Hi,
It is winter here in Northern California, so it is time to fix some of the little things that bother me about my 911. My 70 T has hard started since the day I have bought it a year ago. It would start up fine only if it has been driven within an hour and a half. Now it seems to like to flood itself when I tried to start it the other day. Could this be a "too rich condition" for my MFI system, or could this be bad ignition timing?

Thanks for the help

 

its pretty well known in the 912 community that distributor probs (timing, points, etc) often masquade as carburator probs... im assuming it could be the same with injection. it wouldnt be a dad idea to see where youre sitting timing and ignition wise. better to do that as a first step, than tear appart your whole injection system looking for probs.

 

Points ignition? If so, make sure the inside of the distributor is dry. Use a hair dryer to dry the inside of the distributor cap and distributor itself.

 

well i was saying on the 912.. it has a points ignition. (well i have an pertronix electronic ignition installed in mine, which replaces points.) his is a 70.. not sure if they had points or went to electronic ignition between 69 and 70, or if his is even stock.

either way.. you get the idea.. check the dizzy and ignition, timing etc. same principle, no matter how you go about it.

 

SPD...I don't know specifically about the porsche mfi system...but the symptoms you're talking about would seem to me like you may have an
injector leaking down or fuel pressure regulator bleeding back into the tank. Both will give you a long crank time until you 1. Clear the washed out cylinders enough to fire again or
2. Build up fuel pressure to the system.
This would be a reason for the car to start easily when she's been run
previously because the cyls. are clear and/or the pressure has not bled down yet.
Question to you... are you sure she's flooding? Can you pull a plug to check for fuel moisture ?
The ignition problems such as pionts or a wobble in the dist. should not go away ,or at least you should be able to feel them still when driving
Hope this helps
Russ

 

I am sure she is flooding , because I can smell the gas in the intake. Also it will puff a giant cloud of smoke and gas vapor when I do get it started. The engine runs fine and it doesn't seem to have any flat spot, so I think it does have to do with spark more than it does fuel. It does have a point system so the problem could lie there.

 

Could the timing just be too far advanced. The car seems to hate going slow, it will lurch at low speeds, especially if I hit a speed bump. It doesn't hesitate at all though if i am accelerating.

 

I can think of 2 reasons for this behavior.
First you should check the cold start fuel enrichment soleniod that is mounted on top of the fuel filter. If the soleniod is open for to long or if it does not close properly it will flood the engine with fuel.
If the soleniod is OK then it can be the choke mechanism mounted on the MFI pump. It consists of several bimetal discs that expands when hot air from the heat exchanger flows through it. When the discs get old they dont expand as much as they should and you may have to put in extra discs to get proper fuel enrichment on cold starts.

//Roger

 

The 1970 911T came from the factory with Zenith carbs.Are you sure it has MFI ?

 

Yes I am sure it has MFI. This car had an engine transplant to a 73 2.4L MFI engine. I am going to check the ignition issues tomorrow before I deal with the fuel problems.

Thanks for the help

 

Even a weak coil may cause the low r.p.m. "loading" up of fuel. If the dist.
doesn't have excessive play on the shaft...I'd look into the quality of spark you're getting.
Russ