Fuel pump

[Mikemike36311]

I have a 09 Yukon 4.3L the fuel pump went out a couple days ago checked under the hood in the fuse box there is no fuel pump relay..I have had this truck for 4 yrs never had any problems out of it until now the alternator went out last week replaced it then now the fuel pump so I bought the pump put it in and got everything hooked back up and in went to prime the truck and nothing from the fuel pump so after testing theories I discovered that the fuel pump fuse has no power with the test light and even though there wasn’t a fuel pump relay I put one in and still nothing I am completely lost on this one any information would help at this point

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me in this area will chime in.

 

[Fless]

Welcome to TYF from Colorado!

I would recommend diagnosing the Fuel System Control Module:

 

[j91z28d1]

I didn't watch the video, so it might say the same thing. but I took a peek at the wiring diagram for a 4.8 08 yukon, I don't see a 4.3, I think the 4.3 is a gm c6? but my stuff shows there is no labed fuel pump fuse or relay. you have a fuel pump module that runs everything.

it gets a fuel pump request from the ecm, a dk green/white wire, pin 13 of the fuel pump control module from ecm pin pin 51.(no clue what is sending, I'd guess ground but could. be positive or could be a signal. that module gets its power from ecm fuse ecm fuse #56 15amp. there's also a reference volt in on pin #32 red/white wire running to fuse #21 hot at all times.
the pump itself looks to get + from pin #16 of the module and a switched ground to run the pump on pin #47.

if you look inside where you put that relay there's probably not any terminals, just a blank spot from back when fuel system was return style and the pump just ran non stop. they now have a pwm signal to the pump and no return. there's probably some codes from that module to check, plus pull up some live data of what the requested pressure is and actually pressure reading. plus the scanner can turn the pump on and off to troubleshoot. it's really hard to diagnose things these days without them.

 

[Mikemike36311]

Thank you guys im gonna try to diagnose the Fpcm today as soon as I get off..

 

[Mikemike36311]

K

 

[Mikemike36311]

I didn't watch the video, so it might say the same thing. but I took a peek at the wiring diagram for a 4.8 08 yukon, I don't see a 4.3, I think the 4.3 is a gm c6? but my stuff shows there is no labed fuel pump fuse or relay. you have a fuel pump module that runs everything.

it gets a fuel pump request from the ecm, a dk green/white wire, pin 13 of the fuel pump control module from ecm pin pin 51.(no clue what is sending, I'd guess ground but could. be positive or could be a signal. that module gets its power from ecm fuse ecm fuse #56 15amp. there's also a reference volt in on pin #32 red/white wire running to fuse #21 hot at all times.
the pump itself looks to get + from pin #16 of the module and a switched ground to run the pump on pin #47.

if you look inside where you put that relay there's probably not any terminals, just a blank spot from back when fuel system was return style and the pump just ran non stop. they now have a pwm signal to the pump and no return. there's probably some codes from that module to check, plus pull up some live data of what the requested pressure is and actually pressure reading. plus the scanner can turn the pump on and off to troubleshoot. it's really hard to diagnose things these days without them.

So I diagnosed the fscm there is power to the plug if you jumper the wires on the plug for the Fscm the pump comes on so I purchased a Dorman preprogrammed Fscm and the pump still won’t come on. The code I’m getting is P0230 which is fuel pump circuit I have no idea where to go from here

 

[Mikemike36311]

Welcome to TYF from Colorado!

I would recommend diagnosing the Fuel System Control Module:

So I diagnosed the fscm there is power to the plug if you jumper the wires on the plug for the Fscm the pump comes on so I purchased a Dorman preprogrammed Fscm and the pump still won’t come on. The code I’m getting is P0230 which is fuel pump circuit I have no idea where to go from here

 

[j91z28d1]

do you have a scan tool that can turn on the fuel pump to test? that's kinda step 1 in what I have.

looks like 1 wire from the ecm to the fuel pump module. but then a bunch of data lines. you might be able to check continuity on that one wire if you don't have a scanner that can try to activate it?