Help Please MFI won't run

[matthewb0051]

Let me begin by saying I'm on the verge of selling my '69 911E. I've owned it since 2005 and it has been great, that is until this past spring when I switched from Webers back to MFI. Since the switch there has been multiple issues, bad MFI pump, bad fuel pump, CDI box went bad, and on an on. I've reached my limit.

A few weeks ago I replaced the alternator and voltage regulator. Car fired right up and ran perfectly. The next day it refused to start. Since then I have checked everything and found nothing wrong. Car still won't run. The cold start is not hooked up and it has been cold here but even on warm (60 degree) days with car parked in the sun I can't get the thing to run.

I'm at a loss and frankly very tired. Loved the car before but now it is a huge PITA and I would almost prefer it gone.

Recommendations? Offers? Wish I still had my E30 M3...

Matthew

[TR]

Hi
Don't despair yet!
You have to be methodical with your checking.

There is plenty of good advice on the forum, first read through some of the info attached.

You should also get a copy of the check measure and adjust manual, they are usually available on ebay.

Once you get the system up and running you will be very happy.

Is the mfi system totally complete will all it's components?

Ultimate MFI resources thread

Pelican Technical Article: Mechanical Fuel Injection Troubleshooting and Adjustment - 911 (1969-73) -

[matthewb0051]

Thanks. I have read all MFI related posts as well as CMA. System is complete. When it has run it has been great but that has been seldom.

[Shuie]

If the cold start solenoid has been disabled it is going to take what seems like forever to get the car started when it's cold. That's why there is a cold start solenoid in the system. Otherwise, assuming everything else is in place and working with the MFI and the ignition timing is close, you are probably going to have to crank it for 1-2 minutes to get it to start. Parking the car in the sun on a 60 degree day will not warm the engine up.

There are a lot of threads on the forum about stuff like this. Here is one where the resident MFI gurus helped me get through a similar issue:

Need MFI help or advice...PLEASE

[dicklague]

Originally Posted by Shuie

If the cold start solenoid has been disabled it is going to take what seems like forever to get the car started when it's cold. That's why there is a cold start solenoid in the system. Otherwise, assuming everything else is in place and working with the MFI and the ignition timing is close, you are probably going to have to crank it for 1-2 minutes to get it to start. Parking the car in the sun on a 60 degree day will not warm the engine up.

There are a lot of threads on the forum about stuff like this. Here is one where the resident MFI gurus helped me get through a similar issue:

Need MFI help or advice...PLEASE

You could "hot wire" the cold start solenoid by supplying 12 vdc to it. this would spray raw fuel into the throttle bodies while cranking.

I have a push button on the dash of my 1973 with MFI to do this, and on a cold day here in CA [45 degrees] I have to push the button a few times for 3 to 4 seconds while cranking. Try this only if all your MFI cold start tubing is in good shape.

I have also heard that holding the throttle full open when cranking will supply a very rich mixture......I have no personal experience with this.

[kltarga72]

My 72 S is a little hard to start when its cold even in the summer. I have to pull cold start handle up as far as it will go, turn ignition on and let fuel pump run 7-10 seconds, pump accelerator twice and then hit the starter. It will take 4-6 attempts hitting the starter for 3-5 second duration and then will start to fire.

No problem at all restarting engine when its hot and it runs and idles correctly. So for my car the cold start mechanism is necessary.

I had a 72 T that I purchased new in Germany and I remember it required a similar process in starting a cold engine.

Good luck!!

[Dave Kost]

Sounds like it is something simple. Probably electrical. Wire knocked off, ground missing, etc. Had the same issue with my E and found out the points closed up.

Keep the faith.

[regency]

I wish I had a 69E..........if it were mine, I go through every MFI component, hire the Pro's and get it running again. I did it once before with my 73 T that had been sitting in my Uncles garage for 25 years. It was a worthwhile journey.

1973 911T MFI Coupe, Aubergine

Steve

[Dave Kost]

forgot to add.

Clean all the electrical connections including plug wires with DeOxit. If any of the connection are marginal the cleaning will make a difference. That green slime that builds up on the copper connections needs to be eliminated. Check the coil - plug connection.
Did you check for a weak battery?

[dicklague]

Originally Posted by Dave Kost

forgot to add.

Clean all the electrical connections including plug wires with DeOxit. If any of the connection are marginal the cleaning will make a difference. That green slime that builds up on the copper connections needs to be eliminated. Check the coil - plug connection.
Did you check for a weak battery?

