Possible Fuel Pump related issue

Novice1933

A little background (please read, thank you!): 2016 Traverse, 87,600 miles. Drove it to vacation, about 11 hours away. Night before we leave to come back home, we were leaving a restaurant, and it wouldn't start. It would turn, but not start. Pumped the gas pedal, and still nothing. Sat for 5 minutes, tried again, and it started. Immediately fueled up, and went back to where we were staying. Full tank of gas, got up the next morning and started fine. Took someone 30 minutes away to ride home with someone else, came back to pack up, shut it off. Packed and ready to come home, fired right up. Drive about 4 hours, stopped to fuel up, it started back up, but died a few seconds later. Waited a few minutes, tried again and nothing. A mechanic happened to stop by, and he banged on the fuel tank with a hammer, while I tried to start the car. It started, and 30 seconds later it died, not to start again. (fortunate to have a good friend who operates a tow company that brought us our other car, and towed the Traverse home).

Initial reaction is that the fuel pump went out. Replaced it, wouldn't start. Mechanic unhooked the negative battery cable, let it set for five minutes, hooked back up and it started (assumption was that reset everything). Drove it for a week, filled it up, stopped by a restaurant, came out and nothing. Mechanic comes by, unhooks the fuel module and negative battery cable, waits 5 minutes, and it starts back up. While he was there, he put a code reader on it and it read: PO18B-- defined as “Fuel pressure sensor “B” – circuit range/performance”, and is set when the PCM (Powertrain Control Module) detects an abnormal signal voltage from the fuel pressure sensor." Still a full tank of gas, have drove it all day today, started at least 1/2 dozen times, and fires up fine every time, and the car runs great.

Have an appointment Wednesday to have a dealer run diagnostics on it (I know, should have done that in the first place). Any reaction on what the potential issue could be? Thank you in advance for your insight!!! Matt

imidazol97

Novice1933 said:

A little background (please read, thank you!): 2016 Traverse, 87,600 miles. Drove it to vacation, about 11 hours away. Night before we leave to come back home, we were leaving a restaurant, and it wouldn't start. It would turn, but not start. Pumped the gas pedal, and still nothing. Sat for 5 minutes, tried again, and it started. Immediately fueled up, and went back to where we were staying. Full tank of gas, got up the next morning and started fine. Took someone 30 minutes away to ride home with someone else, came back to pack up, shut it off. Packed and ready to come home, fired right up. Drive about 4 hours, stopped to fuel up, it started back up, but died a few seconds later. Waited a few minutes, tried again and nothing. A mechanic happened to stop by, and he banged on the fuel tank with a hammer, while I tried to start the car. It started, and 30 seconds later it died, not to start again. (fortunate to have a good friend who operates a tow company that brought us our other car, and towed the Traverse home).

Initial reaction is that the fuel pump went out. Replaced it, wouldn't start. Mechanic unhooked the negative battery cable, let it set for five minutes, hooked back up and it started (assumption was that reset everything). Drove it for a week, filled it up, stopped by a restaurant, came out and nothing. Mechanic comes by, unhooks the fuel module and negative battery cable, waits 5 minutes, and it starts back up. While he was there, he put a code reader on it and it read: PO18B-- defined as “Fuel pressure sensor “B” – circuit range/performance”, and is set when the PCM (Powertrain Control Module) detects an abnormal signal voltage from the fuel pressure sensor." Still a full tank of gas, have drove it all day today, started at least 1/2 dozen times, and fires up fine every time, and the car runs great.

Have an appointment Wednesday to have a dealer run diagnostics on it (I know, should have done that in the first place). Any reaction on what the potential issue could be? Thank you in advance for your insight!!! Matt

Is this a direct injection engine. They have a second fuel pump on the engine that gives the high pressure, if I understand the system...

I know when I hooked up my Acton scanner on my 14 Malibu 2.5, it showed hundreds of pounds of pressure from the high level fuel pump.

thecardoc3

imidazol97 said:

Is this a direct injection engine. They have a second fuel pump on the engine that gives the high pressure, if I understand the system...

I know when I hooked up my Acton scanner on my 14 Malibu 2.5, it showed hundreds of pounds of pressure from the high level fuel pump.

This is correct it is a direct injected engine. GM uses two fuel pressure sensors, one on the fuel rail as you are thinking and one on the fuel supply line. This code is referring to the supply side sensor signal. Remember that trouble codes don't always tell you what part is bad, they tell you what test failed. The P018B means that the engine control module didn't see a change in the fuel supply side fuel pressure signal (voltage) when the pump was "supposed to be" running. There are some additional codes that could set such as P018C fuel pressure sensor circuit low voltage (less than .2v) and P018D fuel pressure sensor circuit high voltage (more than 4.8v). If either of those two codes set then that would block the P018B test from running so right away we know that the voltage that the PCM was seeing from that sensor was inside the normal range of .2v - 4.8v which reduces the chances that this is a circuit issue. That's about as far as one can go at this point. It's time to connect some tools and get the car to act up to go further.

BTW the "hammer test". This is far from the first time that an engine started after someone hit the fuel tank with a hammer and replacing the fuel pump didn't fix the car. That's why testing correctly each and every time is so important. The only thing that can be said about the way this one sent down was that "something changed" when that was attempted. From there it may be related to the pump and it's circuit or it may have just been a coincidence.

Novice1933

Thank you both. I appreciate your input. One last question: both times the engine wouldn't start was after I filled the tank with gas. Would this pinpoint anything (I'm probably reaching here, but....)? It started right up again this morning, and is running great (has about 3/4 in the tank). Thank you again! Matt

goodboy123

Thanks for the really helpful vid, i had a question, wen i remove the gas cap there’s a release of pressure, is that n indicator that the fuel pump n its surrounding components r working???