mazing3

Hi folks,

the car is a 78 2 external FPs

This started by chasing a problem of 7 really lean and 1 really rich spark plug that was otherwise making the Wideband think all was fine. Had enough Uber and Enough tow truck time. Oh yeah, It was actually starting and running for a while but read on.


quick summary--including some good and bad stuff I might have done.


-Drove and started "fine" on 2-1,800 mile road trips. Wideband said all the right things along the way but was duped. Technically not but in terms of an overall value but you get the point.

-only 850cc flow rate on fuel return line so started with chasing that. Nothing I did made a difference but it does meet spec on the supply side.
-Replaced bad FA and FF
-Thought it might be fun to rebuild the FD and had the kit already so figured why not. Seemed to go pretty straight forward
-Replaced FF check valve- *could have been a problem because according to the PN this bosch had an internal check valve. I'm guessing some PO added that whilst likely trying to band-aid the obviously kaput FA. And yes the FA was toast.
- when I put the FD back in I inadvertently swapped the WUR and CSV lines. ran a little rich to say the least but it did run. swapped that back.
-tonight I realized this FP doesn't use an external check valve AND that my uber rich plug is due to my #5 line off the FD flowing way too heavy (regardless of what injector was attached and flowing even when the other 7 are off. AND even when the mixture screw is set full lean. yes its the same super rich one from when this all started.

So I'm stumped and just don't know where to look. Mind you I have no problem just yanking things off ***** nilly and looking at everything but I'm more looking for some kind of reasonable direction to pursue.

Any ideas or thoughts are GREATLY appreciated.

Thanks guys!

Robbie
78 928 5spd Black

James Bailey

Basically it is pretty safe to assume that your "rebuild" of the fuel distributor has failed.... if one port is flowing too much and all the time. And that is the why not about rebuilding something which is NOT broken...
The fuel accumulator has nothing to do with how the car runs except for hot restart but once running it does nothing. The check valves are there to hold system pressure for that restart situation as well.

mazing3

Thanks James.

Oh i'm with ya on the if it's not broken don't break it concept for sure. Clearly already re-reminded myself of that one. But unfortunately this over exuberant port was doing this before and after the rebuild.

is that at least the only real conceivable place this over flowing port could be lurking? I have no issue pulling it out and taking another look.

soontobered84

Not a CIS maven, but did you try swapping the injector to another cylinder to see if the problem moved with the injector?

James Bailey

he mentions that he hooked different injector lines to #5 port on the fuel distributor and then they flowed all the time so clearly in the fuel distributor...which was the same problem before and after the rebuild. Number 5 port is way over fueled.....

mazing3

yeah thanks Drift King. I did try that and same effect as James noted too.

However, I did do a little more recon, watched the cis video on the 928classics site to understand what goes on in there a little better and then opened that FD back up today. Found the issue in there. The barrel with the 8 orings on the "slits" was not aligned properly with the ports they needed tp be aiming at so this #5 misfit was basically doing it's own thing in a bad way.

Got it all back together and problem child port is back under control. Now just playing with the mixture screw a bit till it runs. Done a pretty good job of flooding it but I think I am almost home on this. Jussst need it to start...

thanks guys!

James Bailey

Interesting so it was misaligned BEFORE you took it apart for the rebuild ??