1989 Evinrude 15 bogging at WOT after warm

[Baw335]

I bought a new to me boat this spring. It sat for a few years but ran great when I first bought it and then started developing a few issues. It would idle just fine then die whenever you give it throttle. So I rebuilt the carb and fuel pump and tuned it. The carb was actually pretty clean. It was better but would start to bog down at WOT like it may be running on one cylinder or fuel starved. So I pulled the carb again today and was meticulous about making sure nothing was clogging it. I took it down to the lake today, tuned it and it ran at WOT great. I slowed down and tried to get up to speed again and it would start bogging at WOT again. I turned off the motor and let it sit for a couple of minutes. It fired up on first pull and would run at WOT all around the lake. I came to stop and it tried to get it back up to speed and it would start bogging again. It will do this all day and it just needs to cool down a few minutes to run fine again.

I’m thinking maybe coils and it starts to misfire when the temperature increases? The impeller seems to be working just fine, enough water in my opinion and it’s warm and not hot.

One other thing that I noticed when messing with the carb, the white nozzle had a small crack in it around the hose mount. Not ideal but I didn’t think this could be causing my issue as it seems temperature sensitive.

Any insight or thoughts would be much appreciated!!

 

[Baw335]

I forgot to mention, it has a new gas tank, line, and primer bulb. The gas tank is vented when running.

 

[oldboat1]

Run a soft wire through the h.s. orifice at the bottom of the nozzle well, and spray it out with carb cleaner.

 

[Baw335]

You are speaking of the small insert that has 54 on it that screws into the side of the nozzle, correct? Sorry, I’m not up to speed on my names. If so, I cleaned that extra well today and ended up unscrewing it and soaking it to make sure I didn’t miss anything. Or are you talking about the smaller diameter metal tube that the hose mounts on? Thanks for your reply

 

[oldboat1]

Yes. That is the high speed jet, which seems to be your problem (potentially, anyway). For future reference, disassembly and soaking of all metal carb parts is a good idea when rebuilding. Finish by poking gently with soft wire in every opening, and spray with carb cleaner using the plastic nozzle that comes with the can. I normally do not take out the jets as they can be easily damaged. Set the low speed needle on top 1 1/2 turns open to start. When the motor warms up, turn it clockwise (leaner) 1/8 turn at a time until the motor lean sneezes (light backfire) or stalls. Turn the needle c.clockwise 1/4 turn for a final setting.

 

[flyingscott]

Check for spark when that happens. I believe you have the UFI ignition so the module is under the flywheel.

 

[oldboat1]

^^good point. The under-flywheel module can heat up. If the problem occurs only when running after the engine heats up, you might take a timing light with you -- hook up to each plug wire when the problem occurs and see if there is loss of spark (no flash, no spark). Best bet in that case is probably a failing ignition module.

 

[Baw335]

Thanks guys, I appreciate the tips. I’ll take it out again this weekend and see if I can narrow something down.

 

[Baw335]

Alright, I took a timing light with me and it looks like both cylinders are firing as they should under load. So I’m back to a fuel issue. The engine idles and runs at half throttle great.

Here’s a few things I tried while I was out there today. If I pull the choke half way out, it runs worse and kills the motor. Nothing changes if I manually pump the fuel bulb. I’m using the new gas tank (scepter) I bought with new fuel line and have opened the main cap while running to ensure that it’s not a vent issue.

Finally, if I tilt the motor up to the next position, it will bog down even worse and die with a little throttle. I swapped floats with a new one when I rebuilt the carb. Is it possible that I have my float screwed up? I flipped the carb over and it looked parallel when I reinstalled it.