ERKEL

Ive got a square body crew cab with a 2003 LQ9 swap. Ive done a number of harnesses using the LT1swap site. Ive not had an issue til this one. It cranks over fine and has 12+ volts with the key on. During cranking it drops to 10-11 volts on the coils, injectors, switched on wires and constant hot wires on the pcm. The fuel pump does prime with the key in the on position and when returning it to on position from the crank position. I took the harness back of and went back through the pins to check for any mistakes. I also checked all the grounds. Still nothing. I have tried two different pcm's. I know that one is good as it is out of a running rock crawler I did the harness and flash on. What gives? I am pulling my hair out. Any suggestions?

LS6427

iTrader: (2)

Crank Shaft Position sensor.

D you get rpm showing on the scanner when you are cranking the engine over....?

If not......CSP sensor could be the culprit.

.

Bowtie316

iTrader: (1)

Yes, could be crank sensor.

I would start by checking for spark at a plug, if you have spark then check for fuel pressure and signal at injector via a noid light. It would help to rule out a few things.

ERKEL

I checked earlier before I came into work and it hits if I spray some carb cleaner in the throttle body. Now to go back and check the fuel pressure.

Bowtie316

iTrader: (1)

Well if it will take off on carb cleaner, it must be getting spark but not fuel. Could be due to low/no fuel pressure, no signal from pcm, no power to injectors during cranking, stuck injectors, etc.

How long have the injectors been sitting without fuel in them?

ERKEL

The injectors and coils both have 12v+ with the key in the on position. While in the crank position the injectors drop to 10-11v. The pump does prime when you first turn the key on and primes again when the key returns to the on position after cranking. It has the MSD 2225 f/p with the returnless style fuel rails. It has the original injectors. The injectors were soaked in SeaFoam last year before it was brought to me. This is a project that someone started before it came to me. Im going to put a gauge on it today and see what psi it actually has to the rail.

Camaro9969

iTrader: (12)

Did you answer the rpm question?? Also I've had that problem before your positive the grounds are all set? 3 on back of the head and all others