Fuel Pump '96 Suburban

I have a '96 Suburban with a 350. Is there a check valve built into the fuel pump?

I believe fuel is draining back into the tank when the engine is off. It is very hard starting in the AM.

Jim

Jim:
I believe that there is but it's part of the pump assembly. I just went through this on my 97 Suburban (120K on clock, original pump). Check your fuel pressure at the test port on the fuel rail on the drivers side of the engine. Pressure should be 55-61 PSI with the key on and not running. Mine was 54 LBS. and sometimes it would take my wife up to 10 minutes to get it started after sittting overnight, other times it would fire right up. After I replaced the pump the pressure was at 58 LBS. and it's been fine since the end of June. If you don't have a pressure gauge they are about $40...best $40 I ever spent.
Another thought would be to check the inline fuel filter which is along the frame under the driver's seat. If it's clogged it will cause premature failure of the pump. I replaced this first but it didn't help my problem, pressure was the same with the new filter.
Good Luck,
Dave

There is a discharge check valve in the pump. However, the check valve is nearly meaningless in regard to fuel pressure while the pump is running. Any time the engine is turning (from cranking or running) the PCM should be operating the fuel pump relay and running the pump. There is also a fuel pressure regulator, and there are injectors which could be bleeding off the standing fuel pressure. As Old Dave suggested, testing fuel pressure is going to be very helpful.

Dave and Bowtie, thanks for your input----Dave, mine has the same problem, either starts right up or you need to really crank, I finally just cycle the key on /off to prime the pump then it starts right up. I'm trying to burn up a full tank of gas ($$$$) so I siphon the remaining and drop the tank.

Thanks again, Jim

Jim:
I could cycle the key off and on on mine and and the pump would build slightly more pressure and sometimes it would start. I would definatley check the fuel presssure before I dropped the tank just to make sure, but it sounds like your pump has gotten weak just like mine did. My son and I changed mine at the end of June and it fires right up now. I ran mine down to just under a 1/2 tank and siphoned out about 5 gallons before I dropped the tank. FYI, the dealer wanted $152 for an AC Delco pump and I ended up buying one at Car Quest (their brand) made by Airtex with a lifetime warranty for $74. There is a wiring harness available that goes from the pump and sending unit to where the plug is on top of the locking ring. There is link on this site for some pictures of what it can look like when these wires become loose and generate heat. Inspect yours closely when you get into it.:)

Good luck,
Dave