maybe i need to check it with a tach?

[opposedtwin]

Ran my evinrude lark (1959 35 hp) today after going through the carburetor. It started and ran well but had a couple issues.

I adjusted the high speed needle on the water by leaning it out until it threatened to die, then re-installed the cowl cover. Pretty standard stuff for me but it just didn’t seem like the rpms got high enough, like there should be more power to this motor.

Also, at WOT when I make a tight turn (either way) the motor bogs down and rpms drop and it hesitates and stutters. I need to lean the h s needle again to get back to a good solid speed. The needles got new packing in the carb cleaning and are not wandering. If I make a wide more gradual turn, I don’t experience the same bogging and loss of power. could this be a fuel pump OR fuel tank issue? I went through the fuel pump about 7 or 8 years ago. I put new ends and a new squeeze ball on the single line fuel tank about 2 weeks ago. Could the diaphragm in the tank be to blame?

In general, I have never had much to observe by adjusting the l s needle after adjusting the h s needle. The initial needle settings have always apparently been adequate. BUT…I’m wondering if that could be part of the problem here. I have always been told to adjusted the h s needle FIRST while on the water and THEN the l s needle.

What do you guys think is going on here?

The single line tank is the only single line tank I have so I can’t very well try another. But, I could look for a replacement diaphragm for the tank. Is there one? or maybe just a seal?

How do I use a small hand held tachometer on an outboard? I guess it would be handy to have one in the boat to see if my rpms are where they should be at WOT. The decal inside the cover says 35 hp at 4500 rpms.

thanks for any and all advice!
scott

[raglover]

I have had my floats hang up in my ’58 35 hp. The Sierra light tan and older OMC gaskets can swell with ethanol fuel, age, or bad manufacturing. Happened to me twice. In my case the float was held open and the motor flooded out, spitting fuel from the over flow. My guess is it could happen partially closed too. Both times did it after sharp high speed turns.

No diaphragm in the single line tank. Perhaps the fuel pick up line has fallen off and when you turn it moves fuel away from pickup?

Check the link and sync of carb to timing and the fuel economizer rod just to make sure all is OK.

Tiny tach makes a good induction tach that wraps around. Plug wire

[jerry-ahrens]

Sounds like the fuel level in the carb bowl is low. I agree on the Sierra carb kits, they cause problems. I won’t use them. I would suggest using an OEM kit that comes with a new float. The same goes for the fuel line, primer bulb, and connectors….. the aftermarket fuel connectors are junk. They usually suck air and won’t connect to the tank or engine snugly. Otherwise, check for a vacume leak, somewhere in the fuel system. this may not show up as a fuel leak, but rather a vacume leak because of a poor connection. maybe you could squeeze the primer bulb while the motor is malfunctioning?
if you happen to be using a fuel line from Wal Mart, I would replace it. Almost every motor that comes through my shop with one of those has a running issue. This is due to the internal ”barrier liner” collapsing, resulting in poor fuel flow. Some of them will be completly plugged. I have one of those in the trash can right now, as a matter of fact. I’ll try and post some pics later today.

[opposedtwin]

quote Raglover:

I have had my floats hang up in my ’58 35 hp. The Sierra light tan and older OMC gaskets can swell with ethanol fuel, age, or bad manufacturing. Happened to me twice. In my case the float was held open and the motor flooded out, spitting fuel from the over flow. My guess is it could happen partially closed too. Both times did it after sharp high speed turns.

No diaphragm in the single line tank. Perhaps the fuel pick up line has fallen off and when you turn it moves fuel away from pickup?

Check the link and sync of carb to timing and the fuel economizer rod just to make sure all is OK.

Tiny tach makes a good induction tach that wraps around. Plug wire

Where would the "fuel pick up line" be located? Not sure what you’re referencing there.

[fisherman6]

Scott, The fuel pickup line is inside the fuel tank. It goes from the fuel hose connection at the top of the tank to the bottom of the tank inside to draw fuel from the bottom of the tank. There is usually a screen filter at the bottom of the tube. This can become partially clogged and sometimes cause problems. I believe Raglover is suggesting that the end of the tube may have come off and thus not allowing fuel to be picked up from the bottom of the tank. That would mean if the level was low enough, in a turn the pickup tube may come out of the fuel and draw air / lose suction.
-Ben

OldJohnnyRude on YouTube

[fleetwin]

OK, you mention that you have to lean the needle in order to get RPMs back up….Kind of sounds like it is flooding slightly…Some of these carbs do not use the thick nozzle gasket, does this one use it?
PS- What pitch prop are you using? Maybe your rig is over-propped…

[opposedtwin]

Raglover: the tank is full, but I’ll pull the unit out of the tank to check it and report back what I find. (Ben, thanks for the clarification) The link that syncs the carb/timing is a possibility. I will check it as well.

Fleetwin: I did put a fuel nozzle gasket on it. I put on the same one that would be used for a standard RD from the 1950s. Should be the same I would think. It may indeed be over propped. I have a 3 blade bronze prop marked SMC 58 which I believe makes it a 14 pitch prop. My boat is a 15 foot aliminum runabout with very little in it. The catalog says it should be the one for 14-16 foot boats with 1-2 people. It is a deep v-hull with seemingly lots of drag, however. Anybody know what prop would have been standard issue at the dealer? I think 10 3/8 x 12 was standard for the earlier RDs and big twins. But wouldn’t too much pitch make it rev higher?

Jerry: the fuel line should be good. It’s a Mercury quicksilver one. The fuel connector is likely an aftermarket one since the original Mercury one would have been different. I always look for the float hanging up on the gasket when I rebuild them because I’ve heard of this issue before. I believe it did not impede movement at all.

[vintin]

Gotta know the rpm. Just gotta.

[fleetwin]

too much pitch would bring the RPM down….Think of prop pitch kind of like gear selection in a manual shift car…The lower gears give higher RPM at a specific speed, higher gears bring the RPM down. The difference is that boats don’t glide along like cars, lots of drag and friction between the hull and water.

[opposedtwin]

Ok, so the prop pitch might be part of the low rpm issue. I’ll check the timing/carb sync and the fuel vacuum issues and report back.
Scott

[Author]

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