www.iFourWinns.com

Hey guys, quick question....actually a couple questions. I think a couple of my dash gauges aren't working..well I know for SURE one isnt'....I filled my tank full ( 18 gallons) on my 170 freedom. My Fuel gauge is pegged at FULL and as I use gas it stays at FULL. I figured, since it sat so long, my fuel sending unit/float was bad...I pulled up the floor board, and easily removed the OLD fuel sending unit, with a brand new one.cut to length and adjusted the float to fit my gas tank. I checked it with my volt meter set to OHMS, and as I raised and lowered the float, the Ohms when up and down a bit......so figured it was good to go. So now, maybe it's my gauge? How can I tell if my gauge is or is not working?

Also, I know my boat is suppose hit about 40mph at WOT and trimmed (at 4600 rpm)....my speedometer is reading about 25 mph at WOT. I KNOW I gotta be going faster than that. Should I change out the Pitot tube? can I blow a certain PSI of air into the tube to check speedometer accuracy? Can I tell via RPM how fast I am going? I've seen charts for other boats that say if you are going 2600 rpm, you are going 22mph..etc etc.

Any help would be great. Thanks

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1990 Four Winns 170 Freedom, 3.0 OMC Cobra 4 cyl.

Your fuel gauge may be stuck. Did it work before? If so, take and tap the gauge with your hand and see if it bumps down (while ignition is on). If not, then I would verify wires to gauge are good by checking ohm reading at gauge when full and then after running a while.

As for speedo, check your speed with a gps (or gps app on your phone). Next, I would verify the pickup is clean. Then take air and slowly increase pressure as you read the gauge. Be careful as you can damage the gauge (or it may have already been damaged by another. Usually it is just partially clogged at the pickup. To clear take a small pick or something and clean out and then blow about 25 psi back thru the tube from the gauge end.

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The Dance II
2007 278 Vista
6.2L Mercruiser

Thanks, I'll give those ideas a try....I appreciate the help and input

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1990 Four Winns 170 Freedom, 3.0 OMC Cobra 4 cyl.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

I have never seen a chart, but the pressures are fairly low. I know I have blown into the tube by mouth and registered 20-25 mph, which is only about 1-2 psi.

It does not sound like the pitot-tube is clogged, because it would not register at all if clogged, or it would respond slowly but eventually get to the right reading.

Make sure the pitot tube is in the "down" position, as they are made to pop-up if they hit a piece of wood or object.

I would also examine the face of the pitot tube in the area around the little hole. There should be a small flat area around the hole, and this flat area should face straight towards the front of the boat. If this face is damaged then it may reduce the pressure going to the gage. An example is if the little hole is torn out a little towards one side, then it would lose pressure.

Also, a hole (leak) in the tubing would also cause a loss of pressure.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I have a new pick up on the transom for the pitot tube and it does read close to my GPS speed (about 2-3 slower) but it takes longer to start reading. The pick ups get clogged esp in salt water where I am. I'd check that first and see if you can blow through the tube if its disconnected from both ends (ie on the transom and from the back of the speedo)....

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Thanks..I'll use all this info to trouble shoot. I think it MAY be my old pitot/pickup tube...when I push it rearward..it pushes easily up into the air, and does not snap back down. So could be the issue. I am going to remove it and replace it, as it's cheap...and then I'll have one of my kids blow into the rubber tube, and see what the gauge does as well.

LOUC..I read the article you linked here..and for the fuel gauge pegged at FULL, it does not say if I Need to test with ignition ON or OFF..can you verify?

Dan

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1990 Four Winns 170 Freedom, 3.0 OMC Cobra 4 cyl.

try this one its a bit better:
http://www.jamestowndistributors.com/us ... ?docId=833

When they talk about hooking up wires, this is for a gauge that is not installed. Your gauge has 3 connections usually, the IG which is the power from the ignition circuit, the G which is the return path (ground) and the S which comes from the sending unit. These tests are done with the ignition ON .
So here they are telling you to disconnect the wire from the back of the gauge for the sending unit, then the gauge should read below empty. Next make up a jumper wire and connect the S terminal and the Ground, the gauge should read above full. If the gauge responds this way its OK. Next they tell you how to troubleshoot your sending unit.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Yes, that definitely sound like the issue with the speedometer reading low. New pitot tube should fix it.

Ray

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings