please explain 73/MFi Cold start
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Joined: Oct 2005
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From: Southern Utah
please explain 73/MFi Cold start
my car starts really hard when its below 50F degrees. the car is a 73t with MFI.
The car runs fine after it runs a few min. It does always start but really takes some time. There is a lever next to my Handbrake that says throttle. what is that? What ever it is, its disconnected. I know a little about the MFI. I know it has a thermostat and that regulates the fuel for hot and old conditions. Does the car have a cold start injector? if so what triggers it? or is hard start normal in these older 911's on cold days?
Thanks!
The car runs fine after it runs a few min. It does always start but really takes some time. There is a lever next to my Handbrake that says throttle. what is that? What ever it is, its disconnected. I know a little about the MFI. I know it has a thermostat and that regulates the fuel for hot and old conditions. Does the car have a cold start injector? if so what triggers it? or is hard start normal in these older 911's on cold days?
Thanks!
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From: Bakersfield, CA, for now...
The car does not have a cold start injector, but it does have a cold start solenoid that releases fuel directly into the six intake stacks. It's temperature switch controlled and is a tricky little system to diagnose/repair. The hand throttle (next to the handbrake) must also be functional and adjusted. If you have a knowledgable shop close by I respectfully recommend that you turn it over to them. If you have the appropriate factory repair manual you can start running tests... Good luck with it.
Pete
Pete
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From: Southern Utah
yes i have manuals
not factory but pretty good manuals... thanks for the info. I will make sure the solinoid is in working order... but the cable to the hand lever is missing. so i cannot even tell where it goes.. so i will have to look into it more or take it somewhere.... the cars a hobby.. to me a hobby is not letting someone else do all the work..... but when its over my head, its over my head.... if i can not get it i will take your advice.... thanks for info, it will get me headed in the right direction
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Joined: Oct 2004
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From: Bakersfield, CA, for now...
The hand throttle lever is not cable controlled! It has a plastic "shoe" that engages a metal cylinder-like part that slips onto the actual pedal rod between the gas pedal and the throttle lever on the side of the transmission. Lift away the rubber boot on the handbrake and you will see an oval hole just in front of the hand throttle lever. Look inside with a small flashlight, the round, metal thing, with a small set screw in its side, should be visible. Most often the plastic shoe has broken, or popped off the throttle rod because of mis-adjustment. The shoe, or its remains, will hang just out of sight under the lip of the handbrake base. On rare occasion it will be intact, and you can use a skinny screwdriver to position it and pop it back over the rod. Check it out!
Pete
Pete
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From: kinver uk
I used to have all sorts of problems with my MFI (1969 911E). I bought the car 30 years ago, and it was always a bear to start when cold. Even below freezing here in the UK, it would not start.
You can read my story at 911e.org. In short I did a track day at Castle Donnington last June. The car developed a mis-fire, and I thought it was serious.
A local Porsche shop went through everything, from setting valves, timing, new ignition wires, points, rotor, and a host of other things, plus setting the linkage of the MFI, and the fuel delivery.
I started the car on Sunday (weather was not brillant, and in the evening was about 35F) and it started like a normal day. Still not the easiest starting car in the world but it is 37 years old.
Make sure that everything is set to factory standards, and I'll bet your starting problems go away.
Dom
You can read my story at 911e.org. In short I did a track day at Castle Donnington last June. The car developed a mis-fire, and I thought it was serious.
A local Porsche shop went through everything, from setting valves, timing, new ignition wires, points, rotor, and a host of other things, plus setting the linkage of the MFI, and the fuel delivery.
I started the car on Sunday (weather was not brillant, and in the evening was about 35F) and it started like a normal day. Still not the easiest starting car in the world but it is 37 years old.
Make sure that everything is set to factory standards, and I'll bet your starting problems go away.
Dom
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3rd Gear
Joined: Nov 2004
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From: Vancouver, BC
I have a pdf copy of factory MFI manual, obtained from web, I can send it to you if you want it, email me cselden@telus.net
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Joined: Oct 2005
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From: kinver uk
Cold Start MFI
Sharkattack,
FYI, further to my last post, we have had 3 days of freezing tempereatures here in the UK, and I started the car 1 hour ago. Outside temperature was probably about 38F.
With the suggestions I made before (forgot to mention cleaning the thermostat), the car started as if the the day was 70 (still not an easy starting car though but not an impossible bear).
I bought the car in June 1975, and in October 1975, the car was parked at O'hare field for 3 days while I was away on business. When I returned (temps were no less than 40 degrees), the car would not start. It took a jump etc to get me going.
hope this helps.
Dom
FYI, further to my last post, we have had 3 days of freezing tempereatures here in the UK, and I started the car 1 hour ago. Outside temperature was probably about 38F.
With the suggestions I made before (forgot to mention cleaning the thermostat), the car started as if the the day was 70 (still not an easy starting car though but not an impossible bear).
I bought the car in June 1975, and in October 1975, the car was parked at O'hare field for 3 days while I was away on business. When I returned (temps were no less than 40 degrees), the car would not start. It took a jump etc to get me going.
hope this helps.
Dom
Thread Starter
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Joined: Oct 2005
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From: Southern Utah
Thanks
I have a lot of info on my MFI but i always like to look at more info. Yes i would like a copy of that mfi manual. khuber@innovative-pos.com. We just got snow. so the car is in for the winter.
Thanks for the good words
SA
Thanks for the good words
SA
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Joined: Oct 2005
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From: kinver uk
Sharkattack,
Don't horse around the MFI unless you absolutely have to. I had too many hacks (includes a dealer in Chicagoland) ?.,/..es?? it up. Took alot of time and money to sort it out.
It needs to be set correctly, but only but only but only after the other bits are correct.
Domh
Don't horse around the MFI unless you absolutely have to. I had too many hacks (includes a dealer in Chicagoland) ?.,/..es?? it up. Took alot of time and money to sort it out.
It needs to be set correctly, but only but only but only after the other bits are correct.
Domh
Thread Starter
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From: Southern Utah
no fears
if i do not understand completely how something works, i usually will not mess with it. But i see the mfi as no threat to work on at this point. I have read a lot of info. I feel i understand the workings. I have no fears... i will let you be the first to say " i told you so" if i ef it up. 
Advanced
Joined: Mar 2004
Posts: 61
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From: UK
Maybe of interest to you all is that my 73 MFI car has been modified to make cold starting easier. In essence the factory cold start mechanism has been disabled and the cold start solenoid that releases fuel directly into the six intake stacks has been wired to a push button fitted to the dashboard
To start the car I set the hand throttle open some and then use the push button to inject the extra fuel whilst cranking the car until it fires. Then set the hand throttle to a fast idle (if you set it too slow the car backfires a little) until warm. I have never ever had a problem starting the car.
It's a common mod on track/race cars I believe. I don't have any more details as this mod was on the car when I bought it.
Ian.
To start the car I set the hand throttle open some and then use the push button to inject the extra fuel whilst cranking the car until it fires. Then set the hand throttle to a fast idle (if you set it too slow the car backfires a little) until warm. I have never ever had a problem starting the car.
It's a common mod on track/race cars I believe. I don't have any more details as this mod was on the car when I bought it.
Ian.
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From: Summerfield, NC
MFI Resources
I've started two threads on the Pelican Parts board the Ultimate MFI Resources Thread and the MFI Message Board Index to get all the available MFI information together in one place. Please take a look at these threads, they may answer some of your questions. It would help a great deal if you would pass these links around this board so that people can add their resources to the lists I have started. MFI is complicated and the more information we can get together, the better off we'll all be.
