2002 LS 3.9 Cold Start

[raiseyourdrive]

I have had a problem with cold starts lately. I turn the key and I can't hear the fuel pump kick on. So, I changed the Water coolant temp sensor (for the warm start default) thinking that was it...Thanks to QuickLs for the diagram. Still nothing. Tonight I cleaned the MAF sensor but it really wasn't dirty. I am banging my head here!!! The problem only happens when the engine is cold. I can crank the engine three or four times and then I hear the fuel pump kick on behind me. Then starts no prob. Occasionally the engine will run rough after start as if it doesn't have enough fuel. Then runs fine...What am i missing here???

 

[97stscaddy]

Dunno what the pics are for but those intake runners are lookin pretty gunky. You might want to try using some Seafoam to clean those things out.

Test your fuel pump relay, and it wouldn't hurt to replace the fuel filter. Mine was taking a couple seconds longer to crank when it first started getting cold here and a new fuel filter got 'r dun.

 

[scjmc]

Maybe you just need a new fuel pump, or pump relay.

 

[raiseyourdrive]

pictures are from this weekend when I changed the CTS. I changed the fuel filter last year.

 

[raiseyourdrive]

How would I test the fuel pump relay??? Diagram? Which relay is it?

 

[raiseyourdrive]

I have checked a couple of parts websites and I haven't found a fuel pump relay...any suggestions???

 

[Jim Henderson]

Not sure if this is your problem, but maybe the fuel line check valves are leaking. My wifes Mercury van had this problem. Sit over night and it would take 3 or 4 cranks to get started. Rest of the time it would fire up pretty quick.

Turned out that the check valves in the tank were leaky. This allowed the fuel line pressure to bleed off after sitting for a long time. So the fuel pump had to startup and re pressurize the line before the engine would start.

What I have heard is that the pump only turns on for a second or two when you first turn the key. If the line is depressurized, this is not enough time to build pressure. Turning the key multiple times gets the lines to repressurize a bit at a time until there is enough pressure to operate the injectors properly. Meanwhile the injectors may be dribbling raw fuel into the intake and when it does fire up this fuel makes the engine run rich and sloppy. Once the pressure in the line is correct, you will hear the fuel pump sound change and since the engine is running the pump stays on.

So at least that is the theory I have heard about and the cure for the problem with my wife's van.

Fortunately I have heard that accessing the fuel pump etc is easy, it is under the rear seat.

Good Luck,

Jim Henderson

 

[scjmc]

I agree with Jim also, could be an injector leakdown. Leave the car overnight, and hit the pressure release valve on the fuel rail and see if it has pressure like it does after running it. That will tell you if it is a fuel leakdown of some sort.