# Water pressure gauge Tohatsu 50 HP



## lemaymiami (Feb 9, 2007)

You'll have to talk to your dealer for the where to install the pickup - and whether they have a kit... Essentially all you'll be doing is tapping into your motor's water jacket with a fitting -then running a small water tube to where the gauge is to be installed (without any kinks in it) up into your motor's wiring harness - then up into wherever you're mounting that gauge... The only power your gauge will need is a small wire to hook up to an internal light so that you can see your water pressure when running at night (and as a guy that runs quite a bit at night for a lot of years I think that's really important...).

Remember as well that your water line will be salty so make sure all of your connections are carefully done - and an occasional inspection every few months to make sure your line is tight... Salt water in your gauge/ electrical wiring areas - not funny...

Hope this helps - aren't boats fun?


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## jmrodandgun (Sep 20, 2013)

If you order the gauge from Tohatsu it comes with a hose and the fittings but I can't remember if there is a preinstalled fitting on the motor. 

3GF725980M is the part number for the gauge, hose, and nipple.


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## Smackdaddy53 (Dec 31, 2012)

Does this motor have enough pressure to register?


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## devrep (Feb 22, 2009)

my Tohatsu TLDI is HVLP, only reads like 6 psi which is normal for these motors.


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## salt_fly (Apr 23, 2012)

devrep said:


> my Tohatsu TLDI is HVLP, only reads like 6 psi which is normal for these motors.


Interesting. So depending on how the gauge is numbered,it might be hard to see meaningful changes in water pressure?


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## Smackdaddy53 (Dec 31, 2012)

salt_fly said:


> Interesting. So depending on how the gauge is numbered,it might be hard to see meaningful changes in water pressure?


Yep, same with my Yamaha 70TLRZ. I bought a Yamaha water pressure kit with gauge and it wouldn’t even register. You’re better off just glancing back now and then to make sure she’s pissing, it’s what I do. These motors have temperature alarms for a reason, to notify you to stop and figure out why it’s getting hot BEFORE you cook the power head.


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## lemaymiami (Feb 9, 2007)

Wasn't aware that some motors have such low pressure - mine (E-Tec 90) needs to show at least 20 pounds... You still might want to check with the dealer though - it would be a simple matter to design a gauge that reads in relatively low pressure...

By the way -if you run at night (when you can't see the "pee" stream) and wait until that overheating alarm goes off - it might just be a bit too late... to prevent damage. At least that's my take on it...

If the kit has gauge, hose, and nipple (the part that is drilled into your water jacket... ) that's all that's needed. What you still need to find out is exactly where to drill to install that nipple.

Once again contact your dealer and listen to what they say (and make a point of also talking to whoever at that place actually does the installs...

My experience with "other makes" of motors is a bit limited since I've never had anything other than a Johnson or Evinrude motor -since 1974...


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## devrep (Feb 22, 2009)

the hatsu's will shut down to idle at a certain temp, before any damage is done.


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## Smackdaddy53 (Dec 31, 2012)

devrep said:


> the hatsu's will shut down to idle at a certain temp, before any damage is done.


Most outboards have limp mode and if the alarm goes off it’s well before the temperature will do damage.


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## lemaymiami (Feb 9, 2007)

... at least that's the idea....


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## Smackdaddy53 (Dec 31, 2012)

lemaymiami said:


> ... at least that's the idea....


If you hear the alarm and keep running it can definitely cause engine damage.
One thing a lot of folks do that can cause an issue is shutting the ignition off after they hear the alarm when it’s still peeing. Shutting the ignition off will allow the block to stay hotter longer than if the engine is left idling and as long as it’s pissing good it will cool her down. BUT also remember if it’s not peeing or the stream is weak it’s definitely not cooling correctly and you need to just shut down and have a snack then run some weed eater line in the pee hole and crank up to see if it’s just a piece of shell or debris in the telltale hole. Crank up and see if it helped.


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## Zika (Aug 6, 2015)

Mack had a great idea with the weed-eater line. I cut a couple pieces and carry them in my boat box in case I suck up some floating grass or debris. Cheap insurance!


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## Smackdaddy53 (Dec 31, 2012)

Zika said:


> Mack had a great idea with the weed-eater line. I cut a couple pieces and carry them in my boat box in case I suck up some floating grass or debris. Cheap insurance!


Been there, done that! It’s amazing what size debris can make it through the cooling passages, thermostat and clog up at the tip of the pee hole. I usually drill mine out a bit bigger to alleviate issues but with my low water pickup and filter before the motor nothing gets in.


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## devrep (Feb 22, 2009)

Zika said:


> Mack had a great idea with the weed-eater line. I cut a couple pieces and carry them in my boat box in case I suck up some floating grass or debris. Cheap insurance!


I've done the same for years.


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## salt_fly (Apr 23, 2012)

Smackdaddy53 said:


> If you hear the alarm and keep running it can definitely cause engine damage.
> One thing a lot of folks do that can cause an issue is shutting the ignition off after they hear the alarm when it’s still peeing. Shutting the ignition off will allow the block to stay hotter longer than if the engine is left idling and as long as it’s pissing good it will cool her down. BUT also remember if it’s not peeing or the stream is weak it’s definitely not cooling correctly and you need to just shut down and have a snack then run some weed eater line in the pee hole and crank up to see if it’s just a piece of shell or debris in the telltale hole. Crank up and see if it helped.


Good to know!


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## devrep (Feb 22, 2009)

IMHO the tohatsu alarms are not load enough, at least for my hearing.


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## DONAGHUE (Nov 18, 2017)

devrep said:


> my Tohatsu TLDI is HVLP, only reads like 6 psi which is normal for these motors.


Low pressure ,high volume....


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## Surffshr (Dec 28, 2017)

Smackdaddy53 said:


> Been there, done that! It’s amazing what size debris can make it through the cooling passages, thermostat and clog up at the tip of the pee hole. I usually drill mine out a bit bigger to alleviate issues but with my low water pickup and filter before the motor nothing gets in.


Anymore about this low water pickup?


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## Smackdaddy53 (Dec 31, 2012)

Surffshr said:


> Anymore about this low water pickup?


Yes, still running mine since I installed it with no need for tweaking. It has been flawless. The true test was hot summer back lake water full of dead grass and it passed. I am working with a prop guy to make some runs in aluminum and HDPE. Once I get them I’ll sell them in kits with fittings, hose, clamps, filter and drill bit/tap for the lower unit.


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## devrep (Feb 22, 2009)

send me a prototype and I'll put it to the test down here. I'm pretty sure we have less crap to filter out here than you have.


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## Kennerman (Oct 3, 2019)

I ihave a shadetree solution for my old school Merc 90. There was a plug on the water jacket and finding a fitting for that with a hose barb was easy. Then I attached the speedo pito hose to it. 15 psi = about 20 mph. Don't really need a speedo. Actual pressure is not that important, you just want to know if it changes all of a sudden. I also put a car add on thermister on the cylinder head with electrical temp gauge so I can see the temperature change gradually. I notice the most temperature change when I go from boating in a 90 deg lake, like lately to 60 deg this upcoming winter. This temperature gauge came in handy lately as it showed I had a thermostat that would not close enough so running low speed in cool water the motor would frequently die requiring choking to restart. 18 years is not too bad for the original thermostat.


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