92' 30 HP Uses excessive fuel... only hits top RPM when I squeeze fuel line.

[danofthebass]

My 92' 30 HP (C30ELRQ) has a couple symptoms that I can't quite figure out. At WOT it never reaches peak RPM. No tach on my boat, but I'd say it's about 80% power/boat speed and audible pitch. Also, after a quick trip running WOT a couple miles, my 6 gal tank is significantly depleted.

If I squeeze the fuel line, the motor will rev up fully and everything seems peachy. My thought is that too much gas is reaching the carburetor, thus making the mixture way too rich regardless of high speed idle adjustment. To further exacerbate things, I torqued the head off the high speed idle adjustment screw It is currently stuck in the fully tightened position, and I still have the same issue with excessive fuel and low RPM.

My (albeit newfound) understanding of the system leads me to think it's either the main jet, float valve, or fuel pump. Any ideas on where to start? I'm tempted to put a hose clamp on the main line and just crank it down till it runs right . Seems like it should just be a quick adjustment to close down a valve a bit eh?

Thanks,
Daniel

[rodbolt17]

my thought is a simple blown fuel pump.
by squeezing the primer its adding fuel to the fuel bowl bypassing the pump.

[danofthebass]

I meant I have to pinch the line partially shut, not squeeze the primer. It's like the fuel pump is working too well when WOT.

[rodbolt17]

still sounds like a fuel pump diaphram.
the main jet is a drilled piece of brass, not subject to wear.
if the needle valve was bad it would not idle correctly.

[rodbolt17]

and, there is no high speed screws for any adjustments.
that screw can be extracted but only by an experienced tech.
yes <i have extracted several over the years.

[danofthebass]

Hmmm... Ok. The screw I was calling high-speed idle is referred to as "pilot screw" in manual. It does mention that this screw is subject to wear and should be replaced if worn. I have it tightened all the way in, but still have a rich mixture, so it's possible that the needle is worn to the point that it does nothing.

I'll go check the pump diaphragm for holes and pliability. I don't see how that would lead to excessive fuel though. I would think a fuel pump problem would result in lack of fuel, not too much.

As a side note, took it out yesterday and the holster for the throttle remote cable snapped off it's spot welds. To go full throttle, I now have to steer with my knee, pull the throttle cable with my right hand, and pinch the gas line with my left... quite a sight...

Oh what fun owning an old boat is....

[danofthebass]

Well, I disassembled the fuel pump and lo and behold, it's trashed. Both diaphragms/seals are busted. The main diaphragm has a 1/4" tear in it, and the metal is rusted on both caps.

Think it's time for a replacement.

If it fixes the problem (or not), I'll be sure to re-post.

[99yam40]

the fuel pump was sucking fuel directly into the crank case so, when you fix that It will probably not idle anymore as the pilot(idle) screw is shut off and broke not allowing enough fuel, so you need to fix that and the cable before you end up running over something you do not want to. Even old motors and boats do well if you take care of them and fix what is broke

[danofthebass]

Ok. New fuel pump, primer bulb, various fittings, and a replaced busted fuel line between fuel filter and fuel pump. Also brand new spark plugs.

I can get it running for various amounts of time by playing with throttle and choke, but it won't run continuously at idle and choke open.

When running, I get sporadic backfires.

I've tried draining the float bowl and adjusting the idle screw to no avail. Only other adjustment I see is the pilot screw, which of course is broken off and not adjustable. Do these symptoms sound like they would be resolved by adjusting the pilot screw? At this point the screw is beyond your typical extractor kit and would need to be drilled out and re-tapped at best. At-worst, I buy a new carburetor

Thoughts?

[danofthebass]

Thinking about trying this: removing broken carb mixture screw, need idea - Bob Is The Oil Guy

95 degrees outside... want to be on water

[jb123]

sooo rust from the pump you thought wasnt bad is clogging your carb ?

[99yam40]

You can send it to Rodbolt to see if he can get it out or buy a new or used carb, but drilling and rethreading does not sound like a idea that will work to me

[danofthebass]

I can get a used carb on ebay for ~$140 after shipping + about $10 for new gasket shipped. For a brand new carb and gasket, it'll be ~$225. I lean towards a new one, since you never know with a used one. Anyone think I should skimp on the extra $75 for the new part?

I may mess with trying to repair the old carb once I replace it for a backup, but I don't care to miss another couple weeks of boating while I keep noodling with it.

[danofthebass]

Ok. New carb on the way. Just not worth it to have any wear and tear if I go through replacing the carb.

Looking forward to putting it in though and having the motor run like new. (or of course moving on to the next thing I find wrong )

[200090tlry]

Has the fuel damaged the carbs?

I have snowblower with really old gas I purchased. Somehow the old stuff ruined aluminum carb. Threads on bottom snaped the cheap pot metal. New carb got that 2stroke toro working great. The pilot screws you should be gentle when going clockwise to set them closed. If the fuel pump was messed up I would suspect your carbs as well.