1997 new to me Johnson 90hp outboard bogs down above 1/2 throttle

[jstme123]

Idles great, runs great up to 1/2 throttle or so then above that bogs down immediately to a idle even though the controls are above 1/2 throttle. If i back it off and throttle up again it will run fine up to half throttle but not above, what could it be? There was also a intermittent alarm buzzer which i believe is the low oil warning (beep every 20-30 seconds or so) but only beeped at idle, not when throttling up. Any help is appreciated.

 

[Chris1956]

Motor likely has the SLOW system which limits RPM when overheating. You might check for overheat.

Fill oil reservoir to eliminate that possibility.

Also, your symptoms could be fuel starvation. Check filters and antisiphon valve for clogging. Check main strainer under airbox as well.

 

[jstme123]

not overheating, spraying a strong stream of water but I also felt the cylinder heads and they are warm as they should be while running but not hot at all to the touch. I am wondering now if the 2 are related? I checked and the oil was full, ran it on the muffs and now the buzzer is ever second or 2. Would a failing VRO pump make it bog down above 1/2 throttle like that?

 

[jakedaawg]

You need to start at the begining:

1. Post model number.
2. Post compression test results.
3. Open air gap spark check at 7/16"
4. Put 50:1 in tank for duration of diagnostics.
5.

 

[juno pierrat]

push key in while bogging, does engine jump to life. if so probably high speed jets clogged

 

[Lightwin 3]

Motor likely has the SLOW system which limits RPM when overheating. You might check for overheat.

Fill oil reservoir to eliminate that possibility.

Also, your symptoms could be fuel starvation. Check filters and antisiphon valve for clogging. Check main strainer under airbox as well.

"antisiphon valve for clogging" .That valve is the outlet of the fuel tank. It will/can cause that issue.

 

[jstme123]

sorry for the late reply.
today after work i disconnected the 2 vro plugs and plugged the oil line,now running on a external tank with 50:1 to eliminate the vro being the problem and make sure the motor was getting oil. Put the boat over still has same issue....runs good up to 1/2 maybe even 5/8 throttle then boggs bad. Pushed the key in to choke it while it bogged down and motor almost stalled. came home put the motor on muffs and pulled each plug wire 1 by 1 to eliminate that.....all wires puled changed the rpm so not that either. plugs look good. Cheap compression gauge that i have shows 112-118 across all 4 cylinders. whats next?
1997 Johnson model J90ELEUC

 

[jakedaawg]

Take air silencer off. Tilt motor up just a bit to get a slight forward lean. Squeeze bulb till firm. Continue squeezing, your not trying to crush it just a continuous even pressure for a few minutes. Does bulb continue to depress? If so look for fuel leak. Most likely places are bowls warped and vst top gasket bad.

 

[jstme123]

do this while motor is running or not running?

 

[jstme123]

while not running, 4-5 squeezes and bulb gets firm and stays firm

 

[jakedaawg]

Yes, not running. Sure would have been nice to find leak. Well,...

You have confirmed problem exists while running on portable tank? Squeezing bulb aggressively while issue occured did not help? The bogging seems like it's hitting the rev limiter? Or, does it seem like it's more fuel failing?

if rev limit or sense that it's spark goto Cdi electronics . Com and run their trouble shooting.

if fuel, plumb in piece of clear hose at cowl fitting. Tee in vacuum gauge. How many in/hg are you pulling? See any bubbles in clear hose?

 

[jakedaawg]

Maybe one of the other members that's better at describing things could explain the difference between a fuel related feeling and an electrical/"slow" related feeling.

I guess the electrical feels more deliberate in the "bogging". Engine runs rough but sometimes rough with a rythem.

Here, I just cheat. I have known good components that I use to t-shoot cause it's all about time spent...

 

[jstme123]

Yes problem still exists on portable tank, squeezing the bulb does not help any any when it acts up. It feels alot like its dropping a cylinder but only does it at high RPM.

 

[SweetD]

I have a similar problem currently, and I have a current thread on the topic:

https://forums.iboats.com/forum/eng...-j90glsob-some-trouble-shooting-advice-please

It's looking more and more like an electrical issue for me, and likely the powerpack.

 

[jstme123]

I am wondering if it could be the timing is off a little?

 

[SweetD]

When it bogs, does it bog really quickly, like a sharp drop in rpm? Or is it more gradual? Does it drop, then quickly spike back up, and then back down, sort of intermittently? If so, that tends to be symptomatic of an electrical issue. Fuel issues usually exhibit a more gradual, steady failing/bogging symptom. Mine is the sharp drop, bounce up and down in RPM type of thing,..

 

[jstme123]

It boggs down quick and does not go up until i back off the throttle almost to idle, only then can i throttle back up to about 1/2 or 5/8 throttle before it will do it again.

 

[jakedaawg]

As stated earlier, goto cdielectronics. Com and do their troubleshooting.

 

[jstme123]

Cdielectronics was no help and other ideas?

 

[jakedaawg]

It passed all tests? I was really thinking power pack...or optical