Best dry gas/ carb cleaner

[sammidog]

My twin engine Chris Craft has been stored for 2 years. I used stabil but this past weekend I got the boat out and one engine would only run at at 1000 rpm. The other only 2000. After running them for 20 minutes I got both to 2300 rpm but I was uncomfortable with the kids on board so I came back in and put the boat away. Before I went out there was about 12 gallons of old gas and I added 25 gallons of 93 octane fresh gas. I changed a water separater filter and poured the old gas into a glass jar and I found no water in the gas. I don't know if the gas went bad or it is a gummed up carb. The engines start right up, and in neutral they rev up to redline. No miss or stumble. props spin free and it ran fine when I put it away 2 years ago. I'm thinking of putting some dry gas/carb cleaner in the tank and run it this weekend to see if it straightens out. Any thoughts on the best dry gas to use or things Ive overlooked. I took the carb apart and cleaned with gumout but it looked brand new. Which it should since i only have 10 hours on the engines.

 

[Maynard Rupp]

I found the most impressive product to pour in your carburator. It is called "Sea Foam" and is available at any Advance Auto Parts. Probably can find it at any auto parts store. Our 350hp. Crusaders really came alive after a treatement with sea foam. They want you to pour 1/3 can slowly into the carb with the engine idling. Now shut it off for 10 minutes. Start again and avoid the exhaust fumes. It does not smoke at all. Great stuff.

 

[krush]

see this thread about outboard in relation to carb being "clean": http://www.samsmarine.com/forums/showthread.php?t=7106

You may be lucky and not have any gunk in the orifices of the carbs. If you are running where the gas has ethanol in it, there is really no need for dry gas (DG is just alchohol).

Try to get as much new fuel in her as possible and keep draining the fuel/water separaters. I've had 50/50 luck with not having to overhaul inboard carbs after sitting a long time.

 

[Ross]

Sammi, If you got the carbs cleaned and the ignition is in good shape they should turn up. I would not turn up the engines in neutral things might float inside the block( lifters) and any engine will turn with no load on it.Even running poorly.You might try choking the engine while getting on plane to see if it picks up. If it dose then back into the carb.Also possably fuel pump not putting out enough.Should be 5-8 lbs pressure. Adding any thing to the tank now really not going to fix it.

 

[SKYCHENEY]

Napa has SeaFoam too.

 

[krush]

spraying seafoam/cleaner/etc will not clean the "guts" inside the carb. They don't get dirty in the venturi, it's inside in the metering blocks/jets/accel pump/etc.

 

[MikeP]

So it would maintain 2300 for an extended period? Would it initially (under load) rev higher and then drop back or would it just rev to 2300 and stop there?

It could be poor gas - I have seen gas so bad it wouldn't start the engine but I've never seen gas that, having started the engine, couldn't get the engine to run reasonably well. That's not to say it can't happen.

Are you sure the throttle linkages are fully opening? If you haven't done so, check at the carbs with the throttles fully open (engines off!) to be sure the primary butterflies are fully open when the throttle levers are wot.

Two years is a long time to sit. If it has a conventional distributer, it's possible that the advance mechanism has seized up and is not advancing as RPM increases. If the timing doesn't advance, the RPM would not come up under load. I'd stick a timing light on there for a quick verification that the advacne is working and the timing is set correctly - it's a 5 minute job on each engine and something that should be checked/set anyway.

Are you getting any black smoke from the exhaust when the engines are at 2300 under load? Is it misfiring at all? Was there ANY work done on the engines between the last time it ran properly and now?

"Gummed up" carbs don't USUALLY cause a problem at WOT because the main jets are the largest "holes" in the fuel delivery section of the system and at WOT they are the source for fuel to the engine. Again, not saying it's impossible but it is uncommon.

Clogged anti syphon valves have also produced this sort of behavior.

 

[krush]

I forgot to toss in there to make sure the secondaries are opening up.

I would rule out the simple stuff....it's almost impossible to have two failures of the same kind in two engines. Are you sure the props are clean?

 

[sammidog]

OK guys I'm going from bad to worse. I know i should call in a professional but I just don't want to give up yet. As you know from my first post I took the carb apart and cleaned it with gumout. I didn't really dissasemble too much. Pretty much just both float bowls. I started it up and gas was just running down the throat and some was even spraying out the J tubes at the top of the carb. I'm assuming that is symptoms of a stuck float? I took it back apart and the floats seem to move free. I never removed the float from its fulcrum so I don't see how I could have screwed something up. Anyway I reassembled and will try again tomorrow. The boat is on a trailer, not in the water all the time so I could not try it tonight. Rather than take it to a busy ramp I think I will rig the intake hose to a bucket of water and run it in my driveway.

 

[krush]

What kinda carbs? Quadra jet, holley, etc? I'd just take em off and rebuild em yourself. It sounds scary, but it really isn't too bad, especially if it is a holley.

Kits are usually 20-40bux. If you are at least somewhat competent with tools (you said you already popped the top once) then you won't have a problem doing it.

Where are you located?

 

[sammidog]

They are Holley carbs but I am having a heck of a time finding the rebuild kit. 75009-3 is on the carb but the auto parts store says it should start with a R.
I live in Erie, Pa. I consider myself a better than average shadetree mechanic but I lost confidence in myself when gas started dripping down the throat and out the J tubes. When I put the carb back on tonight I shook the carb keeping it level right before I put it on and they both rattle so I think they are free in there. Hindsight is 20/20 but when I replaced the water separator I primed it with gas from a five gallon can. I wonder if a piece of dirt got stuck in the float valve or something unrelated to my assembly. We will see tomorrow.

 

[krush]

try ebasicpower.com for parts. Don't loose confidence, you know more than you give yourself credit for. Holley carbs are reallly easy!

 

[sammidog]

OK! I am at least back to where I started from. No gas spilling down the throat and it's running smooth in the driveway. My grass is now watered too. I did notice something in the carb though. just bumping the gas I get the jet from the accel. pump. The gas flashes off and evaporates very fast but I have these tiny bubbles forming on the plates at the bottom of the carb. They eventually evaporate. Could that be water in the gas?

 

[sammidog]

I was able to get out on the water today and the first 10 minutes was just like last time I ran the boat. After running the boat about an hour the problem seems to have gone away. Boat runs like a champ! My guess is the water settled out in the bottom of the tank and I eventually ran the water out. That, or there was some varnish that eventually broke down and washed away in the carb. I guess the test will be next weekend when I take it out again.