88 Johnson bogging down

[THEFERMANATOR]

Originally Posted by Skools Out

Sounds carb related as stated by Ferm. but be extra careful on the plastic carbs and make sure you put the jets back in the correct location or you will have a worse day.

Or the always fun of reusing the orings and trying to get them to stay in place while you bolt them on because if they fall out of place you will warp a carb tightening it down. I started using trans gel to hold them in place myself.

[phatdaddy]

not even sure i want to know what "trans gel" is..

[THEFERMANATOR]

Originally Posted by phatdaddy

not even sure i want to know what "trans gel" is..

It's more or less vasoline. It is what you use for assembling transmissions. It is a thick yet easily dissolved grease that is made to allow rubber seals and such to slide together VERY easily, but dissolves almost instantly when it comes in contact with oil so as to not plug up a trans valve body. It's great stuff, and I always have a tub on hand. Works great for carbs and fuel system parts as it allows orings to slide together EASY, but will not plug anything.

[thebottomfish]

Well thanks for the advice it was something I found researching, the motor was in s.l.o.w. Mode...one of the temperature sensors was bad, and I found out my warning horn doesn't work! So two quick things to replace, but she ran nice, didn't go out for too long just because I'd rather have a working temperature system.
So thanks for the help, just glad it was something simple.

To get off topic a bit, I was hitting about 33 mph per gps, don't have a tach so I can't tell what rpm it's at but does that seem a bit slow for a 140 on this boat?

[THEFERMANATOR]

Originally Posted by thebottomfish

Well thanks for the advice it was something I found researching, the motor was in s.l.o.w. Mode...one of the temperature sensors was bad, and I found out my warning horn doesn't work! So two quick things to replace, but she ran nice, didn't go out for too long just because I'd rather have a working temperature system.
So thanks for the help, just glad it was something simple.

To get off topic a bit, I was hitting about 33 mph per gps, don't have a tach so I can't tell what rpm it's at but does that seem a bit slow for a 140 on this boat?

A tad slow. Get a tach on it and make sure it is topping out around 5700-5900 RPM's. The 140 likes to turn up some RPM's to run the best, and wil lactually guzzle fuel if you overprop it.

[MIScott]

So I've got an Evinrude 140 (87) that sounds like it's doing somewhat the same thing. Already replaced the fuel filter (which definitely helped start-up), and brand new properly gapped plugs (look great after running, not fouled)

Engine runs great under 2200 rpm trolling along, and occasionally it will let me really open it up (was running 33 knots yesterday), but as soon as I pull back throttle (from fast running) the engine will drop down to 2200-2500 rpm and not let me get back up in engine speed. I can NEVER just get on the throttle and get up to speed. (Which I'd like to do because my kids are DYING to go tubing.)

I'm "up north" and not at home so I don't have my usual set of tools, diagnostics, etc. Any EASY tests I can run to see if I can pinpoint the problem?

[THEFERMANATOR]

Sounds like classic early carb issues. Most early OMC's require rejetting to run on the gas we have today. I had to do a rather large jet change to my 86 140 to get it to run correctly in the mid range without it falling on it's face. Unfortunately this is a known issue with the early small bore(85-87) loopers.

[MIScott]

Originally Posted by MIScott

So I've got an Evinrude 140 (87) that sounds like it's doing somewhat the same thing. Already replaced the fuel filter (which definitely helped start-up), and brand new properly gapped plugs (look great after running, not fouled)

Engine runs great under 2200 rpm trolling along, and occasionally it will let me really open it up (was running 33 knots yesterday), but as soon as I pull back throttle (from fast running) the engine will drop down to 2200-2500 rpm and not let me get back up in engine speed. I can NEVER just get on the throttle and get up to speed. (Which I'd like to do because my kids are DYING to go tubing.)

I'm "up north" and not at home so I don't have my usual set of tools, diagnostics, etc. Any EASY tests I can run to see if I can pinpoint the problem?

Finally figured this sucker out.....after replacing ALL the fuel lines, fuel filter, primer bulb AND rebuilding the carbs....still had the issue.

Then I saw a post talking about the temp sensor wires (tan) being routed near or over spark-plug wires possibly causing a false signal. Opened the cover and sure enough, one of them was laying directly across one of the plug wires. I zip-tied the sender wire up out of the way and took her out for a sea-trial last night.

Boat ran flawlessly for the entire time I was out. Fired up immediately, ran great at all speeds, no bogging/hesitation.

Basically the false signal was making the engine think it was overheating putting it into limp mode and preventing engine speeds higher than ~2200 rpm.

SO HAPPY!