140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2 Min

[nypbbob]

Hi folks, great message board... I finally have a question.....

Never had problem with the motor. ...... Rained cats and dogs for three days straight here in south florida... Took the boat out, was running awesome all day (six hours) at 4,000 rpm's, 38mph... Then all of the sudden it started boggin down... I turned the motor off and tilted it up to check the prop, etc, and all was fine.. Tilted it back down after 2 minutes and I was able to get up on a plane for two minutes tops then it bogged down again.... (note: pump ball was hard)

Took the boat home.... Check fuel/water seperator and seemed pretty clean, checked all electrical wiring etc...

Then we took it for a bay test the next day, started right up, no problems, idle speed for 20 minutes and then I planed it right up and after two mintes or so BAM, it bogged down again... We took the air box cover off to expose the carbs... We sea fomed the **** out them in gear,e tc., etc... Changed plugs.. Cleaned carbs again... ran idle speed for 20 min... Got up on a plane for guess how long? yep, two minutes it started to bog down again.. (when we had the cover off and checking out the carbs with the throttle up, fuel was pumping just fine.....)

OK, then turned the motor off and tilted it up again for two minutes then back down, then puched it out... Got up on a plane again, then after two minutes once again it bogged down (note: it never stalls just cant throttle up past 3,000rpm or so)............

Any thoughts?

Thanks!

 

[Haffiman]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

Fuel restriction somewhere or a failing fuel pump.
Check your anti siphon valve on the tank top?
Try a test with open fuel cap to eliminate vacuum.
Is the primer ball still full of fuel when it happens?
What is the fuel pressure INTO the carbs at WOT?

 

[fshrgy99]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

what happens if you just sit and let the motor cool for 2 minutes without tilting it? Thinking perhaps the rpm limiter is kicking in because of overheat signal. Also might be spark breakdown maifesting at high speed but not noticeable at idle. what year motor?

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

Fuel restriction somewhere or a failing fuel pump.
Check your anti siphon valve on the tank top?
Try a test with open fuel cap to eliminate vacuum.
Is the primer ball still full of fuel when it happens?
What is the fuel pressure INTO the carbs at WOT?

Thanks materchief... Ill try those today. The ball of fuel and was not collapsed. Not to sure on fuel pressure. We could see the hi speed jets spraying big time.. Ill get back to you thank you

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

what happens if you just sit and let the motor cool for 2 minutes without tilting it? Thinking perhaps the rpm limiter is kicking in because of overheat signal. Also might be spark breakdown maifesting at high speed but not noticeable at idle. what year motor?

thanks for the reply... its 1991 motor.. the same problem occured if i didnt tilt it but it went right into bog mode (was unable to get up on plane)..

 

[fireman57]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

You say you cleaned the carbs, did you just spray more seafoam in them? That is not cleaning them.

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

I think we may have found the problem... I had a problem with the tilt wiring in the throttle base and disconnected them a few weeks ago and slapped electrical tape on it to cover the "hot" wires.. Well, when we were checking the ignition switch out, we noticed when the throttle was pushed all the way forward it was arching and arching bad because the electrical tape fell off the wires mentioned previously. When we pulled back the throttle the wires were not arching anymore... So i re-did the wiring and we are going out tonight to check it out.. Im hopeful that was the problem-- and it makes sense because the only time the motor bogged down was when i had the throttle all the way forward and ran fine when i pulled back on the throttle...

Hopefully this is the problem..

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

i also cleaned all the carbs and: 1) compression check ok; 2) spark on all plugs; 3) when it bogged down i pumped the ball and choked and it did not have any effect...

so hopefully it was a short as mentioned above

 

[fireman57]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

sounds like you found it. good case for wire nutting and tape if not solder. Let everyone know.

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

well it worked for 5 miles and damn she was fast as hell probably because of the carb and other works completed.... but then after five miles she starting boggin again (never stalled).... im really leaning towards electrical and or over heat... my buzzer may not be working right, what are the signs of overheating or a cylinder getting to hot? thanks again

 

[fireman57]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

When it bogged did you pump the primer bulb to see if it picked up? does your telltale have a strong water flow? Sounds like you might have a coil or two that are breaking down when they get hot. These engines will idle and run decent on a few cylinders. Check your spark when it does this.

 

[nypbbob]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

When it bogged did you pump the primer bulb to see if it picked up? does your telltale have a strong water flow? Sounds like you might have a coil or two that are breaking down when they get hot. These engines will idle and run decent on a few cylinders. Check your spark when it does this.

Good morning. Yes i pumped the primer ball and choked, to no avail... With all the carb work and fuel work we did, when it got on a plane it ran faster than ever (47.6 mph), but it last for three minutes or so then bogged down. Im thinking coil as well. Its a 1991 140 V4... Dumb question-- sensor coil or ignition coils?

thanks again

 

[fireman57]

Re: 140 Johnson Bogs Down Over 3,000 RPM- But Is Fine After I Tilt The Motor Up For 2

If you miss spark on a cylinder then physically swap that coil with another off of a cylinder that you know is firing. If the problem follows then replace that coil. If it does not then it could be your cdi box.