4.3 mercruiser 2005

[Papakevin63]

I have a 2005 sea Ray 185 sport with the 4.3 mercruiser in it. The last time I went out the engine was acting funny, went to open throttle and its started like backfiring, losing power or puffing and losing power, when I back down on throttle it seemed ok. Now it's been a week or so , trying to start it, and it's acting likes its flooded or not getting gas. It's turns over and begins to start but even adding throttle it won't stay running. When out on water it was like its was making small back fire or burbing, puffing at full throttle. Anyone with ideas or what it may be? Have not changed plugs or tuned up in cpl years. Could it be fouled plugs, bad wires? Any help is appreciated

 

[Rick Stephens]

Welcome to iboats.

Typical kind of issue. Start by checking that your fuel filters are clean, that the carb is getting fuel.

After that is ignition....

Most likely fuel related. No tricks or secrets. Just have to get into it.

Rick

 

[Bondo]

The last time I went out the engine was acting funny, went to open throttle and its started like backfiring, losing power or puffing and losing power, when I back down on throttle it seemed ok.

Ayuh,.... Sounds like water in yer fuel,....

Check the fuel filter's Contents for water, 'n crud,....

 

[Papakevin63]

Ty Rick for the info, thought maybe bad gas. I don't see any fuel filter at all, where would I find it? Could it be the plugs and wires?

 

[Rick Stephens]

Fuel injected or carbureted? The carb model will have a screen behind the fitting for the fuel line into the carburetor.

If you don't have one, you should add an inline spin on fuel filter/water separator. Helps a LOT.

I would pull the fuel line off the carb, check status of the screen. Then poke a empty soda bottle over the fuel line and crank the engine a little bit, see if you are getting fuel there. With the electric fuel pump it will only pump when the engine is cranking or when the engine is running. (power to the pump comes from the starter and from an oil pressure switch) Also give you a chance to observe how clean the fuel getting to your carb is by dumping some into a container.

Yes, it can be ignition. To check that you would look inside cap and rotor first, then plugs to see how they look. Fuel is much more likely and needs checking first.

Rick

 

[Papakevin63]

Hey Rick, just got a chance to check filter, unscrewed line going into carb found larger bolt with a small barrel type filter inside, was totally clean. Tried to start with it disconnected and fueled was pumping out into bottle, looked clean. Any help on next check to find out what problem is? It acts like it wants to start but will not

 

[Papakevin63]

Pulled one plug and this is what it looks like

 

[Papakevin63]

Here is another pic

 

[Rick Stephens]

Is there any spark? Plugs look pretty fouled and wet. Also pop the top off the distributor - everything should look clean.


Rick

 

[Watermann]

Plugs are pretty bad with carbon, a tune up certainly couldn't hurt the situation. I didn't see where you said how the fuel is delivered, if it's carb'd then you may want to check and make sure your choke plate is opening all the way when the motors warm, appears to be running fairly rich. The hard start could be flooding or lack of air with the choke plate closed too tightly.

 

[Papakevin63]

Choke plate wide open when trying to start

 

[Papakevin63]

It's electronic ignition thunderbolt 5, didn't pull distributed cap cause when I pulled the plug I hooked back up to wire and turned over and plug had spark. I bout new plugs. Should I replace rotor after putting new plugs in or try to start engine with just new plugs? Thanks for you help guys I appreciate it. Didn't think I should mess with distributor, since I am not real familiar with it, but open for suggestions. Just got home with 6 new sparks plugs and some sea foam for gas tank, any ideas?

 

[Papakevin63]

Waterman, you said it's seems it running rich, is that something I can fix?

 

[Rick Stephens]

Pulling the cap and inspecting the rotor and inside of cap will tell you if it needs any parts replaced. Carbon buildup and corrosion are the typical signs that those need replacing. Cracks in the cap, metal particle residue. Blow it out, clean it up and inspect.

If the engine is cold then usually the choke plate would be at least partially closed.

If, after you get it back running and the tuneup is finished, and the plugs are still fouling and look rich you may need to rebuild the carburetor.

Rick

 

[Papakevin63]

Pulled cap and rotor look warned going to replace. What about ignition sensor in distributor? Should this be repaced? What are the chances of that going bad?

Ty
Kevin

 

[Scott Danforth]

Pulled cap and rotor look warned going to replace. What about ignition sensor in distributor? Should this be repaced? What are the chances of that going bad?

Ty
Kevin

mine went bad in my '02 5.0 from the salt air. turned all the components green on the board.

 

[Papakevin63]

Replaced cap, rotor, plugs and plug wires, boat started right up. Went on sea trial seemed fine, came home to flush system, started and was flushing out when it stalled out. My neighbor came over(has basic knowledge from being mechanic). He looked at everything we pulled #6 new plug, slapped in palm of hand and saw a some moisture in his hand. He indicates that exhaust manifolds are bad and they are leaking water and says that's why it stalled out and now will not start.

So my question is , do you think this is correct? The exhaust manifolds are bad and water getting in? This is a big expense and want to be sure this is the case. Any advice guys? Ty

 

[Rick Stephens]

If you pull the manifolds off you can usually easily tell if water has been in the exhaust area. The water will flake the carbon off instead of the interior being all smooth soot. Plus your exhaust valve area of the head will look like it has had water in it.

Only way to be sure is to pressure test the manifolds or the entire cooling system. That entails blocking off the exhaust exit for the water and then pressuring from the water input line to about 10 PSI. Best way is to pull the exhaust manifolds, cap the 4inch square hole where water and exhaust go separately into the riser - seal it up. I made a plate to cap the top of the manifold and then made a gasket instead of buying expensive exhaust gaskets to test. Then pressurize the one water line fitting that goes into the manifold - I used water for this so I could see it leaking into the manifold, as opposed to using air which I could only listen for.

If I thought I had water leaks in the manifolds I have em off in a minute checking. Quick way to neede a new motor leaving it.

​RIck

 

[Papakevin63]

Ok update, put new plugs wires cap and rotor, fired right up. Took boat for sea trial seemed all good. Came home to flush system, hard to start backfired. My neighbor came by and looked over things we pulled the num 6 plug slapped on hand and full of water. He not marine mechanic, but he saying the exhaust manifold and elbows are bad letting water in.. They are 10 yrs old. Ant thoughts guys on this please? Does this sound right causing engine not to run? I see this is expensive to replace exhaust manifolds, but want to do what's right cause have no boat now. Can I get your inputs guys on this please? Ty kevin

 

[Bondo]

we pulled the num 6 plug slapped on hand and full of water. He not marine mechanic, but he saying the exhaust manifold and elbows are bad letting water in.. They are 10 yrs old. Ant thoughts guys on this please? Does this sound right causing engine not to run?

Ayuh,..... Very good chance that ya found the problem,....

What manifolds are on it, the 1 pc. or manifolds, 'n risers,..??

If with risers, pull 'em off, that gasket failed,....