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Need help: washdown system, transducer, fuel tank vent.

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  • 2 Post By tarpononecharter

Need help: washdown system, transducer, fuel tank vent.

Old 06-22-2019, 06:14 AM
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Default Need help: washdown system, transducer, fuel tank vent.

I'm pulling the boat out of the water Monday for a few minor repairs. I'm hoping some of the experts on here can help me get a head start so that I minimize down time.

First issue is my raw water system. I can't get any pressure out of my washdown hose or livewell spicket. The flow is non rhythmically intermittent--just kind of burps out. I did notice that there is a pinhole in the hose coming out of the pump. I planned on cutting this hose back an inch and re clamping it on the pump. The system is basic--thru hull with seacock in front of it, about 2 feet of hose to the pump, hose comes out of pump then T's off. One side of the T goes to the livewell, the other side goes to the raw water washdown. A buddy of mine mentioned the possibility that the pin hole allowed air to get in the system and it's causing the problem. The marina thinks the pump is bad. Any ideas?

The second issue I'm having is a partially blocked fuel tank vent. This is the vent that allows air to leave the tank when you fill it with gasoline. The symptom is I'm only able to run the gas pump in about 10 second intervals before the gasoline flows back up out of the reservoir. It takes about an hour to pump 140 gallons in there. What's the best way to go after this problem? I have about 100 gallons in there right now. Figured I should ask some strangers on the internet before I go blasting compressed air into a liquid bomb.

Last issue involves the Simrad Totalscan transducer. I figured out from a previous thread that my ducer is mounted too low. The symptom is that I'm unable to get a reading at speeds over 5 kts. At 5 knots I can sort of hold bottom if I back off the gain. At about 7 knots I just have a bunch of noise. At 20 knots the screen is totally blank. Supposedly with these totalscans, if they're mounted too low an air pocket forms over the lens of the ducer. I figured it was mounted too high but I guess it's designed to see through turbulent water, just not that air pocket that forms when the ducer extends too far below the hull. MFD is Simrad NSS12 Evo 2 using nmea2000. I will probably need to update the thread with pics of the mounting location once the boat comes out monday. Basically, where I need help is deciding how far to raise the transducer. Obviously, "a little at a time" would be the best way to do this but it's not feasible. I'm dealing with a busy ramp, 30 minutes each way of no wake to be able to test the ducer, necessary high tide for launching. And to be honest, I suck with all things trailer. So I'd like to nail this first or 2nd try if possible.

Hopefully THT can come through again. Otherwise I'll just be happy this is ALL thats wrong this time...

Thanks guys and girls.
prestigemid is offline  
Old 06-22-2019, 06:37 AM
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I’m assuming that your livewell and washdown share the same pump.

i doubt the pinhole leak in the washdown hose (after the pump) is much of an issue. More than likely you have a bad pump or corrosion in the wiring. Pull the pump, hook it up to an external 12v source. Drop it in a large bucket of water and see what happens. If it works, you get to find the bad ground or corrosion in that circuit (I’d guess at or near the pump). If it doesn’t work, but a new one.

No idea on the other two.
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Old 06-22-2019, 06:51 AM
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Originally Posted by prestigemid View Post
I did notice that there is a pinhole in the hose coming out of the pump. A buddy of mine mentioned the possibility that the pin hole allowed air to get in the system and it's causing the problem.
If by 'coming out of the pump' you mean between the pump and the Tee/livewell/washdown -
then no - that is the pressure side, that's not going to stop the pump from working

Now a hole on the suction side - between the pump and the thruhull - could 'allow air to get in"

Certainly the pump could be 'bad' - but it seems like it is at least running

it could be that the hose / piping does not allow the pump to be primed with water
some pumps are self-priming - they can pump air to pull water in
some types are not self-priming -
the water has to make it from the thruhull and piping into the pump body 'on its own'
before the pump can work
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Old 06-22-2019, 07:04 AM
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the pin hole is definitely after the pump. not on the suction side. disappointing because that would have been the easiest fix
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Old 06-22-2019, 07:13 AM
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I replaced a live well pump one time only to find a blockage in the intake line ahead of the strainer. New pump didn’t pump any better than the old and that’s when I knew I had a different problem. I cleaned out the entire line and then installed a Groco strainer over the thru hull to prevent from sucking in further debris.
As for transducer should be flush with the bottom of your boat.
Lookinup76 and nuffaredy like this.
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Old 06-23-2019, 05:06 AM
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I had similar issue with my washdown hose just yesterday. There was a connection where the hose goes into a plastic piece with 4 tabs that then goes into the side of the pump. The plastic piece with the 4 tabs had pulled out slightly and was letting air in. I agree it is probably air getting in but doubt it is the pinhole doing it.
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Old 06-23-2019, 05:22 AM
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My pump (Tsunami) was doing the exact same thing. I ordered one from Amazon for $32 and replaced it and it works fine.
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Old 06-23-2019, 06:03 PM
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thanks for the replies guys
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Old 06-23-2019, 06:12 PM
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I'd take your hose off the thru hull if you can and check for debris. My brother sucked a little fish into his and it took us a while to figure out where the problem was.
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Old 06-23-2019, 06:19 PM
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First issue was addressed. Pretty much sounds like a new pump is in order.

