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More MFI

Reading a recent MFI post and responses got me thinking about my cold start problem.When cold,my engine will crank and crank for a long time until it finally starts.After cranking for a while,it seems to start faster if I push the lever back down.Am I "flooding"
it with all the cranking? Do I have an injector problem?
It starts much better when hot....
Car is a 69S,MFI.
Thanks
Old 02-16-2003, 12:41 PM
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Mike
Cold start enrichment.
If your car is the same as mine then a yellow wire from the starter solonoid goes to the thermo time switch (starts timing) and to one side of the relay. A ground is supplied from the other terminal of the thermotime switch to the other side of the relay which then operates and in turn operates the fuel enrichment sol, this squits neat fuel for cold starting.
This squiting will continue until either you stop turning the starter or the thermotime switch times out, around 8 seconds I think.

To test put the hose from from fuel enrichment sol into a jar get someone to op the starter. with the car cold.
Calgary eh, no problen doing when the car is cold!
Jeff

PS if it doesn't work clean your two 14 pin electrical plugs as it goes through 3 times! so it's a high % quess
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Old 02-16-2003, 01:37 PM
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Jeff...thanks for your help.I assume when you say the enrichment solenoid that you mean the one that is above the fuel filter that squirts fuel into the air cleaner...is that correct?
thanks
Mike
Yeh,it's cold up here today,but usually the winter is very tolerable in southern Alberta...
Old 02-16-2003, 02:45 PM
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Mike
Yep, that's the one.
Coolish down here too and lots of the white Canadian stuff.
Jeff
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Old 02-16-2003, 04:01 PM
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Mike, the lever you are referring to just controls the throttle and has no effect on a cold start, just keeps the idle up once you have it started. Think of it as a throttle stop and not as a choke. As to the enrichment solenoid, yes it is above the fuel filter. The fuel line runs to separate lines to each throttle body.
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Old 02-16-2003, 04:03 PM
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Keep in mind that the '69 MFI's are different then '70's and later. Specifically they have a cold start solenoid on the injection pump that the others don't.

An easy way to rig a cold start with a 2.0 MFI is to run a switched 12V wire to the cold start solenoid. I did it on my car and I've heard it is similar to what the factory used to do on some of the race/rally cars.

In the case of my car, I spliced a wire from the start circuit at the ignition switch and ran it to an unused switch on the dash. From there I ran it back and connected it to the cold start solenoid on the MFI. When the switch is closed the solenoid gets 12 volts as long as the starter is engaged. This 12v pegs the MFI's rack at full rich and the engine starts with just a couple of cranks. It's much neater then pouring raw fuel down the stacks.

I just make sure to open the switch after starting the car since trying to hot start the motor with the switch closed will result in the motor flooding.
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Old 02-17-2003, 03:38 AM
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I think I have a brand new cold start solenoid for a 69 MFI in the garage.
Let me know if you need one.

Thanks
Alan.UK

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Old 02-17-2003, 04:49 AM
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mfi cold start problem

Mike,
You might check the condition of the squirters inside of your air cleaner. Mine became clogged and prevented fuel from flowing through them. Carb cleaner did the trick!
Also, when my engne is cold, I let the electric fuel pump run about 30 seconds before I try to start the engine. That 30 seconds gives the pump time to move fuel from the tank to the engine. No crank, crank, crank!! Works for me!
Good luck!!
Rock
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Old 02-18-2003, 09:19 AM
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beware of the cold start

69s have a different fuel squirter design than the later MFI cars and, at least in my case, it is not particularly safe. As others have pointed out, when the thermo switch senses that the car is cold, it opens the cold start solenoid (while the engine is cranking) allowing raw fuel to pass through the braided hose to the air cleaner assembly. The air cleaner has a two metal tubes on the inside with holes above the MFI stacks. Fuel drips from these holes and down into the stacks providing the ultra-rich mixture that allows the engine to immediately roar to life when the system is adjusted properly. crank, crank, crank means that your cold start is not working properly. It should start up immediately (at least mine did). In my view, the system, at least on the earlier cars (pre-72 I believe) is a fire hazard. when I purchased my car a few months ago in Michigan, the system was disconnected and the mechanic told me to leave it that way. I ignored him, tested all of the parts, which worked perfectly, and connected it up. I had a small engine fire in two days that melted one of the upper intake stacks. The fuel ignited, I guess, from a small backfire, and followed the liquid trail of fuel up into the stack and aircleaner. Since the fuel is not mixed with air but is dripped in directly, all of it is not sucked into the intake by the vacumn of the cylinders. While my experience was not catastrophic, I disabled the system and have learned to live without it. According to my mechnic, the later systems have injectors that are screwed into the sides of the stacks well below the air cleaner. As I understood him, there is better mixture and a much lower chance of fire with the later system. My .02, short on science but long on personal experience.
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Old 02-18-2003, 11:40 AM
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I was told the same thing by my mech. I disconnected mine a long time ago. Not much use for it in Floriduh. I gave some thought recently to replacing the solenoid to make it work properly, but when the dealer told me it was a $285.00 part, I decided it worked just fine! Now I just pull the black knob lever up all the way, don't touch the pedal and she fires up rather quickly. I would still be embarrased at a LeMans start, but hell I saved almost $300.00!
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Old 02-18-2003, 11:57 AM
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I guess that Canada has another level of cold but in 20 degree weather I can get my 911 E to start in about 10 seconds. Pull-up the lever, floor the accelerator and release it when the engine starts to catch. It idles for another 5 or 10 seconds before it catches on all six cylinders and the vacumn advance kicks in, whatever is going on. I depress the lever to about 1/2 way and I drive away. The MFI runs horribly rich at start-up so you definately do not want to let it idle if you can avoid it.
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Old 02-18-2003, 12:06 PM
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Mike;
While pulling the hand throttle all the way up and cranking may work in Florida cold, it definitely won't work in Calgary cold. You'll be there an awfully long time since there is a big difference between rich and an opened throttle. You need rich to start a 911.

