View Full Version : replacing fuel lines

01-21-2014, 06:00 AM
My outboards’ fuel lines are now 9 years old and look pretty weathered. The last 3’ of hose is pretty much exposed to the elements year round as it’s run across the top of the pontoons' enroute to the engines. Toward the end of the summer, I squeezed one of the fuel primer bulbs and heard some crackling noises, so I’ve left them alone since – I’ve never needed to use the primer bulbs anyway. Since I have Honda 4 strokers, I checked into Honda’s fuel lines and [good God!!] they want ~$70 for a 7’ section with a primer bulb.

Are there any alternative products, like automotive or general USCG approved products I could buy by the foot instead of a preassembled kit by Honda / Yamaha / Mercury? I need about 9’ per side of ¼” ID. I can buy this stuff all day long at any auto parts store. What’s the difference between auto and marine….I’m betting there are.

Additionally, I bought and will install some fuel water separators, as my boat didn’t come with them to begin with. I was told that Honda now mandates these are installed in any new boats or the warranties are voided. Back in ’05, when my boat was built, this wasn’t commonplace.

01-21-2014, 08:40 AM
Marine fuel lines aren't cheap, but you don't need to pay $10 a foot. I would look at Sierra brand. They are a company that makes marine aftermarket items like filters, oils, and hoses. I normally shy away from "brand X" products, but my local marina talked me into trying some of their stuff and I have had good luck with it. If the line is still expensive in the aftermarket brand, you might be able to cut the end off a $30 Mercury line and replace it with a Honda end or even buy the components separately and make up a line. If you make up the line from scratch, you might want to look into Oetiker clamps instead of screw clamps.

01-21-2014, 09:08 AM
I think I'm going to settle on this http://www.tridentmarine.com/stage/documents/305B1-15FUELHOSESpecificationSheet.pdf

It seems to be a high quality fuel hose and it's specifically built for outboards and above-deck applications where it'll see sun exposure. I don't need any special fittings b/c everything is already clamped into place. Only think I'll need to buy now is a good fuel primer bulb.

01-21-2014, 09:07 PM
Trident is a very high quality hose and meets USCG, EPA and SAE requirements for marine fuel hose. Just so you know, there are significant differences between auto hose and marine fuel hose. Auto hose does not meet the same requirements as marine. Marine fuel hose should be replaced at least every five years anyway. Most of the wear on fuel hose is internal. You can't see it. 9 year old hose does not meet the current standards for marine hose. So by upgrading you will be bringing your boat into compliance with current standards.

01-30-2014, 05:38 AM
Regarding my fuel water seperators, I bought 2 of them. My starboard engine will have its own and my port engine and 12.5K Westerbeke generator will share the other one. The devices will be located very close to the fuel tanks where the fuel lines originate. As I've mentioned before, the outboards take 1/4" ID hose and my generator takes 3/8" ID hose. On my port fuel water seperator that's feeding the gen and outboard, I have concerns that I may have problems with the generator stealing the gas from the outboard causing either the outboard or the generator to stall out. I will have 2 hoses feeding the fuel water seperator, which will be the same size that each motor requires. So, 2 in and 2 out of the same sizes. These devices can filter up to 90 gallons per hour, which is WAYYYY below my fuel consumption rate for both engines combined.

Just wondering if I should feed the fuel water seperator with 2 - 3/8" ID hoses instead of 1 - 1/4" and 1 - 3/8". What do you think?

01-30-2014, 04:58 PM
I am a fan of limiting the number of different size hoses or whatever you have on your boat. You might never need to do a makeshift temporary repair to get out of a tight spot, but if you do you will be glad if you have all the same size hoses so you can swap things around if need be. I would spring for all the same size hose, whatever size you decide on. For many outboards, 5/16" is getting common.

01-31-2014, 06:18 AM
I agree with you there Endurance, however my outboard needs to pull the fuel through ~7' of hose + the fuel water separator now. I was warned that up-sizing the hose would increase the weight of the fluid being pulled through the already long hose and the outboards fuel pump may not be able to handle the increased load. Essentially, it's like sucking a think milkshake through a straw - easier if it's a short run than a long loopy one.

02-03-2014, 09:07 AM
Maybe somebody with a good understanding of fluid dynamics could weigh in on this, but I'm thinking that if I were sucking a a thick milkshake through a straw, I'd rather do it through a larger straw than a smaller one. I think you're 100% right trying to limit your length and wouldn't propose adding to it, but that it would only help your situation to increase your outboard motor fuel lines from 1/4" to either 5/16" or 3/8".

One reason I can think of for the trend for outboard manufacturers to drop from 3/8" to 5/16" lines is that they also seem to be doing away with primer bulbs. A smaller line has less "dry sucking" time before it gets fuel after running dry. That may not be that big a deal on a houseboat with permanent motors and permanent fuel tanks since we try to avoid running out of fuel. Smaller lines also evacuate fuel faster so there's less time with fuel running through a hot line and warming from the (hopefully) cool fuel coming out of the fuel tank.

For what it's worth, two 5/16" lines would have nearly identical cross-section area as a 1/4" line and a 3/8" line. We already know that 5/16" is plenty of fuel line for your outboards since they are working okay with 1/4". It would surprise me if your generator used more gallons per hour than an outboard at wide open throttle. I think I would replace everything with 5/16", but there's nothing wrong with all 3/8" if you worry about starvation.

02-04-2014, 08:41 AM
our boat has 454's and a 9 kw westerbeke. it has 3 fuel/water separators 1 for each engine,all have 1/4 inch lines. so far no problems. not sure if outboards work the same. trident 5/16 marine grade fuel hose on e-bay is 3.49 per foot.

02-04-2014, 01:40 PM
trident 5/16 marine grade fuel hose on e-bay is 3.49 per foot.

It's 2.29 here (http://www.defender.com/product3.jsp?path=-1|2243574|2243581&id=1404060) and they seem to maybe have the best price on other line sizes also.

02-05-2014, 07:37 AM
Thanks for your shopping site suggestions guys, but I searched around to find a site that offered both Trident A1-15 1/4" and Trident B1-15 3/8" type hoses because I didn't want to pay ~$10 for shipping 2 different time. I stumbled upon www.go2marine.com where they had both at the unbelieveable price of only $0.19 per foot and $0.14 per foot respectively! I looked long and hard b/c this pricing is too good to be true. I'm certain it's the correct products I ordered, but I'm betting someone made a pricing error on their site b/c that shouldn't be that cheap!

I'll let you guys know if I have any problems.

02-05-2014, 01:56 PM
I called them and, as I figured, it was their mistake. They were selling by the inch, not the foot, but they didn't note anywhere that it was by the inch. They apologised, fixed their website, adjusted my order, and now I'll get the proper lengths I need, instead of inches of hoses.