Fuel schematic/design help

[Pearl dog]

Hi all,

My buddy is having a fuel issue that’s hard (for us) to diagnose. He running a single Suzuki 140 and a Suzuki 9.9 off the same inboard tank. Both the motors and boat are 2017.
On occasion he gets one of a couple symptoms such as the distinct smell of raw gas while running the main. Or the main bogging down while attempting to come out of the whole. Stuttering and sputtering for a while then catching and running fine.
It was suggested to him that he disconnect the kicker fuel line when it’s not in use and that seemed to help but doesn’t always totally cure these issues. It was also suggested his schrader valve was likely faulty however his fuel system doesn’t seem to even have a valve.
And one other thing, his squeeze ball for the main never truly gets hard even though it’s been replaced and he’s been told it’s “fine” that way right from the installing shop. The kicker also has a ball, that one gets hard as per normal.
I guess what I’m asking for is if anybody has a schematic, drawing or description of how this 2 motor 1 tank system should be plumbed and vented.
Long read. Thanks for getting this far…
Cheers.

 

[Viking]

Has he checked the anti siphon valve? I've had problems with them before.

 

[Pearl dog]

I think the problem is that he doesn’t seem to have any type of valve anywhere between the tank and either motor. I think the kicker fuel line is alternating between allowing air into the system and allowing fuel to escape when it’s not in use. I think a valve should be in the system to isolate the kicker from the main??

 

[Fishin]

Being a 2017 the main motor likely doesn’t need a primer bulb i know my new larger Merc doesn’t use them but my kicker does of course Anti siphon valve can cause issues like stated could also be an air lock issue on my old boat I had similar issues added a shut off valve going to the kicker problem solved. Tank might not be venting properly also, The best way to test the fuel system is to run the motor on a portable tank if the problem follows while running on the portable tank you know the issue is with the motor if the issues go away then you know it’s on the tank side.

 

[Alex_c]

I think the problem is that he doesn’t seem to have any type of valve anywhere between the tank and either motor. I think the kicker fuel line is alternating between allowing air into the system and allowing fuel to escape when it’s not in use. I think a valve should be in the system to isolate the kicker from the main??

I’d just throw a ball valve on the line to the kicker after the tee, and see if that fixes it. The connector at the kicker could be sucking air

 

[Sr SQ]

I think the problem is that he doesn’t seem to have any type of valve anywhere between the tank and either motor. I think the kicker fuel line is alternating between allowing air into the system and allowing fuel to escape when it’s not in use. I think a valve should be in the system to isolate the kicker from the main??

Most likely, however does each motor have a separate tank pick-up, it should.
Ditch the primmer ball on the main, it won't need one and it can give the fuel pump grief.
Don't know anything about the Suzi but there should be a schrader to bleed/test the fuel rail.

 

[Pearl dog]

Thanks all. Going to get at this next week. Appreciate the input.

 

[Reel Time]

The smell of raw gas would get me worried... I had a symptom years ago where the fuel/water separator fixture was lightly corroded and seeping gas, was an oddball. Who knows.

 

[N2013]

I’d check all fuel lines, primer bulbs, clamps, filters, water separators. Everything the fuel passes through on both motors. Or just replace all of it.

I ran my 115 & 8HP kicker from the same tank. Tank to inlet of fuel/water separator, then to each motor from the outlet of the fuel water separator. It had 2 inlets & discharges. No issues.

 

[Alex_c]

Another simple thing to rule out is a bad fuel fitting at the main or kicker. A bad seal in either can cause it to leak fuel and suck air

 

[N2013]

Most likely, however does each motor have a separate tank pick-up, it should.
Ditch the primmer ball on the main, it won't need one and it can give the fuel pump grief.
Don't know anything about the Suzi but there should be a schrader to bleed/test the fuel rail.

Why should the main not have a primer bulb? Curious to know.

 

[ship happens]

I'm going to make more popcorn and see where this goes

What is a VST for 200 Alex

 

[Fritz]

Why should the main not have a primer bulb? Curious to know.

Some outboards specifically tell you not to use a primer bulb. My engine has a fuel supply module with 2 fuel pumps inside. I think the issue was bulb collapse damaging the lift pump. I do what the owners manual says and if it says use a bulb then I do.

 

[Fritz]

Hi all,

My buddy is having a fuel issue that’s hard (for us) to diagnose. He running a single Suzuki 140 and a Suzuki 9.9 off the same inboard tank. Both the motors and boat are 2017.
On occasion he gets one of a couple symptoms such as the distinct smell of raw gas while running the main. Or the main bogging down while attempting to come out of the whole. Stuttering and sputtering for a while then catching and running fine.
It was suggested to him that he disconnect the kicker fuel line when it’s not in use and that seemed to help but doesn’t always totally cure these issues. It was also suggested his schrader valve was likely faulty however his fuel system doesn’t seem to even have a valve.
And one other thing, his squeeze ball for the main never truly gets hard even though it’s been replaced and he’s been told it’s “fine” that way right from the installing shop. The kicker also has a ball, that one gets hard as per normal.
I guess what I’m asking for is if anybody has a schematic, drawing or description of how this 2 motor 1 tank system should be plumbed and vented.
Long read. Thanks for getting this far…
Cheers.

So some other questions:
-Have you made absolutely sure you have zero fuel leaks, including running the engine with the cowl off?
-Do you know what your fuel pressure is?
-When was the last time the fuel filter was changed?
-When was the last time your Racor was changed?
-What does your owners manual say about installing a primer bulb?
-Have you run the engine with a known source of fresh fuel that you are positive is clean and a different batch then what’s in the tank?
-How old are your fuel lines? If they are 2017 and of low quality, used or attwood garbage then they should be replaced because they degrade from the indside out!
-Are the fuel tank vents clear of mud wasps and other foreign debris?
-What is the position of the fuel shut off(s) in the boat?
-Do you have a service/owners manual?

The last time I helped someone with a 140hp Suzuki that supposedly had fuel issues it turned out he had the original spark plugs, and the bottom 2 plugs were degraded from water ingress and the gasoline smell was the unburt fuel from the exhaust when he put the power lever up, so maybe confirm the simple stuff first.

I don’t need to know the answers lol

I hope this helps