Weber Problem, Maybe?

[araine901]

I drove my car from Phoenix to LA and last week. I drove it again on Saturday with no problems and Sunday it gave me a little bobble in a turn (freeway transition I-17 to I-10) just as slight drop in power for less than one second then back to normal. Then agian on the way home as I slowed for a speed bump same thing. Then 1/4 mile father as I slowed to a stop to pull into my driveway Cut out and wouldnt start.

It seemed like a fuel delivery issue but the gage says 1/4 tank. In the past it has been acurate but, just to check I pull the cap move the car a bit to hear if gas is swishing. Not too certian if I could hear it. So I went to the Cheveron station (thats all I feed her) and got two gallons. Come home, turn on the holly fuel pump and it does not change in pitch like they do when they go from no fliud being pumped to havind some. (they quiet down as much as a holly will) So I check the fuel bock in the engine compartment where I have a fuel pressure gage and it is reading 3.5 lbs. Just where I want it. So I crank it for about 10 seconds hodling the throttle half open, it burps to life and runs OK, slightly rough but OK. I try to back out and it stalls. I do this same thing again with the same result. So I get it running again and check the fuel presure when its running, still 3.5 so I press the linkage to get a rev out of it and it kills the motor. I am not opposed to rebuilding the carbs since it has been nearly 10 years since I did it last. I am wondering if I have a stuck float. That is just a guess so I am going to do the following:

I had the leave town the next morning so I am making my list of things to check when I get home.

1) Float height
2) Accell pump delivery
3) Cap & Rotor (no points, Pertronix)
4) Pulgs & Wires
5)
6)

Any suggestions welcome

Thanks

Aaron

[araine901]

bump

[jpnovak]

Have you checked the fuel flow out of the pump? I will guess you have flow volume problems. Since the pump sounds like its cavitating (pumping air) I suspect the screen in the bottom of the tank is choked off with dirt/rust particles. This prevents the pump from getting fuel. Solution: Drain the tank, remove the screen clean and re-install.

I would also clean/replace your fuel filters. You may also want to add a small in-line filter right at the inlet to the carbs. This will save lots of clogged jets.


I don't think its a carb problem since the car was running well before then.

[araine901]

I am getting 3.5# of pressure 6 feet down stream from the pump. The filter catches particals down to 5 microns. Since using this fiter set up, I have never had a clogged idle jet (10 years). My thought was that since I am getting 3.5# PSI at the carbs and the fuel pump, reguator and filter are all in the smugglers box up front that it is not having difficulty pushing the fuel. I could be wrong.

[jpnovak]

Remember that pressure and volume are two different things. What is the pressure when the car cuts out? Have you measured flow? Pull the supply line off the car and look to see that the fuel is flowing strongly. It should not dribble but stream out. Catch the fuel in a suitable container. measure the volume vs. time and compare to the specs for the pump.


You may want to check the float bowl levels. Look down the carb throats and look for running fuel. If a float valve is stuck open you will see fuel running down the intake. this would choke the engine off since it would be so rich.

[dhoward]

I might go with the stuck float thing, but I'd blow out your i-jets, just for fun. Whenever I'm having odd ball carb problems, it usually ends up in the idle circuit...

[RoninLB]

Originally posted by araine901
I-17 to I-10) just as slight drop in power for less than one second then back to normal.
Then agian on the way home as I slowed for a speed bump same thing.
Then 1/4 mile father as I slowed to a stop to pull into my driveway Cut out and wouldnt start.

I crank it for about 10 seconds hodling the throttle half open, it burps to life and runs OK, slightly rough but OK. I try to back out and it stalls. I do this same thing again with the same result. So I get it running again and check the fuel presure when its running, still 3.5 so I press the linkage to get a rev out of it and it kills the motor.
1) Float height
2) Accell pump delivery
3) Cap & Rotor (no points, Pertronix)
4) Pulgs & Wires
5)
6)

3.5 when running will leave enough fuel in the bowls to keep it running when you linkage rev the motor. A blockage of the accelerator pump feed in the bowl, acc pump diaphram, or a bad coil+ is a wild guess.

So I'd probably check the accelerator pump squirt vol first with the engine off. What kind of coil are you using?

[john walker's workshop]

remove the float bowl drainplugs and see if one or more of the bowls is basically empty. hold a small paper cup under the drains.

[araine901]

Thanks guys,

I will check the float height (which means I have to drain the bowls). This will also tell me if I have a reduction or excess of voulme to the bowel. I will also check the fuel delivery to see if there is a a blockage keeping the accelorator pump from doing its thing. (Ronin LB, its a MSD Blaster Coil) I am going get get a couple more gallons of gas in it, It cant hurt.