I installed my dual cp3's and now when the truck sits for awhile it idles very rough when you start it. almost like there isn't enough fuel. after about 10 sec. it is fine. there are no external leaks and it does it even if i turn on my lift pump ahead of time. anyone have any ideas?

Kelly

Kelly, are you losing prime? All connections tight and not leaking air?

that's almost what it seems like. but on the low side i should see a leak with my lift pump shouldn't i? and on the high side it would spray out would it not. Is it possible for a leak to be so small that it would let air in but fuel would not come out?

Under throttle you will see leaks in the high side. At idle it might not show, wear safety glasses when you check and dont put your hand anywhere close to fittings. Low side should show a leak under pressure from your lift pump.

All harness CP3 connections got made properly? Grounds? Kinks in hoses?

Look at your desired vrs commanded fuel rail pressures, I bet it over at idle....

Any idea what PSI the lift pump is giving the CP3? IF it's to high you will get similiar symptoms.

I have a fuel pressure guage and it never goes above 8psi. there are no visible leaks anywhere. this morning the truck didn't want to fire at all, acted like it was out of fuel. had to turn it over about 2-3 minutes with the lift pump on and it finally fired. it only does this only on startup. it runs fine otherwise even wot. one other thing is after it starts it runs really rough for 10-15 seconds then it idles fine.

Look at your desired vrs commanded fuel rail pressures, I bet it over at idle....
are you saying it may have to much pressure at idle?

Does it rattle and sound like a power stroke?

Is there any smoke when it runs rough? Built engine or stock?

A couple things I would check is the crankcase for fuel, and the compression, primarily on the LH cylinder bank.

are you saying it may have to much pressure at idle?


That may be the problem. Turn off the pump and start the truck a few times to see if it continues. May have to turn the pump pressure down or bring it in with a switch that reads boost pressure.

look at the actual pressure when you are cranking the truck, what is it?

Who's dual cp3's?

I will scan the truck later today. thing is it only does this after it has sat for awhile, like over night. it starts fine during the day after the initial startup in the morning. that is why i think it is somehow losing prime. If it was running to much pressure it should start rough every time wouldn't it?