1973 MFI Motor finally started.

[Vintagemotion]

Need support with MFI Questions:
1.After studying the MFI threats and soaking my MFI in B12 I’m looking for hints on how to get a good grip on the fuel rack/rod in the effort to free it up (assembled on the motor in the car). Where is the safest point to grab the rack/rod for back and forth motion?
2.How and how well can the fuel rack be accessed from the front of the pump (toward firewall)
3.Is the fuel rack/ rod in rich position when pushed toward to front of car or to back of car?
4.Is the shut off solenoid in shut off mode with 12V applied? Does it pull out or push in when active?

Background to above question:
Thanks to all the MFI thread contributors I found the information needed to finally get my 1973 started. I disassembled and cleaned / replaced the complete fuel system from tank up to MFI (including a successful electric fuel pump rebuild). The fuel supply works great with 14-15 PSI on the MFI return. The engine runs nice and steady but only with an elevated throttle and the continues flow of a jumped cold start valve. The engine does not run at all with MFI alone (without fuel support from cold start valve). Even when disconnecting the MFI from the throttle linkage and positioned in full rich there is no fuel contribution from the MFI. So the worst case seems true: Fuel rack / rod stuck.

•With MFI still in car I removed both side covers (passenger side) - all is nice and clean no settlements from oil.
•Removed allan-head plug on top right of shut off valve
•Pushed a 4mm rod through hole against the fuel rod – no movement
•Carefully tried to rotate (directly with fingers) the 3 exposed fuel sleeve assemblies – no movement

Now I hope to get help with my questions from above. Thanks

[304065]

1. You cannot grip the rack. Remove the black plastic cover from the rack port on the flywheel end of the engine, you can insert a screwdriver to move the rack. Be gentle.

2. How well-- this depends on whether you have a third joint between your hand and shoulder.

3 & 4. combined answer: When you switch on the stop solenoid, the control rack pulls all the way back. When a clean object is now pressed against the control rack, there should be no movement. This tells you that fuel OFF is with the rack all the way forward. This correlates to the action of the stop solenoid pushing the rack forward when it's engergized.

I still think you need to work through all the items in CMA. Good luck!

[dtw]

The pump is very easy to remove, and really should be pulled for what you're trying to accomplish.

-pull airbox, breathers, etc.
-pull intake stack on left bank
-move engine to 'FE' timing mark according to factory procedure (search archives if you don't have the docs) - so you are ready to put belt back on at correct position when reassembling
-disconnect fuel hardlines on top of pump
-disconnect other misc. pump connections - thermostat hose, fuel & oil supply/return, etc
-remove four nuts retaining pump to bracket
-slide pump out, taking extreme care with pump, shroud, hardlines, etc

Sounds like a lot of work, but you can knock it out in 20 mins or less. I find it less work to just pull the left-side intake, rather than try to get the pump mounting nuts off with the intake in the way.

Once you get the pump on the bench, there are some great threads here to help you qualify & inspect the pump. I'd pull the two side covers covering the plunger assemblies, then turn the pump pulley and see if the plungers are moving, or stuck. They're probably frozen up. I've had good luck freeing them up with alternating doses of Marvel Mystery oil, and Berryman B-12 chem tool.

If the rack is stuck, do NOT apply any leverage or heavy force. Try to let soaks in the fluids do the work, not mechanical action.

Chances are you can get the rack and plungers freed up, but to get it running right you are likely looking at a pump overhaul. If you do get the pump running enough to put back on the car, at least make sure you are getting even fuel distribution - if one hole is going lean under load, you're going to be in a world of hurt.

[356RS]

I was hoping to hear better news after your B12 soaking. To answer some of your questions: 1 & 2. You can only push the rack inward from the access hole (remove rubber cap covering hole) from the front of the pump, pulley end. The access hole is just above the pulley. Normally you should be able to push the rack inward about 8 to 10 mm with very little force and it will then spring back out when you release. 3. The rack normally rests in the idle potion and when pushed in shuts all the fuel off. 4. Shut off solenoid is off (normal) with no voltage applied.
Reading your background statement tells me the rack is frozen. The only other possibility to maybe free it up would be to grab one of the 3 plunger clamps behind the side cover (with the oil return hose) and see if you can rotate them back & forth. I see you already tried this. The only other way to grab the rack is to remover the main rear cover of the pump (catch the oil) and you will be able to grab the end and gently push it back and fourth. The end of the rack has a gray cap with slot in it for adjusting it.
If it were me I would remove the pump so it would be a hole lot easer to work on.
I hope this helps, and if I can help you any more I will be glad to.

