Mechanics

SIERRA 1500 - REPEATED FUEL PUMP PROBLEMS

1997 GMC C1500

1997 GMC Sierra 1500, 2WD, 240,000 kms
I have replaced the fuel pump 3 times in the last 2 years. I've changed the sending unit and the exterior connections. I've check and changed the grounds. I've also tried different makes of fuel pump. The fuel pump has now died again. I cannot figure out why I am still burning out fuel pumps. Does anyone has the same problem? Any suggestions - PLEASE!
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Bmozoe
May 4, 2006.



It sounds like either the pump is floating up out of the gas and catching air or you are repeatedly running it very low on gas either way if the pump catches enough air and runs dry so to speak it will burn the pump out very quickly. I suggest you make sure to always have over a quarter of a tank of gas at all times and make sure when you put the pump in it is less than an eighth of an inch off the bottom of the tank

Tiny
Andycoleman7
May 5, 2006.
I spent 50 years working on GMC, Ford, and other makes as a mechanic, so I speak from experience, not that I'm necessarily the sharpest knife in the drawer.

First, I'm 67, I've had nearly 50 years years of experience repairing numerous makes of vehicles including GMC, so that's out of the way. Yes. I'm old but not ready for the pasture and my brain is working reasonably well.

The 1997 GMC torpedo fuel pumps like so many, are basically prone to failure (I wanted to use another definition about the fuel pump quality - however, I want to keep my comments civil).

Whether original equipment or aftermarket, it makes little or no difference with regard to part quality, basically, we have become China dependent. This isn't just my consensus, you can find hundreds, if not thousands of professional mechanic posts on the Internet about the continual failure of these fuel pumps. The average life span of these pumps is 2 - 4 years, assuming that you keep your gas tank at least 1/2 full, install a decent fuel filter and change it at no less than at 10,000 mile intervals.

There are differences in fuel filter quality/brands as well, many swell up so bad that they become restrictive and can affect fuel delivery placing additional strain on the pump. These fuel pumps also overheat and become toast easily if you run your tank below 1/4, I would recommend that you keep your gas tank between 1/4 and half full.

Contrary to popular belief, the majority, if not all these fuel pumps are manufactured overseas, China being the major resource. Don't be fooled when some tells you about original GM parts/equipment being better than aftermarket parts, GM has many of their parts manufactured in China. As long as the replacement parts are assembled in the U.S, they can be designated as original equipment, when in fact they were manufactured in China or some other third world country. So don't be fooled into believing that when you buy an aftermarket replacement part your getting a part of lesser quality. All they do is stamp their name or logo on the same part.

For example, I recently replaced a GM original equipment ignition control module on a GMC Sierra 1/2 ton 4WD 5.7, while removing the defective control module it was stamped with the original "GM" Equipment Logo" on the front, when you turned it over, it was stamped "Singapore." So, once again, don't be fooled into believing that it was actually made in America and is any better or worse than an aftermarket replacement part.

You can pay $80.00 to $120.00 for an original equipment 1997 GMC fuel pump or you can pay $19.95 plus shipping for a fuel pump From Genesis Auto Parts that's no better or worse than the designated original equipment fuel pump, by the way they have an excellent reputation for automotive replacement parts. (I don't work or get paid any residuals from anyone for my recommendations).

About failing or failed in-tank GMC fuel pumps.

The fuel pumps on the 1997 GMC 5.7 and other years all have the same problem, the torpedo pumps generally fail within 2 - 4 years, regardless of whether you have a fuel pump strainer installed, keep the tank filled to capacity, and have a high quality fuel filter installed, basically, they're all the same. This is more of a problem now-a-days due to an economy which has made it diffcult for families to keep the gas tank 1/2 to full.

I've read so many comments on this fuel pump issue over the years and most are way off base with regard to fuel pump diagnosis, but the most ridiculous of all is, that one must purchase an Original Equipment fuel pump because the others are junk or of lessor quality.

