How I fixed my MFI !!

hbrand · hbrand's Garage

Symptom:
Impossible to adjust for all engine speeds and load.

Reason: The 3 dimensional disc or cam inside the fuel injection pump, on which the pump govenor rides, had lots of "low spots = wear" on it.

Repair:
Since a new disc is $ 800.- or so and you can not fill the lowspots (hardened steel) I evenly grinded off (the high spots) till the lowspots where gone. Now the govenor rides on a nice sureface, just a little lower now as when new, but even through all rpm's loads.
And no more hang ups in the low spots.

Then I readjusted the mfi - woala - all works great.

bell · bell's Garage

nicely done

Jim Richards · 05-30-2003, 08:18 PM

Harold, when you ground down the high spots, did you find yourself running rich or lean? Are there any shortcomings to this appoach such as reducing the duration of time fuel is being provided to the injectors at certain speeds or all speeds? Thanks.

brokke · 05-31-2003, 02:06 AM

Two weeks ago I had a new space cam in my hands and was suprised to see all the high and low spots on it. They told me that is was made that way, it's the analog engine mapping your looking at. It is not supposed to be flat. So I don't understand how you can make your own 'grind' .

Peter
911 2.4S

hbrand · hbrand's Garage

This one was different. I know what you mean - have 4 of those here. This cam was so bad worn, that the pin riding on it got stuck. Newer pumps have a ball riding on the space cam.
After work in that area of the pump, it needs to be adjusted, all 3 adjustments.
thanks, Harold