1997 GMC K1500 fuel pump and sending unit replacement

[AJCK87]

Hey guys,

I'm looking to do a drive way fuel pump replacement and I don't really want to drop the fuel tank or lift the box off. Since this is the second pump to go in less then a year... I wanted to cut an access port in the box to change out the pump. I was wondering if anyone had a good thread showing how they did it? Also wanted to get an idea of how big a hole and where it should be.

Thanks!

[b454rat]

IMO can't replace without doing at least one. I did one to a 97 that I had, dropped tank but didn't lift box. It's a pain. I had to do it in my 96 I have now. Rusty lines makes it even more fun.

[Chris95GT]

Lifting the box really isn't as bad as it seems, I did it myself in the driveway. I removed the rear bumper to make sure I didn't scratch the bed, then I just loosened the passenger side bolts, removed the drivers side bolts, and used a ratchet strap between the front and rear corners on the drivers side and my engine hoist to lift the drivers side up and hold it. It was easy to do by myself and way way easier than wrestling a tank around. Honestly, I didn't even break a sweat. IMO it's easier to do that then it is to cut a hole in the bed with enough access to get lines and such off, and the end result is nicer.

[Chris95GT]

Here's the picture from the first time I did it, this is where I learned the hard way to take off the back bumper.



But seriously, if you have an engine hoist, it's easy.

[pwdcougar]

Great write up and picture. I had to pay to have mine done (and I HATE paying) a few years back. The tank was just filled up and there was no safe way to drain 24 gallons out or lower all that weight.

Paul

[speedygonzales]

Originally Posted by AJCK87

this is the second pump to go in less then a year...

What brand where the replacements, where did you get them and was it pump only or the entire sending unit?

[54 jimmy]

I always pull the bed or lift the drivers side like said. never buy a cheap fuel pump learned that very quick. always replace with a ac delco or Delphi and never any issues. side note change your fuel filter just for good measure.

[91short]

I cut a hole through the bed floor, I had to change it twice one year and just this year the wiring in the tank went bad so I had to pull it out again. My bed was starting to rust so I didn't care about cutting it, now it's so easy to get to. I do have a drop in liner so it's covered up and you cant see the hole when the liner is in place.

[AJCK87]

Picked up a Delphi pump and sending unit, still one the fence about cutting the box or lifting it, thanks for the tips guys!

[AJCK87]

Originally Posted by speedygonzales

What brand where the replacements, where did you get them and was it pump only or the entire sending unit?

Can't remember the brand of The last pump, thinking it was a cheap one. And it was just the pump no sending unit.

[speedygonzales]

Most electrical parts should be ONLY OEM. The fuel pump is one of them. I never saw a cheap auto store pump last very long.

For others, don't change the pump only for a couple of reasons. One, the fuel level sensor is a wear item and should be replaced when ever the pump needs changed. Length of time not withstanding.

Two, there is a check ball in the sending unit that prevents fuel from draining back to the tank, causing long cranking time among others. If you only change the pump and not the sending unit, you chance having to go back in because of a sticking check ball.

[Chris95GT]

Originally Posted by speedygonzales

there is a check ball in the sending unit that prevents fuel from draining back to the tank, causing long cranking time among others. If you only change the pump and not the sending unit, you chance having to go back in because of a sticking check ball.

Slightly off topic, do you know exactly where this check valve is? I intend on replacing my pump only soon with a larger aftermarket, (actually pump and sending unit because I need a new one, but separately, LS Swap with extra fueling demands) and I want to make sure I don't accidentally eliminate it if it's somewhere that I'll be messing with.

[speedygonzales]

Originally Posted by Chris95GT

Slightly off topic, do you know exactly where this check valve is?

The check ball is located in the housing between the pump and the top outlet.

[Chris95GT]

Originally Posted by speedygonzales

The check ball is located in the housing between the pump and the top outlet.

Thanks!

[AJCK87]

If anyone is interested..... These are the measurements that I found on the net. I will be giving it a try. An port to access the pump fuel lines and electrical would have been an excellent factory installation. O well I'll make my own

[speedygonzales]

Pop rivet a 2" metal strip underneath the hole extending into the hole a 1/2 inch all the way round to hold the piece you cut out. Paint the metal strip, rivets, edges of the hatch and think about further sealing the edge of the hatch with RTV after the paint dries.

I hope you don't come to regret cutting the hole.

[AJCK87]

Here's the access port for the fuel pump. I will be the most practical way for changing out the pump. Will post some pics of the hatch when it's done.

