Random P0087 2017 L5P C&C

[DPC]

Have a 2017 GMC 3500 C&C dual fuel tanks throwing a random P0087 (low rail), reduced power, sputters, then shuts off. Wait about a minute, start truck, and runs fine. Will not happen while driving, only when you start the truck. If you start the truck and it runs, it will not give you any problems even at WOT. Very random, seems electrical but no other codes.
Truck has a new fuel filter and rail pressure sensor with pigtail. Passes FPR1 and FPR2 scan tool tests. Lift pump pressure in spec. Any ideas? Thanks.

 

[Chevy1925]

Ecm have the newest update?

 

[DPC]

Ecm have the newest update?

I'll give that a look. Thanks.

 

[TeaBagger2006]

i have a cab and chassis L5P and a LMM, both have dual tanks and both have and still give me fuel problems. the transfer pump is the culprit in both. every so often and just totally random it quits working and starves the trucks. i haven't replaced the pump in either truck since they will run fine for months at a time. my L5P throws a P1235 & P1236 CEL. my L5P has the newest ECM revisions too.

i dont know if that helps but i know its a common problem with the trucks with dual tanks

 

[rmallen30]

I have had 3 L5p cab and chassis trucks with transfer pumps replaced under warranty. And a buddy just had his go out as well,

 

[DPC]

i have a cab and chassis L5P and a LMM, both have dual tanks and both have and still give me fuel problems. the transfer pump is the culprit in both. every so often and just totally random it quits working and starves the trucks. i haven't replaced the pump in either truck since they will run fine for months at a time. my L5P throws a P1235 & P1236 CEL. my L5P has the newest ECM revisions too.

i dont know if that helps but i know its a common problem with the trucks with dual tanks

I have had 3 L5p cab and chassis trucks with transfer pumps replaced under warranty. And a buddy just had his go out as well,

Certainly something I'll check out. The dual tank system on the duramax has had issues since the LB7.

Did more testing today. The truck acts like its running out of fuel. It will run for about 5 seconds max, die, and then reduced power. Also only seems to have the problem when the truck is warm. More testing tomorrow. Thanks

 

[DPC]

Fuel pressure regulator #2 was the problem. Never threw a code for it but when it would act up the voltage would stay at 4.51V. while idling, should be around 4-3.90.