Unless this happens frequently enough were you say the HE!! with it and wire an inline switch to kill the pump in the fused circuit. Starting my car is like starting an airplane engine sometimes!
Fuel pump off...crank...pressure drops....it fires...fuel pump on...runs happily.

 

It seems like the 'problem' strikes those using high-flow toiletflush valves for injectors. With all the playing/working on my car in its life, I don't remember ever having evena hint of flooding problems when starting it. Except when the LH box started to crash. I suspect that this thread may not be relevant to the mere mortals among us.

 

I think this is correct. When cranking, the injectors are opened for a fixed period (3.6 ms as I recall), so larger injectors = more fuel which the engine does NOT generally need for starting. (It is also corrected for temperature, longer pulse-width at colder temp's, hence problems if the Temp-II sensor is not working properly).

The fix is simple (with a Sharktuner), just change the cranking pulsewidth to a smaller number, e.g. 3.2 or 3.3 ms for 24# injectors. That setting is on Sharktuner's Fuel-Parameters page.

We got caught by this also, after changing injectors to 24#. Of course that provided the opportunity to dismantle and check over every part of the fuel and ignitions systems

Cheers,

 

Guys,
If next time your 928 floods please step back and check things before you try to turn the engine any further and take the fuel pump and injector relays out before you try to start again, if you only take the fuel pump relay out you will still have fuel in the fuel lines and the injectors will just flood the cylinders more.
The Alusil bores can get damaged easily from fuel wash. Imagine the cylinders get flooded and then you keep turning the engine, the extra fuel will splash around the cylinder and wash it dry from oil, with no oil on the cylinder walls your compression will drop down which could also help in making the engine more difficult to start.
Last month I was looking at a 944 S2 engine ( basically half a 928 engine same cylinder walls on our engine), the engine got flooded with fuel and he kept turning the engine trying to start it, the engine was completely stock, no big injectors. They end up taking the engine out and pulled the head, the fuel had made the cylinders dry enough to the point that the rings had gauged the cylinder walls badly, chunks of Alusil missing on all cylinders, I wish I had taken a picture to show you guys, it was horrific.

Also Tony,

check your oil, smell it, if the flooding had caused some fresh fuel to pass the rings you now have fuel mixed with your oil and it will bring the viscosity down, so change the oil.

 

AFAIK, I have original injectors. The car has no mods that would call for larger flow injectors, and I have pretty extensive service records that do not mention any work that would have included new injectors.

The problem has happened to me about four times in the 10 months I've had the car. The first time was probably a month after I got it home. It didn't happen for about a six month stretch until it bit again the other day.

On a side note: I don't understand why many people prefer to pull a relay instead of pulling a fuse. In my car, I can pull a fuse with one finger and a thumb. I have yet to pull a relay at all (I mean, I've tried, but they might as well be welded in). I have seen special Porsche and aftermarket tools for pulling them, but I don't (yet) own one. Namas GT's comment about fuel still in the lines with the pump not running is true, but the working pressure, and thus the delivery, will drop off very fast when cranking without a running pump.

 

I -truly- hate no-start problems.

After a lot of cranking (to clear a flooded engine) you can quickly run the battery down to <10 volts when the starter is engaged. Then you have too much fuel -and- the computers won't wake up.

BTDT²

 

How does one know it is flooded ? and not an ignition issue? Both will make the plugs wet. And the ignition has a relay or two And we all know relays go bad ! You have less juice when cranking on the battery yet when it starts and runs it may see 14 volts to the relays so a degrading relay can be intermittent.

 

In the case of the scenarios mentioned in this thread, it's because removing the fuel pump fuse, or relay, and cranking a few seconds, quickly clears the issue. If it were an ignition problem, removing the source of fuel wouldn't help things.

 

I had similar no start problem on my 84 l-jet. I cleared it with full throttle cranking and had gradual return to function then rough running that finally smoothed out. This works fine on my MB LH-jet as well. It assumes a fully charged battery that can handle 20-30 seconds of continuous cranking. Very cold weather would probably spoil this method as well. I ran a can of Techron through it and it did not misbehave since. I assume a leaking injector may have played a part.
Good luck,
Dave

 

Amen? I have no idea why someone would try to pull a relay instead of a fuse. It's not like the relay will get any power through it with the fuse out. Not to mention fuses are much more designed to be pulled than relays are. And yes, when the fuel pump is not running, as soon as the injectors open, the fuel pressure will drop to nothing. It's like closing the outside water connection in your house, then going and opening the outside one, only a couple of drops come out.

Trying to start a flooded car continually without taking any other action (and further flooding it in the process) is stupid. If you pull the fuel pump fuse and crank, there isn't enough time for any damage to occur before the engine starts. Why would anyone want to press the accelerator to the floor and crank the car for 30 seconds !!! and then have the car run rough when pulling the fuse and starting will have the engine running after 5 seconds?

Dan
'91 928GT S/C 475hp/460lb.ft

 

Wifes 90 had this when the temp II crapped out. Also had a GTS do this. Both were on stock injectors. Wot cranking was the only way to get it to start.