1975 911 msd installed idle problem
 

SmileWavy

Hey everyone

got a little problem here. Just installed msd ignition in my 1975 911 after problems with last system. Got it install but it doesn't idle and will die. If you keep rpm at 1500 it sounds like its not missing and drives fine, except when you take your foot off the gas.. it makes driving in vancouvers traffic no fun ,,,please help..

Jared

This is a CSI car? Try adjusting the big idle screw so it will idle. then go on to the CIS troubleshooting list (control pressure, mixture, vacuum leaks, ect) ensure timing is set also.

1975 still uses points. Try rechecking the timing. I recommend Pertronix replacement.

Thx i will look into the pertronix and re check timing
thx

Well ordered pertronix.
Checked all wires, connection,timing and adjusted idle up which works fine for 2-5 mins then just dies..?
If anybody got any other suggestions would be great as i really want to dive further then two blocks from my house.

thx
Jared

Sounds like fuel. Is your fuel pump working? Did you accidently bump the fuel pump and maybe knock one of the wires off during the installation.
Don't remember if there is a fuse for the fuel pump but check that too.

My fuel pump is working, when you turn the key u can hear it. If I keep my foot on gas for high rpms it will not die but will try too. The rpm needle just goes to 0 for a sec and will die if no gas is applied. But i will go through wires again.
Still looking for answers here please and thanku

thx

Does the car surge for a while and die?

Yes sir, It idles all nice or idle jumps up and down 200 rpm. But at the end it dies
If u mean surge while driving, yes but i haven't gone that far from home..lol

Thx Harry your input is always welcome here..

If the car runs for a while and dies, it is most likely a fuel related issue.

Possible causes are a plugged strainer in your gas tank, plugged fuel filter, Vacuum leaks or improper mixture.

It is easy to replace your fuel filter.

Next easiest is to test for vacuum leaks.

If the car runs, will it run continously at 2,000 rpm (surging or not) without stalled for 5+ minutes? If so, your strainer is probably ok.

Check for vacuum leaks (spray carb cleaner around all of the fittings and see if the idle changes).

Once you are convinced you do not have vacuum leaks, your strainer and filter are ok, take your car to a place that knows K-jetronic cars and have them check the mixture. It may be a bit lean.

Wilco (will comply) tomorrow

Thx again for your input.

you clipped that wire to make it a 6 cyl MSD right? gapped plugs? trigger wire is cool?

That was going to be my next suggestion. Go back through your installation instructions and make sure you didn't miss anything.
The reason I thought it might be fuel is because I had the same problem once.
My fuel line was kinked and the car would only run for a short time because it wasn't getting adequate fuel.
Put in a new fuel filter and check the lines just to eliminate that possibility, They are cheap and it couldn't hurt.

I have an MSD on my 75 and I'm trying to think of anything that could help. I have carbs now, but I didn't have any problems with the CIS.
It should either work or not work with a new installation. The dying after a few minutes is strange.

Thx guys good input here.

Well woke up early (no cops/ no traffic) Theres new rules in vancouver that if u are caught speeding they take your car away 48hrs and fees approx 500 bucks..
Any ways drove it on hwy for 30 mins and put my foot to the floor 5 gear and if it had wings it would have taken flight. No surging on hwy, but got to light and had to keep rpms or would stall and do that rpm 800-1200 bounce then 0 rpm and die.

As per your questions
Q-clipped that wire to make it a 6 cyl MSD right?
A-No put the 6al 2 has a switch you turn to 4/6/8 which i put 6 on
Q-gapped plugs?
A-Yes I went with .50 as recommended
Q-trigger wire is cool? Know do you mean white wire to dizzy is connected, but that is the only wire connected down there.. The old neg wire on the bottom side of the dizzy is not connected to anything now as i thought it was not req?

I will go over more later today checking everything u guys have suggested and please get back to me as its greatly Appreciated..

thx again Jared
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When my car had the dying after a few minutes problem, it was points. A Pertronix fixed it. You might also check to see if the MSD has melted the resistor in your rotor. Mine will fry one in about a half hour.

Your filters sound to be ok. Surging in a CIS system is often a vacuum leak or lean mixture. Check for leaks. Bring it to a Porsche shop with a CO sniffer and get it adjusted (may be the best $20 you spend). If not, your sytem pressures could be off. You will need a CIS tester to verify. Again the Porsche shop may be able to help you.

wilco and thx again. Just drove it airport again with no prop's except at red lights rpm stays high for one min then does jumping thing. Will look at rotor, getting pertronix unit on order ( 1 weeeek ) wait.

Going to cross my fingers and drive to whistler for the last day of sun up here.. but will take tool box and extra parts with me...and go see a shop on monday for a tune up.

Wish me luck.. and have a good weekend..

I had a bit of an issue using an MSD and points. They seemed to get a bit dirty and then the car would run erratically at low rpm. They cleaning the points with some sand paper and see if that helps.

Good point. An easy way to fix them up is with an ignition file (small file with teeth on each side). The advanage is thet you can do this in place (not removing the points). A few strokes and you are done.

If he is having a surging problem but wants to drive a bit, if it was me, I would set the idle higher (try 100-1200rpm and see if it can be driven without stalling.

I am still thinking lean mixture which may be caused by vacuum leaks, improper mixture setting or improper cold/hot fuel pressures. He can test for the first but you need gauges to test the other items.

Close the gap on your plugs. I did the same on my MSD install and set them at .045. Had A high RPM miss. After much checking decided that it must be spark. Set gap at .030 and all was well. Of course my 69 has 9.5:1 compression(JE pistons). Anyway I think the MSD recommended gap size is too big for our cars. Easy fix and won't take long to try. Good Luck.