I have a 2007 Suburban with the 5.3L with about 135,000 miles that in the last few months has developed a hard starting issue. The engine requires more cranking time than normal to start and sometimes will not start on the first try. It always starts on the 2nd or 3rd attempt and then has no noticeable issues staying running once started. Engine codes are far and few between with this issue and the only codes that do show up indicate "Lean in Banks 1 and 2" but again, most of the time no codes are triggering the Check Engine light. MPG has dropped according to the onboard computer from around 15-16 to 12.

I checked fuel pressure today and saw fuel pressure increased to arond 20-30 when turning the key on (not starting) and then it dropped to zero. Once engaging the starter, fuel pressure increased to 10-20 for a few seconds and then once the engine started, it rose to 30-40 and then a few seconds later upwards to 50 (I'm not sure what is normal for this vehicle). When the engine is cranking and trying to start, the tach is showing some RPMS (250 or so) if that help rule out a crank position sensor?

Can anyone suggest additional diagnostics/tests I can do to determine what this issue is so we can fix it?

 

Welcome to the forum.

I believe fuel pressure w/ key on, engine off should be about 40-50 psi and hold. Sounds like it might be either fuel pump or regulator.

 

I agree, sounds like the check valve in the fuel pump is letting the fuel bleed back into the tank when not in use. I had that problem and put a check valve in the fuel line and it corrected the problem, It also meant that the tank didn't have to be pulled to replace the pump. A quick and cheaper fix.

 

Yes. Should be at 50

 

I know this is an old post but I'm having the same problem in my 14 Suburban. Exactly how did you fix it? Thanks.

 

The correct way to fix it is to replace the fuel pump assembly. A cheap easy fix is to add a check valve to the fuel line near the tank. The check valve and lines need to be fuel injected rated.

 

Thank you. I had the pump replaced last year. I was hoping for an external pressure regulator so I didn't have to deal with the shop that put the pump in.

 

What brand of pump did they install? I have heard of many off brands failing after a short time. I would only use a Delphi or Delco pump because of the work involved in changing them. A pressure regulator won't help if the fuel is draining back to the tank.

 

I paid for an AC pump.

 

What size is the fuel line you put check valve in for the 2007 Chevy suburban?
Also I assume it is the feeder line to engine that gets the check valve not the return line correct?
Thanks
SNoPro