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Author Topic:   1989 Outrage 18 Fuel Tank Level Indicator
afinelli posted 07-03-2014 04:26 PM ET (US)   Profile for afinelli   Send Email to afinelli  
We have a 1989 Outrage 18 with a 1989 Yamaha 150-HP outboard. Prior to end of last season, never had a problem with the deck-mounted, direct-read fuel tank level gauge (5 bolt-hole magnetic assembly by Rochester). Then end of last season it suddenly stopped showing a reading. I had the entire assembly replaced after it was determined by process of elimination that the in-tank float part of the assembly was water-logged. (Don’t ask me why just the float itself couldn’t be replaced). Due to timing of replacement, didn’t get to fully test new assembly.

Lo and behold, shortly after the start of this season, I put in 25 gallons of fresh fuel (tank capacity is 63 gallons) without the tank level gauge moving a whisker. Removed the dial which sits in the top of the assembly myself, and cleaned out some gunk build-up in the cupped seat. Now the dial moves somewhat, but hasn’t made a believer out of me.

Have looked at a lot of old postings on this site on general topic of fuel gauge trouble, but still have some questions would appreciate help with:

The dial that came with the new assembly is calibrated across a 180 degree arc from full to empty. The prior dial was calibrated across a nearly 360 degree arc. Can this in and of itself have any logical bearing on what is going on? (Can’t comment on the quality of the installation, though tend to trust my boat yard service.)

As a back-up, any rule of thumb I can use for hourly fuel consumption by this outboard? (Not interested in sticking the tank periodically). Our boating generally consists of cruising at moderate speeds in tidal rivers and connecting waterways of mid-coastal Maine, with outboard running at 3500 to 4500 rpms. Occasionally out in the ocean when rounding points of land.

In these Rochester gauge assemblies, can float be replaced independently? Could it have gotten stuck or logged again just via winter storage?

Any other advice? Thanks.

Teak Oil posted 07-03-2014 09:03 PM ET (US)     Profile for Teak Oil  Send Email to Teak Oil     
Expect to be using about 14- to 15-GPH at WOT, so at cruise figure 8- to 10-GPH and you should be somewhat close
afinelli posted 07-03-2014 09:31 PM ET (US)     Profile for afinelli  Send Email to afinelli     
Thanks Teak Oil
jimh posted 07-03-2014 11:17 PM ET (US)     Profile for jimh  Send Email to jimh     
The dial face on the in-deck tank fuel level gauges that I have seen tend to have a dial sweep arc of about 270-degrees. But if you replaced both the float sender mechanism and the dial mechanism, I would assume they are both designed to work with each other, and the change to only a 180-degree sweep of arc on the dial pointer scale would not be a problem.

Those gauges are linked magnetically. I have seen the dial pointer become unlinked magnetically from the tank sender. Are you sure the two are coupled together magnetically?

Peter posted 07-04-2014 07:31 AM ET (US)     Profile for Peter  Send Email to Peter     
The fuel consumption rate of a Yamaha 150 2-stroke at WOT is about 17 GPH.

At 1000 RPM it will consume 2 GPH.

Between 3500 and 4000 RPM between 7.5 and 9 GPH.

If you can determine what your typical running profile is in an hour then you should be able to compute an average hourly rate of consumption. Then just keep track of hours and you should get a rough idea of how much fuel is used.

In a typical afternoon out for me in my Outrage 18 with a Johnson 150, I would use up about 12 to 15 gallons of fuel. That was running about 35 to 40 miles with a good part of that being spent at a 30 MPH cruise (3500 RPM).

afinelli posted 07-04-2014 11:14 AM ET (US)     Profile for afinelli  Send Email to afinelli     
Jim H:

To answer your question, in fact I'm not sure about whether the sender and dial are coupled magnetically as I'm not sure exactly what you mean by this or how to determine it. In this current set up, the dial mechanism, which has a convex bottom, simply sits in a cup on the top of the sending unit, and is held in place by two screws. There is no other mechanical connection, if that is what you are referring to by linked or coupled. I do know that if you pass a magnet under the bottom of the dial when removed, the dial indicator moves.

Any suggestions about further diagnosing this?

afinelli posted 07-04-2014 11:14 AM ET (US)     Profile for afinelli  Send Email to afinelli     
Thanks, Peter.
Jbeaux2000 posted 07-04-2014 02:13 PM ET (US)     Profile for Jbeaux2000    
My results were similar to peters. 1989 outrage 18 with 96' 150 evinrude v6 loop charged carb motor. I usually ran around 3200-3600 rpm and averaged around 3.0-3.2 MPG. I imagine your yamaha is similar in fuel usage.

jimh posted 07-05-2014 06:14 AM ET (US)     Profile for jimh  Send Email to jimh     
The linkage between the float movement and the dial movement is not a direct mechanical one, but is accomplished by magnetic force. I have seen the dial and the float lose this magnetic coupling. It happened when operating the boat in rough seas, where some rapid sloshing of the fuel or sudden pounding of the boat must have jarred the dial and float apart. They re-coupled magnetically by themselves. But the notion of moving the dial around with a magnet is a good one; you could swing the dial pointer around the arc and see if it happens to re-couple to the float magnet.
afinelli posted 07-07-2014 01:45 PM ET (US)     Profile for afinelli  Send Email to afinelli     
Thanks, Jim.

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