Flooded 996 due to very short trip
02-04-2009, 09:03 PM
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Flooded 996 due to very short trip
I just had an interesting problem with my 2001 996 C2. On Saturday I moved the 996 out of the garage so that I could have room to do some work on the 944. I just put it out in the driveway. When I completed the work, I moved it back in (about 20').
On Monday when I tried to start it I just got a whirring sound from the rear end. The battery looked a little low so I put it on a trickle charger for the morrow. The battery had a good charge but when I tried to start it, the same whirring. I spent the evening searching Rennlist and Renntech. I found lots of suggestions so I did some checking and determined that yes the DME and fuel pump relays and fuses were good, the fuel pump seemed to be working (I could hear it spool up when you turned on the ignition, and I confirmed that she was turning over at a good clip, so the starter was OK.
I was running out of things to check, and was wondering if the DME had gone crazy or if I had lost a critical sensor. Or possibly a fuel hose had split inside the tank. I went by the dealer today and spoke to Gary at Barrier Porsche. I gave him the list of symptoms, including the history of the two short moves, and he said "Oh, it's flooded. Happens all the time."
He said that what happened is that the fuel dumped in the cold engine just collects in the cylinder, and washes the oil from the cylinder walls, which wipes out the compression. The horizontally opposed cylinders don't tend to drain. The cure is to floor the throttle (just like on a flooded carbureted car), which on startup tells the DME to shut off the fuel. He said crank it for 30 seconds and it should start up with a big cloud of smoke. "And if it doesn't" I asked. "Tow it in and we'll pull the plugs and squirt oil into them". I knew about that one for building compression.
So I went home and tried it. The first 30 seconds didn't do it, nor did the second 30 seconds (I let the starter cool between attempts). I got out and smelled the exahust area- lots of gas fumes. Then I pulled the fuse for the fuel pump, and it started to stutter and stumble on the fumes. I put the fuse back in and it started with the promised large cloud of smoke. Problem solved.
I should add that the engine turning over without compression is very distinctive, and I now realize that it sounds just like a sailboat diesel with the decompression lever flipped on.
I thought I should put up a detailed account of this because I found only one reference to this sort of thing in the archives. It's pretty subtle. My thanks to Gary at Barrier Porsche in Bellevue for cluing me in.
Bill
On Monday when I tried to start it I just got a whirring sound from the rear end. The battery looked a little low so I put it on a trickle charger for the morrow. The battery had a good charge but when I tried to start it, the same whirring. I spent the evening searching Rennlist and Renntech. I found lots of suggestions so I did some checking and determined that yes the DME and fuel pump relays and fuses were good, the fuel pump seemed to be working (I could hear it spool up when you turned on the ignition, and I confirmed that she was turning over at a good clip, so the starter was OK.
I was running out of things to check, and was wondering if the DME had gone crazy or if I had lost a critical sensor. Or possibly a fuel hose had split inside the tank. I went by the dealer today and spoke to Gary at Barrier Porsche. I gave him the list of symptoms, including the history of the two short moves, and he said "Oh, it's flooded. Happens all the time."
He said that what happened is that the fuel dumped in the cold engine just collects in the cylinder, and washes the oil from the cylinder walls, which wipes out the compression. The horizontally opposed cylinders don't tend to drain. The cure is to floor the throttle (just like on a flooded carbureted car), which on startup tells the DME to shut off the fuel. He said crank it for 30 seconds and it should start up with a big cloud of smoke. "And if it doesn't" I asked. "Tow it in and we'll pull the plugs and squirt oil into them". I knew about that one for building compression.
So I went home and tried it. The first 30 seconds didn't do it, nor did the second 30 seconds (I let the starter cool between attempts). I got out and smelled the exahust area- lots of gas fumes. Then I pulled the fuse for the fuel pump, and it started to stutter and stumble on the fumes. I put the fuse back in and it started with the promised large cloud of smoke. Problem solved.
I should add that the engine turning over without compression is very distinctive, and I now realize that it sounds just like a sailboat diesel with the decompression lever flipped on.
I thought I should put up a detailed account of this because I found only one reference to this sort of thing in the archives. It's pretty subtle. My thanks to Gary at Barrier Porsche in Bellevue for cluing me in.
