StevenL5975

Hello,

well yes, I could need your help concerning my S4 1987 NA FC. Its currently parked as the engine is due for a rebuild (coolant and oil seal blown btw). I removed the upper intake manifold and both fuel rails leaving the ratnests fuel supply open (the one that feeds the fuel from the ratnest to the primary rail and the return from the secondary rail). I did that before on a 86 NA and 91 T2 and 96 Efini FD, never had any trouble. There was no pressure inside and as long as the pump isn't startet there should be no problem.

So today after half a month I parked my other car beside the FC and I notice a heavy fuel smell. So I check things out and I find a huge puddle of fuel under the rear passenger side tire. Sure enough its dripping from the exhaust muffler down. I pop the hood and pull the EGI and IGN fuses to prevent the pump from priming, and put in the key to see how much fuel is left in the tank. Sure enough its empty ... I parked it with 3/4 of a tank left a few weeks ago.


Things I checked already:
Jack the rear end up and check for leaks. The only thing I can see is that its dripping from somewhere behind the heatshield.
Tank itself is dry on the bottom. (underside)
From the trunk bottom (removing access panels) all lines from the pump side and the rubber connector from the filler neck, and a smaller tube beneath it are dry (as far as I can see/feel from these panels)
I plugged both feed and return lines with fuel hose so the feed temporarely now goes directly to return. Leaking in the rear stopped

I don't get that, maybe someone can help me out here I am at a loss.

Best regards
Steven

texFCturboII

iTrader: (17)

You somehow created a siphon?

StevenL5975

I don't know, the tank is almost empty (reserve). The fuel filler is on top of the tank (right side of course) so is that small vent tube. The only thing that could still be emerged in fuel is the fuel pump and maybe the return line (I don't think so). There is not a lot of room for leaks. Or of course the tank itself, but then I would expect to find the fuel running down the tank itself somewhere. It effectively does drip onto the exhaust muffler near the flange where it connects to the Y pipe.

I thought you guys might have an idea, or had the same problem once. I lost over 13 gallons of fuel in 2 weeks, thats almost a complete tank. I can see the puddle and the trace under the car, it only drips from said spot.

texFCturboII

iTrader: (17)

That's weird man, I wish I had an answer.

StevenL5975

Yeah it is

I m gonna drop the tank from my 86 FC shell and see whats behind it. Maybe that can give me a hint. Then proceed to the other one if I find something.

I was like, *whaaat ? You kidding me* when I saw that puddle. Smelled badly too ...

RotaryEvolution

iTrader: (30)

i always plug the feed and return lines and stuff them out of the way near the brake MC.

no idea how it got into your exhaust except maybe it was trickling into the open primary injector ports, through the engine, into the exhaust and coming out the mufflers.

so be prepared for a really flooded engine.

StevenL5975

That would mean that my exhaust will be filled with fuel. But well yes, I had the ratnest fuel feed line open and it wasn't far away from the LIM, even when I stuffed it with towels. Technically that might be possible but that sounds like an adventure

I will check that out. My first reasonable Idea was that the fuel leakes from the feed line on the tank, when I realized that the fuel lines are on the other side of the car, I felt stupid That puddle is not supposed to be at this location, I will make a pic when the snow melts, so you see what Im talking about.

Btw. Rotary Evolution, did you get my PM ?

Steven

misterstyx69

iTrader: (142)

Is the leak at the tank or at the front of the car?
Rear of car: the hoses attach to the car and run down to the frame.

j9fd3s

iTrader: (3)

i've been thinking about this, and maybe they taught us in school or something, but i would have plugged the hoses with a bolt or connected them together or something, wouldn't have left them open.

StevenL5975

Yes, its at the rear of the car behind the passenger side tire. So the drops come from the respective muffler between the flange and the start of the canister. I can't see it that well. The hoses for the fuel pump are at the drivers side, and go down the drivers side frame rail.

You are right, should have connected them together, thats what I did after I found the puddle. Just to be sure, and oh wonder the leak stopped. But it doesn't make sense as the leak is in the rear and there is a very very slight slope towards the front, so technically if its leaking it should have leaked up front. I checked the hoses after I removed the rails and they were not dripping so I left em. (Was already dark and cold, and started snowing)

RotaryEvolution

iTrader: (30)

resent the PM, let me know if you are having difficulty getting the messages.

clokker

iTrader: (2)

This step seems like a diversion, just get right on the tank that's actually leaking.

StevenL5975

OMG if someone sees me dropping a tank on a public parking I might end up in jail
Need to do that in a night and fog action Will do it this weekend