First of all, the majority of all these fuel pumps are now manufactured in China, the only difference being that they have their name or logo stamped on them. "Original Whatever Name" that is stamped on the pump means absolutely nothing. As long as the pump is assembled in the U.S. It can be identified as original equipment made in America, when in fact all the piece parts were manufactured in China, for all I know, they've found away around having to import the piece parts and are importing them already assembled, that what they call "Trade Agreements.". So, you can pay $80.00 to $120.00 for a fuel pump or, you can pay $19.95 plus S&H from Genesis Auto Parts and get the same quality, (I don't work for anyone, I'm retired).

Bottom line, I've replaced three (3) of my own fuel pumps in 11 years on my GMC 5.7 and I've listened to 100's if not thousands of complaints about GMC failed fuel pumps, you can find this information all over the Internet.

So what is "Original GM Equipment" anyway?

Here's one example, I've replaced ignition control modules on GMC's, when I was removing the original equipment defective devices, they were stamped "GM" on the front implying that they where original equipment made in America of the highest quality. BULL, when you remove the module, on the back of the device, it says "Singapore", I think Singapore is in China, don't you?

Back to the pump issue.

The bottom line, you're going to have to live with this fuel pump aggravation and replace the pump numerous times over the life of your vehicle. I would suggest that you replace the fuel filter at intervals of no less than 10,000 miles, also be sure that you install a gas strainer on the pump when you replace it. These pumps overheat easily if you run your gas tank too low, never below 1/4, I would suggest 1/4 to 1/2.

You also need to know how to perform a proper fuel pump test to determine if the fuel pump is beginning to fail or is actually dead. Spend $30.00 and get yourself a fuel pressure gauge, most come with adapters for both GM and Ford vehicles.

Here are the tests that you need to perform.

Be absolutely sure that you inspect your fuel filter for restrictions before performing the following tests. Some fuel filter brands are known to have filter elements that can actually swell and restrict flow. Be sure that your coolant temperature sensor has been checked and known to be in good working condition, that's the one that generally sits up front near the thermostat housing, it can also cause hard starts. Having verified the above we move on.

Perform the following tests when the vehicle is STONE COLD, let the vehicle sit overnight, then perform the tests. This is important because if the vehicle is warm, it may start, but when cold, it won't start.

1. If your vehicle starts hard, or when it's stone cold it fails to start at all or, requires numerous cranking attempts to get it started or, requires that you spray starting fluid or pour a few drops of gas into the throttle body, your pump is on the way out or DEAD.

The 1997 GMC Sierra vehicles have a fuel pressure port on the fuel line under the hood, it's a Schrader Valve port where you can attach the fuel pressure gauge. Now have someone sit in the vehicle and turn on the key (DO NOT CRANK THE STARTER/ENGINE), now observe the reading, it must read at least 60 - 65 PSI, if it reads "0" the pump is dead, if it reads below 60 PSI and does not drop to "0", you have a fuel pump issue that's in the beginning stages of failure. Assuming the fuel pressure test met the 60 - 65 PSI requirement, go to step two (2).

2. If the gauge does read 60 - 65 PSI, now have your friend crank the engine, read the result, if the gauge drops below 50 PSI but does not go to "0" when cranking (NOT RUNNING). Yes. While the engine is cranking. Your fuel pump is on it's way out and will either cause hard starts or, not start at all without a priming assist with starting fluid or a few drops of gas poured into the throttle body. Anything below 50 PSI when cranking, you are going to have to replace the pump. Most fail to perform the cranking test and misdiagnose any fuel pump delivery problem.

Obviously, if the gauge reads "0", the pump IS COMPLETELY DEAD. YEAH, I KNOW, CHECK THE FUSE FIRST.

YES, there are other things that can cause hard starts or failure to start, however, 99% of the time the tests noted above will reveal either a good fuel pump or one that needs to be replaced, or one that's DEAD.

Hope this helps.
TombMech

Tiny
TombMech
Dec 12, 2011.
Check to make sure the fuel filter isn't plugging. Also, make sure the regulator is working properly.