Second issue - Heavy mono. Like 100 or 200 lb test. Push it thru there and you should be fine.

Third issue - Sounds more like something forward of the transducer might be introducing air. Got any pics?
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Old 06-23-2019, 06:33 PM
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First issue is my raw water system. I can't get any pressure out of my washdown hose or livewell spicket. The flow is non rhythmically intermittent-- INTERMITTENT PRESSURE MEANS THE IMPELLER BOWL IS SLOW TO FILL ON THE INTAKE SIDE. IT FILLS SLOWLY PARTIALLY BLOCKED WITH DEBRI THEN AND PUMPS (BURBS) THAT WATER OUT AND TAKES A LONG TIME TO FILL AGAIN BEFORE IT HAS ENOUGH WATER TO BURB AGAIN. SO YOUR PROBLEM IS DEBRI IN THE STRAINER OR INSIDE THE PUMP. PROBABLY BITS OF WEED.
YOU CAN TRY TAKING THE HOSE OFF AND CONNECTING IT TO A GARDEN HOSE TO BACKFLUSH, BUT IF YOU APPLY TOO MUCH PRESSURE YOU WILL BLOW OUT THE LOW PRESSURE RATED HOSE. THE SAFEST WAY IS TO PULL THE PUMP CARTRIDGE OR ENTIRE PUMP OFF THE SEACOCK TO CLEAN IT UP AND THEN BACK FLUSH THE STEEL FITTINGS WITH A HOSE AS THAT WILL TAKE THE CITY WATER PRESSURE.

The second issue I'm having is a partially blocked fuel tank vent. This is the vent that allows air to leave the tank when you fill it with gasoline. The symptom is I'm only able to run the gas pump in about 10 second intervals before the gasoline flows back up out of the reservoir. It takes about an hour to pump 140 gallons in there. What's the best way to go after this problem? I have about 100 gallons in there right now. Figured I should ask some strangers on the internet before I go blasting compressed air into a liquid bomb.
MOST VENTS HAVE A SMALL SCREEN TO KEEP BUGS FROM CRAWLING INTO THEM ON THE SIDE OF THE HULL. THIS GETS CRUSTED UP WITH SALT AND THE SCREEN CAN BE CLEANED WITH A TOOTHBRUSH AND WATER, OR WITH SOME VINEGAR BEING CAREFUL TO KEEP LIQUID OUT VENT HOSE AS IT WILL CONTAMINATE YOUR FUEL. ONCE THAT IS CLEAN YOU CAN BLOW AIR INTO THE FILL LINE WITH YOUR MOUTH, A LAWN BLOWER, OR VACUUM CLEANER EXHAUST HOSE TO BLOW THE VENT LINE OUT WITH AIR UNDER 3 PSI. mORE PRESSURE CAN BLOW THE FUEL TANK SO NEVER USE A COMPRESSOR.

Last issue involves the Simrad Totalscan transducer. I figured out from a previous thread that my ducer is mounted too low. The symptom is that I'm unable to get a reading at speeds over 5 kts. At 5 knots I can sort of hold bottom if I back off the gain. At about 7 knots I just have a bunch of noise. At 20 knots the screen is totally blank. Supposedly with these totalscans, if they're mounted too low an air pocket forms over the lens of the ducer. I figured it was mounted too high but I guess it's designed to see through turbulent water, just not that air pocket that forms when the ducer extends too far below the hull. MFD is Simrad NSS12 Evo 2 using nmea2000. I will probably need to update the thread with pics of the mounting location once the boat comes out monday. Basically, where I need help is deciding how far to raise the transducer. Obviously, "a little at a time" would be the best way to do this but it's not feasible. I'm dealing with a busy ramp, 30 minutes each way of no wake to be able to test the ducer, necessary high tide for launching. And to be honest, I suck with all things trailer. So I'd like to nail this first or 2nd try if possible.
YOU HAVE TURBULENCE IN FRONT OF YOUR DUCER. IN NO CASE DOES A DUCER LOOSE BOTTOM WHEN ITS MOUNTED TOO LOW. IF ANYTHING, IT HAS TO BE LOWERED OR MOVED AWAY FROM THE UPSTREAM STRAKE OR FITTING CREATING BUBBLES THAT ARE BLOCKING YOUR SIGNAL. THE 455/850 HZ FREQUENCY TOTAL SCAN DUCERS ARE NOT MUCH GOOD AFTER 100 FEET ANYWAYS, SO HOW DEEP IS IT WHEN YOU LOOSE BOTTOM?
YOUR 200 HZ SETTING WILL READ DEEPER, AND OF COURSE 50/83 HZ IS FOR GREATER DEPTHS, BUT THE TRANSDUCER YOU ARE PROBABLY USING IS FOR LAKE AND BASS FISHERMAN WITH ITS WIDE ANGLE THAT DOES NOT CONCENTRATE YOUR SIGNAL AT DEPTH.
a GOOD DUCER FOR WATER UP TO 700' DEEP IS THE 50/200 455/850 HDI SKIMMER THAT COSTS $235, BUT YOU DO NEED A GOOD LOCATIONS. MINE HOLD 700' AT 30 MPH IN WARM SALT AT 68% GAIN WITH NO SNOW ON THE SCREEN.

Last edited by Bullshipper; 06-23-2019 at 06:43 PM.
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