hupp

I tested my CIS system yesterday and need some advice. What follows are the test results:

-1979 5-speed
-New Green wire and timing checked
-New fuel filter
-New pressure control regulator
-New injectors (excluding the cold start injector)
-Car had been running rich, flat spot during acceleration, some loss of power and started poorly when cold.

Vacuum was applied during testing

-Cold control pressure = 1.7bar (tolerance per manual at temp is 1.0 to 1.5 bar). appears to be .2 bar too high.

- Warm control pressure = 3.9bar (tolerance per manual is 3.4 - 3.8bar). appears to be .1bar too high

- System pressure = 5.2 bar (tolerance is 5.2 - 5.8 bar). Within spec. but at the very low end.

Leak test = Within 17 min the fuel pressure leaked down to .5 bar. Failed miserably here.

I relatively sure I have a leaking cold start injector and a replacement is on the way. The warm and cold control pressures were just above the upper tolerance. Will this cause problems or can this be left alone? Also, if the control pressures needed to be adjusted, how do I do so.

Paul D

The check valve in the fuel accumulator could be bad. I've heard that is a common problem associated with leakdown pressure. I'm sure someone else will offer more info. My car starts hard sometimes only when warm so I'm getting ready for a pump/accumulator replacement soon.

Dennis Wilson

Scott,

The leakdown could be causing the low system pressure, but it is doubtful that it is causing the high control pressure. The relief valve at the back of the fuel distributor could cause both pressures to be bad if the small o ring had broken up.

Dennis

jpitman2

Mine runs VERY well with system at that level, but warm control down at 3.4 or less. Warm control at that level, mine wouldnt get past 20mph. Watson gives warm control as low as 3.1bar. As above a damaged piece at the fuel distributor regulator can affect all pressures. One method of isolation I found in Watson is easy to do when pressures are higher than spec - you have high pressure at regulator - crack open the exit line (CAREFULLY!) (the one going back to distributor, horizontal exit from regulator) - if the pressure drops now, the blockage is downstream of that connection. close that connector up, open the fitting where the return line meets the distributor - if the pressure drops now, problem is in distributor, or the return line to tank. If it doesnt drop, the pipe upstream is the problem - clean it out. Your system pressure seems ok to me, so I dont think its the main system pressure regulator in the distrutor. Check the return line to tank - pull it off the tank top - connect it to a longer hose to a container, bridge the pump relay, check for good flow - dont know a quantitative figure here. I dant remember leak down time - I wasnt too worried about it as long as it starts on demand (sometimes takes a bit of cranking), and hauls, which it does. If in the end it comes back to regulator, you can lower control pressure, both hot and cold, by tapping the recessed pin (carries the bimetallic strip etc) inwards VERY slightly. Open up your old unit to see how it goes together and works.
Mine is an 83 K jet, so pressures may be slightly different.
jp