Kicker motor dies when fuel level drops to half-full

[WadeSc]

Hi everyone.<br />I'm new to this forum and have searched for my question without success. I have a 22' Starcraft Islander with a 4.3L Mercruiser I/O and a 9.9hp 4 stroke Honda kicker motor for trolling. I have the Honda's fuel line plumbed from the I/O's fuel/water separator through about 10 feet of fuel hose straight to the Honda. The boat has a 50 gallon fuel tank. When the tank gets down to about half-full, the Honda's fuel pump can no longer pump the fuel up and it dies. This is a brand new motor and my previous 9.9hp Merc did the same thing. I'm considering T'ing the fuel line just off the main tank thus bypassing the fuel/water separator for the trolling motor. Do you guys think this would help or does anyone have any other ideas? I would appreciate any suggestions. Thanks<br />Wade

 

[bubbakat]

Re: Kicker motor dies when fuel level drops to half-full

You probably would be better off doing as you suggested. The smaller kicker fuel pump probably can't pull that fuel that far when the volume of fuel recedes.

 

[Canuck 16]

Re: Kicker motor dies when fuel level drops to half-full

You could always carry a 6gal portable tank, and run your kicker off it if your main goes below half.

 

[navigator336]

Re: Kicker motor dies when fuel level drops to half-full

You could try using larger fuel line and then adapt it back down at the kicker. The larger diameter hose will have much less restriction to flow. It sounds like what's happening is as the hydrostatic pressure of the fuel in the tank drops (12" of fuel head equals about .38 PSI), the 10 foot run of fuel line presents enough restriction to flow that the kicker's fuel pump can't overcome it without the added hydrostatic pressure from the tank.

 

[Catchem]

Re: Kicker motor dies when fuel level drops to half-full

WadeSC,Same thing exactly happenned to a friend of mine.We went from 5/8" hose to 1" hose.Approximately 10' long.Problem resolved.Try it and hopfully it will work for you too.

 

[navigator336]

Re: Kicker motor dies when fuel level drops to half-full

Just a quick point of reference. Hose and tubing and pipe, etc. is sold by inside diameter (and wall thickness) not outside diameter. Typical hose I.D. for a kicker motor would be 5/16" (or 3/8" max). If it is currently 5/16", going to 3/8" will reduce resistance to flow by 43%.

 

[WadeSc]

Re: Kicker motor dies when fuel level drops to half-full

Thanks for the responses. I've bypassed the fuel/water separator of the I/O motor and the kicker ran fine idling in the driveway. If that doesn't fix the problem, I'll try the larger diameter fuel hose. <br />Wade

 

[Solittle]

Re: Kicker motor dies when fuel level drops to half-full

Wade - Not a good idea to bypass the fuel/water seperator.

 

[Catchem]

Re: Kicker motor dies when fuel level drops to half-full

Whoa Wade,I agree with SoLitte,not a good idea to bypass fuel/water seperator unless you like rebuilds onyour kicker.Do you think part of the problem your having is because of flow restrictions thru the water/fuel seperator?Bypassing the filter will be less restrictive but... more damaging if water gets to your motor.

 

[WadeSc]

Re: Kicker motor dies when fuel level drops to half-full

Thanks for the warnings. After reading all the helpful advice here, here's what I've decided to do: Replace the 5/16" fuel hose with 3/8" and place a small Racor brand water separating fuel filter in line with the fuel hose close to the kicker motor.<br />Wade

 

[Catchem]

Re: Kicker motor dies when fuel level drops to half-full

Hey Wade,don't forget to post your results,OK.

 

[WadeSc]

Re: Kicker motor dies when fuel level drops to half-full

Just a follow-up to let anyone interested know what I did and what results I had. <br /><br />I placed a T in-line with the main fuel hose just aft of the fuel tank (bypassing the Mercruiser's fuel/water separator). Then I ran 3/8" hose back towards the kicker motor. About 2 feet before the hose exits out the transom to the kicker, I placed a new small Racor brand water separting fuel filter in-line. (I found it here for a good price, by the way.) I then reduced the fuel hose diameter back down to 5/16" at the outlet of the Racor filter and ran it out the transom to the primer bulb and the trolling motor.<br /><br />I squeezed the primer bulb to fill the Racor about 2/3 full, then started the kicker and let it run at fast idle for about 45 minutes. The fuel tank was slightly less than half full and the motor ran fine and the fuel level in the filter actually increased as the motor idled. So I think this has fixed the problem while still keeping a water separating fuel filter in-line. That big Mercruiser filter must have just had too much resistance for the small fuel pump in my 9.9 hp Honda.<br /><br />Thanks for all your help and I'll let you know, if the problem recurs. <br /><br />Wade

 

[DJ]

Re: Kicker motor dies when fuel level drops to half-full

Wade,<br /><br />Good info.<br /><br />Thanks for sharing your results.