[philippeF]

you can trust Mark
he's a true specialist , , same advice, remove the unit, and then ask him

[Grady Clay]

One thing that may have happened is:
When you first turned over the pump drive, all the pistons may have stuck in the ‘up’ position. It won’t pump any fuel if that happens.

Since the pistons are at the top of the pump, any solvents will not get there unless you invert the pump and let it sit for a while.

I suspect you will end up sending the pump out for a rebuild.

Best,
Grady

[philippeF]

yes !
you may remove the pump, remove the upper pressure valves and then gently try to push the pistons downward, we shouldn't not advice that, be careful with this accurate mechanism ...
once again, ask Mark (356RS)

[356RS]

Like Grady said, pistons might be stuck. Even if 1 piston gets stuck due to either old gas or corrosion that can jam the rack. Below are some photos of such a pump that had the rack frozen. Disassembly shows the rack in perfect condistion, but one bad piston jammed in the cylinder and not letting the rack turn the clamping sleeve.

[Vintagemotion]

Thanks everyone!
With your information the puzzle pieces have come together.
Obviously it is better for the pump and my back/knees to take it out.
I still hope I can make the MFI work without a rebuild. The hope dies last Especially since I just got a quote from Bosch Service Koller + Schwemmer in Germany. PFI would be an alternative of course.

[Vintagemotion]

Originally Posted by Grady Clay

One thing that may have happened is:
Since the pistons are at the top of the pump, any solvents will not get there unless you invert the pump and let it sit for a while.
Grady

Here are some more questions:
1.Besides B12 and Mystic oil, would WD40 or AERO KROIL be too aggressive?
2.Are there any components in the fuel chamber / piston / sleeve assembly that could be damaged by the above chemicals?
3.How exactly is the fuel chamber / piston / sleeve assembly sealed to the cam / rack portion of the MFI

Additional Thoughts:
Maybe someone has tried this already but here an idea to help the solvent to penetrate sleeves and pistons:
•Connect a long hose to the pump fuel inlet and one at the out let.
•Connect the hoses with a short pipe including a Schrader valve. (valve stud from car or bicycle tire). http://www.mcmaster.com/#schrader-valves/=4dwqya
•Before connecting the 2 hoses together the MFI fuel chamber and partially the hose could be filled with B12 and or Mystery oil.
•This contraption could be pressurized to 2 bar via the Schrader valve.
•Per Grady's’ suggestion this setup could be put upside down, (sideways etc.)

The pressure may help to penetrate clogged or enclosed areas with contamination if there is any pressure differential??

A rough sketch for better understanding:

[dtw]

1. No, but I think the B12 and MMO are better choices.
2. No (they live in gasoline, remember)
3. Shockingly, as I learned recently, just metal on metal fit - they are lapped in.

I set up a system a lot like what you have diagrammed! It is really nice to know I am not crazy...I used some spare fuel line and connected one end to the pump inlet. I then filled the line (and fuel chamber) with B12, then connected the other end to the pump outlet. Endless loop. Then I chucked a socket into my cordless drill and spun the pump with the drill at low speed. Eventually, the nozzles began spurting solvent. I kept repeating the process, alternating B12 and MMO, until I had excellent, strong spray from all nozzles.

Keep in mind, this was on a pump that was essentially brand new and had been stored indoors for a few years...your pump may just be beyond resurrection without stuffing some kilodollars into the pump inlet and shaking vigorously.

Keep in mind also the earlier advice - if you have pistons stuck in the up position, the above procedure probably won't help you.

[Vintagemotion]

Originally Posted by dtw

3. Shockingly, as I learned recently, just metal on metal fit - they are lapped in.

though on answer #3
It is surprising that the fuel does not penetrate into the oil chamber by gravity or 14 PSI chamber pressure.

Pump rebuild:
As mentioned before the hope dies last. I realize that eventually I will have to send the pump for rebuild but it is my nature not to give up until all reasonable / carefull attempts are exhausted. Especially on technical issues beeing an engineer that likes to show off with black under the fingernails wearing a pressed shirt on Monday.

DTW,
Thanks for the feadback on circulation method. Is there any harm in changing rotation direction on the pump?

[al lkosmal]

Vintage,
I am with you......Monday morning engineering meetings often turn into Porsche project status reports.

I rebuilt my pump to the point that I thought it was in good, working condition, but once I got it to that point, I decided to send it to Mark Jung (356RS) for calibration. I had been following his posts regarding his test bench and was impressed. Mark calibrated my pump and while he was in there, replaced all gaskets, a pulley, etc. Now, it really is in great, working condition and cal'd to spec. I fired up my engine, last weekend and it runs very good. This was my 1st time, rebuilding an MFI engine...like all projects, at some point, it pays to consult/contract with a specialist.

