Leaking fuel issue in the engine compartment

[Joeaksa]

I have a 1985 911 thats been back-dated (1973RS style) and a 1992 964 3.6 (Bill Verburgs old engine) stuffed in the back. This was done a good 10+ years ago and its been running great ever since.

Coming home a while back someone waved at me saying "you are leaking fuel out of the right rear of the car!" I turned the corner and pulled into the garage and shut the engine down. Yep, a nice stream of fuel from the right side of the rear followed me home.

Now the car still runs and when I start it its spraying fuel out on the right side. I was thinking that the main fuel line that comes from the fuel filter on the Left Hand side of the car, then runs behind the engine, was the issue. Now that I get in there with a light and start looking, the fuel line appears to be fine, but the metal fitting that its screwed onto appears to be loose.

I am by myself, and the engine is not happy idling, so I cannot run it and see where the fuel is coming from so....

Has anyone ever had an issue like this before? If so where in the world could this leak be coming from?

Thanks!

[Marc Bixen]

Possibly the fuel crossover hose from the R/S fuel damper to the L/S fuel pressure regulator. Just replaced one last week! 930 110 411 04

[boyt911sc]

Joe,

Test run the FP without running the motor. The leak would be easy to locate with a running fuel pump. Do not start the motor until you fix this fuel leak.

Tony

[Joeaksa]

Tony,

I thought that the fuel pump would not run without seeing rotation from the flywheel on the 3.6 engine? Am I wrong?

Mark,

Is this a metal line that hooks up to the flex hose that runs behind the engine?

Thanks Guys!!

[porschedude996]

I’m not familiar with a electrical bypass to turn the FP on, even though I owned a 964 for years. Never really worked on the engine except a distributor belt and a clutch. My SC is easy to jump. There may be a relay easy to jump. And there is always jumping the pump directly. Someone must know here or on the 964 section???

[BoxsterGT]

The 964 Fuel Feed Hose comes from the Filter.....



and runs forward and across to the right side and back to the 4-5-6 Fuel Rail.

Many of the early 3.6 swaps used AN braided hose & fittings.

This hose can be from an unknown source. It is sometimes from China and of poor quality. Only way to know for certain is to peel back the SS braid to identify the source.

Modern Rubber Hose compounds are superior even to the original Porsche factory issue.

The above is what I offer and is E-85 Rated; it is crimped as factory, and expected to last for the lifetime of the vehicle.



For info, please email me: len.cummings @ verizon.net

I am happy to help you.

Len

[Joeaksa]

Len,

Thanks and I am not adverse to changing the long hose out but I have this feeling that the leak is not coming from that hose. Where does the shorter hose in your photo above go?

[Joeaksa]

Originally Posted by Marc Bixen

Possibly the fuel crossover hose from the R/S fuel damper to the L/S fuel pressure regulator. Just replaced one last week! 930 110 411 04

Marc,

Did you have to remove the intake manifold to do this? Things are a bit tight in there, but my A/C compressor is not helping things!! Thanks!

[boyt911sc]

Originally Posted by Joeaksa

Tony,

I thought that the fuel pump would not run without seeing rotation from the flywheel on the 3.6 engine? Am I wrong?

Mark,

Is this a metal line that hooks up to the flex hose that runs behind the engine?

Thanks Guys!!

Joe,

I have been using the factory DME test plan for my ‘89 Carrera 3.2 for years now. There are two (2) ways to run the FP without running the motor.

• Bridge fuses #16 and #17, lower terminals counting from the front bumper.
• Or bridge terminals #30 and #87b at the DME relay socket.

Since you have ‘85 Carrera 3.2 chassis, the above procedures should be applicable. I have no hands on experience with a 3.6 motor. Keep us posted.

Tony

[BoxsterGT]

Good day Joe.

The shorter hose with the 180 is for the Return of a late 911SC with original Green Steel Hardlines.



You can see the Green Steel Return Hardline in the very center of the photo. This is only for the 80-83 SC.

The top photo has a full length Return Hose from the motor to the Tunnel, and is used with most early models that do not have rear hardlines.

