25/30-hp Johnson Intermittent Power Loss

Hi Folks,<br /><br />I have at J30RLCED block (late 1980's or early 90's, very low hours) with carb, power packs, etc. from a J25 attached. I put this combo togeter in November, rebuilt carb, new lines, water pump, fuel pump, tank, hose, bulb, etc. Everything has run great for about 80-hours (average 2 trips per week). 5-8 hours ago, started losing power under load. I would get on plane, run for 30-60 seconds, then the motor would lose power and die. Checked plugs, one was fouled more than the other, replaced both. Problem has now returned. Boat idles great, get on plane, then dies. After a few hours, try again, and problem has gone away, motor runs great. Wait a few hours, problem returns. Any ideas where to start? Air leak? Power pack? I've searched the archives and FAQ's with no match found. Thanks for your help!

Re: 25/30-hp Johnson Intermittent Power Loss

Welcome to iboats TC.<br />First, the engine, according to the model nr., is an '89.<br />Have you tried either pumping the priming bulb or bumping the priming (choke) switch when it's falling on it's face? Try giving the (choke) priming switch a short, quick bump and see what happens. If it chokes down immediately, the problem is probably ignition. If, when you bump the primer, the engine picks up, even for just a second or two, ya got a fuel delivery problem. Probably carburetor. <br />Check those two thangs out, then get back to us, using this same post, a tell us what happened.<br /><br />c/6<br />Hooty

Re: 25/30-hp Johnson Intermittent Power Loss

Thanks for the welcome and the reply. Yes I have bumped the goofy "primer/choke" as it is dieing and it hasn't helped. Neither has pumping the primer bulb. Thought I had found the problem when I noticed that the ground wire that runs from the pack, to the block, with a male/female plus was a little loose. Plugged it in, ran the motor, ran better, then back to the same. Checked the same connector, completely unconnected now (?), reconnected, re-ran, didn't help....Top cylinder plug was a little wet, bottom was dry. Noticed little flecks of something on the plug, then noticed that a piece of the sound insulation from inside the cowling was loose and might have been destroyed by the flywheel. So now I'm worried the motor sucked in a bunch of the insulation fuzz. I limped around today to fish a little, motor would hardly idle at the end of the day. It acts kind of like the timing is way off, but after seeing the insulation, I worry about the carb as well. Thanks for the help!

Re: 25/30-hp Johnson Intermittent Power Loss

It's real difficult for the engine to get out of time without some helping hands. <br /><br />The little "flecks" on the plugs would worry me. Do they look like shiney little balls of metal? <br /><br /><br />c/6<br />Hooty

Re: 25/30-hp Johnson Intermittent Power Loss

Hi Hooty,<br /><br />No the flecks did not look like metal, they looked exactly like the fuzz from the top of the motor. If it was locking up, it wouldn't idle as well as it does....I pulled the carb today and found that the "jet?" (one of the ports on the top, has a fuel line from the pump/choke running to it, constricts from large to small) was clogged with the same black flake. Cleaned the ports out, bowl of carb was spotless, cleaned catb, cleaned all the fuzz out from around the block, removed fuzzy insulation from cowling, checked fuel pump, installed new plugs, ran the motor on the muffs, ran great. Put the boat in the water (feeling very hopeful) idled around a few minutes, everything running great (better than before), throttle up, get on plane, then the same response, sputter sputter, die. I had the cowling off and could watch gas being sprayed into the carb even when the motor was dieing. I pulled the plugs while on the water, top plug normal, bottom plug wet. Cleaned plugs and reinstalled. Motor cranked right up, idled around more, then got back on plane, same response, spray carb cleaner down the carb throat when the motor starts to die, and it surges back to life. I have a clear fuel hose running from the pump to my fuel filter and I can see that fuel is continuing to be provided (pumping line bulb or choke/primer doesn't help when it is dieing. Should I buy the power packs and give it a try? Thanks for your help. I have to use my boat at work a good bit and need to get up and running ASAP.<br /><br />Tin Cup

Re: 25/30-hp Johnson Intermittent Power Loss

Ya know, it sounds like ignition except when you spray carb cleaner in the carbs and it comes back to life. That's fuel related. A word of caution though. That carb cleaner has NO lubricant in it and will wash the oil right off the cylinder walls. Get yerself a spray bottle and squirt premix in the carbs instead. Also, if you spray the premix into one particular carburetor barrel and that "fixes" it for a second or so, it's probably that carburetor that needs attention.<br /><br />c/6<br />Hooty

Re: 25/30-hp Johnson Intermittent Power Loss

Hi Tin Cup<br /><br />It soundslike it needs a good carb cleaning, which includes total disassembly and 12 hrs soaking in carb cleaning solvent, without plastic parts. Afterwards blow thru everything with compressed air. Is carb bowl full when it happens ? Did you try to take fuel pump off, and squeze primer bulb hard to see if it has a pinhole in diaphrame that feeds and floods lower cylinder thru vacuum hole. This can happen and will make lower plug foul. When carb is off take a penlight and check that all reeds blades are intact - that being said reed failure is rare.

Re: 25/30-hp Johnson Intermittent Power Loss

Thanks everyone for the suggestions. I'll try and find some time tonight to take everything back apart. The motor just has one carb, so that makes things a little easier.<br /><br />bp