http://www.youtube.com/watch?v=9_DMguaI8_k


Here is a video clip of my RX7 at idle. It is idling about 850 RPM here. As long as I have owned this car, fuel has dribbled out of the left (at least left in this video) booster fuel nozzle.

What causes this? It does not dribble out of the other one. My float levels are perfect, the jets and air bleeds are clean. It runs perfect other than this.

Any ideas?????

 

either the float level is too high, or fuel pressure too high.

you could try and play with the fuel pressure. the float too high part is more like the fix, the problem is a carb problem. if the floats are fine on the bench, but not in the car, is the carb level?

the dripping isn't really a problem on a race car, once you're moving a drop or fuel here and there isn't a big deal

also see what happens if you bounce the car up and down

 

Pressure is right on the money and level is set perfect. It does not dribble with engine off and fuel pump on. Only when you start it and you are idling.

It really is not a big issue, I just want to learn ALL I can about these little nikkis!!!

 

Have you taken the carb apart recently? Or better question based on ur info...did the previous owner take the carb apart?

It COULD be that side's float not sitting level...or at the right height. I spent the last 2 months working on my carb...on and off the car. The last thing I had to fix was a rush job on taking it apart that I did...accidentally tweaked the floats just a touch....and boy I tell you, the car would barely run. It was dumping gas in like crazy...stalled it out from all the gas. Exactly like your video...only intensified from both sides. That side's float could be hung up.

 

Fuel pressure too high, which goes along with your left hand turn bogging issue.

How did you determine that the pressure was perfect?




.

 

With a calibrated gage. This dribble seems to be there regardless of fuel pressure.

 

I have had the carb apart several times. I just changed the floats and adjusted them. The float level is not the problem. It is NOT the fuel issue like some folks have had where it just floods the carb even with the engine off. When my engine is off.... no fuel leakage.

My fuel bowl vent solenoid has been deleted and I just have an open vent. (Mod that Sterling does)

 

it turns out that webers do the same thing, so i actually have had the same problem, except the weber parts are bigger....

anyways, the way the circuit works is that the fuel is in the bowl, with air pushing down on it. on the side of the bowl there is a sideways passage to go to the booster. so air pushes down on the fuel, and the engine air going past the horizontal passage pulls the fuel UP and ACROSS and into the engine.

since the pressures involved are actually very small (don't forget there is an air bleed/air corrector between the bowl and the passage), little things make a huge difference.

so since yours ONLY does it with the engine running, and not with it off, we could actually say that the main circuit is starting to work, even at idle.

its not a big deal in a race car, the engine will just push the extra fuel out the tailpipe, although it wouldn't smog like that.

also you should set the fuel pressure by HOW THE ENGINE RUNS, not someones web page, and even that web page gives a range for fuel pressures

 

Good advice.... It is the same advice that Kentetsu gave me. I am not going to worry about the dribble...

 

Clearly they are not, since fuel is dribbling out of the booster, which is only caused by a high fuel level in the bowl.

I like 1.5-2psi fuel pressure on Nikkis.

 

A plugged or undersize air bleed could cause that, I'd think.

 

Ding Ding Ding.... this is the kind of thinking I am thinking about. I live in Houston which is about 15 feet above sea level.... In fact my house is 9 feet above sea level...

So, would I need to increase my bleed??? I am telling you guys my pressure is OK and my level is OK... I turned OFF my friggin fuel pump today and it still dribbled!!! Any ideas guys???? Think outside of the box!!!

 

dribble with fuel pump off = bad needle and seat = too much gas in the float bowl...

i betcha if you lowered the float level like .5mm it fixes it

 

Fuel pressure is okay, but you've had the same type of issues with three different carbs now, correct? If it has been the same type of issue with all three carbs, then the last thing you should be looking at is the carb, right?

Tell you what.... We've got a two day autocross up here in two weeks. Bring her up and we'll throw my Sterling on her and see what she says. Dammit, one of us has to move. lol

 

I agree with Mike here. The best carb guru's on this site have all told you the same thing. It's fuel level in the float bown related. Unless a clogged air bleed caused it, it's either a bad needle valve, too much pressure, or incorrect float levels.

 

I lowered the fuel pressure a little and it practically went away. When you raise the fuel pressure it gets worse. I also lowered the idle and that helped.

I just ordered a calibrated 0-5 psi gage so I can at least pin point my pressure.

 

Cars are so much easier than women. At least when you do something right with a car, it will tell you that you did something right.