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Hi all. so horrily Rich running as started again on the 6!.

2 questions. Should it be easy to blow air (human powered lol) through the fuel retun line back to the tank with fuel in?? My return line is very difficult to blow air back through, it resists a lot, then suddently allows air through then seems to block up again when you try again. I'm suspecting that this is not normal, and sludge may be the culprit.

additionally my fuel tank is vacuming to 3-4 psi when the car is running, and stays that way with engine shut down, until you remove fuel cap. does the tank have an inward vent valve to stop tank vacuming? or is some vacum normal?

I think you probably have a clogged fuel return line mate..

Im thinking the fuel tanks is clogged with slime/sludge. ah well another job to do this weekend!

The tank vent returns eventually to the engine. Disconnect the vent at the filler and try the return line blow back again. If it is free, you have a blocked vent.
If the tank is vacuuming, it obviously cannot back fill with air if it has a blocked vent.

returns to the engine? surely that's an outward vent for over pressure with vapour build up, and goes back to the engine for vapour recovery. are we sayinjg there is only one valve in the tank and its a two way shuttle?

Seems odd to me that inward tank venting would go back to the engine too

Fuel return to tank you have right....and as stated above, blocked.

The vent is routed to the front of the car, and depending on where your car is from, goes to a charcoal can in the right front fender behind the tire and then to the intake hose or just to the intake hose in some other way. Point is to not let fuel vapor get to the atmosphere.

One way old hose fails is to colapse...and it looks like you need to go thru the car and replace all the odd hoses that you wouldn't ordinarily think about replacing.


hth,

thanks guys, but what you are talking about is an outward vent valve, hence why it goes back to the intake to be reclaimed of vapour. The fuel tank must still have an inward vent function to prevent vacuming of the tank. I cant see why Inward venting would be sent back to the engine, it defeats the purpose of inward venting. there must be a valve somewhere on the tank which opens at a particular negative pressure to allow air in.

The hose that goes to the intake betweenthe air filter and AFM takes care of that function. There isn't enough vacum to cause fuel feed issues and gas fumes get sucked into the engine.