Fuel line length

Rusty nail · 05 April 2020, 19:21

Hi, looking for a bit of advice. I need to lengthen the fuel supply line to my Honda BF150 on my 6.8m rib by 8ft, 2.5m. It is 8mm internal dia line. Is there a limit to length before pump will struggle to lift? Thanks.

Last Tango · 05 April 2020, 20:37

My fuel line is 8mm about 5 meters feeding a Merc F150..... No issues ��

Rusty nail · 05 April 2020, 21:09

Sorry, I should have said it is 3.6m now so it will be 6m when run, so should be ok? Thanks for reply much appreciated.

Pikey Dave · 05 April 2020, 21:50

Check the manufacturers spec. It’ll be in the rigging instructions.

Rusty nail · 05 April 2020, 22:39

Thanks Pikey Dave but I've the manual and instal instructiins but can't see anything relating to hose length.

Pikey Dave · 05 April 2020, 22:56

Quote:

Originally Posted by Rusty nail

Thanks Pikey Dave but I've the manual and instal instructiins but can't see anything relating to hose length.

8mm-5/16th is pretty standard for most medium sized 4strokes. BRP specify 10mm-3/8th for etecs over 90hp. I’d be tempted to go 10mm but that’s just me being over cautious.

Orwell boy · 05 April 2020, 23:35

Quote:

Originally Posted by Rusty nail

Thanks Pikey Dave but I've the manual and instal instructiins but can't see anything relating to hose length.

i suspect the hose length is pretty insignificant ,when compared to the pressure drop /flow characteristics of your filter ,you are getting enough fuel thru 5/16" hose assembly; so partially blocked filter ,and if you were changing height differential would have far more effect than adding a few metres of smooth bore hose i would guess . you could always try your desired hose length fitted on a tempory tank ,but dont forget to go via filter and have the tank at the right height .

jeffstevens763@g · 06 April 2020, 10:21

i left my tank vent shut once it dawned on me when my tank started to collapse i doubt 8 m will be an issue although you could fit an inline electric pump if it did.

Rusty nail · 06 April 2020, 18:56

Thanks everyone for replies, I have rigged up an electric pump which lifts from the under deck tank and feeds a header tank, overflowing back to main tank. This smaller tank 2.5l in turn supplies the engine. My friend has suggested this is overkill and a single feed would suffice, I now tend to agree with him. Thanks

Searider · 07 April 2020, 10:17

Quote:

Originally Posted by Rusty nail

Thanks everyone for replies, I have rigged up an electric pump which lifts from the under deck tank and feeds a header tank, overflowing back to main tank. This smaller tank 2.5l in turn supplies the engine. My friend has suggested this is overkill and a single feed would suffice, I now tend to agree with him. Thanks

I'd agree with your friend - the pump is another thing to go wrong and prevent you getting fuel at all!

I'd recommend a single length of hose if you can - or at least with as few joints as possible. Each joint is a restriction.

GuyC · 07 April 2020, 12:04

Whilst I'm not partcularly H&S orientated, just check the pump is OK for pumping petrol.

Whilst the majority are probably in agreement that it might be considered overkill, if you've gone down this route already, you could fit a filter in the line between the under deck tank and the header tank and you would, in effect, polish the fuel.

Last Tango · 07 April 2020, 12:51

Quote:

Originally Posted by Rusty nail

Thanks everyone for replies, I have rigged up an electric pump which lifts from the under deck tank and feeds a header tank, overflowing back to main tank. This smaller tank 2.5l in turn supplies the engine. My friend has suggested this is overkill and a single feed would suffice, I now tend to agree with him. Thanks

Yep your friend is right. just something else to go wrong.

If you're increasing the length of the hose I'm guessing the tank is further forward, hence higher relative to the engine. Remember, it's not just ribs these engines are used on and a 6 meter fuel line is probably nothing exceptional in general "boat" terms. I'd just give it a try and if there's a problem (and there won't be) up the diameter of the line.....

Rusty nail · 08 April 2020, 20:14

Quote:

Originally Posted by Searider

I'd agree with your friend - the pump is another thing to go wrong and prevent you getting fuel at all!

I'd recommend a single length of hose if you can - or at least with as few joints as possible. Each joint is a restriction.

I have opted for 10mm hose, join at tank and join at filter/separator reduced joins from 10 to 2. It has been running fine in my flushing tank. I think it will be ok on the water, (whenever I get a chance to try it)

Rusty nail · 08 April 2020, 20:19

Quote:

Originally Posted by GuyC

Whilst I'm not partcularly H&S orientated, just check the pump is OK for pumping petrol.

Whilst the majority are probably in agreement that it might be considered overkill, if you've gone down this route already, you could fit a filter in the line between the under deck tank and the header tank and you would, in effect, polish the fuel.

That is exactly the set up that I had, the fuel was getting polished as it re-circulated through a filter separator. I have now simplified the whole set up, removing pump, back up pump, filter and 2.5 litre tank. I now have a 10mm hose with two connections and a whole load of space in my console. I'm sure it will be fine, What can go wrong???