86 Carrera 3.2 Fuel Leak

[Toddio]

Hi, Newbie here. Love the forum, first time poster, long time lurker.

After many searches on the subject, and some great advice, I still find myself perplexed by the ails of our beloved '86 M491.
Our car (Blue Velvet) which had not started in over a month is finally running after a relatively simple speed and reference sensor replacement.
For anyone keeping score, I used the BMW equivalent sensors and had no trouble whatsoever installing them. This was my first project since buying the car and with my newfound mechanical courage, I'm looking forward to the next project.

This leads me to my current situation... After starting her up, I noticed an overwhelming raw fuel smell in the cabin and engine bay.
My wife Alison and I went for a mellow drive to get the kinks out. We topped up with fuel and a half litre of oil, since we had had a small oil leak while she sat.
On our return I noticed a trail of fuel following us to our parking space. We killed the engine and coasted to a stop.
I quickly opened the rear deck lid and saw curling white smoke coming from deep within the driver's side cavity.
We stood by with our extinguisher while she cooled off just to be safe.

The next morning I went back and examined the fuel lines which all look to be in good shape.
I turned the ignition to start the fuel pump and immediately heard rushing (more than usual) fuel along with the raw fuel smell.
Nothing was happening in the engine bay that I could detect, but from underneath the car, I observed a steady stream of fuel pouring out from around the left lower valve cover area onto the heat exchangers. This was likely the source of the smoke observed the night earlier. See photo.
I have been searching and reading, and searching more, but have yet to make a diagnosis.

Any thoughts?

Thanks in advance for your replies.

Sincerely,
Todd Connell

[rusnak]

The fuel pressure regulator is in that area right above the speed and ref sensors. One of the fuel lines to it are clamped on. It's possible that this clamp has come off, or one of the fuel lines is loose.

If you have a Bentley manual or are good with Google, you can jumper the socket to the DME relay, run the fuel pump, and find the source of the leak.

[Toddio]

Thanks Rusnak.

I'll try this tonight.

We have the Clymer manual, and the shop manuals, but the Bently manual is coming soon.

Cheers. Todd

[rusnak]

just take a look back there with a mirror and flashlight.

[Toddio]

Will do. Good tip with the mirror. I was secretly dreading the lift, since there's not much room to work with. Thanks again.

[rusnak]

I would start by removing the heater elbow, the heater blower, and maybe the cruise control cable. Then use a small inspection mirror (Sears has nice ones, auto parts stores havr them too) about 2"x3" and look in there with a small, stromg flashlight.

[KTL]

There's three sections of fuel line back there that could be suspect:

1. Tiny hose that rusnak mentioned. This is a poor design by Porsche in that it is a straight section of rubber hose that was bent to make the connection. It should be a pre-formed rubber elbow or should have been a solid connection altogether.

2. There is a hose at the forward area of the engine that joins the regulator and damper to the fuel rails.

3. There is the notorious Y-shaped hose that has plagued the 3.2 engine. This hose has three sections of rubber that go bad, due to the swivel crimp joints. The updated factory hose is fixed hose ends with better crimping. This hose is connected to the rearward ends of the fuel rail and is fed from the fuel filter. This is a hose that should always be rebuilt or replaced if it is original. It's a problem lying in wait

[88911coupe]

In my case it was the line Kevin refers to as #2. Something of a PITA to do but dropping the engine partially helped tremendously. If its the Y line then substantially more things need to be removed. Several have cut up the soft parts so it could be removed piecemeal and then repaired using flexible hoses sourced locally by a shop who is familiar with high pressure systems.

[Toddio]

Thanks Kevin.
I'm going to pull out the parts rusnak suggested too and get in there for a closer look at the areas you've mentioned.

It's very possible that I've damaged or dislodged one of the hoses or connectors while looming the new sensors through the firewall. It wasn't exactly a hack job but wasn't super tidy either given the limited space.

Cheers,
Todd

[Toddio]

Thanks Buck,

I've read about the custom hoses here on the forum and have plans to go this route eventually.
Maybe sooner than later by the looks of it.

Being in a shared garage, there is little hope for me doing a partial drop anytime soon without getting the hairy eyeball, or worse, getting the boot.

I'll try the piecemeal approach first and see what happens.

[BoxsterGT]

Once you find the leaking hose, I can supply the assy needed............



or you can buy the Metric hose from our host,

and the fittings from me to assemble it yourself.......



I also offer braided Metric hose.........



but this must be crimped, as the metal braid prevents the hose clamps from tightening enough to not leak.

Len at Autosportengineering dot com

[burgermeister]

If you didn't replace any / all of those hoses yet, chances are one or more of them have cracks galore (KTL's #1 and #2 were cracked to the reinforcement mesh on my 88), and you just sped the process up by a few months. I'd replace all of them.

[Toddio]

Thanks Len, and Burgermeister.
I'll be back in the pit tomorrow morning to get to it, mirror and light in hand and a wrench friend to provide the laugh track. I've accepted that we could be doing a full replacement now, and have arranged for a spot to do the partial drop if need be.

[CRNT918]

I had #3 a couple of years back. No engine drop, but had to remove the heater blower and the passenger side of the intake manifold. Most of the time it took was trying to snake the old line out without removing anything, but finally gave up and started removing anything in the way.

[Toddio]

A quick update. With the help of a good friend willing to meet up at 5am, we've located the source of the fuel leak. Turns out it was a faulty injector seal on #2. New injector o-rings on the way. While I had an extra set of eyes, we went through all of the fuel lines as well, most of which look suprisingly good for their age, others... not so good. I'll be watching the dodgy ones closely. Thanks guys, for all your advice. Cheers.