Modified 150 2.0 Mariner idle problems

**tlwjkw** · 04-26-2022, 01:57 AM

when ya takin' tha carbs apart and puttin' 'em back together are ya usin' same gaskets (inside and out)??? most wh's don't like re-used gaskets.. especially tha little "triangle" ones even if they "look" ok...

**4Speed** · 04-26-2022, 09:16 AM

Have a JD lawn riding mower and had the same issue with gas running out the carb. like you I found pieces of degraded fuel line in the carb and carb hose. Replaced the fuel lines and the leak slowed down but didn't stop. replaced the fuel pump and it solved the problem... I suspect that also had pieces of fuel line in it. May be worth checking...

**merc1250bayliner** · 04-26-2022, 09:46 AM

All the fuel lines are brand new. Fuel pump was just rebuilt as well. I did reuse the gaskets. I will have to check for a vacuum leak the next time I run it.

**FORBESAUTO** · 04-26-2022, 09:46 PM

As long as all butterflies are completely shut and you can’t get the idle down with idle timing that low, I’m definitely thinking vacuum leak or really lean mixture at idle. Leaking fuel would cause rich mixture which would load it up and lower idle speed. Make sure to check crank seals and all bleed lines, if no leaks are found, go through carbs thoroughly, but with that big of a idle issue, I’m thinking unmetered air coming from somewhere

**merc1250bayliner** · 04-30-2022, 07:13 PM

I'm still chasing the issue. I sprayed carb cleaner all over the intake and bleed lines with no change. I sprayed fuel into the carbs and the idle went way down. I next removed the idle jets and opened them up and the idle went up 200rpm. Of course I realized after that the idle jets are for air not fuel. I also replaced all my bleed hoses with new rubber line. It's still idling at about 1500rpm.

**rgsauger** · 04-30-2022, 10:54 PM

Have you 100% disconnected your throttle cable from the motor when all this is going in? Made certain that the throttle cam is not or just barely touching the roller? Then started walking down on your initial timing?

**rgsauger** · 04-30-2022, 10:54 PM

Do you still have black boxes on motor?

**merc1250bayliner** · 05-01-2022, 06:39 AM

Black boxes were removed a couple years ago. I will go double check the link and sync today.

**merc1250bayliner** · 05-01-2022, 06:47 PM

I double checked the link and sync. There is no preload on the throttle roller. I'm gonna try smaller idle air jets. If there's no vacuum leaks, throttle blades are closed, and primary timing is real low the only thing I can think of is to give it more fuel.

**Baker343** · 05-02-2022, 08:45 AM

Have you tried starting it with the throttle arm removed from your carbs.

Try another set of carbs

**merc1250bayliner** · 05-02-2022, 09:11 AM

I have not tried it with the linkage removed but as I said it's not touching and the blades are 100% closed. I have two other sets of carbs I can try. The stock wmh 31s and xr6 wmv carbs. I need to get gasket kits for the wmv carbs first.

**rgsauger** · 05-02-2022, 10:46 PM

Pull the three little tiny pins that hold the linkage arm onto the three carburetors. That way, there can be nothing external influencing them. With that arm removed, look at each single butterfly to make sure it is 100% shut. Then, play with your idle timing a little bit and see what you can get.

I am assuming that you have decent spark plugs in this thing and that half of them are not fouled out