Holley 4 Brrl gm ecm

[Laura & Neil]

Shane Buss wrote:

> it has no problems... his ecm is the 747 ecm..
>
> i got mine working fine yesterday.. my car is running and VERY clean..
> the only problem i have now is i have a vacuum leak somewhere..
>
> map reads like 27 when it's idling... it idles for 5 seconds, revs up a
> little, then dies..  i cannot find the damn vacuum leak to save my life...
> hmmmmmm

I spend half my day tracking down vacuum leaks. I'll pass on some of ther
methods I use.
As your car will only idle for 5 seconds good old "let's start a fire" carb
cleaner won't work.
Pull off the vacuum line to the brake booster and plug it. If the car runs it's
the booster, if not, hook up the hose to the booster to a compressed air source.
You need about 15psi. Now with a small spray bottle filled with a 20% solution
of dishwashing detergent start spraying all the vacuum lines, and look for the
bubbles.
If you have a V4/6/8  with a valley type inlet manifold, e.g SBC, remove and
plug the pcv valve hole and the air intake on the opposite side. This seals the
crankcase. Now connect a vacuum/low pressure guage to the dipstick tube. If,
when cranking or idling, the pressure drops below atmospheric, you have an
intake manifold leak.
These methods find about 99% of vacuum leaks.

Neil

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org