View Full Version : so freakin close- after 3 years - long

01-29-2007, 02:04 AM
After a very trying comedy of errors, it appears we have an internal oil leak remedied on my dad's pristine '90 SC (ends up being a very small crack in a pushrod bore that only showed up after pressurizing the longblock which we should have done long ago). Thanks Dave D. for guidance. Pardon my excitement, but we have countless hours and dollars into a Kroyer's racing machined, nitrous built short block and big valve, ported heads.

Motor is running strong when warm, albeit we think a tad rich given plug evidence. The only remaining obvious poor driveability symptom is a hard start when cold. Please don't fry me as I have been tasking the search function pretty well. Here are some conclusions:

Fuel Pressure - only 14-18 lbs. upon KOEO unless key is trurned on and off several times which then primes it to 40lbs. Replaced the Regulator, no change. However, not likely the source since if I prime it with a few key ons prior to start (again 40lbs.) it still starts hard. Once started and during cranking, pressure is good. I think the pump needs to be replaced but I think this is unrelated to cold hard start condition. No noticeable leakdown.

Cam Sensor - if it was a bad sensor, wouldn't the condition exist whether cold or warm?

Crank sensor - shift light on when in Run, goes off when cranking. BHJ balancer so that's not the issue. Would crank sensor act differently with cold motor (garage is 60 degrees, incidentally and this is Vegas) vs. warm?

Vaccuum leak - can't find one. Been over lines and plumbing numerous times.

02 - relationship to cold?

TPS - checked and .85 closed then 4.5 wide open.

IAC - relationship to cold?

DIS - relationship to cold?

MAF - Cleaned. Relationship to cold?

Sorry for the long note I just wanted to address some of the potential questions up front. Any help to bring at least this phase of the ordeal to a conclusion would be immensely helpful.


01-29-2007, 02:19 AM
Could be the pump..You may also have a leaky injector which could cause a hard start and appear to be rich on initial startup.

So what injectors/ MAF do you have?

And does this pressure issue go away after driving the car for awhile..I have seen injectors leak because they were stuck opne then get unstuck after a few on off with the key..By then you will have slightly flooded some if not all the cylinders causing for a hard start.

01-29-2007, 02:20 AM
If its a stock pump...YA probably should be changing it anyways:O)

01-29-2007, 02:35 AM
The fuel pressure issue seems to dissapear completey after priming and then motor is running. The pump is a 255lph Holley unit if I recall (been quite some time since install).

Injectors are 38lbs. (I know....we just need to work the bugs out first and then that is clearly next). Can't recall MAF but it's certainly not stock (again, it's been some time).

Injector leaking down...hmmmmmm. They are clearly not leaking down after prime, but maybe after first KO when theyv are at 14-18lbs.? Possible, I will let it sit after that condition and see. It does seem like it's flooding. L

01-29-2007, 01:54 PM
I did notice that the idle is jumping around a little bit. Seems to climb to 1500 and then settle back down and then back up and down again. The frequency is quite regular now.

XR7 Dave
01-29-2007, 02:04 PM
The motor is running quite rich. Do you have the chip installed? Have you tried running it without a chip?

01-29-2007, 03:13 PM
What Maf do you have for those 38lb injectors?..

01-29-2007, 09:32 PM
My guess is it is indeed runnning rich as evidenced by some fairly dark plugs. The MAF is a Pro M and is calibrated for the 38 lb injectors.

Dave, the chip is installed and i have not pulled it to see if there is a change. I was not convinced that it was related to the cold start issue and did not want to guess as I knew you would ask if I had installed a WBO2. I'll search the forums to source the pillar, guage, and necessasary exhaust work. Thanks L