1972 911t fuel injection issue?

[rowingone]

I am new to Porsche and just purchased a 1972 911T Bosch injected in non running condition. I does start and drive but runs very poorly and very rich. compression is good on all cylinders and has had a new distributor installed and has the Mark 10B ignition with the blue coil. I have attached a video showing how it currently "runs" and I am looking for suggestions on what approach to take in diagnosing the problem. The previous owner was not mechanically inclined and got frustrated with the car and hence sold it running poorly. https://youtu.be/3i5gDjCcqGE

[gptom]

have you done a basic maintence? plugs, wires, oil, fuel and air filters, oil change, drain the fuel tank, adjust valves
how far have you driven it?

[rowingone]

Everything but the valve adjustment has been done. Hasn't been driven far because of how poorly it runs.

[Jonny042]

You'll be best to do a search for "mfi" and go from there. First thing to check is if the warm-up thermostat is getting warm air from the exhaust so the car goes from warm up enrichment mode to normal running mode as it warms up.

[al lkosmal]

PM me with your email address and I'll mail you a copy of MFI:Check, Measure, Adjust

regards,
al

[47silver]

Do not make any adjustments to the mechanical pump until you do the check, measure and adjust.
Every part of the mfi has to be in synch or it wont run correctly. It is a fine watch.
Tools: good timing light, valve asjustment tool, mfi adjustment tool, air flow measuring tool, volt ohm meter. Dwell meter, And gas testing device.
Dont bother doing anything without these tools as you will need everyone of them

[porschedude996]

Air leaks, warping flanges to the heads, wrong double insulated heater ducting from heat exchanger and injection pump.

It may be that someone cranked the idle mixture screw in too far to compensate for leaks. That was exactly what happened to me one my 1972.

The Mechanical Fuel Injection of this era are solid when all the air leaks are taken care of. I had to turn my idle mixture screw in 6 turns, yes, six turns to get the car from burning my eyes out. Stupid kalifornia smog checks drove me crazy for a while, but I got it.

[HarryD]

Search here for posts by Grady Clay on how to review and adjust your car including the MFI system.

As noted above, if everything outside of the MFI Pump is NOT Spot on, you will have great difficulty getting your car to run correctly.

There are some MFI gurus out there. Include your location in your profile and maybe there is one nearby. Tuning a MFI system is a dying art.

[rowingone]

Thanks all for the warnings and info. I haven't gotten the car yet but expect it to arrive this coming week. As I was looking thru the photos of the car I saw this . . well there is part of the problem . . the heat riser hose to the cold start thermostat is missing!

[rowingone]

Since I am new to the Porsche restoration world I do have a few more questions. I have restored a few C2 Corvettes and there are preferred and recommended vendors that produce the most accurate reproduction parts. For Porsche I don't yet know . . who is recommended for the best carpet kit, seat upholstery and foam, weatherstrip kits and headliner for the Targa top?

[bkreigsr]

Originally Posted by rowingone

.....As I was looking thru the photos of the car I saw this . . well there is part of the problem . . the heat riser hose to the cold start thermostat is missing!

That's probably 90% of your problem

[tobluforu]

Like stated, you need the mfi heater hose. Get that first, fire her up, report back. Now, if you have some time, pull the linkage off and make sure each goes on without any pre-load/movement. That's easy. Then measure the rod that goes from the pump itself to the rack, should be 114mm center to center of the ball joint. Also, easy to do.
From edmayo... the pump rod length is the starting point, and the only measured length. The procedure is to disconnect ALL rods from the cross bar, then attach the 114 mm pump rod to the cross bar, then adjust the two-throttle body to cross bar rods to just snap on without any pretension, with throttle plates at their stops, then adjust bell crank to cross bar linkage rod to snap on without any pretension. Then adjust all remaining linkage and throttle pedal stop so that you will have full throttle just as the pedal hits the floorboard stop. When MFI first came out Porsche called for a fairly elaborate protractor adjustment for the throttle links, that was later superseded to the method described above.

https://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm

[rowingone]

Great info . . just talked to the shippers and the car with be here next Saturday. I will keep everyone informed about my progress or lack thereof.

[30westrob]

Some info about why the small heater hose is so important. It’s purpose is to bring hot air from the left heat exchanger to the MFI pump as the engine warms. If the hose is not functioning the MFI pump thinks the engine is always cold and maintains a very rich mixture. Even a rusty, leaky left heat exchanger will result in very poor running. Rob

[bkreigsr]

This is all going be for nothing if you don’t have a socket in/on the left side heat exchanger.
The correct hoses that Pelican sells have a metal shield (Al ?) and a black composite inner.

[47silver]

The heater hose is a hose within a hose. When you order you may need to order each separately

[72doug2,2S]

Inspect that fine brass fuel filter located inside the fuel tank, replace. Mine was corroded and gave me issues after running for longer times. I don't think it had ever been replaced

[rowingone]

I have ordered the correct paper/metal/paper hose from Pelican. The gas tank and all lines were replaced about 7 years ago so that should be all good. Since I have little confidence in the previous owners mechanical ability, I will do as suggested here and start with an oil change and complete tune . . add the new hose . . and see where we end up. It is a 1972 911T Targa, black interior, and I am getting conflicting views on which carpet was original . .was it the perlon? Any advice on which carpet supplier is best?

[bkreigsr]

You ordered the hoses before you checked to see if you had the correct heat exchangers ??

[rowingone]

from the pictures I have they look correct with no rust . . the hose was only $15 so no worries.