Fuel in AAR hose

[flatsixguy]

hi Guys

I was in the process of checking fuel pressures on my 80SC with set of gauges I recently purchased.

not having a switch to makeup a fuel pump relay bypass I disconnected the green/teal connector off the back of the fuel distributor to run the fuel pump for the testing with the iginition.

after the initial System Pressure and Cold control pressure tests which checked out fine according to the Bentley manual, i prceeded to the warm control test with the connector plugged back into the WUR I couldn't get the pressure to rise. Quickly checked with the multimeter for 12V at the connector which reported back with 10.8V.

while having a think about warm fuel pressure issue, I checked the AAR opening to confirm it was fully open as the engine was cold. when I removed the hose to see inside with the aid of a small mirror I had fuel pour out ?? is this bad ?? have I stuffed something ??

[SkiVT]

AAR adds air during cold idle. I think the only way to have fuel in the AAR is from extreme flooding. The AAR has nothing to do with fuel pressure check, cold or warm. Someone else will likely explain the problem with your process as I am not 100% sure. I think disconnecting the green wire is not equivalent to jumping the fuel pump relay.

[tirwin]

The OP probably means disconnecting the green/teal wire that connects to the air pressure plate sensor, not THE green wire that connects to the dizzy. Doing so is fine for the fuel pressure tests. It removes the ground from pin 85 on the FP relay which accomplishes the same thing as jumping 30 and 87a for the tests.

I have never heard of fuel in the AAR before. That is a new one to me! My first thought is there is a leak somewhere. Did it come out of the rubber hose?

[flatsixguy]

Correct tirwin the green connector on the sensor plate sorry for confusion. In relation to the fuel yes came out of the rubber hose end crimped to the aluminium tube. Not the AAR end. It surprised me as I know the AAR works with air. As I kept fuel pump running for 5 minutes to log pressures I guess a fair amount of fuel has leaked in somehow. Any suggestions to what to do next to clear the fuel ??

Definitely won’t try starting it


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[tirwin]

My first thought would be to pull a spark plug and see if the cylinders are flooded.

If they are, that means either the air pressure plate is set incorrectly (causing injectors to spray when they shouldn't) or the injectors are leaking. CSV could also be leaking.

If the cylinders are not flooded then you probably have a leak somewhere else but I can't immediately think of how fuel could get into the AAR hose.

[tirwin]

One other thought. If you jump pins 30 and 87a on the FP relay, you should hear just the hum of the FP running. There should be no fuel going into the cylinders. If you then briefly push up on the pressure plate arm, you will hear and feel a distinctive buzz. That is the sound of the injectors firing. Again, it is very different from the hum of the fuel pump.

If you heard a buzzing sound when you ran the test, then your cylinders are most definitely flooded.

[SkiVT]

The fuel would have to come from number 10 in this diagram, based on your description? Presumably it is getting there from some other, yet to be identified, reason.

911 CIS Primer - Vacuum Lines

[Paulporsche]

AFA your WCP not rising, this could be due to the bimetal strip being burned out. This happened to my WUR and is very common. I replaced mine. Some have rewired theirs. You can check its resistance. You may have to do a search to verify, but I think the resistance should be something like 26 ohms.

[flatsixguy]

Pulled all 6 plugs and manually cranked engine over few times, cylinders were definitely full of fuel. Will I need to replace oil? As the fuel sat in the cylinders over night. I just put the motor back in last week the with new oil, injectors and plugs and fuel filter




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[tirwin]

It sounds like your injectors were firing. Need to figure out why that happened. The injectors fire when the pressure plate arm moves up (opens). That is where I would start. Pressure plate is not properly adjusted or something to do with the FD. Could also be leaking CSV but with that much fuel dumped into the cylinders, that seems unlikely.

I don’t know about the oil. I’ll let other chime in on that. I would try to figure out the other problems first and then let the oil be the last thing to tackle.

