Fuel Pump Failure Mode

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May 10, 2005
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My 16 year old truck has 235K kms/ 147K mi and is on its original fuel pump. I just scoped the current waveform and it looks fine with no hint of brushes reaching the end of their life. Current draw and fuel pressure is normal and the pump sounds normal. Of note is that this truck is driven in a big congested city and the lifetime average speed of the truck is 30 km/hr / 19 mi/hr. So the 147K mi would be more like 200K mi if the truck had been driven in a less congested area, as far as fuel pump wear is concerned.

I do not let the fuel tank go below 1/8 tank, which still leaves 15l / 4gal of fuel in the tank. I buy fuel exclusively from Costco which ensures fuel quality. I am tempted to leave it be and not prophylactically change the pump. I was wondering how much warning signs would I get of an impending pump failure - erratic current waveform, abnormal noise, low fuel pressure leading to a code for some engine performance related parameter like STFT, LTFT or O2 sensors. Or is the pump going to lockup on me without any warning? If the latter I will lift the bed up and replace the pump with a Delphi from RockAuto.
 
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I was wondering how much warning signs would I get of an impending pump failure - erratic current waveform, abnormal noise, low fuel pressure leading to a code
Doubt there is a code directly for low fuel pressure on something that old. And unless you connect a scope and gauge weekly to check, whats the point. Better to install a permanent fuel pressure gauge to let you know all the time.
 
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My experience with GM fuel injection trucks is they get louder with age. As soon as mine start making noise I'm checking fuel pressure. Now I did have the fuel pump on my 2000 Blazer make noise for about 10 years, lol, but it was a local vehicle, I just replaced it a couple of months ago. My 2002 GMC fuel l pump I replaced last year after it started whining. I put Delphi pumps in both of them.
 
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I would leave it be untill it actually fails.. a replacement could fail anytime also, that's my experience.
 
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Back in the day when I would take my cars past 200k miles I would change fuel pump and alternator at around 150k. Parts were cheap back then on newer cars some of these parts are insane. On a 16 year pickup I cant imagine the part being that expensive. 147k at those speeds is alot of wear and tear in my opinion. If it were me I would change it with a good quality unit. Parts seem to fail at the most inopertune time. Case in point I make it a habit of changing batteries after 5 years, I forgot to do it once and my daughter couldnt start the car and she was about 60 miles away. Lesson learned for me do what worked in the past.
 
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My experience says this ☝️
Since he's got a scope and can actually read the pump's health, then his experiences won't be like most. Just because it's old doesn't mean it's going to die unexpectedly.

If you were to wind back the clock on a couple of dozen dead pumps and scope them in the days or weeks before their demise, you'd see all or the overwhelming majority of them going bad.
 
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Since he's got a scope and can actually read the pump's health, then his experiences won't be like most. Just because it's old doesn't mean it's going to die unexpectedly.

If you were to wind back the clock on a couple of dozen dead pumps and scope them in the days or weeks before their demise, you'd see all or the overwhelming majority of them going bad.
I agree. Is that something @George7941 is willing to do though on an on going basis?
 
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I've had two fuel pumps fail on me in 40 years of driving. Both failed while driving, like the key switched off, both right after filling the tank smh.
 

D60

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Interesting that people want to act like pump failure on their personal vehicle is unlikely but I'm guessing most techs would tell you this is one of the more regular R&R's they perform?

Perhaps not? Maybe shops just aren't replacing many fuel pumps these days? Would be interesting to poll the techs working under the vehicles all day every day.
 

George7941

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I agree. Is that something @George7941 is willing to do though on an on going basis?
I have been doing it twice a year, both on my truck and on some trucks I maintain for a moving company. Also scope starter current to look for signs of impending starter failure.
I thought my pump was on its way out last year from its current trace on a scope but the trace has settled back to normal. If I do not change the pump out now, I will monitor it more frequently.
 

George7941

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I would leave it be untill it actually fails.. a replacement could fail anytime also, that's my experience.
Were your replacement pumps Delphi/Bosch/ Denso or were they Carter/ Airtex/TYC?

The quality of a pump makes a huge difference. One Freightliner with a Cummins 5.9 diesel came with a Carter fuel pump and the pumps would last at most a couple of years. This went on from 1999 to 2008 till I replaced the Carter with a Walbro and the pump problems were over. That Walbro is still going strong. I scope its current twice a year just to keep an eye on it.
 

George7941

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GM trucks have had high failure rates of fuel pumps. Hard to understand why GM truck engineers could not come up with better fuel pumps when other vehicle engineers could.
 
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In my experience the GM fuel pumps from the mid 90's to the early 2000's (00-02) were pretty loud even when healthy, you could hear them standing next to the vehicle. Plan on replacing those somewhere between 80-120,000mi, do not buy the airtex pumps unless you like changing them. After that they seem to be quieter but fail about the same till around 2008 or whenever they went to the in tank non-serviceable filter and got rid of the frame mounted fuel filter. Those pumps seem to hold up pretty well, might be that they use a finer filter sock in the tank or they aren't pushing against a dirty frame mounted filter trying to maintain rail pressure (pump needs to make 75psi to get 55-60 at the rail with the engine under load due to a dirty filter).

Any kind of growling noise is a sign of the pump failing soon, a constant high pitched buzz is normal though. Low fuel pressure codes or lean condition codes are another sign of a pump failing.
 

George7941

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My 2006 has in in-tank pump with the non-seviceable filter. So you are saying that my pump might have lots of life left in it?

My pump has the constant high pitched buzz, has had it since day one..
 
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