1980 CIS: Injector's not flowing the same

[MatthewBrum]

I just finished rebuilding the engine in my 80 SC. I purchased the car not running and have never heard it run. I wanted to clean the injection system before I ran it on the rebuilt engine.

I have a professional fuel injector cleaning tool that uses a pressurized canister of cleaner that screws into a regulator that attaches to the fuel distributor. Note that the return on the distributor is blocked off.

I have the CIS injection on the car with the injectors off and each injector is in an emty water bottle so I can measure flow and view the spray.

The problem is that I got un equal flow through the injectors. With one injector flowing half as much as the rest. I could only set my cleaning pressure to 60psig.

Does anybody have experience with CIS that has been sitting for a while? Also was 60psig enough to open the injectors all the way?

thanks-Matt

[john walker's workshop]

may not be the injector's fault. i would send them out to a cleaning outfit to see if they flow the same, rather than checking them through a possibly dirty FD.

[MatthewBrum]

I also did not assume that it is the injector's fault, could be a number of items but in the end I need equal and consistant flow for all six injectors when the air vane is lifted. It may be possible to connect my cleaning tool directly to the injector and test all six. I did some CIS work on a few cars in the past and I remember seeing fine screens somewhere in the system, possibly in the FD, can anyone confirm?

John is there any usual spots where crud is known to accumulate in a system that has been out of service for a number of years?

[porsche930dude]

I would connect directly to the injectors one at a time so you can rule out everything else

[Phillip_G]

Yes, on the screens in the FD. On the 74 and 75 systems I've messed with there were tiny filters under each banjo bolt on the FD.

[j_mancini]

+1 on screens in the FD under the banjo bolt. I too had uneven flow, which my mechanic found was due to the fact that 2 screens (yes 2) were jammed together in one injector port. He removed all of the screens, with a big improvement in performance! He said that those screens were somewhat redundant, and that removal had no ill effects as long as you change the fuel filter often.

Also replaced the 2 injectors that, despite repeated cleaning, never would spray evenly.

[Jim Williams]

I'd suggest you might trade out the injector and its attached injection line that is flowing 1/2 rate with one of the other injectors, at the FD ports. This should tell you if the problem is internal to the FD or if the injector is the problem.

Your '80 FD will also have the filters under the banjo bolts. If you are REALLY careful, you can use a drill bit to coax out the filter without damaging it. Did I mention Real careful? If the drill bit is too small in diameter, you can "hole" it. The filters are effective only on the injectors, and the FD relies on the external system filter to keep crud out. Some where on this forum is a journal of the opening and cleaning of a fuel distributor. There was a significant amount of rust under the diaphragm, which could plug one of the ports.