Fuel Line Size

T

Tug

New member
I am finally getting around to replacing my fuel lines.The fuel line size from the gas/water separator to the motor is 5/16 inch ID. The fuel line from the gas/water separator to the gas tank is not marked.( the size of the hose). Can i assume that the gas line entering the gas/water separator is the same size existing the gas/water separator.Also should the squeeze bulb and fittings be a size lager than the hose to get a tight leak proof fit.Tug
 
Bulbs and fittings are sized for the I/D hose. You need good hose clamps.

Don't assume that all fittings are the same size. 1/4", 5/16" and 3/8" fuel lines are used in outboard boats. I have had boats which had 3/8 from the tank to the filter,and then 5/16 from the filter to the engine. The fuel line should have the size marked on it. Check before replacing. Be sure that you get fuel line which is approved for alcohol, because of the E 10 issues.
 
Bob, i think your correct, i remember i just replaced the primer bulb and it was 3/8 inch. I probably have 5/16 inch from the fuel filter to the engine and 3/8 inch from the gas tank to the fuel filter. I will re-check tomorrow before i order new hose.Earlier today i notice that some of the fuel line hose was cracked ( outer casing ) around the fuel line clamps, better to replaced them all. Will order Trident "Barrier Lined" Fuel Hose Type A -15 # 365 from Defenders.Tug
 
If you add a fuel flow setup,make sure you design the setup so you can easily bypass the paddle wheel and the small filter that goes in front of the paddle wheel should it get clogged. That filter is the first one in line usually. I left the hose from the tank fuel valve to the fuel filter and paddle wheel a little long so I could remove it and still have enough to bypass the fuel flow assembly and go straight to the main 10 micron filter.

Dave
 
another comment

I added a on/off valve to the filter head for the kicker fuel line and plan to add another one for the OB fuel line
 
There should always be a valve for the kicker line to prevent the main engine from being able to draw air from the kicker line and running lean.

Usually the valve at the connector works just fine, but should it fail, you can risk an expensive engine repair.
 
Great advice Matt

Here is a corrected report

I had a valve for the kicker and removed it for cleaning, replaced the tape with fuel resistant thread sealant and repositioned the on/off lever
 
Just ordered my new fuel hose from Defenders,went down to my boat and re-checked the ID of the fuel lines.They were indeed different, 3/8 & 5/16 inch I.D..... bought the Trident " Barrier Lined" Type A-15 # 365 .Tug
 
Just a note for information:

All marine (and probably automotive) fuel lines and hoses have their date of manufacture stamped onto them by a continuous ink stamp roller using contrasting color ink.

Officially, the marine industry (according to my previous marine dealer) says you should completely replace all fuel hoses every five years.

To me, that seems excessive for light recreational use, but it still behoves us all to check their condition every few months, and replace any that are showing wear/brittleness/cracking/etc.

Joe. :teeth :thup
 
Mystery solved, in one of the spare parts boxs that came with the purchase of the boat i found this information about the fuel hoses: 3/8" x 60" from bulb to filter---- 3/8 " x 20 ' from bulb to tanks---5/16" x 30" from water separator to engine. It seems that the 5/16 " fuel hose came from a Sierra Silverado 2000 Universal fuel line assembly kit and the 3/8 " fuel hose(s) came from a Tempo Universal Fuel Line Assembly kit. I am not sure how old these hoses are but they are probably about 10 years old, the kits sold for $25.95 @ Morrow Bay RV & Marine. I feel alot better now about replacing them. Tug
 
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