Fuel line for Merc 9.9 Outboard-gctid371570

[Guest]

Last step to complete my kicker install is to run the new fuel line. I know running off the same tank as the main motor is not recommended by some as if the tank get's contaminated both motors will be effected but feel it is the best option for me.

I have tapped a new shutoff valve off the empty exit port on my fuel filter body 1/4" NPT and have the quick connect hose with primer bulb (I think this is 3/8" hose).

Going to have about 100" run of hose to get to the outboard on the Port corner.

1) What diameter hose is recommended?

2) Any specific grade of fuel hose?

3) I was going to cut the tank end of the quick connect off the primer bulb hose and connect that to the new hose I am running. What is the recommended connection for this?

[Guest]

I am of the opposite regarding running tow motors off of the same fuel tank. It's in the "How It's Done" that protects both motors. I run a Dual Outlet Raccor fuel filter, one outlet to the main motor, and the second one to a OMC Accumix (2 stroke oiler) and then out to the 15 HP kicker. Another advantage to this method is that I put my Lowrance Fuel Flow sensor ahead of the Raccor, that way I am monitoring the fuel rate usage of two engines with one filter.

[Guest]

That's what I am doing outside of the fuel flow sensor and oil mixer (this is a 4 stroke outboard).

Any recommendations on the hose size/rating?

[Guest]

I also have a 2452, and I found that using the typical 5/16 hose I would lose the prime on the fuel bulb, probably due to the distance/height between the tank and the kicker (imagine sucking water through a straw - the larger diameter the straw, the harder you have to suck. The fuel pump on the kicker could not suck hard enough for the large 5/16" straw). Anyway, switching to 1/4" solved this and the kicker runs exactly the same from idle to WOT. Oh yeah, and of course use the right USCG MMA certified hose for inside an engine compartment.

[Guest]

Alright. Got 3/8 fuel line run from the exit on the water/fuel seperator to the outboard. Hooked a standard primer bulb hose from the hose to the motor.

Issue is i cant seem to get any or enough fuel to the motor. Pump the bulb for a good 10 minutes but it never got firm. Yes, the shut off valve after the filter is open. I can hear air getting pumped into the main tank and into the ob.

Had a few small drops of fuel when i diisconnected the primer buld hose but that was it.

Tried turning on the main engine key to energize the fuel pump and even tried starting the main engine for a short while.

Any ideas what i need to do to get good fuel to the kicker?

[Guest]

Got the fuel issue figured out today. It was a combination of a bad pump bulb on my hose and i made a mistake and ran the fuel line too high above the tank (40").

Lowered the hose and borrowed a different hose and all is good.

Now if only WM will take the brand new hose back even though i bought it last year. I spent enough this year at that store with all my projects.

[bhawes]

Keith. You should install a gasoline rated shut off valve in that auxillary fuel line. It can happen that your main motor's fuel pump will suck the fuel out of that line rather than the main fuel line to the tank. Once the hose and float assembly bowl are empty, it then starts sucking air, and your main motor suddenly quits (for no good reason that you're aware of), because it is starved for fuel. Oh well you say, that's why I have a kicker. Then when you try and start your kicker, old reliable fails to start on the first few pullls as usual, because you have no idea that it has been sucked dry. Don't ask me how I know this. It cost $150 for the tow in, and as the main motor quit while in gear and under power, it misfired (backfired) a couple of times before finally dying. My those larger engines make wonderful water pumps when they run backwards! I didn't get around to working on it for a week or so, so didn't realize that the crancase had injested a couple quarts of saltwater. Yep, figure in another$2,500 for a total overhaul, plus my own time to pull it, strip it down and off to the machine shop. Even after all of that, it wasn't until a mechanic doing some work my boat noticed that I didn't have a shutoff valve, and warned me of what could happen! Now you tell me!! It had a shutoff before my next outing.

[Guest]

bhawes wrote:
Keith. You should install a gasoline rated shut off valve in that auxillary fuel line. It can happen that your main motor's fuel pump will suck the fuel out of that line rather than the main fuel line to the tank. Once the hose and float assembly bowl are empty, it then starts sucking air, and your main motor suddenly quits (for no good reason that you're aware of), because it is starved for fuel. Oh well you say, that's why I have a kicker. Then when you try and start your kicker, old reliable fails to start on the first few pullls as usual, because you have no idea that it has been sucked dry. Don't ask me how I know this. It cost $150 for the tow in, and as the main motor quit while in gear and under power, it misfired (backfired) a couple of times before finally dying. My those larger engines make wonderful water pumps when they run backwards! I didn't get around to working on it for a week or so, so didn't realize that the crancase had injested a couple quarts of saltwater. Yep, figure in another$2,500 for a total overhaul, plus my own time to pull it, strip it down and off to the machine shop. Even after all of that, it wasn't until a mechanic doing some work my boat noticed that I didn't have a shutoff valve, and warned me of what could happen! Now you tell me!! It had a shutoff before my next outing.

