# 5.3 loosing power (no power)



## DJ Contracting (Dec 16, 2003)

I was on the highway today (70 mph) and raining, anyway the truck loss power and I had to pull over...I shut the truck off for a couple of minutes, restarted the truck and was on my way for about 10 miles then it did it again, and again and again. When I got to where I was going I had the fuel filter changed (that's what it acted like). It didn't help as I was on my way home it started all over again. Now I have a truck that won't get out of it's own way.

This is what I had checked 
1.Fuel filter replaced (was not able to have fuel pres. checked)
2.Check for codes and found O2's codes (expected)
3.Test drove with a scan tool to watch activity showed nothing abnormal. 
#3 leads me to believe that maybe it could be a mass airflow sensor as sometimes they will not leave any codes or show anything abnormal. any help would be appreciated Thanks Joe


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## Sydenstricker Landscaping (Dec 17, 2006)

If you suspect mass air flow, pull it out and clean it with some good MAF cleaner. I recommend the stuff by CRC. I would next have the fuel pressure checked while driving it. Im willing to bet that you have a weak fuel pump and the engine is starving for fuel, causing a lean condition and that could be throwing the O2 codes. When my fuel pump was on its way out, the truck had no testes, and was throwing all kinds of O2 codes. Turned out to be the fuel pump. If it is, replace the pressure regulator on the fuel rail as well


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## DJ Contracting (Dec 16, 2003)

What seem strange is when I shut off the truck and let it set for a couple of minutes it seems to run good for about ten miles or so, but yes I'll have the fuel pressure checked and clean the sensor.


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## Banksy (Aug 31, 2005)

It sounds like the fuel pump can't keep up or something.


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## DJ Contracting (Dec 16, 2003)

Yeah this might be it's second one, the truck has 128,000 mile on it and I put one in it about fifty thousand ago because of the sending unit we'll see what the fuel pressure reads on Monday


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## B&B (Nov 4, 2006)

Don't bother doing anything until you get a FP gauge on it and drive it. As I believe you'll discover that the pressure is dropping off. It's also not unheard of for a brief "cooling period" to bring a dying pump back to life briefly.


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## DJ Contracting (Dec 16, 2003)

So how much fuel pressure should I be looking for ?


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## DJ Contracting (Dec 16, 2003)

Well I ran a fuel pressure test and at Idle it has 45 psi and going down the road it will maintain 45 psi however during WOT it drops down to 20 psi so now I'll be putting in a new fuel pump/sending unit tomorrow :crying:


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## 2COR517 (Oct 23, 2008)

Do it the easy way, and lift the bed to access the fuel pump. Be glad that it didn't leave you stranded. Usually a dead fuel pump involves a wrecker bill.


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## ahoron (Jan 22, 2007)

Get a factory replacement not autozone junk. Also replace the electrical connector on the unit. Should come with the new wiring


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## DJ Contracting (Dec 16, 2003)

2COR517;1027685 said:


> Do it the easy way, and lift the bed to access the fuel pump. Be glad that it didn't leave you stranded. Usually a dead fuel pump involves a wrecker bill.


Yeah I know i did everything I could to make this 200 mile round trip it was very stressful



ahoron;1027692 said:


> Get a factory replacement not autozone junk. Also replace the electrical connector on the unit. Should come with the new wiring


I had replaced the unit in Oct. of 07 with a Advance auto one now I have been on-line looking for one. I found some on ebay however I'm leery because the are selling them for under $100.00 shipped. I did find one at Carquest for $220.00 my cost through my business account.


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## 2COR517 (Oct 23, 2008)

ahoron;1027692 said:


> Get a factory replacement not autozone junk. Also replace the electrical connector on the unit. Should come with the new wiring


x2. I just replaced the fuel pump on my Tahoe. New GM pump was just about the same price as a Carter unit from Napa. It included the new pigtail.


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## DJ Contracting (Dec 16, 2003)

The one I bought three years ago had the new pigtail so that has been changed already


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## 2COR517 (Oct 23, 2008)

The new pump (GM) will likely have a new connector style. The latest one is a very robust electrical connection. There's a good chance you will find evidence of overheating on the pigtail/sending unit.


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## DJ Contracting (Dec 16, 2003)

Some of you say to remove the bed but when I replaced it the last time I removed the front removed the heat shield and loosened up the rear strap enough to lower the front of the tank and replaced the unit all with a broken left thumb. It took me about two hours and I blame the thumb on that


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## DJ Contracting (Dec 16, 2003)

Sorry I'm on my phone that was supposed to read remove the front strap


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## Sydenstricker Landscaping (Dec 17, 2006)

Napa carries the Delphi pump, which is the GM oem one. Little more pricey, but 100x better than the autozone junk. I highly highly recommend doing the fuel pressure regulator too. Those can be faulty and cause premature failure of the pump. It is extra $$$, but it is good insurance to have everything last longer this time around


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## 2COR517 (Oct 23, 2008)

Went I was looking for a pump for the Tahoe, Napa indeed had the Delphi pump. But it was the pump only, no sending unit. I needed the entire module, because one of the electrical pins corroded, overheated, then caused the pump to fail. Napa had a Carter assy, but not Delphi. So I went to the GM dealer. When I put it all back together, I liberally slobbered everything will Fluid Film.


