Engine Choking out at full throttle

[SweetLou]

I have a 1972, 65 hp Johnson, 3 cylinder. It was not in the water at all last year. I started the engine on the trailer this year and the engine appeared to run fine. I put the boat in the water, started the engine and it idles fine at 1200rpm's. When I throttle up, at around 3000 rpms, it "chokes" out. It bogs down and the rpms drop quickly. It will run fine at 2200rpms at about 5 knots. As soon as I throttle up, she boggs down. I changed the gas..cleaned the filter screen...added a fuel injector cleaner, changed the plugs and idled for agout 20 minutes. Still the same. What can it be? What else can I do?? Please help!<br />Lou

 

[jimraelee]

Re: Engine Choking out at full throttle

sounds like it could be starving for fuel... id check basics... like fuel presure... if you have access to eng while driving id spray some fuel / wd40 or other flamable fluid w/ lube properties in carb while running and see if rpm increases...also check to see if your main jets are plugged or blocked. I had a ford v-8 with plugged main jet on one side of carb and so it would get over 2500 rpm... really boggled me since it had good fuel pres and spark / ign.... jim

 

[SweetLou]

Re: Engine Choking out at full throttle

It is getting fuel. I can rev the engine to 6000 rpm's with the warm up throttle. I was afraid that the jets were clogged. Can I clean the jets myself?? I was worried that a "shellac" built up on the jets from using bad gas. What about the electrical???<br />Thanks for your help!!<br />Lou

 

[SweetLou]

Re: Engine Choking out at full throttle

ps: how do I check the jets???<br />Lou

 

[JB]

Re: Engine Choking out at full throttle

Howdy Hinkle.<br /><br />First: Get a manual.<br /><br />Next: NEVER rev your engine high without a load. You are inviting your engine to self destruct.<br /><br />What an engine will do without a load tells you nothing about what it will do under load. Your engine will over-rev and blow up easily on one cylinder without a load.<br /><br />With the engine idling on the hose, disable each spark plug, in turn. If there is no drop in rpm that is a dead cylinder.<br /><br />If all cylinders are making power at idle, try pumping your primer bulb when under load. If the rpms go up, you have a bad fuel pump. If rpms stay low, squirt some fuel mix into each carb. If that gets you your rpms back that carb needs overhaul.<br /><br />Let us know what you find.

 

[SweetLou]

Re: Engine Choking out at full throttle

thanks for your help jb!! I was not thinking when I reved the engine!!! How do get a manual?? Where? How do I check the cylinder while the engine is running?? Do I pull the wire with pliers so I don't get shocked?? or should I pull the carb cover and check the coars firstg?? Thanks for any advice you can provide.<br />Lou

 

[rickdb1boat]

Re: Engine Choking out at full throttle

Hinkle,<br /><br />You can get a Factory Manual Here:<br /><br /> http://theoutboardwizard.bizhosting.com/parts_service_and_owners_manuals.html <br />-------------------------------------------------------------------<br /><br />Use pliers with a rubber handle, so you don't get zapped when you remove the boot. Also, auto part stores have spark plug boot pullers if you are really concerned about getting shocked!<br /><br />Rick

 

[lakensea]

Re: Engine Choking out at full throttle

It's not a good idea to pull plug wires while an outboard is running. If the engine has a solid state ignition (CDI, switchbox, etc.) and you pull a plug wire, the high voltage has now where to go and can damage the electronics.

 

[SweetLou]

Re: Engine Choking out at full throttle

thanks! I have to get back home and wont be able to work on the engine this week. I will let you all know how it goes next weekend!<br />thanks again!!<br />Lou

 

[Pro Crappie Guide]

Re: Engine Choking out at full throttle

The electronics will not be damgaged, as the electricity has YOU to go through...You get shocked..It doesn't feel good.<br /><br />Remove the plug wires while the engine is off.<br /><br />If you determine that you have a cylinder not firing, do a spark tes. If you have spark, replace the plug, leaving the plug wire off, and start the engine. Kill the engine and check the plug for "wetness".<br /><br />If it is wet, you have weak spark. If it is dry, you have a dead cylinder.