Not sure why you'd need an auxiliary shutoff valve since squeeze bulbs have integrated check valves... isn't this redundant?

[Guest]

I did install a fuel shut off directly after the fuel/water seperator. It will be closed whenever the kicker is not running. The problem with just the check valve in the hose is that is only a few feet from the kicker, nothing stopping the main motor from sucking the rest of the fuel out of the kicker feed line.

[Guest]

keithjabber wrote:
I did install a fuel shut off directly after the fuel/water seperator. It will be closed whenever the kicker is not running. The problem with just the check valve in the hose is that is only a few feet from the kicker, nothing stopping the main motor from sucking the rest of the fuel out of the kicker feed line.

Doesn't make sense to me. Regardless where the check valve is, if it's working then it's impossible for the main to suck fuel from that line. If it only sucked fuel from the first few feet of the line, where does the air (void) come from that displaces that fuel? Doesn't seem to follow the laws of physics...

[Guest]

I guess if you assume that absolutely no air can escape through the check valve then that might be true. It might also create a vacuum in the hose and collapse it.

Heard similar stories to bhawes. Not going to risk it over a $25 fuel valve. That will also keep all of the fuel in the line to to the kicker making it easier to prime the next time.

[Guest]

keithjabber wrote:
I guess if you assume that absolutely no air can escape through the check valve then that might be true. It might also create a vacuum in the hose and collapse it.

Heard similar stories to bhawes. Not going to risk it over a $25 fuel valve. That will also keep all of the fuel in the line to to the kicker making it easier to prime the next time.

Makes sense. I haven't had an issue w/ just the bulb but I can see how it's possible.

[Guest]

A few thoughts after reading this thread.

1.Primer bulbs will lift a LONG way but they like to have fuel in them,air not so good. Ive found they work best vertical,pumping uphill not downhill, You can nearly always get fuel going by the squeeze ball/kink outlet shut/release ball/repeat/repeat technique. Once ball has gotten fuel in it by doing this sequence the kinking shut becomes unnecessary usually. Primer bulbs dont have a real good grade of check valve I guess. Some(the little ones) only have a check on one end.

2.No way would I have my aux running off the same fuel filter or any part of the fuel line for the main engine. If you have a main eng failure theres a real good chance its fuel related. (Maybe youre even OUT of fuel?).Why would one want that fuel issue,whatever shape or form it is,presented,gift wrapped, to the supposed "get home" motor.

[bhawes]

If it wouldn't have hapened to me, I probably wouldn't believe it either. I did have a primer bulb, but that didn't stop it from occurring. Take it for what it's worth.

As far as running off of the same tank, with adequate filtration, (and I have 3 in line, including 2 water separators) I either been very lucky, or well equiped. I've not had a problem (since adding the fuel stut off to my kicker), in over 25 years. I just find that carrying that extra tank for the kicker, leaves a 5 gallon container of fuel somewhere that you don't want it. I do, however, carry a 5 gallon jerry can when there's a possibility that I may go offshore, but that seldon is the case.

[Guest]

telstar1 wrote:
A few thoughts after reading this thread.

1.Primer bulbs will lift a LONG way but they like to have fuel in them,air not so good. Ive found they work best vertical,pumping uphill not downhill, You can nearly always get fuel going by the squeeze ball/kink outlet shut/release ball/repeat/repeat technique. Once ball has gotten fuel in it by doing this sequence the kinking shut becomes unnecessary usually. Primer bulbs dont have a real good grade of check valve I guess. Some(the little ones) only have a check on one end.

2.No way would I have my aux running off the same fuel filter or any part of the fuel line for the main engine. If you have a main eng failure theres a real good chance its fuel related. (Maybe youre even OUT of fuel?).Why would one want that fuel issue,whatever shape or form it is,presented,gift wrapped, to the supposed "get home" motor.

Thanks for the advice on the squeeze, pinch technique. That might have been the issue with the new hose.

Regarding #2 I went back/forth with this for awhile also. The hassle of portable tanks or installing a 2nd tank, fill, vent, etc lost out eventually. Still open to differing opinions on this but in my research I found the the majority of boaters opted for plumbing off the main tank (not that that means it is the best choice by any means).