Bill
02-04-2009, 11:23 PM
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Thanks Bill. I had this happen to my BMW which resulted in misfiring in one of my cylinders and a CEL. It came from not running the car long enough. I will let my cars run long enough to get the "idle drop" now even if I only need it to run for a short minute.
02-05-2009, 02:20 AM
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Believe it. No compression, definitely. It just spins along merrily, with a smooth whir. Very little drain on the battery. When the gas was blown out you could feel it start to bog down just like a regular start, as the oil film was restored and a better seal was obtained. When hand starting a Yanmar three cylinder sailboat diesel it runs smoothly, with constant effort until you pop the decompression lever, at which point the effort now becomes cyclical and much harder. The fallback position of squirting oil in the plug holes to gain compression is certainly consistent with his explanation. And this is a classic technique for a compression test to test for worn rings.
But hey, I don't know all the answers. Do you have an alternative theory to propose that fits the experimental facts?
But hey, I don't know all the answers. Do you have an alternative theory to propose that fits the experimental facts?
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02-05-2009, 11:25 AM
#8
Three Wheelin'
After you pulled the fuel pump fuse, did you turn it over with wide open throtte while the fuse was out?
After you replaced the fuse, were you using WOT for the start?
After you replaced the fuse, were you using WOT for the start?
02-05-2009, 11:55 AM
#9
Burning Brakes
Though OBVIOUSLY a TON more work, I would think it be better for the rings & cylinder walls to just go ahead and squirt some oil in each plug hole, rather than stroke them dry, no? Or is it inconsequential wear for such a short period?
02-05-2009, 12:50 PM
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Yes to both questions. Once it started to catch (with the fuse in) I backed off to give it some fuel, and then it started.
02-05-2009, 12:56 PM
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Clearly it would be a huge amount of work. Easy on the 944 but not on this one. And in an ideal situation, that would be the safest course of action. I have no way to judge how damaging this procedure might be. The dealer didn't seem very concerned. I'm surprised this sort of thing isn't mentioned in the owners manual (or if it is I missed it somehow).
02-05-2009, 04:14 PM
#13
Race Director
Horse feathers! No compression cause gas washed all oil off all cylinders....
I just had an interesting problem with my 2001 996 C2. On Saturday I moved the 996 out of the garage so that I could have room to do some work on the 944. I just put it out in the driveway. When I completed the work, I moved it back in (about 20').
On Monday when I tried to start it I just got a whirring sound from the rear end. The battery looked a little low so I put it on a trickle charger for the morrow. The battery had a good charge but when I tried to start it, the same whirring. I spent the evening searching Rennlist and Renntech. I found lots of suggestions so I did some checking and determined that yes the DME and fuel pump relays and fuses were good, the fuel pump seemed to be working (I could hear it spool up when you turned on the ignition, and I confirmed that she was turning over at a good clip, so the starter was OK.
I was running out of things to check, and was wondering if the DME had gone crazy or if I had lost a critical sensor. Or possibly a fuel hose had split inside the tank. I went by the dealer today and spoke to Gary at Barrier Porsche. I gave him the list of symptoms, including the history of the two short moves, and he said "Oh, it's flooded. Happens all the time."
He said that what happened is that the fuel dumped in the cold engine just collects in the cylinder, and washes the oil from the cylinder walls, which wipes out the compression. The horizontally opposed cylinders don't tend to drain. The cure is to floor the throttle (just like on a flooded carbureted car), which on startup tells the DME to shut off the fuel. He said crank it for 30 seconds and it should start up with a big cloud of smoke. "And if it doesn't" I asked. "Tow it in and we'll pull the plugs and squirt oil into them". I knew about that one for building compression.
So I went home and tried it. The first 30 seconds didn't do it, nor did the second 30 seconds (I let the starter cool between attempts). I got out and smelled the exahust area- lots of gas fumes. Then I pulled the fuse for the fuel pump, and it started to stutter and stumble on the fumes. I put the fuse back in and it started with the promised large cloud of smoke. Problem solved.
I should add that the engine turning over without compression is very distinctive, and I now realize that it sounds just like a sailboat diesel with the decompression lever flipped on.
I thought I should put up a detailed account of this because I found only one reference to this sort of thing in the archives. It's pretty subtle. My thanks to Gary at Barrier Porsche in Bellevue for cluing me in.