Trust me. Disconnect the enrichment solenoid on the fuel filter that feeds those nozzles in the air-box. They're dangerous. Then hook up the switch to the enrichment solenoid and it will work like a dream. I've used it to start my '69 911E within 2 or 3 "chugs" in freezing temperatures. (Note - this means turn the key once and chug-chug-chug - Vrooom!)

BTW - while your fixing safety issues in your engine compartment, put a piece of duct-tape over the exposed 12V connection in the back left of the engine bay. You can check out CamB's picture of the offending item here.
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Last edited by jluetjen; 02-18-2003 at 12:23 PM..
Old 02-18-2003, 12:09 PM
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The copper colored screw on the left of this picture has an unswitched 12 volts going to it. So it is always live. It is also apparently was never covered by the factory. The two fuses in the fuse block below it are supposed to have a plastic cover on them, but in this picture don't. Uncovered, they are as dangerous as the post on the left is.

BEWARE!
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Old 02-18-2003, 12:33 PM
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Thanks everyone for all the replies...I think I will disable the solenoid on the fuel filter that dumps fuel into the stacks. I've always thought that was potential for trouble. Interestingly,I'm getting conflicting opinions about the hand throttle.Some say it has nothing to do with cold start,my mechanic says it is connected to the microswitch on the linkage and sends the solenoid power.
John...I'm not entirely sure how you rigged that switch to get the rack at full rich but that sounds like a great idea.
Just so everyone is aware.I don't drive the car in the winter.It can get very cold here,with verrying amounts of snow.The car is hard to start in the summer,when the engine is cold.
Thanks again for all your help....
Mike
Old 02-18-2003, 03:55 PM
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Mike,
The micro switch on the linkage is to op the fuel shut off sol on over run.
John's post looks like a good option for you if you don't want to keep it original.
The hand throttle only does the same as resting your foot on the pedal.
It "grabs" the throttle cable in the tunnel and holds the butterflys open a little
Jeff
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Old 02-18-2003, 08:10 PM
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mfi squirters a fire hazzard?

Rich,
The mfi fuel squirters on my 70 911E are the same as you described having on your 69. Mine, however, doesn't just drip raw fuel down into the stacks. The raw fuel is delivered in a very fine spray into each stack. Once cleaned, my squirters have worked very well! I'm curious about the reported fire hazzard. I can see the potential for a problem, but haven't read about it being one. Can anyone provide documentation that this setup is a fire hazzard? Thanks!
Rock
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Old 02-19-2003, 04:12 AM
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I think I posted something about this a few months ago. Simply put, mine caught on fire inside the air cleaner. It put itself out but not before it melted one of the plastic intakes. It looks like a backfire ignited it and then it followed the liquid trail of fuel up the side of the intake.
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Old 02-19-2003, 04:51 AM
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On my 69S, the fuel line from the top of the gas filter has been blocked off....and the top solenoid on the MFI pump has been wired to a switch in the cab.
When cold starting....I turn the key..and a second later turn on the switch.
This lets the air flow establish before the gas goes to full rich.
I find in very cold weather that it turns over for about one revolution or so before it fires up....then a second or so later...I turn off the switch....before it begins to "load up" with too much fuel.
In order to clean up the engine compartment...I am going to relplace the top of the filter solenoid with a block off fitting...and get rid of the extra fuel line and wire.
Bob
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Old 02-19-2003, 06:51 AM
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I left the original setup, but connected the solonoid to a switch on the dash.
1 Be sure and use a momentary push switsh, to make sue it can't get left on.
2 If car fails to start, release button and crank for a few more seconds; this makes sure that if there is a flame in the stacks it will be sucked in.
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Old 02-19-2003, 08:31 AM
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