Porsche 911sc Won't Start after Fuel Flood

[thunderroad]

Greetings all. Inadvertently (and quite stupidly) fuel flooded the engine of my Porsche 911sc after installing new fuel filter and fuel accumulator earlier this week. Now we have removed all of the plugs and believe we have cleared up the flood. Have spark again and engine cranks but won't fire up.

I have been advised to try two things. First, attempt a "pop start" or "hill start" by placing car on a hill in second gear and popping the clutch with the engine turning. Second, if the above doesn't work, lift the air flow sensor with key on and bleed the lines. I'm a little leery about lifting the air flow sensor because I would hate to reflood the engine.

I would much appreciate any advice. Beautiful fall driving this weekend if I can get engine to turn!

Many thanks!

[Joe Bob]

Ether/quick start shot into the intake. If that doesn't do it you have other issues.

[thunderroad]

Originally Posted by Joe Bob

Ether/quick start shot into the intake. If that doesn't do it you have other issues.

Thanks. Seems like other pelicaners have advise against spraying ether into the intake for fear of causing other problems? Any concern here?

I appreciate your help.

[Joe Bob]

Nope....if you don't have a pop off valve in the air box you should have....

[euro911sc]

Are you actually getting fuel? You said you have spark.

[boyt911sc]

Originally Posted by thunderroad

Greetings all. Inadvertently (and quite stupidly) fuel flooded the engine of my Porsche 911sc after installing new fuel filter and fuel accumulator earlier this week. Now we have removed all of the plugs and believe we have cleared up the flood. Have spark again and engine cranks but won't fire up.

I have been advised to try two things. First, attempt a "pop start" or "hill start" by placing car on a hill in second gear and popping the clutch with the engine turning. Second, if the above doesn't work, lift the air flow sensor with key on and bleed the lines. I'm a little leery about lifting the air flow sensor because I would hate to reflood the engine.

I would much appreciate any advice. Beautiful fall driving this weekend if I can get engine to turn!

Many thanks!

Thunderroad,

How were you able to flood the engine by replacing the fuel filter and fuel accumulator? This does not make sense to me and I've been tinkering CIS for awhile. Maybe we could learn something from your experience. Thanks.

Tony

[thunderroad]

Originally Posted by boyt911sc

Thunderroad,

How were you able to flood the engine by replacing the fuel filter and fuel accumulator? This does not make sense to me and I've been tinkering CIS for awhile. Maybe we could learn something from your experience. Thanks.

Tony

Tony: first off I have read as many of your posts as I can find for many years. Thanks for chiming in. I have great respect for you and you have saved me many times in the past. Now the embarrassing part of the story...

I hired a mechanically inclined friend of mine to install the new fuel filter and accumulator in my home garage. Before I got home, he had removed the old filter and accumulator as well as the CDI. After installing the new filter and accumulator, we attempted to start the engine and got crank but no start. We then also lifted the air flow sensor during this process. My friend and I then observed that there was a blown fuse leading to the CDI. My friend then confessed that he accidentally caused a spark before removing the CDI, which ultimately led him to disconnect the battery. In sum we were obviously cranking the engine with no spark, which led to the fuel flooding. Fuel was in dripping from the exhaust. Quite an event.

A different friend has now assisted in removing the spark plugs and installing the new fuse and confirmed spark.

What to do now?

Thanks for your help.

[T77911S]

tony, that was my big Q.
did you clean the plugs or replace the plugs.

have you pulled the plugs again to see if they are fouled from too much fuel and cranking.
how are you checking for spark? put a spare plug on a plug wire and ground it to check it.

I would replace the plugs, let it sit overnight and crank it the next day. if it started ok before, it should start up now.

[euro911sc]

Air, fuel, spark. If you have all 3 something should be happening. After those, the only thing I can think of is timing... but you didn't touch that...

Are you sure you have the three magic ingredients working?