Lots of different combinations depending on model & year.

Len

[Joeaksa]

Tony, thanks much for the tip.

Len, email is on the way to you about the hose.

Thx, Joe A

[boyt911sc]

Joe,

Have you located and identified the culprit for the fuel leak in the engine bay? Thanks.

Tony

[Joeaksa]

Tony,

We are fairly sure that its the hose that runs from the fuel filter behind the engine.

Its been raining and cold here the last week so not really a great time to try to remove the hose. Today its going to be almost 60 and no clouds today so the weather is finally on my side but the Dentist has other plans for me this afternoon so its looking like Thursday.

Plus am still waiting on hearing from Len about the hoses.

Thx, Joe A

[Marc Bixen]

Joeaksa,
Sorry, I missed the comment that you had a 3.6 in it, My comment was 3.2 related. I did have a 3.6 last year with a failed F.P. regulator, and fuel was dumping out through the vacuum fitting. Dead center beneath the intake manifold above the breather cover.
On the 3.2 you can replace the crossover by removing the air filter housing, AFM, and heater blower fan assembly. If you need to replace any of the lines or pressure reg on the 3.6, you'll probably have to remove the intake manifold, or a portion of it. Not too bad, you don't have to remove the motor.

[Joeaksa]

Marc,

Thanks and most of the equipment that you mention has been removed. No heater blower and so on in my car, it went by the way-side when we stuffed the 3.6 into the car.

Hmmm, fuel pressure regulator also sounds like its in the same area. Guessing that I will pull the fuel hose that runs behind the engine and check it for leaks, and if its good then will focus on the giblets under the manifold.

Thanks!

[Joeaksa]

Ok, found the time to spend an hour out in the garage today. The afternoon sun helped a bit.

I removed both ends of the main fuel feed hose from the fuel filter across the back of the engine to the manifold. Thats the good part, but someone had placed a wire-tie on the hose in the middle and I could not get that loose, so have to head to the hangar tomorrow for more tools.

That said, I pulled the hose up and moved it around and could not find any abrasion on the sleeve or hose. The hose has a silver barrier/cover on the outside that I assume was put on there by Patrick Motor Sports when they helped with the 3.6 conversion. (I did the grunt work but could not get it to run, so took it down to them and they found the issue (wiring) and finished things up for me)

Am wondering more and more if its what Marc mentioned (fuel crossover hose from the R/S fuel damper to the L/S fuel pressure regulator.) after not finding any obvious issues with the main fuel feed line.

Suggestions? Thanks!

[walt]

I had the same issue as Marc mentions above with a damaged diaphrgm in the FP regulator. Fuel leaked out and ran towards the left side of the engine case. Have you tried to jump the terminals on the FP relay to run the fuel pump. It should be easy to find if it's leaking as bad as you indicated.

[boyt911sc]

Do a pressure test and stop guessing.

Tony

[Joeaksa]

Originally Posted by walt

I had the same issue as Marc mentions above with a damaged diaphrgm in the FP regulator. Fuel leaked out and ran towards the left side of the engine case. Have you tried to jump the terminals on the FP relay to run the fuel pump. It should be easy to find if it's leaking as bad as you indicated.

Walt, thanks and thats the next step.

Tony, if I had everything required to do a pressure test would have done it long ago. Do not have the adapters & fittings needed for metric. If it was for an airplane (SAE) I have that stuff on hand.

Thx, Joe A

[boyt911sc]

Originally Posted by Joeaksa

Walt, thanks and thats the next step.

Tony, if I had everything required to do a pressure test would have done it long ago. Do not have the adapters & fittings needed for metric. If it was for an airplane (SAE) I have that stuff on hand.

Thx, Joe A

Joe,

Put everything back together and test run the FP for a few seconds. This brief test run would pressurize the fuel system and leak some where. If you still could not locate the source of the leak, keep the FP running longer and start your search.

You don’t need anything except a jumper wire between fuse #16 and #17(bottom terminals). This is how I test run the FP for my ‘89 911. Keep us posted.

Tony