2008 Mercury 90hp 2 stroke fueling issue

[chizzle1979]

Hello, this is my first posting here and am hoping to get some assistance on a problem I am having with my mercury outboard.
The boat is a 2008 Suncruiser pontoon with a 90hp mercury 2 stroke outboard.
The motor ran strong until it was stored for the last deployment, has approximately 2 tanks of gas on it regarding usage (about 40 gallons) since purchase.

Upon returning I drained the fuel from the tank, which had gone bad, refilled with 5 gallons of fuel & 2 bottles of carb cleaner and ran it at idle for about 15 minutes on the clamshell. Then put 10 gallons of reg in it (E10).

I am 99% sure their is a blockage in the carbs. It will die completely under power unless the elec choke is constantly actuated. The primer bulb gets extremely hard, like there is no fuel going through the carbs when attempting to prime. When disconnected, or when the plugs are out of any of the 3 carbs, the fuel flows out and the primer bulb works fine.
It will not start unless the neutral throttle is applied and you grind on it for about 10-15 seconds.
When trying to start the usual puff of blue smoke is not present either. The oil mixer is full, and I'm not getting an alarm for no oil so I assume that is working.
Also, when attempting a field fix at the lake, the adjustment of the mixture screws didn't seem to have an effect on the lower 2 carbs.

My question is where do I find a dowloadable manual (free preferably) on removal, cleaning, and reassembly of the carbs? I do extensive engine work on autos but have not done too much on outboard motors other than changing the occasional water pump, lower unit oil, etc.

I do not believe it's a compression problem as the engine has very low hours on it.

I plan on doing the work myself but was hoping some of the experts could provide some guidance / advice. Do I need to order any other parts besides the Mallory carb kit 9-37303 ?

Thanks in advance.

 

[lncoop]

Re: 2008 Mercury 90hp 2 stroke fueling issue

Have you checked here?
http://forums.iboats.com/showthread.php?t=415403

 

[chizzle1979]

Re: 2008 Mercury 90hp 2 stroke fueling issue

I checked their before registering, but the links are not working.
Not sure if it's the gov network I am on or if they have been removed at the source.

 

[chizzle1979]

Re: 2008 Mercury 90hp 2 stroke fueling issue

I tried squeezing the primer bulb when it would start stalling and it seemed to make no difference. Does that eliminate the pump?
When priming shouldn't fuel flow through the carbs slowly and the bulb eventually collapse when squeezed?
The fact that the bulb does not collapse at all is what makes me think their is a blockage in one or all of the carbs.
When I remove the drain plugs in any one of the 3 carbs the fuel flows freely and the bulb goes flat when squeezed.
Would this be the float, diaphram? Should I order a rebuild kit and replace all parts in all 3 carbs?

 

[lncoop]

Re: 2008 Mercury 90hp 2 stroke fueling issue

Sorry pal, you're over my head. Not to worry though, there are a couple of very knowledgeable guys who will be along to help soon.

 

[mikeneal]

Re: 2008 Mercury 90hp 2 stroke fueling issue

Sounds like trouble is in the carbs. Squeezing the primer bulb takes fuel pump out of the equation.

 

[chizzle1979]

Re: 2008 Mercury 90hp 2 stroke fueling issue

thanks. I will try cleaning the carbs.
Should I order a rebuild kit? The carbs on only 2 years old and are probably sludged up with old fuel / oil.

I am assuming I need a carb kit 18-7211-1 ? Looks to be just a gasket set.

Does anyone think it's worth a try to remove the adjustment screw & plug on each carb and simply spray carb cleaner into the openings? I am not looking forward to removing all the linkage and re-syncing it all.

The primer bulb should collapse when squeezed if I remove the blockage right?

thanks in advance.

 

[chizzle1979]

Re: 2008 Mercury 90hp 2 stroke fueling issue

After inspecting the area, I don't think it will be possible to pull the carbs one at a time due to the linkage, so I'll be pulling all 3. I will mark the linkage with tape so I can get it back to near calibrated when I'm reassembling.

Here is a pic of the motor from the side.

 

[chizzle1979]

Re: 2008 Mercury 90hp 2 stroke fueling issue

BTW, what is the button on the top, just to the right of the upper carb? It has 2 wires coming from it? Is it some sort of reset? There are 2 hoses going to it on the other side.

 

[carholme]

Re: 2008 Mercury 90hp 2 stroke fueling issue

chizzle;

Looks like it is the manual control for the enrichment valve. If you have a look through the following link, you will see what I mean. Do you have a s/n for your engine and is it a 2008 as well?

Also read the section about the anti-siphon valves to see if this may be part of your problem.

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/13645_2/3a.pdf

 

[chizzle1]

Re: 2008 Mercury 90hp 2 stroke fueling issue

chizzle;

Looks like it is the manual control for the enrichment valve. If you have a look through the following link, you will see what I mean. Do you have a s/n for your engine and is it a 2008 as well?

Also read the section about the anti-siphon valves to see if this may be part of your problem.

http://1manual.com/Mercury manuals/Service Manual PDFs/TwoStroke/13645_2/3a.pdf

I don't have the serial number and yes it's a 2008 Mercury 90 hp 2 stroke.

Thank you very much for the manual. That is exactly what I needed, a break-down of the carb & components of the engine.

After reading the entire excerpt, I will first try cleaning the nozzles & off idles holes with seafoam & compressed air.
If that does not rectify the problem I will remove the carbs and rebuild them.

