Possible Bad Gas/Fuel Delivery - Thanks SP

[CaptJohn]

I had a chance over the weekend to try a few things:
1. Changed mercury fuel filter, the one I removed was about 1.5 years old, it was not clogged. (Still would not start)
2. Hooked up fresh gas from a different tank. (Would not start) Drained all old fuel from the lines.
3. Replaced spark plugs, the removed plugs where installed in April 2013. (Would not start)
4. Removed air cleaner and for some unknown reason it starts. Runs well at around 3000rpm, but I do notice a miss at idle speed. I ran it for about a 1/2 hour with the air cleaner off.
5. Turned off, and replace the air cleaner. Took awile but I got it started again with throttle lever abour 1/2. Ran again for about 5 minutes.
6. Shut down to replace the cowl. Would not start again??? Tried for about 15 minutes and gave up.

Anyone have any ideas? Carbs?

Thanks

John

[PAFireGuy]

You may want to try to compression test the cylinders. Take note of any noticeable differences between each cylinder. You may have more than a fuel problem.

[Gerry Zagorski]

Good advice from PA above.... Given the age of your engine, before I'd invest any money on rebuilding carbs or other stuff, I want to know the compression is good. No sense throwing good money after bad.

[CaptJohn]

Thanks for the advice, I am going to check compression next!

[CaptJohn]

Had the motor running yesterday, still seems like its missing.

I checked the compression last night, Port side T-115 M-116 B-115 Starboard side T-120 M-121 B-121.

Maybe I will try seafoam to clean the carbs.

[Gerry Zagorski]

Compression seems OK... I would not worry about a difference of 4 or 5 lbs.


Seafoam spray is not going to clean your carbs.... What Seafoam spray does do is decarbon the pistons, rings and cylinder walls which is a good thing to do, especially on the older 2 strokes.

If you want to try and clean the carbs without taking them apart then you will need some sort of fuel treatment. Probabaly best to do this with a portable tank so you don't have to treat all the fuel in your main tank to get the ratio you need. Having said that, the best thing to do is remove the carbs and clean/rebuild them.. They sell kits for this but not something I would attempt.

Before I went that route I would check other places first like spark....

When you take the plugs out, are any of them more fouled then others ? If so you could have a bad wire, coil pack, ECM etc....

Wires are an easy fix and place to start but Coil packs and ECM testing way over my head and probably something I would have a mechanic check out who has the right test equipment.

[maxturbo]

I also have a 2001 Merc 150 2 stroke. Had same issues, end result I removed the carbs and overhauled them. very simple to do. Kits are cheap. Once doing the carbs. Started right up on first shot every time. If you have any questions you can PM me and ill explain what i did.

Do you have a fuel /water separator? This helps determine if u have any water in ur fuel also if your primer bulb is original. you should consider replacing that.