1966 merc 650 carbs leaking engine wont stay running

[hoss62773]

I have just rebuild the carbs on my merc 650 because they were pouring fuel out of the main nozzle plug screw. These are side bowl type carbs. I was told the float might be stuck. After reassembly and installation, I'm having the same problem. there is a small pinhole in the bottom of this plug that's dumping fuel all over the lower carb. I can't tell if the lower carb is leaking too because it's soaked from the top carb. <br /><br />Also during rebuilding, i didn't replace the intake needle and seat because the original had a nylon seat. The ones in the kit were solid brass. Should i have replaced them anyway? <br /><br />The engine will start and run for a few seconds and then cut out. After it cuts out, that's when i see the fuel comming out of that plug. I have been using the seloc manual as a guide, but i'm at a loss now. <br /><br />Comppression is at or near 110 for all 4 cylinders. I have good spark and plugs are set at .025 gap per the manual. Any help would be appreciated, thanks

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

You need the replace the needle and seats if you just need them you can get them at NAPA

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

that's kinda what i was thinking. the ones that came in the rebuild kit are a bit different though. the needle is the same, but the seat in the kit is brass. the original is nylon. should i just use the kit or try to find one with nylon seats like the ones in there now?

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

If you go to NAPA just buy the needles unless you can get a refund from the first place

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

ok laddies, i replaced the needle and seat. tried to start it, it wouldn't go. I cranked it about 5 times. the leak is still there. it looks like its draining all the remaining fuel in the bowl out of the main nozzle plug screw. i can't tell if the lower carb is draining the same way because it's already drenched from the top carb. what next?

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

You need to ck float levels the spring height on the floats and make sure the needle levers are free

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

HERE'S AN INTERESTING OBSERVATION. I OPENED UP THE BOWLES AGAIN. THE TOP CARB HAD NO FUEL IN IT AT ALL, THE LOWER WAS STIL HALF FULL. I'M ORDERING NEW FLOATS AS THEY PROBABLY NEVER HAVE BEEN CHANGED. THE SPRING ON THE TOP FLOAT WAS 4/32" (SHOULD BE 3/32").THE LOWER FLOAT WAS AT 3/32". <br /><br />I ALSO NOTICED THAT WHEN I RELEASE THE LEVERS ON THAT TOP CARB, THE NEEDLE STAYS IN THE UP POSITION. ALL LEVERS MOVE FREELY. <br /><br />THERE APPEARS TO BE NO VACCUUM IN THAT TOP BOWL. <br /><br />THANKS FOR ALL THE HELP, I CAN'T GET ANYONE TO COME TAKE A LOOK. I'M ON MY OWN HERE

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

hoss, I went back and read this post again and the first time I read it I thought you were talking about the high speed nozzle in the throat of the carb. Now reading it a second time I am afraid you mean the brass plug that is the access for the high speed jet. If thats the case I'm full of crap with the advice I have been giving please let me know one way or the other--Bob

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

bob, you're close. It's the plug directly below the jet access plug you just mentioned. the plug i'm having the problem with is the one coming up into the bottom of the carb. it's to access the main nozzle from the bottom of the carb body. the plug you mention has a hex head AND a gasket. This one is a slot screw and NO gasket. I thought some permatex thread sealer would work, but that's when i noticed the pinhole in the center. <br />I tried scanning my diagram here, but i'm not much of a techie either. <br /><br />while i have the bowl covers off i put about 1 oz. of mix in the bowl to see what was happening. so far the carb lost about half the mix. the rest is still in the bowl. let me know if you think of anything else.<br /><br />Bill

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

If that plug won't come out so you can replace it or you can't find a used carb body, I have drilled and tapped them with a smaller size and used a screw to plug them, It's not a job that is easy and takes care and luck. The other choise would be epoxy it or use a good fuel proof product to seal the area

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

I've had it out of the body. i haven't seen it on oldmercs.com. is that pinhole supposed to be there? the whole set up just doesn't make any sense to me. I'll check for a replacement thanks. keep u posted on progress thanks again

 

[Laddies]

Re: 1966 merc 650 carbs leaking engine wont stay running

No thats just a plug, rhet come in factory carb kits but the kit is to expencive so ck the local marina they should have a old carb with 1 in they are the same in at lests all the KA series tillsons and I think all tillsons. If you can't find one locally I guess I could send you one, I've got a bunch in old carb stuff

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

THANKS A BUNCH. MY MARINAS HERE IN CO ARE FEW AND FAR BETWEEN. THE ONLY THING I CANT STAND ABOUT COLORADO. I'LL START CALLING AROUND. KEEP YOU POSTED.

 

[hoss62773]

Re: 1966 merc 650 carbs leaking engine wont stay running

my mechaninc says that the hole is an air bleed. i'm going to put in the new floats and see if that changes anything. if it still doesnt work, i'll drop in some solder to seal it off per the local merc repair shop here. he didn't feel like rummaging through his stuff for another plug.