Thanks again for the link.

 

[Alumarine]

Re: 2008 Mercury 90hp 2 stroke fueling issue

The bulb should get firm after a few squeezes.

 

[backyard mechanic]

Re: 2008 Mercury 90hp 2 stroke fueling issue

This does sound like a fuel issue. Fuel corrosion, varnish and gunk will screw up a lot of parts and gaskets. A thorough rebuild of the fuel system is a good start. When flushing the fuel system remember the fuel pumps and lines are part of the system but the forgotten parts are the hoses and fittings from tank to the engine. You very well may need to pull that tank and clean it. Access to the tank will tell.

That said; there is NEVER a reason not to check compression. On a 2 stroke, compression and piston stroke is all about getting fuel to the cylinder and of course the power stroke.

Any question on carb rebuilds should be answered with a Haynes a Chilton's repair manual. Not to mention when done, a link and sync will need to be precisely set.

 

[chizzle1]

Re: 2008 Mercury 90hp 2 stroke fueling issue

The bulb should get firm after a few squeezes.

The bulb gets very firm, there is a blockage in one of the carbs. Probably due to the fuel tank running completely dry (fuel gauge malfunction) and getting trash into the fuel system.

This does sound like a fuel issue. Fuel corrosion, varnish and gunk will screw up a lot of parts and gaskets. A thorough rebuild of the fuel system is a good start. When flushing the fuel system remember the fuel pumps and lines are part of the system but the forgotten parts are the hoses and fittings from tank to the engine. You very well may need to pull that tank and clean it. Access to the tank will tell.

That said; there is NEVER a reason not to check compression. On a 2 stroke, compression and piston stroke is all about getting fuel to the cylinder and of course the power stroke.

Any question on carb rebuilds should be answered with a Haynes a Chilton's repair manual. Not to mention when done, a link and sync will need to be precisely set.

I think it was a combination of the fuel sitting the entire time I was deployed and the tank being run completely out of fuel by mistake.
I ran a concentrated amount of fuel system cleaner through the motor while it was hooked up to the clamshell, after draining & flushing the tank, and all was fine until it ran completely out of fuel 2 trips later.

I am confident that I will be able to troubleshoot and complete the repairs now that I have the information from the link provided by carholme.

I do appreciate all the feedback and advice. I am a gearhead but don't wrench on too many 2 cycles.

 

[chizzle1]

Re: 2008 Mercury 90hp 2 stroke fueling issue

How often should the spark plugs be changed?
I inspected them and noticed they are quite different from automotive type spark plugs as they have a flat center electrode.

 

[jerryjerry05]

Re: 2008 Mercury 90hp 2 stroke fueling issue

The plugs are perma gap plugs.They last a LONG time.Just wire brush them and spray some carb cleaner on them.
The carbs setting, probably gummed them up.
Your gonna have to remove them and clean them out.Stay away from carb soaks.
There aren't any anti-siphon valves used in outboards.
The pump doesn't produce enough draw pressure to open the valve.
The little button is the manual choke.Or enrichment solenoid.
No shortcuts.Take them apart and clean them right.J

 

[carholme]

Re: 2008 Mercury 90hp 2 stroke fueling issue

Quote:
There aren't any anti-siphon valves used in outboards.


I suppose if there was no person available to start the engine, you might say that persons are not used on outboards too!

I am pretty sure that the poster knows they are used in various fuel tank setups and not a part of the engine.

Quote:
The little button is the manual choke.Or enrichment solenoid.

If you look at the picture the poster provided, do you think that looks like a "choke"?

carholme

 

[Silvertip]

Re: 2008 Mercury 90hp 2 stroke fueling issue

With the engine off, squeezing the primer bulb fills the float bowls in the carbs after which the rising float closes off fuel suppply after which the primer bulb becomes firm. Ok - you now know how that is supposed to work. If the engine dies at speed, look at the primer bulb just before it does die. If it is being sucked flat, there is a restriction between the bulb and the bottom of the pickup in the fuel tank -- not between the bulb and the engine. If squeezing the primer bulb as the engine begins to bog causes it to pick up again, you very likely have a fuel pump going bad. The reason the engine is dying is because the pump can't keep the float bowls full, and squeezing the primer bulb helps do that. If turning idle mixture screws has no effect on how the engine idles, there is a carb problem. And just so you know, using the fast idle lever is normal starting procedure on a carbed two stroke.

 

[fedpo]

Re: 2008 Mercury 90hp 2 stroke fueling issue

I'm having a very similar problem with my motor. I'm waiting for fuel pump kit to be delivered. Several posts on this thread have briefly mentioned the enrichner solenoid. I don't know what this part does so forgive me if this is a dumb question! Can this solenoid be the problem? Is there a way to test or clean the solenoid?

 

[Silvertip]

Re: 2008 Mercury 90hp 2 stroke fueling issue

Anti-siphon valves have nothing to do with the style of engine (outboard or otherwise). Anti-siphon valves are placed at the outlet of the fuel tank to prevent siphoning of fuel into the engine or into the boat should a fuel system leak occur. This is especially important on pontoon boats or any other boat where the fuel tank outlet is higher than the engine or where the fuel line would run below the tank outlet anywhere between the tank and the engine. They are used almost universally these days. Besides, one carb not functioning would not be due to the anti-siphon valve.