Takes to long to start

[driver456]

I just replaced my LS1 motor with an LS7,So far everything is fine,But it takes to long to start.It cranks for a few seconds then starts.What can I adjust to fix that?.Thanks.................Paul

[Garry]

Hm ... getting a bit more detail might help ...
Congrats on the upgrade anyway!!

[eboggs_jkvl]

Long cranks are losing your "pressure" in the fuel line. This causes the pump to have to reprime the line and then it starts. I had this when I went to an external fuel pump. I put in a check valve to hold pressure and it starts at the first fire of the plugs. Check your fuel pressure. IF it falls to 0, that is wrong. I should drop but halt and hold in the 40 PSI range

That would be my best uneducated guess.

Elmer

[McRat]

You should listen to Elmer. He's had the Long Time to Get Started problem for a few decades.

[Redline Motorsports]

Does it make a difference if you have the throttle cracked open a bit?

[driver456]

Long cranks are losing your "pressure" in the fuel line. This causes the pump to have to reprime the line and then it starts. I had this when I went to an external fuel pump. I put in a check valve to hold pressure and it starts at the first fire of the plugs. Check your fuel pressure. IF it falls to 0, that is wrong. I should drop but halt and hold in the 40 PSI range

That would be my best uneducated guess.

Elmer

Its holding pressure.When I turn the key on but don't start it the fuel pump comes on and the fuel pressure goes to about 55psi then drops to 40psi and holds there. On a cold start up it started right up first shot.I shut the car off and tried to start it again and it cranked a few times then started It sounds like its getting fuel and no spark for a few seconds.The reason I say that is because it sounds like a violent start,I have open header's right now and it scares the crap out of ya when it starts Thats the only way I can describe it.It does not backfire or anything.I pressed on the gas pedal a little,One time it started doing that and another time it just kept cranking.I have alot of tuning ahead of me that I know,I guess getting it to start is a good place to start ..............Paul

[SSpdDmon]

I increased my Startup Friction Airflow Correction table to help a little with cold starts, but mostly for warm starts. After I would start it (warm), it would stumble for about 5~10 seconds before finding desired idle speeds. So for a quick fix, I increased the {B4343} table by 4 grams/sec across the board. No more issues on startup.

[Bruce Melton]

Do you have any DIC codes?
I am thinking CKP or cam sensor. I did exactly the same swap and had that problem related to the cam sensor wiring harness as discussed on the other forum--

[driver456]

Do you have any DIC codes?
I am thinking CKP or cam sensor. I did exactly the same swap and had that problem related to the cam sensor wiring harness as discussed on the other forum--

Its funny you ask,I did get a P0343 CMP Sensor Circuit High Voltage.But I read in the service manual,At the end It says "A slightly longer cranking time may be a symptom of this condition" I did flop the cam sensor plug like K-tek suggested.What did you do to fix it.Also I pulled the plugs today and they were wet with gas.Whats CKP?I'm waiting for my header's to come in so I can take it for a test ride and see if this clear's up.I had 1 3/4 I'm going to 1 7/8.................Paul

[joecar]

CMP = cam position
CKP = crank position