Outboard modification

[Guest]

Hi!
Beeing fed up with my integrated gasoline tank on my Tohatsu 3,5HP, I intend
to modify it to accept a separate tank. I believe there was an article covering the
subject some years ago in PBO or MBM. Can anyone direct me to the correct
issue ?? Have searched through my mags without any luck several times.

Thanks!

Pelle

 

[BarryH]

I think your main problem will be not having a petrol pump, I may be wrong, but isn't your tohatsu gravity fed with a fuel tap in the line. If its got a pump, then it sould be quiet easy to plumb in a fuel connecter. But the main thing is to make sure all the fuel connections are leak free.

OK, to hell with it. Unbolt it and we'll use it as an anchor!

 

[David2452]

There is usually a complete conversion kit available from the manufacturer, as the Tohatsu is the base for almost every other small OB you should be able to use Mariner, Merc etc as well as the Tohatsu kit.
David

 

[jollyjacktar]

You get fed up easily.

How far do you need to go? They go about a million miles on one tank full, why not just take a spare can of gas with you and fill it up on the move when you need to. You could use a standard fuel line with a pressure bulb and pump it into the existing tank when you need to, or else modify a fuel can to take a pump and pump it with air to force the fuel into a delivery hose to top up the existing tank.

 

[Guest]

Well, Jolly! Perhaps. I find this a golden opportunity as the Mickey Mouse fuel valve broke just the other day. Quite a few items has rattled loose on the engine, but no (until now) major parts beeing critical for its functions.
Yes, I can go very far with it as I usually go only at about half speed, loosing just a 0.2 knots or so of top speed. However, at least for me using the boat all year round, it can be quite difficult to re-fuel the integral tank when out there, you know, with the wind and waves. It gets
messy!! That's why I asked for somebody to direct me to the appropriate article in one of the mags.

BarryH: Good point regarding the fuel pump. I think you're right!
David: Thanks. I'll check it out

Per Olav

 

[Seal_surfer]

I had the same thoughts with my 1998 Tohatsu 5. It turned out that this already had the fuel pump fitted and merely required the "external tank" kit fitted. This comprised of the fuel hose connector, T piece, fuel hose, clips...- I think it came to a bit over £30 from a local agent in Felixtowe. There were no instructions, but it was reasonably straight forward. You'll obviously need to budget for the tank, fuel line and matching connector.

Good luck.

 

[steve_cronin]

The fuel pump on most outboards works from....

changes in crankcase pressure- the piston moving up and down moves a diaphragm back and forth, the other side of which pumps the fuel via a pair of valves. Therefore you will need a pump from some model which already has a remote tank set-up. You will need to drill a hole if there isn't a blanked off one already plus the two tapped holes to take the pump mounting screws. Then you need to alter the length of the previous fuel line from the tap and connect it to the pump outlet and buy a fuel connector suitable for the tank line you intend to use and mount this again on the engine somewhere convenient (& safe -look at other motors).

I have done it on the smaller OMC engines and it works well.

I even once had a petrol/kerosene conversion on an old Evinrude 40. Crossed Yarmouth to Aldrney with it but the consumption was wicked! - that's another story!

Steve Cronin

 

[blue_anchor]

as before..ive converted my merc/mariner hybrid and uprated at the same time,putting a 5 head (mariner)onto a merc 4 chassis,and all the tank connections came free!!as noted,refuelling at sea is downright dangerous,plus also its inevitable that tiny but lethal drops of rainwater get past the breather cap..do check the diaphragm rubbers on the pump..previously gravity assisted,they may not be as good on a remote tank-service literature states 100 hours use only,replaced mine after doing the mod..big difference..regards.