Bad fuel pump?

[06 H3]

On the last day of KOH the Hummer cranked for about 30 seconds, didn’t start, cranked again for another 10-15, started and then ran like **** for 10 seconds or so, cleared up and was happy.

Since day 1, the I5, 5.3 and 6.2 have always started immediately, I can’t think of a single time this has happened so I don’t have a history of this issue.

I turned it off and on every few hours that day and it started immediately like it always has.

If it sat overnight, the same thing would happen.

My fuel pump is old, the sending unit stopped working accurately about a year ago and I had planned on swapping it out for that reason but haven’t yet.

Has anyone had these symptoms before and have it NOT be the fuel pump? Could it be electrical? Or an injector being crap? I have roughly 150k on this 6.2...

I assume for a fuel pump stick with AC delco...from what I have read, off brand pumps suck. For what it’s worth, I can run a factory pump successfully with a 6.2 and have for a few years so I don’t think it’s 6.2 related.

 

[08H3]

I have not had any fuel pump issue on the H3, but did have the same symptoms on a C4 due to fuel pump. That said, I had an truck that was opposite. Always started without issue, then ran like crap so it's hard to say. With the H3 I have had similar issue if I kill it on a hill and then the engine turns a partial revolution while not running. It will start hard, then run fine. My theory had always been that the cam or crank position sensors get confused momentarily. Have no idea if that's right, but it always seemed like a possibility. I know I didn't answer the question and probably just confused things more, but maybe something in there will eventually help. Good luck getting it sorted out.

 

[JPaul]

Could put a pressure gauge on the line to see what the pump is doing. It should pump up just fine when you first turn the key on. Might be getting weak pressure or a bad contact or something. Pretty sure we have schrader valves on the V8's fuel bars you can hook to, but maybe that was just on my Neon.

 

[06 H3]

I’ll check to see if there’s a fuel rail port

 

[Reloader]

Yup, sounds like fuel pump going away. Real common for GMs. Long crank to start is a good sign. Next time it doesn’t start right away, stop cranking, turn key to off, then immediately try to start again. Another start cycle can shock the pump into producing enough fuel pressure to start and run the engine. These pumps need to produce a minimum certain fuel pressure to start . A pump that produces a couple pounds less pressure can cause a no start. Also thumping the tank with a dead blow hammer or even a rock can shock a bad pump into running again but don’t shut it off till you are somewhere you can fix it. That may be its last hurrah.
The genuine GM pump is no longer available for the older H3s. The AC Delco one is the recommended replacement and is what the dealer uses. I got mine on Amazon a year ago for like $267. Amazon was cheaper that Rock Auto at the time and free shipping too. Delphi would be the next choice after AC Delco.

 

[Reloader]

If your fuel gauge has been erratic , that is probably a bad fuel card on the fuel pump assembly. The tiny fingers that make contact with the reostat on the fuel card break off. You can replace fuel card separately but you need to remove pump to do so. Might as well replace whole thing then too. Once again a common GM problem.

 

[06 H3]

Yup, sounds like fuel pump going away. Real common for GMs. Long crank to start is a good sign. Next time it doesn’t start right away, stop cranking, turn key to off, then immediately try to start again. Another start cycle can shock the pump into producing enough fuel pressure to start and run the engine. These pumps need to produce a minimum certain fuel pressure to start . A pump that produces a couple pounds less pressure can cause a no start. Also thumping the tank with a dead blow hammer or even a rock can shock a bad pump into running again but don’t shut it off till you are somewhere you can fix it. That may be its last hurrah.
The genuine GM pump is no longer available for the older H3s. The AC Delco one is the recommended replacement and is what the dealer uses. I got mine on Amazon a year ago for like $267. Amazon was cheaper that Rock Auto at the time and free shipping too. Delphi would be the next choice after AC Delco.

When you say the genuine pump isn’t available for older H3s are they still around for 08-09-10s? Was there a difference between 06 and 08-09-10?

 

[Reloader]

Pumps for 06-08 are the same I believe. My 08 Alpha and your 06 use same pump me thinks. 09s and 10s and maybe some early 08s use a modulated fuel pump with the controller mounted under the rear above the spare on H3Ts and above the exhaust on H3s. Not interchangeable. When I bought my AC Delco on Amazon last year or maybe it was end of 2019, it cost $267. My cost at dealer for exactly the same part number was around $500 with retail at $700ish. I see thatRock auto is listing the AC Delco out of stock and couldn’t find it on Amazon last night. Rock has .the Delphi one though. AC Delco and Delphi are not the same thing but Delphi is probably better than crap like Airtex or Spectrum or anything from O Reilly’s or Autozone

 

[Reloader]

When you change pump be sure and get a new genuine GM fuel pump relay too. It’s the little grey one that’s used in a **** ton of GMs. You can usually swap the horn relay or a/c mag clutch into fuel relay in a pinch if needed.

 

[06 H3]

Thanks! I will see if I can find an AC delco before going the Delphi route.

If I let the Hummer sit for a day and tried to start it the truck would just crank excessively. This morning I went to start it after letting it sit for 4 days, before starting it I put the key on and off 3 times allowing the pump to prime, started right up, I’m assuming that’s another indicator that it’s the pump

 

[Reloader]

Yeah it definitely sounds like it’s on borrowed time.

 

[08H3]

Just out of curiosity, how many miles did you get our of your fuel pump (assuming that's the issue)? The one in the H3 has outlasted any fuel pump in any vehicle I have ever owned. I'm not in the habit of replacing things that aren't broken, but it does make me question just how much time is left on it. Good friend who is also a mechanic by trade says GM fuel pumps aren't the pieces of crap they used to be and not to sweat it. He claims that they usually outlast the vehicle. No idea if that's true across the board or just from what he has experienced.

 

[06 H3]

I have 173k on my H3. After my engine swap (first one) with the 5.3 I thought I had a bad fuel pump and changed it out but it wasn’t the pump, it was the wiring. That was around 130k? I changed it with a AC delco unit.

First one was still good when pulled and I bet it would be fine today if I didn’t change it.

2nd one had 40-50k on it and is 6 years old.