Bill
On Monday when I tried to start it I just got a whirring sound from the rear end. The battery looked a little low so I put it on a trickle charger for the morrow. The battery had a good charge but when I tried to start it, the same whirring. I spent the evening searching Rennlist and Renntech. I found lots of suggestions so I did some checking and determined that yes the DME and fuel pump relays and fuses were good, the fuel pump seemed to be working (I could hear it spool up when you turned on the ignition, and I confirmed that she was turning over at a good clip, so the starter was OK.
I was running out of things to check, and was wondering if the DME had gone crazy or if I had lost a critical sensor. Or possibly a fuel hose had split inside the tank. I went by the dealer today and spoke to Gary at Barrier Porsche. I gave him the list of symptoms, including the history of the two short moves, and he said "Oh, it's flooded. Happens all the time."
He said that what happened is that the fuel dumped in the cold engine just collects in the cylinder, and washes the oil from the cylinder walls, which wipes out the compression. The horizontally opposed cylinders don't tend to drain. The cure is to floor the throttle (just like on a flooded carbureted car), which on startup tells the DME to shut off the fuel. He said crank it for 30 seconds and it should start up with a big cloud of smoke. "And if it doesn't" I asked. "Tow it in and we'll pull the plugs and squirt oil into them". I knew about that one for building compression.
So I went home and tried it. The first 30 seconds didn't do it, nor did the second 30 seconds (I let the starter cool between attempts). I got out and smelled the exahust area- lots of gas fumes. Then I pulled the fuse for the fuel pump, and it started to stutter and stumble on the fumes. I put the fuse back in and it started with the promised large cloud of smoke. Problem solved.
I should add that the engine turning over without compression is very distinctive, and I now realize that it sounds just like a sailboat diesel with the decompression lever flipped on.
I thought I should put up a detailed account of this because I found only one reference to this sort of thing in the archives. It's pretty subtle. My thanks to Gary at Barrier Porsche in Bellevue for cluing me in.
Bill
Engine not firing because of gas washed cylinders/ Not likely, not at all.
Also, remind dealership these engines have oil jets that continuously squirt oil into underside of piston and piston/rings/cylinder walls receive plently of oil.
Noise with no engine fire might actually be due to starter not engaging flywheel which can arise if battery low or ignition switch on way out. IOWs, the engine wasn't actually being cranked.
Even a normal properly functioning engine upon cold start will smell strongly of gasoline. This is why these engines have secondary air injection system to inject air after combustion chambers into exhaust ports to help burn this gasoline and heat up converters quicker so they can begin their own processing of these hydrocarbons. But early on some gas will make it all the way through the exhaust.
Sincerely,
Macster.
02-05-2009, 04:22 PM
#14
Race Car
You'll see numerous old posts by me explaining why this happens and that it is common for ALL fuel injected cars. When your car is cold it runs rich. If you shut it down rich, it can be hard or impossible to start due to wet plugs. It has absolutely nothing to do with compression. Some people just like sounding smart by making up things to explain what they don't know. 
02-05-2009, 06:58 PM
#15
Race Director
Horse feathers! No properly functioning modern fuel injected...
You'll see numerous old posts by me explaining why this happens and that it is common for ALL fuel injected cars. When your car is cold it runs rich. If you shut it down rich, it can be hard or impossible to start due to wet plugs. It has absolutely nothing to do with compression. Some people just like sounding smart by making up things to explain what they don't know.
Modern cars with their engines and engine controllers and high powered ignition systems have the power to properly fuel and spark an engine that it can run just fine in even exceptional situations.
For example; My car has gone through 2 AOSs and each time the car ended up smoking like the worst chimmy in the rust belt. If the engine could run with oil wetted plugs I think it'll run with a bit of gas on them, if they actually end up with any on them in the first place.
No doubt some have come across a flooded car but barring some failing of the coolant temp sensor which causes the Ecu to inject way too much fuel for the engine's temperature or one or more leaking injectors no way and I note both of these conditions violate my condition that the engine is properly funcitioning.
Sorry, I just don't buy it.
If insist it happens then I'm afraid we're going to have to agree to disagree.
Sincerely,
Macster.