[Bob Kontak]

I have done this.

I pulled the exhaust and poured out a half gallon after cranking engine with plugs out. Be careful.

Beer was involved.

The early years......

[boyt911sc]

Originally Posted by thunderroad

Tony: first off I have read as many of your posts as I can find for many years. Thanks for chiming in. I have great respect for you and you have saved me many times in the past. Now the embarrassing part of the story...

I hired a mechanically inclined friend of mine to install the new fuel filter and accumulator in my home garage. Before I got home, he had removed the old filter and accumulator as well as the CDI. After installing the new filter and accumulator, we attempted to start the engine and got crank but no start. We then also lifted the air flow sensor during this process. My friend and I then observed that there was a blown fuse leading to the CDI. My friend then confessed that he accidentally caused a spark before removing the CDI, which ultimately led him to disconnect the battery. In sum we were obviously cranking the engine with no spark, which led to the fuel flooding. Fuel was in dripping from the exhaust. Quite an event.

A different friend has now assisted in removing the spark plugs and installing the new fuse and confirmed spark.

What to do now?

Thanks for your help.

Thunderroad,

We all make mistakes and learn from this experience. Nothing to be ashamed off. Sometimes, sharing this unfortunate bad experiences help others to be aware of the problem/s lurking ahead of us.

If you have a CIS pressure gauge install it and measure your cold control and system fuel pressures without running the engine. Just the fuel pump and your system will be primed and ready for start up. There is no need to use starting fluid because you are dealing with a fuel injection system particularly a CIS. There is sufficient fuel delivered by the 7 fuel injectors during a cold start. And this is one of the basic tests you have to perform before attempting to start the engine during troubleshooting.

Make sure you have a fully charged battery and able to crank the engine fast and strong. Three (3) important things to check and verify:
a). Ignition (spark, timing, etc.).
b). Sufficient fuel pressure for the injectors to form a uniform spray patterns.
c). Absence of significant air leak in the system.

You should have no problem getting a CIS motor to start and run. Your success in dealing with CIS is all about preparation and verifications of conditions. Keep us posted.

Tony

[thunderroad]

Thanks all. I am back after a few hours of testing with my friend who is much more mechanically inclined than me. He has confirmed that we in fact have no spark. The good news is that I know we have a working CDI and a working coil because I have two of each. Still no spark. I also cannot say definitively that either CDI "hums."

Any thoughts?

I very much appreciate all of your help.

[thunderroad]

I am really perplexed which is not surprising. Does anyone have a wiring diagram for a 1983 911SC for the CDI. I think perhaps we should trace and test the wires.

Thanks

[timmy2]

CDI power is from the front of the car, not the back. The fuse at the back is on the same circuit after the CDI power is connected upstream.
Check fuse 11 or 12 in the front trunk to see if either is blown.

[T77911S]

Originally Posted by thunderroad

Thanks all. I am back after a few hours of testing with my friend who is much more mechanically inclined than me. He has confirmed that we in fact have no spark. The good news is that I know we have a working CDI and a working coil because I have two of each. Still no spark. I also cannot say definitively that either CDI "hums."

Any thoughts?

I very much appreciate all of your help.

not sure how you know for sure you have a god CD and coil if you don't have spark?

check the fuse timmy suggested.

if fuse is good verify power to the CD at the connector

[thunderroad]

Good morning and thanks for your help. I’m confident CDI and Coil are working because I have backups for each. We have swapped them both in and out and still no spark. I will check the fuse Timmy suggested shortly. Thanks.

[SalParadise]

I have done this as well.

My advice - change your oil ASAP. A lot may have gotten past the rings.

[thunderroad]

Okay. Checked fuses 11 and 12. They checked out okay. At this point, I am WAY out over my ski's. Time to call in my mechanic I guess. Hopefully get it back in time for some fall driving. Thanks again all.

Nick

[T77911S]

check for power at the connector to the CD.