Hello and new at this forum!
I need help. I have an 87 4000S quattro sedan, and for a few days now, seems to hesitate when getting the throttle past half way after warm up and driving, especially if I have to head up a hill for instance.It doesn't seem to start easy after I drive it and park for say 15 minutes, but after a couple hours will start right up when cooled down I noticed a little fuel leaking from the bottom area of the air filter/intake box, towards the front and also from the rear, engine side. It seems a bit worse when not under load, such as idle and can see fuel running out pretty good down there now, like it got a bit worse. Any ideas what is going on? I have a good shop and all the tools, just need some direction. I was thinking I had an air leak, but would that cause such a fuel leak? I checked my hoses etc already.
Any ideas appreciated.
Thanks

 

Seems to me like the only way fuel can leak from the air filter area is if you have a leak in the fuel distributor, mounted in front of the air filter, around the plunger activated by the air sensor.

You should never have ANY fuel leaks from the injection system.

I think there may be room to remove the screws holding it down, and checking to see if there is leakage with the key on, when you lift it up, flexible lines permitting, but, there just may be a solid line or 2 also. Too dark to go look.

Cheers,

George

 

George has summed it up rather well. What I want to add is that there is a small (green) Viton seal that has either broken or wore out. The plunger rests on this seal and stops the fuel from dripping during shut down and prevents vapor luck. You can probably get the o-ring by itself from Audi if not you will need to buy 100 pieces from McMaster and it will probably cost you about the same. The leaking fuel is probably gumming up your mass air flow sensor plate, causing it to stick and giving you drivability problems. Take it out and clean it with Carb and choke cleaner and blow it out with compressed air. Never use WD-40 as it leaves a gummy and sticky residue.

 

Thanks guys, will tear it apart today. Seems like a seal or somthing, since there shouldn't be any fuel leaking anywhere, like you say.

 

This is probably a long shot based on the age of this thread, but can anyone expand on this portion of the post?

"small (green) Viton seal that has either broken or wore out. The plunger rests on this seal and stops the fuel from dripping during shut down and prevents vapor luck?"

I am expereincing a similar leak from the bottom of the airbox. I just rebuilt the fuel distributor and the car idles and runs "like new" but I still have some leaking fuel from the airbox. I'm hoping the fuel is left over in the airbox from the fuel distributor before the rebuild when the car would not start and I had a large amount of fuel leaking.

During the rebuild of my fuel distributor I cannot picture what part of the fuel system the original poster is referring to. My car is an '86 4000 Quattro (5 Cyl) so that may be the difference.

Thanks for any input.