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## t-sig (Feb 5, 2010)

DJ, 

If you do drop the tank completely, or remove the bed, you may want to check/change the brakeline going from the block under the cab to the rear axle. It is alot easier to change when you have some extra room. I don't know if Michigan uses salt on the roads, but in NY, a truck with that much mileage doesn't have too many stock brakelines that aren't rotten.


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## DJ Contracting (Dec 16, 2003)

t-sig;1028040 said:


> DJ,
> 
> If you do drop the tank completely, or remove the bed, you may want to check/change the brakeline going from the block under the cab to the rear axle. It is alot easier to change when you have some extra room. I don't know if Michigan uses salt on the roads, but in NY, a truck with that much mileage doesn't have too many stock brakelines that aren't rotten.


Of coarse I had to check this after I replaced it, anyway I took some pictures while the bed was sitting on the tires and rear bumper. 
Now it has a new fuel filter, fuel pump, and sending unit,
The new pump reads 60 psi at start up then goes down to 53 psi at idle, at cruising speed ( anywhere from city driving 70 mph highway) it maintains 55 psi if I gun it to pass the pressure would rise up to about 57-58 psi. Now do you think that if I replace my fuel pressure regulator I might be able to maintain 60 psi all the time?

Oh I removed (broke) the ground bolt for the ground strap, this also had a ground wire coming out of the fuel pump wire harness, I believe for the fuel system because it would not restart until I reattached the grounds just FYI.


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## Sydenstricker Landscaping (Dec 17, 2006)

Sounds like the diaphragm in the regulator is bad. Also check the vacuum line going to it for cracks, etc. That will cause the fuel pump to fail prematurely. A new regulator will keep your psi in check and probably a lil higher as well. Any time I have done a fuel pump, the regulator automatically gets replaced. It is nice to have the peace of mind knowing that it is all new and maintaining the pressure properly. Just make sure you bleed the pressure off the rail before doing the regulator. I forgot to do that on my truck and got a face full of gas. Not very fun, lol


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## DJ Contracting (Dec 16, 2003)

So how hard is the fp regulator to do on the 5.3 Chevy?


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## Sydenstricker Landscaping (Dec 17, 2006)

Im guessing it is like my 6.0 Pop the vacuum line off, and take the ring from around it that holds it in the fuel rail, it falls out and installation is reverse of normal. Just make sure the o-ring seats properly. Took me 5 minutes to do my fp regulator after I wiped the gas off of my face, lol


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## DJ Contracting (Dec 16, 2003)

Lol ok I'll have to pick one up tomorrow


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## Sydenstricker Landscaping (Dec 17, 2006)

DJ Contracting;1028219 said:


> Lol ok I'll have to pick one up tomorrow


Just be forewarned, it will run you about 75 bucks. For what they are, it really isnt cheap


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## B&B (Nov 4, 2006)

DJ Contracting;1028080 said:


> The new pump reads 60 psi at start up then goes down to 53 psi at idle, at cruising speed ( anywhere from city driving 70 mph highway) it maintains 55 psi if I gun it to pass the pressure would rise up to about 57-58 psi. Now do you think that if I replace my fuel pressure regulator I might be able to maintain 60 psi all the time?


Those pressures are near perfect so there's nothing wrong with the regulator and your new pump is working perfectly. The press SHOULD change at various loads as the regulator is vacuum referenced.

However, if you like to follow the preventative route it's not a bad idea to throw a fresh regulator on there anyway as they're well known to wear out and with the mileage your truck has accumulated it wouldn't be money wasted.


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## DJ Contracting (Dec 16, 2003)

Yeah B&B I'll put one in


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## tracerich (Oct 25, 2004)

Consider yourself lucky in two respects. One, being able to remove the bed and change that pump module. Two, that you didnt have a serious fire while doing it. Do yourself a favlor, and toss the incandescent trouble light in the garbage. They should be outlawed. Most of the fires that originate in a repair shop relating to servicing the fuel system, involve an incandescent trouble light..


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## DJ Contracting (Dec 16, 2003)

The light was nowhere near me when I was actually replacing the pump, it was on the bench for safety reasons as you can see no fuel line were disconnected at the time of the picture but thanks for the advice.


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## tracerich (Oct 25, 2004)

Good deal then. Just last month the tow company I use had bit of a fire.. Incandescent drop light and fumes. Hundreds of thousands of dollars worth of damage. Regarding the difference in fuel pressure, consider your gauge accuracy. Just curious, what brand of pump module did you install and what did it cost?


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## DJ Contracting (Dec 16, 2003)

I'd have to look at the box again to see what brand it cost $219.00 plus tax at Carquest


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## DJ Contracting (Dec 16, 2003)

tracerich;1028326 said:


> Good deal then. Just last month the tow company I use had bit of a fire.. Incandescent drop light and fumes. Hundreds of thousands of dollars worth of damage. Regarding the difference in fuel pressure, consider your gauge accuracy. Just curious, what brand of pump module did you install and what did it cost?


The name brand was Spectra Premium from Carquest $219.00 plus tax


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## bru z71 (May 10, 2009)

i am not looking foward to doing this to my truck when my pump goes i got the same truck


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## DJ Contracting (Dec 16, 2003)

It would have been worse if it was cold out, but when I did it it was 50 degrees.


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