Hard starting

[cattig]

My ty has been hard to start in the morning. It seems to be related to fuel pressure. As i turn up the fuel pressure the truck becomes harder to start in the morning.

The fuel pressure will drop off after the truck is turned off for about 20 minutes. Is this normal or is it possible that the injectors are leaking making it hard to start?

Chip

 

[G.D. Bryson]

Hey cattig. Do system check for fuel pump relay. If it passses, you proooobably have leaking fuel injector(s). I don't know how to isolate which one(s) without a tester GM Service Manual recommends; visit a tech you trust. Reference your Fuel Pressure post, you are measuring with vac line disconnected and plugged...? Also, FP shuld hold after IGN is turned on, engine off past 2 seconds time;if not another indicator of leaking fuel injector(s), or system leak.

 

[Daron]

Hard starts are one symptom of a failing fuel pump.

 

[cattig]

is there an easy way to tell if it is the fuel pump or the injectors? I don't want to just start replacing parts if nothing is wrong with them.

Chip

 

[V6 Kompressor]

Use the fuel pressure gauge, If in the morning, your fuel pressure is low, after turning the key to on, before start, then your fuel pump/regulator could be going bad. If the fuel pressure comes right up, and you have black smoke after it starts, or a fuel smell on your oil dipstick (where the oil is on the bottom) then more than likely, you have one or more injectors bleeding down and leaking fuel into the manifold. You might try to get them cleaned with a cleaning system that runs the cleaner through the fuel rail, or if they are stock, it may be time to upgrade them in size and quality... There are places that will clean/rebuild them (You remove) for about $20 to $25 each, but for a few more bucks, you can get new ones (Even larger).

 

[cattig]

The fuel pressure looks fine when I turn on the key it jumps right up to where it is set. I don't see any black smoke when it starts up. I will check the oil.

I have read different things about the fuel pressure dropping. After the car is turned off the fuel pressure will hold for about 10 minutes and then start to fall to zero. Is this normal or is there something wrong?

Chip

 

[V6 Kompressor]

That appears to be about the norm... there is a check valve in the pump and the fuel regulator can let the fuel by in that time period... I have seen gm ignition coils do that when they get cold, hook up a timing light to the coil wire and then one of the plug wires and see if you get a flash out of the light when you spin the engine over when cold... if you are not getting the flashes, then suspect something in the ignition system. Your fuel system sounds like it is fine. When was the last time you changed out/tuned up your truck, IE: cap, rotor, plug wires, plugs, ect..? (good stuff, not wal-mart)

 

[cattig]

plugs and fuel filter 1000 miles ago
cap and rotor about 4000 miles (I was going to change soon anyway)

Chip

 

[myclone]

Does the fuel pump come on when the ign key is turned to the "run" position (turning the key "on" but not starting the eng)? If not then the fuel pump relay could have died. There is an interlock tied into the oil pressure that will energize the fuel pump once the oil pressure has came up. Extended cranking of the eng would build oil pressure then turn the pump on.

If your not getting black smoke, raw fuel odor out of the exh, or the oil doesnt smell like it has fuel in it then the relay may be something to look at.

HTH