire in the middle of the harness at the fuel tank and sparks!!!! i put the new fuel pump, with the new inside harness, can the sending unit be shorted?

i checked fuel pressure it low .i also sprayd starter fluid in manifold it ran for a few sec. pressure regulator change,fuel pump change and fuel filter changed.getting fuel to injector pump what cani try next?

The gray wire powers the fuel pump-Sparks you shorted something out could be the pump or the sending unit.

How low is the fuel pressure? It should be 55-61psi if not in this range injector/s could be leaking and dropping the pressure. Also check if the injector/s are pulsing if not could be power source to it or the computer's injector drivers.

well i put the new fuel pump and hook up every thing, i turn the key on, and nothing, then i did that with the hot wire, i will check it tomorrow, if smthg happen i will let you know of course i will not forgot about the donation thanks for your time.

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.

i did that before installing the new fuel pump. is kind of weird, i hate this kind of problems, is not usual.

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.

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.

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.

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?