mfi questions

[svandamme]

last weekend, i did some messing with my mfi pump ,
quite interesting


i do have some questions about it :

#1

i'm running headers, so i'll modify the pump , remove the thermostat...

mine appears to be stuck , it doesn't move when the temp changes ( tried it with my oven, no movement whatsoever)

what is the cold position , and what is the hot?

usually i'de expect hot to be the setting where the little shaft pushes the compensation lever (2 on the schematic) inwards to the pump , is this correct?


#2
all the internals of the pump move around, when i rotate the pump drive wheel, i see the springs go up and down

but i can't see any movement above the springs
the round thing above it , and the adjustment screws don't move

i think it's normal , am i right in thinking that?
i heard a lot of pumps gumming up and plungers beeing stuck, but the plunger is not visible ?


#3
the oil supply modification , i heard that you can run the pump with it's own oil supply , no looped system running of the engine

what kind of oil is best? since the engine won't heat up the oil , would it be better to use an oil that's thinner at colder temps? or is that overkill?

also , how much oil does it take? how far do you fill the pump?
can it be overfilled?


#4
i'm looking into cost savings here, allready running a large bill for my engine rebuild, and if i can safely save 1500 bucks (mfi pump rebuild) then i wouldn't mind doing so

i just have one little leak on the pump , the idle control, i think it's easy to fix

are there any other things i can do while the pump is opened?

cleaning wise? is it good to just run a can of carbcleaner over the pumpt?


#5
does anybody know if there's a book on these pumps?
i know there's a bosch book by Probst, but i don't think it covers MFI?
factory manuals??

i'm interested in testing values , how much fuel the pump should deliver at what rpm's

so i can test my pump and figure out if it needs rebuild/calibration

or maybe even calibrate it myself?



#6 am i beeing a freak here ,and should i just fork out the cash to the black magic mfi rebuild company that holds all the dark secrets locked up somewhere in a vault?

[thastings]

#6 Yes, your freaking out.
You need to annswer a couple of questions first.
1. Was the car running and the pump working ok before starting the rebuild?
2. If yes, why are you messing with the MFI? This system is all mechanical and there is little you can do to improve or change it.
3. If no, how was it runnining? If not running, what do you know about this pump?

Do a search for "MFI Problems" to see what I went thru and it appears the main problem was only that the fuse block had to be cleaned for the fuel pump. Don't panic. There are lots of threads and guys on this board that can direct you on how to solve your problems IF YOU LESSON.
The above thread has references to all of the available manuals etc.
Terry Hastings

[svandamme]

yes it was running , and it was running quite good
i even though my engine was in primo condition
that is , till i tried to start it again after 6 months restoring on the chassis

no fuel , then to much fuel ( cold start injectors) , then scraping sound
and done

open engine , everything well worn , beyond the good tolerances

so i'm rebuilding...

i don't want to mess with a newly rebuilt engine , and a possibly not calibrated , worn fuel pump, the thermostat clearly didn't work , so i want to make absolutely sure that the mfi is also as good as i can make it... but if possible, not burn money when i can prevent it

my electrics and wiring will be completely replaced with my own custom harness and fuse block , so all i'm trying to accomplish is a functioning mfi pump, with couple of simplifying modifications ( less is better )

[thastings]

If the spark plugs looked normal when you removed them, I would say leave the MFI alone. The thermostat does little to affect the performance after the engine is warm. I ran mine without it for weeks and saw no change. So unless there is something wrong, don't try to fix it. This MFI is well made and is a rather simple design that normally does not fail except in those rare times that a plunger locks up (normally due to long periods of non use) and breaks. Most of the problems can be traced back to the fuel pump, fuel filter or crap in the gas tank. There are few adjustments that can be made to this unit.
Terry

[Grady Clay]

Stijn,

I assume you have CMA:
Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf


I would not adjust anything in the pump.
Yes, I would clean it and install fresh oil.
Once it has fresh oil you can rinse the fuel passage with
carb cleaner while rotating the pump.
Do not leave it “carb cleaner dry” put gasoline or WD-40
or some lube in there right away and rotate more.

You should remove and clean the thermostat.
See the threads on this subject.

“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
MFI thermostat spacers
“More Fun with MFI and LM1”
How to use protractors for correlation.
More fun with MFI and LM-1
“MFI Problems”
MFI Problems
“MFI Speed Switch”
MFI Fuel Shut off solenoid questions


Porsche provides an easy test of the rack function.
There is a rubber boot over the forward (drive gear) end of the pump.
Use a M5 x 30 bolt to lightly screw in the end of the rack.
Pull the rack forward and it should snap back to its original position.



"
"
(C) Dr. Ing. h.c. F. Porsche A.G.

Best,
Grady

[svandamme]

yep the the CMA i know , but that's more for engine tuning with a pump on an engine , was hoping for some more specific , non engine connected stuff

the thermostat , gonna ****can that one, i'll put on a button , ( i'm running headers)

that rack thing , that's interesting, i came across the boot , but it didn't come off right away , so wasn't sure and left it on , need to explore that a bit more

my shutoff is working fine , tested it yesterday , it works with less than 3 volts ( didn't have other transformator laying around , nokia phone charger worked brilliantly), so i'm sure it'll work with the cars voltage