will a low float level affect idle?

[OldNBold51]

I'm having idle problems now after setting my float level lower than spec'd. Boat runs fine when idle at 1K rpms but shudders and barely runs at below 800 rpms. this is a new problem developed after my old gas issue from a few weeks ago. No issues at all when cruising down the lake but idle rpms need to be at 1k or it dies. Last year 600 rpms was idle.

this is on a webber carbed 4 bl 7.4L '95 mercruiser bravo1.

 

[rickryder]

Re: will a low float level affect idle?

A lower float setting if I'm understanding would leave less fuel in the bowl..... I can't see that affecting the idle curcut.....more like one of the passages in the idle curcut is blocked.... Did you rebuild the carb or just play with the float? I would go back in and set it to spec...

Might also have a slight vacuum leak causing a stalling issue....

My resto link below shows a rebuild on that carb in detail starting on page 12

 

[Scott Danforth]

Re: will a low float level affect idle?

^+1

how low is low?

 

[Bondo]

Re: will a low float level affect idle?

now after setting my float level lower than spec'd.

Ayuh,.... Why would ya do That,..??

 

[OldNBold51]

Re: will a low float level affect idle?

Ayuh,.... Why would ya do That,..??

Good ?? Don, and Rick, Dayam you did a lot of work to your boat!!!! If you'd read my post from a few weeks ago that ended up being ethanol/water old gas issues, i kept thinking I was having carb problems due to the fact that I HAD PUT 16 gallons of new fuel in the boat, thinking that I'd ruled out bad gas as the problem. While cranking without any hint of firing, I'd end up with a POOL of fuel in the intake. I was using the accel pump sparingly and wrongly jumped to the conclusion my float was sticking open. I disassembled the carb and checked both float level 1 9/32 and needle/seat operation with compressed air (it would seal under pressure) and cleaned passageways with cleaner and air, put back together and reinstalled. cranked the boat with same results of pool of fuel and no fire. I repeated the carb tear down and passageway cleaning 2 more times with same results. On last carb teardown I set the float level at 1" just to change up something and still got the pool of fuel. Once I finally got it running this latest issue with idle issues showed up.

 

[mpdive]

Re: will a low float level affect idle?

First thing I would have checked would have been the idle mixture screws. Sounds like they are leaned out. Would explain the problem when coming off the main metering circuit. I advise against changing float levels, and really dont think your pooling is anything more than the accel. pumps unused blasts. Again, check the mixture screws.

 

[achris]

Re: will a low float level affect idle?

.... I disassembled the carb and checked both float level 1 9/32 and needle/seat operation with compressed air (it would seal under pressure) .... I set the float level at 1" .....

That is a massive change. In fact, I would say too much. And because the fuel must take a fairly torturous path to the idle and progression discharge holes, I would say that such a low fuel level may have an effect on it... Bring the float level back to about 1 1/4" and I suspect your problems will go away....

Chris......

 

[OldNBold51]

Re: will a low float level affect idle?

UPDATE:

after 3 outings, 10 hrs and another 20 gallons of gas thru this boat it runs perfectly once again. I still have the lowered float level w/o any issues. In fact, I've done nothing but run it. As previously stated, it would hardly run under 1K rpms. That gradually got better. I've got the idle back down to a very smooth 650 rpms in gear.

My only idea was it had to be the old ethanol gasoline full of water.

 

[dn010]

Re: will a low float level affect idle?

I had the same problem with my carb. I CLEANED it & adjusted the float countless times only for the intake to flood and the boat to run poorly...

After I REBUILT it (including a new float), it now runs good and with the proper specs. Idle, you'll be fine - but from what I have been told, a low float can lead to problems running when the waves are bouncing your boat around...

Guess my .02 - it might run fine now but I'd recommend getting it rebuilt and properly adjusted...