Mercruiser 3.0 - 2 barrel merc carb

[savetexomabeaches]

I've searched around and cannot come to any real conclusions about my issue, so I decided to ask here.
I'm running a 1992 mercruiser 3.0 with a 2 barrel merc carb. Boat has ran great, idles around 650. It always had the (sometimes it wants to bog down if you try to go WOT from an idle) -- carb rebuilt twice, new accelerator pump, new filters, etc. Though, I have noticed lately, that sometimes fuel is either leaking from the top of the carb, or somewhere right around the back side (towards back of the boat). Normally I run the boat for about 20 minutes and park it (I arrive where I am going). But on Memorial Day, I ran it 3/4 WOT for a long time.. It suddenly started to bog down, so I shut it down. I could smell fuel bad. I opened my engine cover and noticed fuel in the bilge and fuel splatter on the starboard side of the fuel cover (side with the fuel pump). I turned my vents on, poured some water into the bilge and was going to limp it to shore. It started, I tried to give it a bit more throttle out of idle speed, but it would bog down. Almost stalling out. Before diving in and pulling things apart, I'm guessing my mechanical fuel pump diaphragm may have tore, or decided to leak? I'm also wondering if the fuel leaking from the top, if my float may be adjusted wrong.. Thoughts?

 

[Scott Danforth]

your fuel pump is designed with a vent that is connected to the clear tube that runs to the carb spark arrestor. if the fuel pump starts to fail, it pushes the excess fuel up to the carb to cause it to flood out like you noticed.

 

[savetexomabeaches]

I don't think my fuel pump ever had a tube of any sort going from it to the carb. It has the fuel in, and the main fuel line out. I can go double check, but pretty sure mine has never had such a piece... Maybe that might be the problem lol

 

[savetexomabeaches]

Ok, just looked at the fuel pump.. No clear tube at all. What I did notice was horrible. It has just a regular rubber hose on it, not a safety tube that seals/shrinks if a fire. I also noticed a lot of discoloration on the tip of the tube itself and around the fuel pump. (Im trying to get the photos uploaded) -- So I'm guessing time for a new fuel pump

 

[Fastatv]

Ok, just looked at the fuel pump.. No clear tube at all. What I did notice was horrible. It has just a regular rubber hose on it, not a safety tube that seals/shrinks if a fire. I also noticed a lot of discoloration on the tip of the tube itself and around the fuel pump. (Im trying to get the photos uploaded) -- So I'm guessing time for a new fuel pump

It appears that your currently installed carb is an automotive still carb, not a marine application. Yes, get yourself a marine fuel pump for sure, but it appears that you have another issue....cracked fuel line....flooding carb.....?

 

[Rick Stephens]

Yup,

Start with the simple stuff and work your way through everything, make it right. Good way to make the 6 O'clock News blowing up your boat in the harbor.

Replace the pump and get the clear site tube installed up to the carb. There is a screw in fitting on the Mercarb that dumps fuel directly into the throat of the carb if the diaphragm should leak.

Rebuild your carb and be extra careful of your float levels.

Go on from there.

 

[savetexomabeaches]

Alright. Getting a new fuel pump and going to replace that black rubber tube with the proper type of safety tubing. It was all wet when I was on the water, so it did not look this nasty at the time. It never went off in my head that the black tube was the wrong tube until I saw it was attached to the fuel pump. The carb has been rebuilt twice, I'm thinking the float level may be off a hair. I know they are intended to be level as if the boat is running across plane? (I said I know, but I'm guessing here) The first time I rebuilt it myself, of course it didn't run right after *I* did it, so I took it to a shop and had them do it lol

 

[Alumarine]

When you take the old pump off check to make sure there isn't an extra port on it for venting fuel to the carb.
You might just need a diaphragm kit and a hose to the carb.

 

[savetexomabeaches]

Ok, Im having issues finding a diaphrahm kit -- fuel pump is mercruiser 42725a 3 --- Can you help me out?

 

[Alumarine]

Looks like there isn't a rebuild kit available for that one.

 

[savetexomabeaches]

Ok, that number was via boats.net site.. I took the pump off and its a Carter 0-2210 fuel pump

 

[Alumarine]

That number you posted is what's listed for a 92.
Always best to use the serial number for the motor when looking for motor parts.

 

[savetexomabeaches]

Alright, I'm finding out that just because it says Carter 0-2210 on the side, really doesn't mean anything. Because the flanges are different on several carter's with the same number on them. ?? I'm thinking there isn't a rebuild kit for these things, or just diaphragms to buy. Its looking like I may have to buy an entire fuel pump. If that is the case, are there brands like AirTex or something a bit cheaper. Some post say they order fuel pumps from autozone and other places.

 

[savetexomabeaches]

1992 Mercruiser 3.0l
Serial Number: 0D717077

 

[Rick Stephens]

The OEM part number is 8M0073435. I found them to run $140-150 from Mercruiser sources. Hard to believe, but the Sierra replacement (18-7278) costs more.

 

[savetexomabeaches]

Thanks. That is what I was finding too.. The Sierra is around 168.. I was hoping to keep it under 100.00 -- Even hoping more a simple diaphragm 10.00 part would be better. The used ones (which I would hate to buy used) are around 60.00 -- So now I'm facing a situation because the cost will be about the same.. To either 1) buy mechanical and replace or 2) Go ahead and convert to electric fuel pump with an inline filter and a low oil pressure shut off switch

 

[Fastatv]

It appears that your currently installed carb is an automotive type carb, not a marine application. Yes, get yourself a marine fuel pump for sure, but it appears that you have another issue....cracked fuel line....flooding carb.....?

I must have been tired ( late at night ) when I typed the above statement. What I meant to say was that the "fuel pump" was not a marine app. Anyway, I'm still saying you have an issue with the carb and those two bbl's are fairly simple to rebuild.

 

[savetexomabeaches]

Thanks for the "updated" reply lol -- Yes, both fuel pump and carb are marine. They do indeed have the vent hose. I did luck out though, my neighbor has a ton of merc fuel pumps. None identical to mine though, but I did find one that the top half was the same. The flange, mounting holes, everything identical. The bottom half was not. I took mine apart, and the bottom part was fine, but the plunger at the top was cracked everywhere (the one with the big spring and all that jazz). So what I did was take the top off of one of his and put it on the bottom part of mine. And I got some clear fuel line to boot. Then it started raining (figures). So after it stops, I'm hooking it up and gonna see how it runs. I need to make sure nothing is going to leak gas.

 

[Rick Stephens]

Installing an electric is not as easy as it sounds. The electric pumps get their power from 2 sources. First is the starter solenoid that has the fourth lug for powering the pump during start. The second is an oil pressure switch then through a electric solenoid with 10 amp fused power to the pump. Never ever want an electric fuel pump on the ignition switch like a car. Good way to go boom.

 

[savetexomabeaches]

Just an update --- Installed the "rebuilt" fuel pump, new line and it fired right up. I let it run for awhile, no more fuel leaking and no fuel going up clear hose.