I have been driving my 2056 with D-jet everyday. I am putting about 2400 miles a month on this engine. IT IS FREEKIN AWESOME ! I am very happy with the engine temps, the oil pressure has been right on or just a bit under after long 1hour spirit driving. BUT......

Couple of days ago I heard a loud bang in the front of the car. I pulled over and looked around a bit. Discoverd the sound was the fuel tank, mostly empty had sucked the side of the tank inward a bit. It popped back out when I removed the gas tank lid. I also noticed that the tank is always way pressurized every time I get gas, no matter how full or empty.



So I pulled the tiny rubber hose off of the charcoal cannistor (the one to the fuel tank) and put it into the plastic drain hose that exits from the bottom of the car, so no fumes in the cabin. Then I took it back on the road and really opened it up. It ran SOOO much better

3 days later I have noticed most of the bucking at speed is gone, engine temps are 20 % less then they ewre. I can drive 1 hour at 4k and the needle is not even getting to the E in "TEMP"

Oil pressure is now staying high for longer on cold start and then it stays always above the tach (Incredible) the whole ride 3500rpm @ 40psi. I even get 20psi @ hot idle and I have never ever seen that before.

So please explain how this 1 second fix improved my engine performance so well. What do you think the problem was, how to fix, is it cool to leave it as is. I am having one heck of a good time in the rain today







p.s. I did not plug the nipple comming of the cannistor so the line is open, not sure what that does either.

How is this system supposed to work.

Engine was running lean due to fuel pump pulling a vacuum on the tank. Vent is/was clogged.

Good idea, but I have a AFR gauge and it reads the same as it did with the pressurized tank. No change in the AFR.



Does the vacume line from the engine actually draw any vacume on the tank?

I guess indirectly the engine creates a vacuum by reducing the volume of gas in the tank but it doesn't per se pull a vacuum in the tank. Agree that there is an obstruction in the venting system.

Keith

So over on the bird board is this cool diagram, but there is no diagram of the front trunk ?


This is what I imagine is happening in the front trunk. Does this look right? If not please correct the picture. If it is correct, please show me where the clog you are talking about might be.

This has been discussed in detail already right here:
http://www.914world.com/bbs2/index.php?showtopic=108524

Thanks Andy !

So if all the air is sucked out of the tank, where is the clog, and how/ why the heck would my car run soooo much better by just removing the small rubber hose. I still can't believe how much better it runs. Trust me I am abusing the car, trying to get the temps up, but it just keeps pulling faster and meaner and cooler. OMG

Looking at your link again, it seems both ends comming from the charcoal cannistor are open to the air, no vacume. Wind from the fan is blowing into one end and the other is open to the atmosphere. So there is no vacume, if the fuel pump is creating that much vacume, the clog is in the charcoal can or evaporitive can?

I have a vacume tester, what should i check?

I like posting on my own thread

Wrong oh salted one ..... the air is blown thru the charcoal canister back to the air cleaner where you would have a small suction. The vent on the tank is the 1/8" hose that goes from the filler neck to the expansion chamber to the charcoal canister. It is emissions control by burning fuel vapors from the tank.

If the path from the fan housing to the canister is blocked, the air filter suction would be enough to create negative pressure in your tank.
Which in turn would work against your fuel pump.

I get it

This whole section is an emmissions thing. If I leave it as is / OPEN. I should have no problems.




Right?

I am still waiting an answere from the unsalted guru My first question. How in the HECK could any of this emmissions system drop engine temps and create better oil pressure.

salted.... ....... me? ........

you drive in the snow.
We use road salt.

If it were me I'd just leave it open, but my car has not had a charcaol canister hooked up as long as I have owned it.

Zach

Hey Mister Salty,

Did you not ever hear your fuel pump squealing in agony since it wasn't vented? The strain on the pump that would cause it to suck an indent in the tank is pretty substantial.

Ask me how I know.

Ok non-believer ... you can collapse the tank if the suction of the pump is sufficient and there is no vent open to supply air to the space that has been evacuated. Regardless of your AFR, the engine was running lean ... lean equals hotter.

An engine makes the most horsepower (and heat) at stoic near lean stumble, just before it blows up.

The unsalted guru

On the big Diesel generators I work on, the fuel circulating actually removes heat from the engine.

Your case is the same. Your D Jet was still getting fuel at pressure but... The added circulation of fuel through the system reduced heat soak making the fuel denser, air denser, run better.

The clogged vent line causes a vacuum in the tank that fights fuel flow to the pump...

Has the oil consumption decreased since the improved performance?