Mercury 4Hp 2 stroke, from an external fuel tank

[jimbouy]

Does any one know if i can conert the above OB to run off a tank kept in the aft locker/

<hr width=100% size=1> "It is a pleasure to give advice, humiliating to need it, normal to ignore it"

 

[extravert]

If it has an integral fuel tank which sits above the engine inside the cowl, the problem with running from an external tank is that the engine may not have a fuel lift pump, and instead be gravity fed. If the engine has no fuel lift pump, you are probably a bit stuck.

<hr width=100% size=1>One day, I want to be a real sailor. In the mean time I'll just keep tri-ing.

 

[duncan]

I have the same engine and wish to do this as I still have the external tank from the previous engine that was 'lifted' last year.

I have been advised that the 4hp is basically the same engine as the 5hp but does not have the connectors as standard. You need (1) an inline fuel filter (2) some pipe (3) a tee piece and (4) the tank connector.

Have a look under the cowl of someones Merc/Mariner/ Tomahasu 5hp to see how they are put together!

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[jimbouy]

I'll have to do some digging.

It really would be far more usefull to be able to do so.


Jim

<hr width=100% size=1> "It is a pleasure to give advice, humiliating to need it, normal to ignore it"

 

[aitchw]

I have been looking at the same idea with mine. The bottom casting has all the holes, lugs and other paraphanalia and the gear shift has the keyhole/bayonet for the cable as has the lift handle on the front for steering. There is no switch for the fuel line to go from external to top tank but that would be easy to get round. Simplest (but least likely to be available) would be to find a scrap 5hp to vandalise but how do you find one. I'm not sure about the lift pump. I figured the carb maybe produces enough suction to draw fuel the foot or so (vertical) needed but what do I know?

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[duncan]

I had assumed it was capable of grabbbing the fuel along the standard fittings and up a reasonable distance - 5hp and (4hp /4s) has about 3.5m of fuel line and in most situations is unlikely to be mounted much more than a couple of feet below the powerhead.
Regarding on/off/remote I was planning on using off as swithched to remote.

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[sophie4]

My last boat had a 4hp Merc. and that ran from an external tank, I took out the internal one and put in more sound insulation. I am sure you can get a kit to convert them but it is probably v. expensive, from what I remember the previous post is right, there is a two way tap and an inline filter. Sorry not to be more help but itwas converted when I got it.

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[fastjedi]

Yeep! I have a 1996 Mercury 4 Saildrive running an external tank. I assumed it was plumbed for an external tank from new ..... but on closer inspection the fuel hose to the external connector is a different type. Here's a run down on how it works.

With the fuel tap in the on position it takes fuel from the internal tank
With the fuel hose in the off position it takes fuel from the external tank

An external connector is mounted directly above the RHS of the handle (The choke is directly above the LHS) The external connector is Teed into the pipe between the fuel tap and the filter (on the way to the carb)

Not sure if it is an official kit ..... Looks like the external connector screws to the handle ... so it might be. Let me know if you would like photos


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[jimbouy]

Picturtes would be really usefull if you have the time, may be you could post them as there seem to be others with the same thought. Or P.M. me for my email address.

<hr width=100% size=1> "It is a pleasure to give advice, humiliating to need it, normal to ignore it"

 

[tross]

I did this on my Yam a few years ago. You need some internal fuel pipe, a Y or T section joiner and the external tank connection valve from the Yam dealer.

Remove the internal tank on/off externtion lever that goes between the fuel switch and the "panel" - this nomally is held in via a 10mm bolt, and replace this with the external tank valve using the same bolt.

Connect the external valve and the internal tank fuel lines to the carb via the Y /T piece joiner.

You can run from the external tank by switching off the internal tank - you can still do this with your fingers directly on to the switch. For internal tank - switch on your internal tank and remove the external connection.

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[aitchw]

Good, I'm glad you think as I do that no pump is necessary. Having weighed up other posts I reckon the bits needed shouldn't be more than a few quid and needn't come from a swindlery apart from the fuel connector.

I'll have to give it a go. Now all I need to do is get my two sailing dinghies sorted, collect the Sharky and do what's needed on her, finish the building work out back, sort the kitchen, put the new bathroom in, spend time with my son and remember to say hello to SWMBO occasionally and make a living. No Problem!!!!!!!!

Howard

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[duncan]

alternatively you could just go boating................./forums/images/icons/smile.gif

On the piece/bits it's the male connector that seems the mercury specific component - where will you source this (so that I can get one too!)

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[aitchw]

Being the only family member with nautical asperations it's difficult.

On the bits and pieces front, haven't started to look yet but my at my favourite online chandler they list a few bits which suggest they might not be too pricy though not obviously the particular part.

http://marinestore.co.uk/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=fuelcons

There appears to be some choice. I'll have a look at the club Yamaha to get an idea what I'm looking for. If you find a suitable part in the meantime I'd be glad to hear from you.

I've got to call in at my local(ish) service centre soon so will ask there too.

How did I end up this far from the sea?

Howard

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