Security.. Fuel Pump.. Problems!?

[MT-2500]

The PCM turns on the fuel pump relay.

But first swap relays with another one of same no.
There should be several in the relay box.

Next find the gray wire or fuel pump prime test wire from relay to fuel pump and jumper it with a 12 volt fused jumper wire.
If fuel pump runs and it will start.
Your relay is bad or pcm is shutting off relay.
If fuel pump will not run with it jumpered the fuel pump or wiring is bad.

Let us know how this test goes.
MT

[MSimpson]

After testing the gray wire we found that we had voltage. So we just decided to drop the tank and get a new fuel pump... That fixed it.. All this running around for just that..

My buddy can't believe it was that because it just happened out of no where..

[MSimpson]

What else would you guys suggest to do while the vehicle is still up and half was takin apart.. (Not really) In all seriousness... What else should I change or clean before we finish..

[MT-2500]

It did pick a strange time to quit.
But they do that sometimes.
Always install.
New fuel filter.
Make sure you use a good quality AC Delco / or Delphi fuel pump module.
And make sure the wiring plug to fuel pump is good.
Some have a wiring plug change over.

And always keep over a 1/4 tank of fuel in the tank.
Good Luck

[Rick Norwood]

Originally Posted by MT-2500

And always keep over a 1/4 tank of fuel in the tank.

I keep hearing this, but why? I seem remember a few years ago there was a post where someone ran one of these fuel pumps on the bench dry (it may have been pumping fluid, but it wasn't submerged) for about a month and it never hurt a thing.

Is there any studies or reports to support the 1/4 tank theory?

[MT-2500]

Originally Posted by Rick Norwood

I keep hearing this, but why? I seem remember a few years ago there was a post where someone ran one of these fuel pumps on the bench dry (it may have been pumping fluid, but it wasn't submerged) for about a month and it never hurt a thing.

Is there any studies or reports to support the 1/4 tank theory?

Bench test is a long way from a fuel pump in the tank pumping 65 lbs of pressure.

The pump needs fuel in the tank to cool it and lubricate it.

Over the last 30 years years I have noticed that.
People that keep 1/4 tank or more of fuel in there tank replace a lot less fuel pumps than people that run them empty.

[Rick Norwood]

Originally Posted by MT-2500

The pump need fuel in the tank to cool it and lubricate it.

People that keep 1/4 tank or more of fuel in there tank replace a lot less fuel pumps than people that run them empty.

I knew that all along (the cooling and lubricating), and it makes perfect sense, I just wonder if the statistics back up the excessive replacement. Thanks for yor reply.

[MT-2500]

Originally Posted by Rick Norwood

I knew that all along (the cooling and lubricating), and it makes perfect sense, I just wonder if the statistics back up the excessive replacement. Thanks for yor reply.

I have worked on cars and trucks for over 45 years.
Some Big trucks had them 45 years ago in the tank and the had the same problem.
Run the tank empty and they were replacing the fuel pump.
I have watched cars and light trucks with them for 30 years.
Same problem run the empty and you replace the fuel pump.
That is good enough statics for me.

But if you want book statics do a google search.
MT

[Rick Norwood]

Originally Posted by MT-2500

I have worked on cars and trucks for over 45 years.
Some Big trucks had them 45 years ago in the tank and the had the same problem.
Run the tank empty and they were replacing the fuel pump.
I have watched cars and light trucks with them for 30 years.
Same problem run the empty and you replace the fuel pump.
That is good enough statics for me.

But if you want book statics do a google search.
MT

As I said Brother, it makes perfect sense. Clogged fuel filters and a host of other issues may also contribute. We'll probably never know.

[MT-2500]

Yes dirty filters and even bad wiring and ground to fuel pump..
The wiring is to a fuel pump is not very hevey.
Bad wirng can take out a fuel pump to.

If you know some people that always run there tank low before putting gas in.
Watch and see how many ful pumps they replace compared to people that keep a 1/4 tank or more of fuel in them.
MT.

[Rick Norwood]

Originally Posted by MT-2500

Yes dirty filters and even bad wiring and ground to fuel pump..
The wiring is to a fuel pump is not very hevey.
Bad wirng can take out a fuel pump to.

If you know some people that always run there tank low before putting gas in.
Watch and see how many ful pumps they replace compared to people that keep a 1/4 tank or more of fuel in them.
MT.

Just as food for thought, I have owned 4 different Blazers/Jimmy's. An 89, a 93, and 2001 Blazers, and a 2000 Jimmy. Out of the 4, I have only 1 fuel Pump go bad, and that was on the 93. I have always run them to empty or near empty. My 89 had 200,000 miles on it with the original fuel pump when I sold it. Maybe I am just lucky. Routine maintenance goes along way.

It certainly makes sense to keep the tank 1/4 full if you want to discipline your self to do it. Factor in the wife and kids and it is a new ball game.

I have a lot of respect for you and anyone else that has twisted wrenches for that long. I have been doing it for 35+ years myself, but never did it for a living.

Thanks MT for all your contributions.