Mariner V-150 Idle Problem

[TACOMATruckin98]

Well guys, I developed a problem the other day on the lake, luckily I wasn't far from the dock. Went out to go fishing on Friday the 13th, maybe that was the problem. We started to boat that morning to make sure that it was running correctly. When I started it, after a few seconds of idling it began to rev up like it was going lean. Upon closer inspection I found that I had a leak in the fuel line that connects the connector on the front of the motor, to the intake of the fuel pump. Replaced the line and went on to the lake. Got there and ran around and it was running great, great power, great idle, great running throughout the range, no problems at all, fished and when headed back to the ramp I let off to go under a bridge. When I idled back and the boat came off plane and the nose pulled up the motor chugged for a moment and cut off. I immediately tried to start it back but wouldn't even begin to hit a lick. Trolled back to the dock, and if I gave it just throttle I could push it forward while starting and it would crank, but if I tried to pull the control back to full neutral, it would just die out. Talked to several people and nobody knows. Here's what I do know. No fuel leaks, bulb gets firm. I took a fuel sample for phase separation but the fuel did not show any problems after 3 days of sitting. Drained the 3 bowls anyways, and hooked up to an external tank. When the motor is cold it starts right up perfectly and idles fine, but within probably 30-60 seconds the motor does the same thing and dies out, and can only start by throttling up. I do know that when it is running it seems to have excess oil through the exhaust/smoke enough that it blackened the grass below it after a few minutes. Checked the compression and it is 110-115 with the throttles closed, no change since I first bought it a few years ago. Plugs all look fine, and are not wet at least not excessively wet, nor excessively fouled out. Checked spark to each plug and they were all receiving spark. Honestly I'm completely lost on what is wrong with it, I honestly thought water in the fuel but it's on new gas right now. The motor is an 83 Mariner V-6 150hp. I've searched around, and asked everyone I know but we're all lost. Thanks guys for any help!

 

[1nebel0]

Re: Mariner V-150 Idle Problem

You most likely have a fuel problem....rebuilding those carbs is easy and will eliminate guessing if you have dirt in them blocking the ports and or hanging the needle open and causing flooding as you don't mention excessive fuel...After that it is time to test the stator.. If you have spark shouldn't be a switch box.. You have done everything I would do. Get rid of the black box that is called idle stable box. When these go bad cause all kind of problems and you don't need it... it helps if the motor falls on it face by advancing the timing...keep us posted as this is an interesting one to say the least...

 

[TACOMATruckin98]

Re: Mariner V-150 Idle Problem

Yeah I've never rebuilt a boat carb, last time I tried to rebuild one, didn't go so well but my buddy can do them without any problem, so I may just have to have that done. The only thing I can think of, is possibly a stuck choke, but I can't seem to find out anything about the choke nor its operation. As best I have read, when you push the key it pretty much only activates the enricher valve to just dump some fuel into the intake, but the choke itself is completely automatic. I am not sure if maybe when I push the throttle up and it opens the butterflys it just lets in enough air to make it run, and thats why it only runs for as long as I suspect the choke would normally operate then cuts off. That is my only thought because it seems that it is running extra rich, but all 3 carbs wouldn't suddenly go rich while running.

 

[j_martin]

Re: Mariner V-150 Idle Problem

Why don't you investigate?

Fuel pump? I consider a kit ('bout 25 bucks, 1 hour) to be annual maintenance. You can screw a 1/8" pipe to hose adapter in the bottom port carb fuel fitting (now plugged) and put piece of hose and a gauge on it. Needs to be above 0. Normally runs 2-5 lbs.

You said you repaired a hose. The hoses shell out on the inside and the debris plugs up carbs. Could be your problem. All you probably need on the carbs is gasket kits, about ten bucks each. usually all the metal parts are good. Don't forget new base gaskets.

Get a factory manual and read it. Well worth the bucks in saved parts.

 

[TACOMATruckin98]

Re: Mariner V-150 Idle Problem

Ok guys, looks like we FINALLY got it all worked out. A buddy of mine diagnosed two cracked carbs from overtightened by some previous person. Rebuilt fuel pump, 3 new carbs, and was doing the same exact thing again. Looks like the main problem turned out to be the enricher valve was stuck open, so it started flawlessly every time, but after about 30 seconds died, and wouldn't run without giving it throttle, but when tested first time it looked good. Thanks for the help guys it definitely gave me a good starting point to run down multiple problems

 

[aussieflash]

Re: Mariner V-150 Idle Problem

Thanks for the heads up.Always seems to be the simple things that can stuff up.