Author Topic: Fuel Line Question  (Read 191 times)

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Offline ThePatriot

Fuel Line Question
« on: March 30, 2020, 08:34:15 AM »
Hi all

I have a 2005 Honda BF150 on my SR.

The fuel hoses from the tanks to separator filters are all 3/8.  From the separator to the motor (bulb hose) the line is 5/16?

The bulb hose is looking tired and I want to change it out.  Honda parts are calling for a hose labeled 7.3x2000.  I’m assuming that’s mm.  Which would make it slightly smaller than 5/16. 

I always thought that motors over 100hp should have 3/8 fuel hoses?

Any thoughts?


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Offline ohmytodd

Re: Fuel Line Question
« Reply #1 on: March 30, 2020, 08:51:52 AM »
I have the same main as well as a kicker that take 5/16. Everything works just fine, and yes, that factory Honda line is a tight fit on a 5/16 barb, but it works. Sportcraft should have those fuel line assemblies in stock, but they're pricey!
1997 Sea Ranger 19 Hey Nineteen, Honda BF150, 2019 Suzuki df9.9

Offline ThePatriot

Re: Fuel Line Question
« Reply #2 on: March 30, 2020, 10:40:42 AM »
Yeah mine has worked fine too but I’ve been reading that 5/16 on that size motor could make it run lean at higher RPMs.


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Offline ohmytodd

Re: Fuel Line Question
« Reply #3 on: March 30, 2020, 11:27:34 AM »
Yeah mine has worked fine too but I’ve been reading that 5/16 on that size motor could make it run lean at higher RPMs.


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I don't think you'd have an issue, it's factory spec. Larger probably won't hurt anything, but you'd need an adapter to size down to the motor connection or find an aftermarket connector.

I had Sportcraft replace all of my lines last Fall to factory spec and they used the smaller diameter.
1997 Sea Ranger 19 Hey Nineteen, Honda BF150, 2019 Suzuki df9.9

Offline Fisherdv

Re: Fuel Line Question
« Reply #4 on: March 30, 2020, 11:49:23 AM »
With the Honda motors being so fuel efficient, I think you will be fine with the factory rated diameter. 5/16 under pressure should be more than enough fuel.
2018 Sea Chaser 16, Honda 60HP

Offline davidsea

Re: Fuel Line Question
« Reply #5 on: March 30, 2020, 01:42:02 PM »
   Back in the middle ages, when I used to race boats, we had similar concerns.  In the days of carburetted 2-stroke motors, with wimpy diapragm fuel pumps run on crankcase pressure pulses, going lean on top end was a very expensive no-no. Engine RPM would increase momentarily, followed by loud noises and then complete silence. The old rule-of-thumb was that fuel flow was 1 gallon per hour for every 10 horsepower being developed - a motor putting out 100 horsepower would burn 10 GPH.  That old rule is pretty much still true, although newer 4-stroke, fuel-injected, electric fuel pump, computer-controlled motors do a little better than that, and are a lot less likely to be affected by restricted fuel flow.   Some of the race guys set up a very simple test - they hung lengths of fuel line vertically, stuck funnels in the top, and measured how long it took for gravity to push a measured amount of fuel through.  Without a pump (actually, without vacuum), it was thought that 5/16" was good to about 125-150 HP, and 3/8" from there up, except for the 300+ HP race motors, which used 1/2" line and regulated electric pumps.  For Arima-size modern motors, I'd be comfortable with 5/16" for everything except for 200-250 V6's.
1996 SR19 Hdtp. - 2018 Honda 115
2009 Duroboat 16 CC, Honda 50  -  SOLD
and 19 other boats (I think, lost count)

Offline ThePatriot

Re: Fuel Line Question
« Reply #6 on: March 30, 2020, 03:40:34 PM »
Thank you.  I think I’ll stick with the recommended 5/16 replacement. 


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Online mariner

Re: Fuel Line Question
« Reply #7 on: March 30, 2020, 05:00:50 PM »
Thank you.  I think I’ll stick with the recommended 5/16 replacement. 


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If the fuel hose that comes out from under the cowling of your BF150 is 5/16 and the manual states 5/16 is appropriate, stick with it.   Wouldn't hurt to contact a Honda dealer and ask what they recommend.  I don't know about Honda but current generation midsized to large Mercury OB have on their manual and from Merc technicians to NOT put a primer bulb or any additional in-line fuel filters(apart from the dedicated water/fuel separating filter) or anything that can restrict fuel flow to the engine. 
1999 19 Sea Ranger HT: 2018 Merc115 CT ProXS: 2018 Merc9.9 ProKicker

 

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