Sticky MFI cold start valve

dtw · 11-30-2009, 05:59 AM

Looking for some help with the latest issue...my '72 has never had a functioning cold start system in my ownership. I have put the system together and it now working well...the car now starts perfectly, just like the driver's manual says. Lift hand throttle, put right foot on floor, crank...and it fires instantly.

The problem is that the check valve doesn't seem to be re-seating. The solenoid is working properly - when 12V is released, the solenoid retracts. However, fuel keeps flowing to the cold start injectors. I am assuming that the ball check valve is not returning, or is not seating properly - correct?

Tonight I am going to pull the check valve assembly and see what I can see. Is there anything in there that can be serviced or adjusted? I love having cold start functional again.

dtw · 11-30-2009, 11:01 AM

afternoon bump.

356RS · 356RS's Garage

Dave, your right on track. The check valve (ball) is not seating. Easy to clean. Remove the solenoid screws with solenoid then remove the checkvalve housing from the filter console. Now you can see the ball check valve. I used a wooden end of a Q-tip to push on the ball while washing in the solvent tank. Check the screen on the bottom of the inlet also.

dtw · 06:23 PM

Thanks, Mark. I pulled the assembly tonight and checked it out. Seems like maybe the pill got cocked up in the bore - it seems to return fine now after repeated poking with a brake cleaner spray tube, and some flushing w/solvent.

I reassembled everything and tested it out with the fuel pump on, after repeated engine starts to give the solenoid a few chances to do what it does. After all that, I am getting a drip every couple seconds from the cold start fitting. What do you think? Should my goal be 100% sealing?

If so, PM me if you've got a cold start valve assembly for sale - my pill has some light pitting here and there and is probably not going to seal up 100%.

Rusty 356 · 12-01-2009, 07:02 AM

Just a personal opinion, but I would try cleaning again, I have a couple of complete units that I can check if you end up needing one. What about installing an external check valve.?
If you are down to a drip then you are making progress. The cold start system, especially early one are known for their ability to cause a fire. NO DRIP

356RS · 356RS's Garage

No leaks @ 1.8+ bar.

dtw · 12-01-2009, 10:42 AM

Nice - I'll take it! PM me with payment information. And not sure I answered your other PM - yes, I already have the solenoid in good shape, so I just need that piece that the solenoid mounts on.