[AJCK87]

Originally Posted by speedygonzales

Pop rivet a 2" metal strip underneath the hole extending into the hole a 1/2 inch all the way round to hold the piece you cut out. Paint the metal strip, rivets, edges of the hatch and think about further sealing the edge of the hatch with RTV after the paint dries.

I hope you don't come to regret cutting the hole.

Thanks for the tips. I was really on the fence about how to go about it. I don't have a garage or an engine hoist so it would have been difficult for me to lift the box. Plus I live on the north end of Vancouver island and its rainy season. The hole turned out pretty good and I'm going to brace the hatch

[68C15]

Originally Posted by Chris95GT

Lifting the box really isn't as bad as it seems, I did it myself in the driveway. I removed the rear bumper to make sure I didn't scratch the bed, then I just loosened the passenger side bolts, removed the drivers side bolts, and used a ratchet strap between the front and rear corners on the drivers side and my engine hoist to lift the drivers side up and hold it. It was easy to do by myself and way way easier than wrestling a tank around. Honestly, I didn't even break a sweat. IMO it's easier to do that then it is to cut a hole in the bed with enough access to get lines and such off, and the end result is nicer.

You're in Texas, he's in Canada. Us up north have rusty bolts and stuff to deal with.

Speaking of rust. I'd highly suggest dropping the tank. Then replace the metal brake line between the tank and frame. I see so many rupture behind the tank that I sell people a new brake line when I do a pump

[Phillip Pennartz]

The last time I replaced my fuel pump in my 97 c1500 with 4.3 and I have
replaced many over the years. The man at the parts counter told me that the
reason I was having fuel pump failures was because of bad design of connector
at the fuel pump housing. that plug was causing a voltage drop and that
was causing the pumps to go bad. The store was an O'Reilleys. He sold me a
pump and pump housing with improved connector and it came with a short
piece of wiring harness that you replace the factory plug with. So far this new
pump has about 10k mi on it

[MrBillPro]

Dropping the tank is not bad, it's just seems that I always have a full tank of gas when mine dies.

[speedygonzales]

They always are full. The pump gets hot and boom fill it with a bunch of cold fuel. Seems when we did tanks they were always full.

On a pickup take the bed up. Gives you a chance to do other things too.

[shifty]

Bumping a really old [but related] thread to keep topics consolidated.

The high pitched whining from the fuel pump on my '98 has been driving me nuts for nearly a year now. I know, probably seems like I'm fixing everything in my truck right now, that's not lost on me! But I figure after a year, I should start ironing stuff out and I just got a bonus at work...

See mixed info online, like "whining on fuel pump means imminent failure, better replace it asap or get stranded!" then others say "all of the 95-98 C1500 OEM fuel pumps whined and it's totally normal!"

So I'm curious after reading this thread. Clearly the job will be a pain in the ass and I'm treading cautiously, asking questions. This specific statement caught my eye while reading up because I was looking at getting a Bosch 67381 to replace the OEM part...

Originally Posted by speedygonzales

Most electrical parts should be ONLY OEM. The fuel pump is one of them. I never saw a cheap auto store pump last very long.

I checked my three big local stores and - excluding off-brands - the name brands that keep coming up for my truck w/pricing are Bosch 67381 ($85), Delphi FG0086 ($145) or AC Delco MU1745 ($175).

For what it's worth the Delphi and AC Delco parts look damn near identical. Bosch's version looks similar to those two but way more robust and meaty.

Anyone in a position to help clear up some questions related to the topic/thread at hand? Like ...

Is a high pitch whine from the fuel pump really normal on a 21 year old truck with less than 90k miles? Never heard similar on my '03...

Realistically, will the Delco part outlast a very well known name brand like Bosch, and is there actually a difference between the Delphi and AC Delco part for a 97/98 5.7L C1500?

Any other helpful tips not already covered in this thread about the pumps? I'm cool on install, tank is only 1/8 full right now so I could potentially drop it this weekend....

Edit: Also found this tip from our resident expert

Originally Posted by speedygonzales

It's a good idea when ever possible to change out the module instead of just the pump since the gauge sending unit wears also.

[95 S_Trucker]

Your 98 should have a big plastic sending unit/pump assembly with quick connect nylon fuel line ends. 97 was the last year for the metal sending unit with line nuts where you can replace just the pump.

The pump for your truck will look a lot different than the one pictured in this thread.



Edit: Your replacemt pump will also come with a new connector. You will have to cut off your old one and hook up the old one. If you get Delphi or ac delco, the butt connectors with built in heat shrink are ok to use. You can also solder and use heat shrink tubing to seal the splice from the elements. Don’t use standard butt connectors or rely on tape alone to seal the splice.