Intermittent Bogging

[ewk1116]

I just got my 87 Johnson 90hp back in the water the past weekend. It has brand new ignition (box, plugs, wires), rebuilt carbs, new batteries, water pump, fuel sep, and fluids. I also had a mechanic sync the ignition, throttle adjustments, and give it the once over. Clean bill of health with 100 across all cylinders.

So I took it out and it ran great from idle to WOT for about an hour. I then started to have issues with it hesitating on acceleration. I would advance the throttle and the RPM would stay fairly low for a few seconds, then jump up to match the position of the throttle. This progressively got worse where it took longer and longer to respond. Eventually, I couldn?t get it past 3.5K.

I removed it hood and immediately noticed that a water hose cracked around the clamp, however, my issues lead me to believe that it is a fuel issue. Idle is fine, it ran on the muffs just fine for about 15 min after brining it in. Any suggestions? I live in an area where there are a ton of boaters and not enough ramps, so it?s hard to bring it out on the water just to test things. Thanks in advance!!!

 

[wdm2]

Re: Intermittent Bogging

Definately sounds like a fuel problem. I would iliminate that possibility first before messing with the carb adjustments. Start with your gas tank, if you're using a belly tank type they have a micro pick-up screen, which if there is any gunk inside your tank it will block fuel supply. Also check the one way valve on tank that connect's your fuel hose for dirt. Continue checking the rest of the fuel hose. Disconnect both sides and blow compressed air through it. Check water seperator if you have one on your boat as well, along with any other fuel filter you may have. One last thing, and it probably should be done first. Get yourself a spare clean tank and try a test run with the new tank, if that works without problems, you'll know the problem is in your fuel supply somewhere. It could also be a loose fuel line somewhere between the tank and carbs. They're is no easy way to find the problem. I've had a couple of these problems in years past, and I always find it easier to start at the tank, and work foward toward the carbs, checking everything along the way. Good luck.

 

[tashasdaddy]

Re: Intermittent Bogging

fix the water hose, and try again, water spraying under the cowl, can effect it. water can get sucked into the carb.

sounds to me the carb picked up some trash, and is clogging a high speed jet.

 

[ewk1116]

Re: Intermittent Bogging

Good point, I didn't think of that. I know that water was spraying in there b/c I had to wipe the salt build-up off most of the motor. I then sprayed it down with some wd-40.

I'll replace the water hoses, drain/clean the tank, check out the fuel line/fittings, and give it another try. If that doesn't work, then I guess I'm pulling the carbs which is annoying since they were just installed.