[dtw]

Originally Posted by Vintagemotion

though on answer #3
It is surprising that the fuel does not penetrate into the oil chamber by gravity or 14 PSI chamber pressure.

Pump rebuild:
As mentioned before the hope dies last. I realize that eventually I will have to send the pump for rebuild but it is my nature not to give up until all reasonable / carefull attempts are exhausted. Especially on technical issues beeing an engineer that likes to show off with black under the fingernails wearing a pressed shirt on Monday.

DTW,
Thanks for the feadback on circulation method. Is there any harm in changing rotation direction on the pump?

Not to get off track of your thread, but yes, it is surprising. Poorly seated fittings, or fittings seated with imperfections/debris, will allow fuel seepage. My pump was filling itself with fuel (to my utter dismay) because of excessive inlet pressure. If you'd like to read more about that, check out this thread:

MFI pump leaking gas into pump housing

I hear you on the rebuild - we're just trying to ease you into the 'worst case' scenario . Consider Supertec as one of your rebuild alternatives, if it comes to it. Shorter lead time and lower price than PFI.

You shouldn't have to change pump direction? I honestly don't know if it could be harmed from reverse direction, but I doubt it?

[Vintagemotion]

Originally Posted by dtw

I hear you on the rebuild - we're just trying to ease you into the 'worst case' scenario .

Thanks for the advanced emotional support, I probably will need more once I submit the 2010 gadget budget to my houshold CFO & wife

[356RS]

Vintage, I'm hoping your pump fuel head & pistons don't look like this:



This will definitely jam the pistons in the cylinders.
The sealing surface of the cylinder as you and Dave talked about is pictured below and is held down by the pressure valve holder on top of the pump. There is also a second seal on top of the pressure valve. All 3 are held in place with 18 ft lbs of torque on the pressure valve holder.


About the pump rotation. The pump will work in either direction and pass all specs.

[Vintagemotion]

Mark,

The pictures are hopefully much worse than what my segments look like. I actually found your threat about the MFI – tester that you constructed. I admire the accomplishment not only for the obvious functionality but also for the elegant finish. My envy for having this in your own garage Regardless of the cost of an MFI rebuild it must be fascinating to master it. Thanks for sharing your unique knowledge.
It is actually the MFI why I have a Porsche, the other side of my hobby are 60’s Mercedes with MFI that are not as sensitive. My family car is a 220SEB with MFI that I woke up in 2005 after being stored since the 80’s. Except the warm up regulator (water) being stuck and a weekend of CMA the MFI did not require anything. The rack/segment being stuck is less prevalent on Mercedes.

[Vintagemotion]

Today was my first ride!!!!!

Lessons learned over the last 2 weeks:
Yes it is better to take the pump out of the car for cleaning etc. Thanks for the advice Dave W.
I pretty much wasted a couple of evenings when I was trying to work the pump while still in the car. It really only took 20-30 minutes to get it out!

Next step was exterior cleaning: I got some rubber plugs from Home Depot to close the injector outlets, the Oil feed /overflow. Connected the fuel in/ out with a 30cm fuel line. With that in place I cleaned the exterior of the pump.

When I took all the side covers off my disappointment was great: I found 5 of 6 pistons stuck in top dead center position. Like you guys predicted.
The rack did not move at all! Frustrated I tried for the last week to free stuff up but only 3 pistons would move. The rack still did not butch.

It did not look hopeful but than I tried the following:

Again I filled the fuel chamber with AERO KROIL connected the fuel inlet and outlet with a fuel line and tight clamps. Than I stuck the pump in the oven and warmed it for a couple hours to 150 Celsius. My assumption was that the pressure in the fuel chamber building up with temperature would help the oil to penetrate the pistons and sleeves. Indeed it did! While still hot (cold enough to touch with a cloth) it took only 15 minutes of working the rack and pistons to free everything up nicely. The rack snap back without any help. I reassembled covers etc and pre filled the pump with about ½ liter of oil.







The pump went back in the car. This was not as easy as taking it out!!! A big help was to take one of the threaded studs out of the mounting bracket.

Without to much adjustment I was able to take my 911 around the block after 15 years of storage. This was a very existing moment!!!! It runs good and sounds awesome!! Hours later and I‘m still grinning.

The only thing left to do on the fuel system is to replace one on the T pieces from the cold start nozzles see picture. I need the T piece and suggestion on how to get it out of the stack.



I need this plastic T piece

[Vintagemotion]

Has anyone successfully removed on of the above plastic nozzles. Is this even possible?