Fuel gauge / Filling issue

[Bird Blaster]

Looking for some help

2008 GW 232.
The last few times I have been out I cannot get my gauge to read full on fuel. It reads 1/2 to 3-4. When I drop the throttle to get out of the hole the gauge will go up to "full" but then settle back down when on plane.
I did a full day the other day and put in 65mi and when I came back and now to put gas in it so was only able to put 12g (should've been more) and the fuel was flowing out the side of the boat. I was using a battery operated transfer pump.

Is there a way to check my gauge or fix?

could I some how be getting air that needs burped?

Thanks for the help.

 

[Bird Blaster]

I seem to have a vent issue I think.
Just took boat out for a quick spin. All of a sudden I could put another 2 gal in it

what is the way to troubleshoot the exact issue and fix?

thabks for advice.

 

[Hookup1]

What year is your boat? Good chance it’s bad sending units. Burn off 1/4 tank of fuel and pull the sending units. Once you know the correct length order new WEMA senders. Install with a new rubber gasket with a little Permatex fuel safe sealant.

 

[Bird Blaster]

2008

 

[SkunkBoat]

There are a lot of variables.
Have you recently replaced anything related to the fuel fill/gauge/hoses/sender?

Are you gassing up on a trailer? if the tank is not level when you fill you can have a problem.

If your tank is not venting it can overflow before it is full unless you pump really slowly. A venting issue usually causes problems when running also.
It can be caused by a blocked vent or a sag in the vent line that fills with gas.

Do you have an analog gauge or a digital gauge or are you reading it on an MFD?

There are two types of sending units. Old school units had a float on an arm. If it is not adjusted correctly it will not read correctly.

new style units have a vertical post with a magnetic float. .."WEMA" or "KUS" brand...
Some digital gauges can be calibrated to WEMA style units.

 

[Hookup1]

You don't really have to keep the tanks that full. No burping. If you want to troubleshoot the diagrams are below.

 

[Bird Blaster]

Thanks!!
I have a digital gauge.
Is there a different sending unit for different gauges? I will pull off the digital gauge today and find out if there is a model number.

 

[Bird Blaster]

I definitely have a venting issue.
I popped one of the screws from around the sending unit and the air all escapes. With that the fill neck then empties down.
Would it be as simple as changing the vent tubing?

 

[Hookup1]

Changing the vent tubing isn't that easy. They feed up thru the hull to the fuel fill.

Your deck is a pretty good indicator of the tanks. While you are doing this is the deck level, bow down or bow up? My guess is the boat is bow down and air was trapped in the tank. Tank pickups, vent and fill are all at the back/aft end of the tanks.

I know its hard without gauges but don't mess with sending units if you have nearly full tanks. You will have fuel all over the place.

My best advice is to get tank level down, pull sending unit and test it. You can do this with a voltmeter set on ohm's. You can also leave it connected and move the sensor on the sending unit. Be sure to pause at stops as the gauges have "debounce" logic in them.

 

[SkunkBoat]

Changing Tank pickups, vent and fill are all at the back/aft end “

fills and vents are forward. Bow down will cause venting problems

do you have a vented fill or a separate vent?
separate vent can get blocked by mud wasps
You might need to pull the tank deck and look for a dip in the vent hose

 

[Bird Blaster]

The boat is sitting slightly bow up.
The vent looks to be in the top of the PERKO deck fill (both under same cap)

 

[Hookup1]

fills and vents are forward. Bow down will cause venting problems

On my boat fill, vent and pickup are all aft.

 

[SkunkBoat]

On my boat fill, vent and pickup are all aft.

View attachment 26457

Not gonna say I’ve never seen that before. But it doesn’t make sense. With a full tank when you go up on plane you’re going to block the vent . On my 265 and on my previous boats the pick ups were aft in the fill and vent were forward

 

[seasick]

I believe your tank is poly. Pickup is aft, vent and fill are forward.
If you think that you can estimate how much gas is in the tank based on the gauge display at various conditions, you are in for a let down.
On the 208, the gauge can read 3-4 bars or more when getting on plane and then when at rest and sitting for a while, drop to one bar.
The reading is not that accurate since the angle of the hull changes dramatically under different conditions.
The most accurate reading is when the boat has sat for a while in calm waters, with no-one on it
Just you moving forward or aft can cause the display to change a bar.
One flashing bar means there is 10 or less gallons in the tank. You can't measure better than that. One solid bar means approximately 10 to 20 gallons but note that could mean 11 gallons or 20 gallons.
With a half or a bit less than half a tank of gas, at time when getting on plane or plowing, the gauge may read close to full.
Remember that the pickup is above the bottom of the tank. The sender length for a poly tank is spec's at 1 inch above the tank floor, 1/2 inch for metal tanks. Ther eis gas in the tank that you can not suck up
Do not relay on the gauge to make sure you have enough gas to get home..Keep records of the number of bars when you take a trip and when you get back. Note how many bars before adding gas and after.
Remember that the gauge takes time to update the bars. It can take 20 seconds or more for the reading to stabilize.
The air trapped in the tank under certain conditions is normal. Don't top off the tank.

 

[Hookup1]

These fuel gauges are more of a guide than absolute. First thing I did when I bought my boat was to replace both sending units. Two tanks on a switch to one Yamaha gauge. Readings at anything other than idling around are useful but inaccurate especially at low fuel levels. But empty is good - one bar blinking.

Full tanks are not full for long. Make sure things are good from 1/4 to 3/4 and you will be fine.

 

[DennisG01]

Check the vent hose, itself, for a low spot where excess fuel could have accumulated. That would cause the exact problem you're seeing. Fix the low spot if this is the case.

For now, open the fill and remove the vent hose from the tank. Blow into the vent hose - do you hear/feel a gurgle? That's a surefire way to know you have a low spot. You can try stretching the hose out to see if you can get the fuel to drain out.

 

[seasick]

If you filled to the filler neck (topped off) you blocked the vent tube. It will fill with gas as you click the nozzle, wait a bit, click again etc. Assuming the vent hose is plumbed correctly , it will eventually drain as you burn fuel but you may have excessive back pressure. So, don't over fill the tank.