Question for the MFI people out there...

[bbthomson]

Thanks Warren...I knew something wasn't quite right.

Stay tuned.

Brent

[bbthomson]

Hey Guys,

I did as Warren suggested and it does not make a sound. Is it safe to say that the starter is dead? Do they normally go this fast?

Thanks,

Brent

[Grady Clay]

Brent,

The easiest solution, and not very expensive, is to simply replace the starter with a Bosch rebuilt unit. Yes, you can rebuild yours yourself. Certainly for less money and possible better than a “factory” rebuild. That said, I usually have better things to do with my time.

Like solving the MFI issues.

Best,
Grady

[bbthomson]

I found a starter locally and have already picked it up. While I was out, my gauges arrived back from NH Speedo...This is a good day!

There will be some wrenching tonight. I will let you know how it goes.

Thanks!!!

Brent

[bbthomson]

OK - I got the car going.

The new starter is in and working well.

New problem:..?

I started the car and ran it in my garage for a minute or two...I went around to the back of the car as it was starting to smoke quite a bit.

This is what I found...Gas was spraying from cylinder # 1 from the injection line coming off of the MFI pump. I could also see fuel pooling at the back of the engine. I immediately turned off the car. (I have attached a pic to help illustrate exactly what I saw.) The gas at the back of the engine did have some oil mixed in but it appeared to be more gas than oil.

There were no oil drips but some gas drips underneath my car.

This may have been happening before but I cannot be certain.

Thoughts?...Thanks,

Brent

[Zeke]

Originally posted by bbthomson


Thoughts?...Thanks,

Brent

Thoughts? Did you wrench tighten those injectors? Did you use new sealing rings? Once a ring has been compressed, it won't compress a 2nd time. This is true on your banjo fittings on your brakes and your gas tank, too.

[Grady Clay]

STOP

Push the 911 outside and get a big fire extinguisher. You don’t want to burn down your 911, garage or house! !! !!! !!!!

Once you have the fuel leak repaired, we can get back to the real issue – MFI tuning.

Best,
Grady

[bbthomson]

Thanks Milt & Grady.

Grady - I did push the car outside before starting and yes I have several fire extinguishers nearby.

I will start a fresh post for this specific problem.

Thanks,

Brent

[orange911]

Brent,

Please update us with the progress. I am hoping for a good ending here.

[bbthomson]

Hey Olin,

Here is an update - Thanks for asking.

I had new hope but that has now dissapeared. I deduced the fuel leak problem down to one of 3 parts (injector, crush washer and line) So I replaced them all.

I still have the same problem...gas leaking out of cylinder # 3 from just under the red engine cover.

I will post on technical forum again but at this point, I am at a complete loss.

I need to get some miles on this before the winter.

Brent (Super frustrated)

[TargaT]

Hey Brent, where are located at? I'm in Burlington Ontario and also working through a number of issues on my MFI car.

Joe

[Grady Clay]

Brent,

I just went back and read trough a few of the prior posts (particularly page 3). It occurs to me that we may have a recurring hydraulic situation on #3 cylinder. If a #3 valve does not open, the intake can fill with gas (and some oil) and leak out the throttle shaft.

While you have the situation where there is a leak at #3, take a flashlight and mirror and inspect down #3 intake with the throttle held wide open. What do you see? Turn the engine CW by hand. Does the intake valve open and close? If you turn the engine on the starter (ignition disconnected) does the #3 pull a vacuum under your hand if placed over the stack?

I deeply sympathize with your frustration. Hang in there. This WILL get solved.

Best,
Grady

[bbthomson]

Hey Joe - Unfortunately we are a good 6 hours away from each other - I am in Ottawa.

Grady - Your advice sounds logical and eases my frustration. (It is a hobby after all...)

Two questions:

1) How do I turn the engine on the starter with the ignition disconnected? I think I am missing something here.

2) Typically, what could cause this hydraulic lock?

Thanks,

Brent

[bkreigsr]

remove the rotor, or just pull the coil wire

[Grady Clay]

Brent,

NO, NO, NO – don’t pull the coil wire or remove the rotor, you will have sparks everywhere (fire danger) and can damage some of the high voltage components (“coil” transformer, cap).

To crank the engine without spark, simply pull the points connector at the distributor. Be sure to wrap some tape around it so it can’t accidentally contact ground and cause a spark. Of course the sure way is to unplug the CDI box however it is sometimes difficult to re-install that plug. There is a single fast-on connection for CDI power near the CDI box.

“what could cause this hydraulic lock?”

Actually lots of things. I was studying your image of the #2 & #3 exhaust rockers and couldn’t see the right end of the #3 exhaust rocker arm shaft. From that camera angle I don’t think I should be able to see it but it occurred to me that the shaft could have slid all the way to the left (stopped by the tin) and not be supporting the rocker. This would prevent the exhaust valve from ever opening. All the fuel (from the cold start and the MFI pump) and some oil would remain in the cylinder. In the intake stroke the gas and oil would be forced up the intake and past the butterfly with some being forced out the shaft or at a gasket.

You should be able to see this by simply looking down the intake with a mirror and flashlight.

Of course there are other possibilities. The #3 cylinder is the shortest path for the cold start gasoline. A slight leak at the solenoid valve could find its way solely (or predominantly) to the #3 cylinder. In all your testing, has the electric pump run for extended times while the engine isn’t running?

Still another (very remote) possibility is an internal malfunction in the MFI pump (loose clamp for tooth segment) where #3 is full rich. This would be VERY unlikely.

Take more pictures at every opportunity. Perhaps we may see something that isn’t apparent to you.

Hang in there and best wishes, think of this as a fun educational exercise
Grady

[bbthomson]

Thanks Grady.

I will work on it tonight and will report back in the morning with my findings. I will take lots of pictures as well.

Brent

[bbthomson]

Hey Guys,

I did as Grady suggested.

I removed the air filter housing and looked down the stack to inspect the intake valve.

I was unable to get a proper view using a flashlight and mirror...it just was not clear and from what I could see. I also want to note that I could barely turn the engine manually. Based on the poor view and not being able to manually turn the engine, I decided to continue and follow Grady's additional suggestions.

I disconnected the CDI box and turned the engine over on the starter. I was alone so I video taped my synchrometer that was placed in the stack while I cranked the engine using the starter. There was significant movement.

I also removed the top valve cover to inspect. Once I had cranked the motor using the starter, it was easy for me to manually turn the engine by hand. All the rockers appear to be in place.

Here are some pictures;






Thoughts? Thanks,

Brent

[bbthomson]

Hello All,

Does anyone have any thoughts on this...should I get better pictures? Any ideas on what I should/could do next?

Thanks,

Brent

[BURN-BROS]

Pull the injector and inspect the sealing surface between the line and the injector. over-torqing can result in a crack at that location.

[Grady Clay]

Brent,

Well … so much for that idea. Back to basics.

What year did your 911 engine start as?

Do you have the clamp between the MFI pipes for 1-2-3 cylinders (the one between the MFI pump and the left stacks)? Any chance there could be a leak under that clamp and then the gas traveling along the #3 pipe?

If there is a leak at the MFI pump, I would think it would end up off the forward edge of the fan shroud nearer the case than the #3 injection nozzle.

Have you tried swapping the #3 injector with #4 and see if the leak follows?

Best,
Grady