Fuel pump check valve

[silky28]

Hey all,

03 Z71 flex fuel - just a beater truck I am trying to keep going as long as possible!

Changed fuel pump a few months back with the correct Carter pump for Flex engine. I also changed the filter and the lines that go from the filter to the pump.

Since I changed the pump truck has been harder to start after sitting for a bit unless I prime the pump for a few seconds with KOEO. With a primed pump it starts instantly.

From what I gather it is either injector leaks or bad fuel pump check valve...it seems to be the latter as fuel pressure doesn’t drop if return line is blocked.

So my question is this: can I install an inline check valve on the return line and, if so, is there a particular type I need, and where would I put it? Would it be best to put it on the plastic return line just before it goes into tank?

 

[Fless]

Thought: has the fuel pressure regulator been verified as not leaking into the vacuum line?

 

[exp500]

How long does it take to leak down 10# from key off?

 

[LM7Tahoe01]

Sounds like a bad fuel pressure regulator to me.

You can’t put a check valve in the return line. It needs to be unrestricted to allow the fuel from the regulator to return to the tank. If the fuel pressure drops with the truck off but holds with the return line blocked that means that the regulator is bleeding down.

FYI the check valve in the fuel pump is in the feed line. If that was leaking the pressure would still drop even with the return line blocked.

 

[silky28]

Hey all,

So I haven’t. He led regulator since I replaced the pump and there was no issue with it.

I don’t have a fuel pressure gauge with me atm but it seems to lose pressure quickly. Like, I can park for 10 mins and if I try to start without going KOEO to let pump prime it will crank but not start.

Once fuel pressure builds the engine fires immediately and runs strong. So I doubt an injector has flooded a cylinder.

Breakdown:

So January-ish of this year truck suddenly won’t start. Felts like lack of fuel pressure. Depressed Schrader valve on fuel rail and only dribbles - pulled fuel line, ran pump - no pressure. Got a good price on a Carter pump so I bought it - while putting it in the metal fied line for fuel filter broke from rust. Long story short, I bent a new piece for that and joined it to factor plastic fuel line out of tank. Truck has run perfectly since other than this fuel pressure issue which has been there since I changed the pump.