Fuel Pump Control Module

[opfor2]

so yesterday I was doing some PM on my 2011 Tahoe and decided to run a test on all of the modules with my bi-direction scanner. A few codes came up but the most concerning for me were in the Fuel Pressure Control Module. (FPCM) The reason that these are concerning for me is I explore some very remote areas in the Mohave desert and I don't want to get stranded. They were at follows.

P018B-00 Fuel pressure sensor performance
P0562-00 System low voltage
P2534-00 Ignition 1 switch circuit low voltage
P2635-00 Fuel pump flow performance

Any thoughts?

 

[rdezs]

Wow, I think all of that taken together is pretty suggestive that your fuel pump isn't long for this world.

I would clear the codes, then run it through several drive cycles and check it again. Confirm your fuel pressure readings with your bidirectional scanner. If it's not capable, check it at the fuel rail. (This is where a Tech 2 pays for itself. Gives you a lot of info on your fuel system)

When you first turn the key on but don't start the engine, it should pressurize to 58 to 60 PSI. Start the engine and it should drop to around 43 to 45 PSI. It will fluctuate depending on engine load up from that figure, like pulling a trailer uphill.

Just changed the fuel pump in my wife's 2014 Escalade a couple weeks ago. 175,000 miles out of preventative maintenance was the plan for the upcoming weekend.... And as she pulled in the driveway I noticed the idol was very erratic. Tech 2 showed fuel pressure was dipping down to 30 PSI randomly at idle. Replace that with a GM OEM unit, found the carbon canister sounded like a baby rattle with loose carbon, so change that and the vent solenoid. Runs like new. Would have been a nightmare in the middle of the Mojave.

 

[2017sltXL]

Has the drivability changed at all recently?
Any stumbling, etc? No CEL?
At the surface it sounds like your pump is going south.

Nevermind, rdezs was posting my thoughts while I was typing them.

​

 

[rdezs]

She also just filled up with gas 20 mi earlier. I guarantee you're not siphoning the fuel out of that except through the opening for the fuel pump once it's removed. There's a check valve blocking where the filler tube connects to the tank. It's built into the tank. Tried pumping out through the fuel connections on top of the pump, that didn't work either. An inexpensive harbor freight transmission jack made it quite easy.

The only connection that's really a PITA.... Drop the spare tire, reach up above the back left of the fuel tank and you'll see the fitting with the hose that goes over across member. The rest are reasonably accessible. One at each corner of the front of the tank, then disconnect the fittings at the rear passenger side of the tank that connect to the carbon canister. Mine had plenty of slack in the harness to lower the tank down at least 12 in to disconnect the harness plugs on the fuel pump.

 

[rdezs]

Has the drivability changed at all recently?
Any stumbling, etc? No CEL?
At the surface it sounds like your pump is going south.

Nevermind, rdezs was posting my thoughts while I was typing them.

​

Lol, my wife accuses me of reading her mind

 

[Fless]

Are those "current" or "history" codes? The low voltage could affect the way the modules work; any recent issues with the battery, cables, or charging system?

 

[rdezs]

Good point, Fless.

With a marginal battery, turning the key to the on position without starting for some period of time could trigger all of that. (If I remember correctly, if you drop under 10 volts with the key on, engine off for more than a minute or two)

I think he needs a Tech 2 to see if it's a historic code or current? If so, I would have the battery and charging system tested for free at most Auto parts stores.... They do that free in their parking lot. Test the fuel pressure at the fuel rail with a mechanical gauge. If it checks out I would clear all codes and check again after a few drive cycles.

 

[Geotrash]

I also suspect a weak battery or cabling/ground issues, given that there were other codes present (he didn't say which, apart from the FPCM). Marginal battery voltage causes all kinds of gremlins in these things.

 

[Fless]

Good point, Fless.

With a marginal battery, turning the key to the on position without starting for some period of time could trigger all of that. (If I remember correctly, if you drop under 10 volts with the key on, engine off for more than a minute or two)

I think he needs a Tech 2 to see if it's a historic code or current? If so, I would have the battery and charging system tested for free at most Auto parts stores.... They do that free in their parking lot. Test the fuel pressure at the fuel rail with a mechanical gauge. If it checks out I would clear all codes and check again after a few drive cycles.

A good code reader or scanner will show the pending or history codes.

 

[opfor2]

The cel is not on I will double check the battery voltage when I get home. I will also pull the connector and clean everything, reinstall it, clear codes and see if they return

 

[opfor2]

 

[j91z28d1]

Wow, I think all of that taken together is pretty suggestive that your fuel pump isn't long for this world.

I would clear the codes, then run it through several drive cycles and check it again. Confirm your fuel pressure readings with your bidirectional scanner. If it's not capable, check it at the fuel rail. (This is where a Tech 2 pays for itself. Gives you a lot of info on your fuel system)

When you first turn the key on but don't start the engine, it should pressurize to 58 to 60 PSI. Start the engine and it should drop to around 43 to 45 PSI. It will fluctuate depending on engine load up from that figure, like pulling a trailer uphill.

Just changed the fuel pump in my wife's 2014 Escalade a couple weeks ago. 175,000 miles out of preventative maintenance was the plan for the upcoming weekend.... And as she pulled in the driveway I noticed the idol was very erratic. Tech 2 showed fuel pressure was dipping down to 30 PSI randomly at idle. Replace that with a GM OEM unit, found the carbon canister sounded like a baby rattle with loose carbon, so change that and the vent solenoid. Runs like new. Would have been a nightmare in the middle of the Mojave.

where did you buy the oem one? it on my list to do but rock auto shows without level sender and some have posted here that they have a Bosch sticker on their oem they removed. sounds weird for gm to use Bosch parts and I've never had good luck with Bosch parts.

 

[rdezs]

Due to the time factor, went down to my local Chevrolet dealer, $372. I actually expected it to be a bit more.

There's nothing wrong with using a Delphi fuel pump..... They've made them for GM for years.

 

[j91z28d1]

that's actually cheaper than I thought too. I'll have to swing by

 

[rdezs]

The parts manager told me they are trying to compete with online sales as best they can.... Is selling point was that if you buy it from him, they will warranty the part right there at the counter.

If you have a couple days, when I usually do is get the GM part number either from RockAuto or on GM's parts website, and search that part number on Amazon. ACDelco has a presence on Amazon, for some reason you can find their parts by the part number but not by the vehicle application. Just make damn sure when you're looking at the page showing the part that in the upper left under seller it says AC Delco.

My local GM parts manager told me they use a personal account to do that exact same thing to get parts faster than through GM, and cheaper than what GM will sell to them for.

 

[rdezs]

Here's an example for the 2011 Tahoe, using the GM mu2139 fuel pump.... And you'll see in the upper left it's the AC Delco GM store. It shows next day delivery to my location, which has usually been the case when I order from their storefront on Amazon.

 

[Fless]

The cel is not on I will double check the battery voltage when I get home. I will also pull the connector and clean everything, reinstall it, clear codes and see if they return

If the MIL is not on, but the codes are in the scanner, they are history or pending codes.