DIYguy

I probably should have mentioned this but I did not see any fuel coming from either vacuum nipple on the FPR or Damper. I suppose I’ll check fuel pressure next.

walfreyydo

I also strongly believe its the FPR or dampener leaking. Fuel pressure check should give you clarity.

The hose leading to your idle air control valve is a vacuum line and part of the vacuum system. There is only one way fuel can get into your vacuum system and thats through the FPR or dampener.

Do not drive the car - you are at a very large risk of an engine fire, hydrolock or worse.

Dr. 914

agree. We install many of them here at our Porsche shop.

Jfrahm

"I probably should have mentioned this"
Yes. But maybe it only leaks when a vacuum is applied. Or you didn't jumper the fuel pump and look then.

Steve Pratel

I had the same situation when pulling the line at the FPR, but when I pulled the line where it enters the Intake manifold, fuel ran out. I had already replaced the FPD where I did see fuel. If the vaccum diaphram is shot, you are pulling raw fuel into the intake while running and once shut off. 944 Online sells a FPR with their brand, not sure what it is.

DIYguy

I just connected a fuel pressure gauge to the end of the fuel rail. I was not able jumper the relay (well when I tried, no fuel pump noise or pressure). So I went ahead and started the car. At idle (which it only did for a few seconds before dying) we were seeing 36 psi. I believe the spec at idle is 29 +/- 3. I was hoping it would be higher to confirm a bad FPR. But being that y'all (southern term) think its the FPR, I will go ahead and replace that. I'm not sure if the damper is shot, too. Maybe when I get the new FPR, I'll pull the vacuum line off the damper just to make sure no fuel is going back thru that line.

Jfrahm

"Bad" often means leaking fuel into the vacuum system, not stuck and causing high or low fuel pressure. The damper can also leak. They may not leak (or not leak much) unless vacuum is applied, I'm not sure anyone has studied the failure modes.
It's dangerous to test with the engine running due to the risk of fire. With a DME relay jumper in place you might see them leak when connected to a hand vacuum pump.

DIYguy

I ordered a new FPR. I also went ahead and removed the intake to get a look underneath and also see if it was full of anything. Lots of oil/dirt near the AOS. Hopefully just the oring seals. I plan to open that up and see if it's clogged. I also found that the hose I say fluid coming from was the one to the top of the AOS, not the idle control valve. So it was probably a mixture of oil and fuel in my air box (oil from the AOS and fuel in the vacuum lines?). Regardless, I see no leaks and the engine reeks of fuel.

I did not order a FP damper yet--looks like I'd go aftermarket here, but I was going to try the FPR first.

DIYguy

I’m putting things back together now. While cleaning the block around the removed AOS I could smell a strong odor of fuel/gas. Thus I was dying to drain the oil just to Check that as well. When we bought the car last month, the oil had been recently changed and from the dipstick it looked clean. I just drained the pan and it definitely mixed with fuel. So my question is how does gas get into the oil?. I can only think of two ways either backwards through the AOS from the intake/vacuum system or can it actually leak by the piston rings if the cylinders get filled with unburned gas? A little help here because I’ve never ever had gas in my oil.

I think I mentioned that I did purchase a new FPR and plan on putting that in as well. Would high fuel pressure cause this gas in the oil? I haven’t diagnosed the damper yet, but that would be next. After that I’m out of ideas.

I just pulled the plugs to help air this puppy out some and I noticed that the front three plugs are all wet, showing signs of richness but the back one closest to the firewall was completely clean and dry. These are all brand new plugs too and I’ve only been run for maybe 15 minutes at idle.

jeyjey

If your FPR or damper gets a split or holed diaphragm then it will leak fuel into the intake. When hot I expect this fuel would not be burned, but would still be vaporised and expelled out the exhaust.

However, when cold maybe it could run down past the piston rings? Still seems unlikely.

The vent line of the AOS appears to be up-stream of the FPR/damper vacuum line, so I don't see how it could enter through the AOS.

DIYguy

I agree. I’m just logically thinking of the only places fuel is connect to anything leading to the crankcase. I have 160+ psi in all four cylinders so rings are not bad. Just never experienced gas in oil.

DSMblue

I think you are definitely doing all the right things. With plugs out, you could take a borescope and check the inside of each chamber to see if there is any residual fuel, although it's not super likely. If any of the injectors are leaky, that could also deposit fuel into the chambers (more than is desired). You may also want to do a leakdown test to verify that valves are sealing well in addition to the rings. If you don't find any fuel in the chambers, once the FPR is replaced and you have everything cleaned and replaced, seems like you should be able to fire it up and enjoy.

DIYguy

I’ve had it all opened up to air out with the oil out as well so I doubt there is any fuel in the cylinders. After talking with a friend a few minutes ago I’m going to pull the fuel rail back off (got most of the fuel system back together yesterday) and check the injectors. While the fuel pressure is slightly high (35 vs 30) I don’t think that is enough to cause the rich issues in having. I suspect the injectors are leaking (at least three are since I had 3 wet plugs and one dry). The seller said they replaced the injectors so it was the last thing I suspected. At least I got a brand new FPR installed now, too.

also, while I can’t edit my first post above (from 3/12) after draining the oil pan I realize that the fuel I said that was in my airbox was, indeed, not that it was mixed oil and fuel from the crank case because it was coming back through the AOS line. I had thought it was fuel because it reached so bad, but it’s mostly oil, but it’s pretty thin. I was glad to get that stuff out of my crank case yesterday, though.

DIYguy

Well well well. I took off the fuel rail with the injectors still mounted to it and placed each in a plastic water bottle. Hit the ignition and 3 sprayed a nice mist while the 4th spewed like a garden hose. I’ve got 4 bottles with maybe a teaspoon of fuel and the fourth is probably a cup of fuel. I disconnected the electrical to see if I could drive it on 3 cylinders but it still leaked bad. So it’s shot. Ordered a new injector and will have to wait for it to come in before I can crank over. Not sure if the FPR was bad or not but I got a spare now if I need one. Maybe it was bad and the pressure blew the injector? Who knows. Hopefully this will do the trick.

jeyjey

Old cars are like that. Sometimes it's as much about the chase as the final repair....

Anyway, well done.