Very High Rev

[shesellswhisky]

I have an 1150 1976. I have put in new fuel premium of course, bought a new primer bulb stays hard after prime and fuel line , have good spark and rebuilt the lower end.
When i start the motor in the test tank it instanly revs up and then dies out after about 3 seconds. It will fire everytime but runs at the most 20 seconds. I have tested the compression and all of the cylinders sit at approx 115 psi with very little variance.
Im not sure what to do at this point?

 

[aussieflash]

Re: Very High Rev

Are you choking on start up,does it rev high on its own or have you opened throttle?Tank vent open?
Try pumping bulb while running and if that helps its time for a fuel pump rebuild.

 

[shesellswhisky]

Re: Very High Rev

I dont use the choke, it starts better when i dont i guess it could be somewhat warmed up after cranking it so much. The tank vent is open and i have the throttle opened up on first start. I will try te bulb test right now.

 

[shesellswhisky]

Re: Very High Rev

I tried pumping the primer bulb and noticed that i saw gas coming out of the small brass screw on the third carb?

 

[hotrod53]

Re: Very High Rev

It's common for a 2 stroke engine to rev up as it runs out of fuel, my outboard as well as my dirtbikes were all the same way. Your problem is fuel related somehow. If your bulb gets and stays hard, it sounds like you're not pumping fuel.

I would try replacing the fuel lines, maybe the ethanol destroyed them, if not that, maybe fuel pump issues. I find it odd that the whole motor quits, I wouldn't think that every fuel pump in every carb went bad at the same time, these motors will run with one carb dead. I also thought that maybe your needle valves were stuck shut, I had that happen multiple times. I kind of discount that because you are getting enough fuel to start for that 20 seconds each time. I'll bet that pumping the ball when running will keep it running indicating fuel pump or fuel line issues.

 

[shesellswhisky]

Re: Very High Rev

Would that explain the fuel coming out of the brass screw on the bottom carb?

 

[Chris1956]

Re: Very High Rev

The bottom carb has a problem with the float, inlet needle and seat or both. It probably makes sense to rebuild all three carbs with new floats, inlet needles and seats and gaskets. If this motor is new to you, check the idle pickup and max spark advance, and rebuild the water pump.

 

[shesellswhisky]

Re: Very High Rev

I took apart the fuel pump this morning and the diaphram looks good the check valve seem fine as well. When i take the fuel line off the top carb and pump the priming ball fuel come out in a good stream so the lines seem ok. I also opened up the bottom carb fuel bowl to access the float and it was moving freely, i did notice the center spring was recessed into the float quite far. Im not to smart with this stuff but before i take it to a shop i figured id give it a shot.

 

[shesellswhisky]

Re: Very High Rev

I just picked up a new battery and spme carb cleaner. I noticed after i sprayed the carbs it would run a little longer but still dies out. When i took apart the float canister attached to the carb im wondering if the switches are possibly the problem. I called NAPA to see if they have carb rebuild kits and te guy couldnt tell me yes or no lol. Im guessing there is a carb kit part number i have to supply him possibly from Mercury

 

[Mi duckdown]

Re: Very High Rev

need to rebuild the carbs and new floats.

 

[shesellswhisky]

Re: Very High Rev

Would you know where i should order these rebuild kits from?

 

[aussieflash]

Re: Very High Rev

Try here ,http://www.crowleymarine.com/mercury-outboard/parts/463_10.cfm.They still have floats available.I would buy them even if yours are still OK.

 

[shesellswhisky]

Re: Very High Rev

One more dumb question how do I know what carb I have? I noticed there are two different kits

 

[Chris1956]

Re: Very High Rev

Crowley allows you to pick parts by model and year. You should therefore get the right kits. Also, carb kits fit lots of carb models. Serial group 2 looks to be the back drag carb. if that is what you have, then pick that kit.

Floats are identical as is gasket kits. The inlet needle part number has serial number ranges listed.

 

[shesellswhisky]

Re: Very High Rev

I took all three carbs off and examined them. I found that all the parts with the exception of the floats in good shape and very clean. I will need new gaskets and float for sure. Now the question i have is the float chamber has a pin that moves up and down when the float moves. This pin seem to get stuck every once and awhile. I will order the rebuild kits but is it really this easy to rebuild a carb?

 

[aussieflash]

Re: Very High Rev

That would be your needle and seat.Replace all of them.Replace floats and adjust float heights.....go boating.

 

[shesellswhisky]

Re: Very High Rev

awsome thank you all for the help. My order will be here in about 12 pluse days. I should also replace my wires and plugs too i do have good spark but why not