[flatsixguy]

I was thinking of pulling all injectors including cold start and placing them in bottles to eliminate the cylinder flooding issue while I try to adjust the pressure plate. Could I have affected the pressure plate with the 3mm adjustment screw ??

[boyt911sc]

Originally Posted by flatsixguy

I was thinking of pulling all injectors including cold start and placing them in bottles to eliminate the cylinder flooding issue while I try to adjust the pressure plate. Could I have affected the pressure plate with the 3mm adjustment screw ??

Flatsix,

You have your fuel mixture setting too RICH thus causing the fuel to be delivered prematurely. I have seen and witnessed fuel and engine oil deposited in the AAR vacuum hoses over the years. You need to evacuate the gasoline in the combustion chambers and replace the contaminated engine oil.

Next is to test the fuel mixture set screw setting. There should be no fuel delivery while the FP is running with the FD plunger down at rest up to 1/4 turn (clockwise). This would be your starting point. The succeeding adjustments should be done only in small increments after you are able to get the engine to idle and run unassisted.

Don’t worry about the “correct fuel mixture” at this point. You have plenty of time to do the fine tuning later on. You primary objective is to get the engine to start and idle unassisted. With a fuel pressure gauge hook up, you will know if your WUR is good or bad. You need a good working WUR first and foremost.

BTW, before you do anything, test the FUEL DISTRIBUTOR. Remove all six (6) fuel injectors and place them in container/s to collect fuel if any and run the FP. There should be no sign of fuel coming out from these fuel lines. Keep us posted.

Tony

[uwanna]

Originally Posted by flatsixguy

Pulled all 6 plugs and manually cranked engine over few times, cylinders were definitely full of fuel. Will I need to replace oil? As the fuel sat in the cylinders over night. I just put the motor back in last week the with new oil, injectors and plugs and fuel filter




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Just drain the small amount of oil/gas from the crankcase, no need the
replace the new oil in the tank if the motor has not been started.

[flatsixguy]

Ok so finally got some time today to address the fuel issue. Pulled all injectors and placed in individual bottles. Adjusted mixture screw to lean out till the injectors stopped spraying with the fuel pump running.

The problem I’m facing now is the warm pressure isn’t rising, results below

1980SC US
WUR 0438140072
Ambient temp 28 degrees Celsius
WUR resistance 16.2ohm
System pressure 4.9 bar
Cold control pressure 2.8 bar (2.6-3.1)@28c
Warm not rising from 2.8

I have check the power connector for 12v and both WUR and AAR have power. Any suggestions will be greatly appreciated



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[flatsixguy]

I also pulled apart the WUR and gave it a clean, nothing looks out of place pin spring etc all good. The previous owner has make it adjustable obviously as a band aid to some other issue in the past. Forgot to mention I have also went though and checked for vacuum leaks and resealed and tested the air box. Pretty confident it’s not leaking





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[boyt911sc]

Originally Posted by flatsixguy

Ok so finally got some time today to address the fuel issue. Pulled all injectors and placed in individual bottles. Adjusted mixture screw to lean out till the injectors stopped spraying with the fuel pump running.

The problem I’m facing now is the warm pressure isn’t rising, results below

1980SC US
WUR 0438140072
Ambient temp 28 degrees Celsius
WUR resistance 16.2ohm
System pressure 4.9 bar
Cold control pressure 2.8 bar (2.6-3.1)@28c
Warm not rising from 2.8

I have check the power connector for 12v and both WUR and AAR have power. Any suggestions will be greatly appreciated



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Please double check your heater resistance (Ohms). It should not read 16.2 Ohms @ 28°C for WUR-072 unless there is something wrong with it. There is a simple test to determine your WCP (warm control pressure). Put the WUR in a pre-heated oven @ 175~180°F for 10 mins. Immediately install the WUR back to the car and run the FP with the pressure gauge installed. The pressure reading is the WCP. Keep us posted.

Tony