Good point. Years and years ago my Speedster would not start.....fiddled with everything and then I changed the coil. Cranked right up.

You ALWAYS assume the coil is good!

[Dan J]

Maybe you need a can:Start Ya Bastard Instant Engine Starter- Nulon Australia

You sure you've got good spark? I agree with Shuei you need that cold start

[69911e]

Are both cold start solenoids disconnected? The one on the pump('69 only) and the one mounted on the fuel filter?

I use a dash mounted switch also mentioned by dicklague above. Others have used the pump mounted one only. Read:jluetjen
More MFI

Obviously, check spark first. Cautious use of starting fluid will also help diagnose.

[Shuie]

At the end of the day, I think the cold start issues that I had with my '72 were a combination of things that went wrong on the 800 mile drive home when I bought the car. Some of my heat exchanger hoses disintegrated, so no hot air was getting to the thermostat on the pump. IIRC, the fuse on the engine relay panel for my cold start solenoid either fell out during the drive or had been removed by the PO to disable it, so that wasn't working either. I finally swapped the ignition points for a Petronix and the Permatune that was in the car with a known good CDI box from another car and that solved almost all of my starting issues. I did hook my CS solenoid back up after replacing all of my old fuel lines. Once everything was back in place and in good working condition the car would start and run just fine.

If I were dealing with this today and I had a complete MFI system I would check the ignition first. I would still change the points for something like a Petronix. I definitely would not just hook the CS system back up without testing it for fuel leaks and replacing all of those soft fuel lines. I think the push button switch for the CS is a good idea, so I would add that. I would not adjust anything on the MFI unless all of the heater hoses and components were in place and working properly.

[Shuie]

Originally Posted by 69911e

Are both cold start solenoids disconnected? The one on the pump('69 only) and the one mounted on the fuel filter?

This is a good point. The systems are different.

Im a hack and my experience with MFI is really limited to a '72T that was basically unmessed with and still had every original component. My car was a lot easier to get running again than something with missing MFI components or a system that may have already been adjusted. There is a lot of really great info from real gurus in old threads on the forum. Look for old posts from guys like targa911S, Grady Clay, Zeke, Early_S_Man, etc.. Those guys really helped me a lot when I had my MFI car.

Good luck.

[matthewb0051]

Thanks for all the input. I had to take off the '69 pump because one of the plungers did not work, so only 5 cylinders getting gas. It now has a '70 pump.

I alluded to this before, the night after the last time it ran the temps dropped to upper 30's and have been the same since. Here in El Paso, we get a 30 degree temp swing every day, from 30's at night to 50/60 degrees in day. So I will wire the cold start and see if that has impact.

Recently replaced: cap, rotor, plugs, Pertronix. Found another Bosch CD and took the Permatune out. But it had ran on the Permatune fine, I just had a bad experience once so wanted to go back to Bosch.

[dicklague]

Originally Posted by matthewb0051

Thanks for all the input. I had to take off the '69 pump because one of the plungers did not work, so only 5 cylinders getting gas. It now has a '70 pump.

I alluded to this before, the night after the last time it ran the temps dropped to upper 30's and have been the same since. Here in El Paso, we get a 30 degree temp swing every day, from 30's at night to 50/60 degrees in day. So I will wire the cold start and see if that has impact.

Recently replaced: cap, rotor, plugs, Pertronix. Found another Bosch CD and took the Permatune out. But it had ran on the Permatune fine, I just had a bad experience once so wanted to go back to Bosch.

Are you sure you have spark??

[boba]

As some have pointed out many problems attributed to MFI are in fact ignition problems. If CMA all checks it is worth checking electrical.
There is a another issue that has been cropping up and manifests itself with hard cold start. The check valve in the fuel filter canister are failing. This allows the system to lose prime. Quick fix (temporary) is to let the pump run for 30-45 sec prior to first crank to refill the system. There is some speculation that ethenal is effecting the seals, they swell and the check valve sticks.

[matthewb0051]

No spark. Now to run that down. Plenty of fuel.

thanks to all. Now any thoughts on spark? As I said from the outset, it ran well and next day nothing. All I did was close engine lid and front trunk lid.

[Shuie]

Is there any chance you accidentally swapped the +/- leads from the Petronix and tried to start the car? It's easy to do. I've done it. It will definitely kill the spark in an otherwise fine running car.

[kwikt 911]

Are you getting the high pitch whistle from the CDI when the key is in the on position? If not check the connection or the CDI is bad.