Mercruiser 3.0 stalling at idle.

Am attempting to do some work on 1998 Mercruiser 3.0 on my SeaRay i/o. It starts fine but stalls at idle and then doesn't want to restart. Previous threads have stated that I should "remove" fuel filter. Some threads mentioned safety wire without any suggestion on best way to remove it. I finally yanked it off with a pair of pliers but can't see putting it back on. I had to remove it to get to the screw. I can't actually see what it was connected to and there is very little manuvering room to work. So how do I get the safety wire back on? After that I want to clean the filter on the carb. Any advice on removing that? Thank you.

Re: Mercruiser 3.0 stalling at idle.

Without troublshooting I would guess you are due for a carb rebuild and the culprit of this issue is from the lack of fuel from resticted flow. I would not tear any else off the motor until you have completely educated yourself by reading the service manual for your 4 cylinder.

Re: Mercruiser 3.0 stalling at idle.

I have read the manual that came with the boat, bought a SELOC and searched the net. The beset advice is "remove safety wire" and "replace safety wire." Some don't even mention it at all. Other engines worked on: car, lawn mower, generator, do not have a safety wire. Does anyone know how to put one back on? I know I probably will have to clean the carb, but thought I would try the filters first.

Re: Mercruiser 3.0 stalling at idle.

maine15 said:

I have read the manual that came with the boat, bought a SELOC and searched the net. The beset advice is "remove safety wire" and "replace safety wire." Some don't even mention it at all. Other engines worked on: car, lawn mower, generator, do not have a safety wire. Does anyone know how to put one back on? I know I probably will have to clean the carb, but thought I would try the filters first.

Click to expand...

Ayuh,.... I have No idea of what Safety Wire yer talkin' 'bout....

On the fuel pump, ya loosen the screw, shift the bale to the side 'n remove the filter bowl, clean it, replace the filter, 'n put it back together...

For the Carb filter, use 2 tubing wrenches, or you'll round off the nut holdin' the filter in the carb...

Re: Mercruiser 3.0 stalling at idle.

Well, when I couldn't seem to connect to the screw on the fuel pump filter with either a screw driver or wrench, I got a magnifying mirror on a stick and had a good look. There was a small piece of stainless steel wire running across the head of the screw that needed to be removed to access the screw. With no other info available, I worked it off with pliers, but as I said manual says to "replace safety wire" without indicating how to connect it. I am starting to think this is the "secret handshake" of boat repair. When I searched the 'net for fuel pump safety wire I find they are common on airplanes to prevent fire, I assume it is the same theory for the boat. Thank you for the info on the carb though, I will use your method.

Re: Mercruiser 3.0 stalling at idle.

maine15 said:

Well, when I couldn't seem to connect to the screw on the fuel pump filter with either a screw driver or wrench, I got a magnifying mirror on a stick and had a good look. There was a small piece of stainless steel wire running across the head of the screw that needed to be removed to access the screw. With no other info available, I worked it off with pliers, but as I said manual says to "replace safety wire" without indicating how to connect it. I am starting to think this is the "secret handshake" of boat repair. When I searched the 'net for fuel pump safety wire I find they are common on airplanes to prevent fire, I assume it is the same theory for the boat. Thank you for the info on the carb though, I will use your method.

Click to expand...

I have the same issue, my 3.0L Alpha is stalling under 3K RPM. Need advanced throttle to keep running. I've seen your safety wire as I'm looking at my fuel filter. Have not changed it yet - have done plugs, new fuel, etc. The problem is still there for me as well.... any answers on your end? I was pretty much full throttle when the boat just died and had a tough time getting to the dock. I'm still searching for the answer.

Re: Mercruiser 3.0 stalling at idle.

maine15 said:

Well, when I couldn't seem to connect to the screw on the fuel pump filter with either a screw driver or wrench, I got a magnifying mirror on a stick and had a good look. There was a small piece of stainless steel wire running across the head of the screw that needed to be removed to access the screw. With no other info available, I worked it off with pliers, but as I said manual says to "replace safety wire" without indicating how to connect it. I am starting to think this is the "secret handshake" of boat repair. When I searched the 'net for fuel pump safety wire I find they are common on airplanes to prevent fire, I assume it is the same theory for the boat. Thank you for the info on the carb though, I will use your method.

Click to expand...

Ayuh,.... use a 5/16" socket, 'n throw the wire away...

Better yet,... After ya change those filters,...

Mount a canister style filter, just ahead of the fuel pump,...
It's Easy to check, 'n change,....
'n if so done, the little filters yer fightin' Now, will Never need changin' again...

Re: Mercruiser 3.0 stalling at idle.

Well I cleaned the fuel filter (I decided to use original ceramic filter rather than paper replacement). There was a small amount of grit in bottom of fuel filter (very small amount). When I replaced fuel filter screw I did my best to reattach safety wire, put it under "lip" and tighten screw. It seems to stay in place. Still had stalling problem so I "rebuilt" carb. Called boat yards up to 50 miles away and could not find right kit (one boat yard on a LAKE told me they did not deal in parts for the 3.0 because it was too small) so I ordered it online. Took carb off cleaned it, added new parts (including filter), reinstalled, adjusted idle speed and it worked! Used it for two weeks on vacation with no problem. Used it mostly for kids skiing and so lots of starts and stops, no problem. I plan to have someone look at gas tank before I take it out again because I think it likely that ethanol in fuel is real source of problem. Only other thing I can tell you is that I had a gallon or two of last years' (stabilized) gas in tank. I filled tank completely before putting it in lake.

Re: Mercruiser 3.0 stalling at idle.

Been meaning to get back to this and give my results... hate it when a good thread is left hanging, but that's what threads do right?

To fix my Merc 3.0L Alpha 1 idle issue, it did end up with a carb re-build. $50 kit and some time, but as usual, I learned a lot. In order, I did check fuel, change plugs, fuel filter, then carb re-build. Fuel was ok - no water, plugs were good but needed new anyway, fuel filter had a clue. The filter bottom plastic was kind of disintegrated to the point it had a hole.
This was the interior of the filter.

The accelerator pump filter in the carb had minute particles of grayed plastic. Of course - it went through the system, so it had to be rebuilt and thoroughly cleaned. After that and setting the idle, this engine has never run better. No hesitation at all, idles fine, and good smooth throttle both up and down.

The only strange thing that I really didn't understand.... WHY, or WHY did Mercruiser paint the inside of the fuel filter bowl??? The bowl that the filter sits in was completely painted Mercury black and, due to my boat's age, it was all peeling off in a big way. Nothing like having your gasoline/filter sit in a bowl of peeling paint that is bound to have particles available for being sucked into your engine.

I ended up just sanding all paint off the interior of the bowl, cleaned it very well with carb cleaner, put in the new filter and reassembled. Can't see where this would rust given it's full of gas.

Ok, that's it. I'm back on the water and hope this helps someone.