76s pre start CIS questions

g rad · 01-07-2008, 08:47 AM

After three years of taking up space, I've repaired the rusted out front pan and installed a front center mounted oil cooler.. I'm about to start my professionally rebuilt, 2.7... All rubbers and gaskets replaced on CIS,, hooked up fuel and return lines only,, nothing electrical , jump fuel pump relay and get 65 lb system pressure on CIS test gauge, turn 3 way valve toward gauge and get 15lb..control pressure. (40 deg. F. today)... Fuel Injectors are squirting all the time, so system pressure falls in 30 sec. to 15 lbs... control pressure also falls that quick... I haven't even gotten to the cold start injector stuff yet.. Does this sound OK? thanks, g rad

T77911S · 01-07-2008, 09:22 AM

no it does not. what you did and your results sounds a little confusing.
the injectors should only spray when the plate in the air flow meter (AFM) is raised. i dont remember what the pressures should be in lbs, only bar. i am at work, working hard of course. about 1.8 bar cold control. 3.7 bar when the warm up regulator (WUR) heats up for a 77, i would not think yours are that different.

stevemfr · 01-07-2008, 01:44 PM

t77911s is absolutely right. Your fuel injectors should not be squirting until the AFM moves (cranking). Sounds like something is sticking. Give the FD a rap.

I only remember the bar values as well, but 1 bar is roughly 15psi, so 1.8bar should be about 27psi. Did you have the WUR apart? Are you familiar with setting up cold/warm control pressures?

Hope you have a pop-off valve installed.

g rad · 01-08-2008, 07:09 AM

Yesterday I lifted the plug in the WUR and got 2.3 bar control pressure,cold (OK?) thought that might stop fine spray at injectors, with Air Flow Plate at rest.. (it didn't) put a shim in primary pressure regulator, to just under 70 lb. system pressure. (OK?) also checked the Oring there, seemed OK.. in an attempt to address the quick fall in system pressure,, ( 0 in 30 sec) I had all the mixture control unit stripped including the FD, which was clean except the piston was gummed up.. (have a few observation on FD cleaning) I have great fuel flow, new filter... today will check fuel pump check valve,, (wonder how one checks that,?) wonder if looking at lean-rich crew on mixture control unit would stop injectors (2.5 bar cracking pressure) leaking down system pressure... to be continued..... gerry rad

g rad · 01-17-2008, 06:57 AM

I re dismantled my FD, and got all washer- spring- aluminum outlet collars much more even with the diagram plate then reassembled and pressurized,, ( I screwed up by not keeping each separate) with much improved individual flow rates to injectors.. My buddy Tim who has a 944 cis.. Had me... Take all injectors, use fine strand from multi strand copper auto wire,, (knife blade to lift) loop under (knife blade to lift) tiny (2mm) valve head, give one twist and pull to side of injector and bend alongside... exposing long valve stem,, soke in strong carb cleaner overnight (Carbo Saul) ........ I pushed scrap 3/8 hose over my air gun and blew backward in injector,, attempting to clean internal screen..... many times..... My buddy said he was able to rotate the valve head,, attempting to lap and clean up ,, I didn't have much luck,, though I did lightly tap valve head into seat.... end result is better flow pattern and all but one was sealing below the 3 bar injector pressure cut off.. to be continued....... gerry