Let's play a game; shall we... (what's causing the leak?)

[notny41]

First off, to whomever guesses the root cause of this leak first: I will mail you out the much coveted Hot Wheels 911 Carrera keychain

hw.jpg (721.22 KiB) Viewed 240 times

Here's the background:

My red '86 951 sat on dolleys over the winter in my heated garage. I knew the battery was getting tired and it was still under warranty so in March or so, I yanked it out and swapped it for a new battery and installed it. I can't remember if I started the car when I put it in or not.

A couple months go by and yesterday I decided to get it off the dolleys, start it up, move it to the street, and give it a wash since it had a ton of dust on it from the winter hybernation. After washing it, it started up and ran a little rough and the engine died. I started it again and same thing. It seemed like it wasn't running on all 4 cylinders. I started it again and feathered the throttle and took it for a spin thinking one of the plugs had some carbon on it or something. After going down the road a while it seemed like it was running better and I pulled off and let it idle for a bit - still seemed like it was idling a little lower rpm than usual but after taking off it seemed like it was running ok.

I get home, drive it onto the lift, and put it up. After parking the white one under it, I noticed some wetness on the track of the lift behind the rear tire. I looked up and saw a couple drips hanging down from the gas tank. I thought - well there's why it was idling and running a little rough. I figured that I am dealing with a leak from the fuel pump while the car is running (since there was no puddle on the floor when I took it off the dolleys). I grabbed a paper towel and soaked up the drips and it didn't look like it was dripping any more.

I didn't think much of it (like maybe I should check this later and see if it is still dripping...) duh

Today I come home and felt like I could smell something in the garage so I went back over to the red car and noticed that the wet spot on the lift track had gotten bigger and now I have gas traces on the top of my white car

So I put my oil change catch-bucket under it to find out how much gas is dripping over a period of time (and prevent more gas from landing on my other car). Turns out there isn't much coming out, but it is definitely not just coming out while the car is running.

So.........

Where do you think this leak is coming from? I will investigate and after fixing it, if someone guessed correctly, I will send them a cool little keychain.

Only one guess per person please. I will be using guesses as my starting point for trying to find the source of the leak.

Here are some pictures of the leak:

leak1.jpg (687.36 KiB) Viewed 240 times

leak2.jpg (755.16 KiB) Viewed 240 times

leak onto other car.jpg (815.65 KiB) Viewed 240 times

[944m3]

Nice garage!

My guess is the fuel hose between fuel pump and fuel filter. But you will need to remove the cover or pan covering/protecting those components. I’d say you need to remove the cover regardless to see everything and confirm. Fairly straightforward to do, especially with a lift.

[Tom]

Well if you take the cover off and run the pump (if needed) I'm guessing it will be pretty obvious. Since it only started leaking after running the pump, I'd say 944m3 has the best guess. If it keeps leaking for days, then maybe the little elbow hose from the tank to the pump. There aren't that many options under that cover -- tank fitting, elbow hose, pump, line to filter, fitting/couplers. Though I suppose it's possible to have a crack in the tank right there, or the fuel is coming from above where the filler is, but I'd say that's highly unlikely.

I have what looks like the same plastic trays on my lift and am moderately horrified to hear fuel was able to get below. On my Bendpak, there is a gutter on the inner edge of the runners, so I'd think that would need to fill up and overflow before fluid could get below. I sometimes park my 992 under the 944, so I'm all ears if there is a fluid-spill failure mode I haven't thought of....

[walfreyydo]

As others noted, it appears to be coming from the fuel pump/filter and related hoses connected between them and the tank itself (first thing I would check, and would be a pretty easy fix if so). Your fuel system stays under pressure for a while after shutting off the car, and gravity can cause it to still leak from the gas tank if the hose connections or hoses are loose or cracked, even when not under pressure.

It could also be coming from the connection between the filler neck and tank, dripping down the side of the tank and onto the ground. I would expect that you would have some fuel smells inside the car if that were the case, and this does not seem likely based on your photos and would not leak incessantly - only when fuel is added to the vehicle or under high g forces.

But yeah, you gotta remove the cover and see. Thats a substantial fuel leak and safety hazard so no driving the car in its current state and keep your garage door open for ventilation until its resolved.

This link will give you some insight into how to remove the cover and investigate
https://www.pelicanparts.com/techarticl ... PCrDv9hnuN

[notny41]

Well, the leak is fixed. It ended up being the fuel pump itself. It was a bosch pump so probably the original I am guessing. I replaced the pump and all is good now. Thanks for the ideas/suggestions. I actually have multiple keychains so @944m3 , @walfreyydo , and @Tom if you pm me your mailing addresses, I will get you each out a cute little Porsche Hot Wheels keychain.