95 Johnson 130 WOT Loss of RPM and power

Striper500

Seaman
Joined
Nov 20, 2005
Messages
52
I have posted other problems - misfire loud popping etc - finally did a Sync & Link and engine runs smooth as silk at idle and at 2500 - now all 4 plugs are burning equal and I would say on the wet side. But - that's it can't get her on plane, can't rev over 2500 at WOT. All checks were done in the water after engine was warm - This was the 1st compression check warm - 3 at 125 1 at 120 - all close. I ran the engine at idle with the silencer off and put my hand on each carb and found good suction - I was told compression could lie so check to see if I had good suction - this checked out. So far electrically everything checks out - all tests with a high peak volt meter on the stator, timer base, and power pack. I bought this boat used so everything is a mystery or a challenge. I have no history. I suspect an air, vacuum leak or fuel pressure leak. Note at idle you can rev no problem - of course it's not under load. I tried choking with the key at 2500 RPM under load - no change. Also for starters I did the triple play for temperature - 2 stats and a new water pump to insure = and proper operating temp. I tried a few more electrical tests while running - disconnecting Black & Yellow - no change, disconnected White & black on port stat - no change, Even disconnected tan wires - I did not however disconnect tan off VRO - didn't have the manual with me & wasn't sure if it was tied into the SLOW system. Next week I will check all hoses - Electronics I can hold my own - fuel systems I have a lot of questions.
Regarding fuel - there is a new spin on filter and a new ball, when I prime the fuel I did see leakage at the line to the fuel rail at the T which feeds the choke cellunoid - Only when I 'm squeezing the ball and applying pressure- I tightened it with a straps on the nipple. also - I will shorten that line next week after 10 years I guess the hoses should either be replaced or tightened. This was a preformed hose.
Can the thin diameter hose coming off the cylinders that go to the carbs cause a problem under load ? Will the intermediate orifices (no needle - fixed orifice) be a problem at WOT ? - Last week I dumped the High speed plugs and drained the carbs - didn't see any problems - I'm not a carb rebuilder so I would like to do that last. Can I assume under load there is a much greater draw - vacuum & fuel wise hence replace or tighten up lines ?? - It amazes me how the small hoses are on the fittings not clamped to the carbs and Powerhead etc - Also I don;t have a fuel fitting with orings - Main fuel line attaches right to motor - I know these orings go bad. I also tried pumping ball at WOT - nothing happened. This may be a dumb question - The engine ran so smooth at 2500 RPM - for those that know I have spark when I check it at the dock - but will these V4 loopers run that smooth if I'm losing spark at WOT ?
Before I take every line apart - remove valve that feeds VRO etc - any usual culprits here ????? By the way this engine has fixed orifices for idle & intermediate - no adjustment.

Any help would be appreceiated -
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 95 Johnson 130 WOT Loss of RPM and power

Any chance the engine thinks it is overheating? Your engine has the S.L.O.W. overheat feature. If the engine gets hot, it will limit rpm's to 2500. Coincidence that your problem is at 2500 rpm?
 

Striper500

Seaman
Joined
Nov 20, 2005
Messages
52
Re: 95 Johnson 130 WOT Loss of RPM and power

emdsapmgr said:
Any chance the engine thinks it is overheating? Your engine has the S.L.O.W. overheat feature. If the engine gets hot, it will limit rpm's to 2500. Coincidence that your problem is at 2500 rpm?

It's definitely not overheating - after a run you can put your hand on the block & it is barely warm - Putting that aside I shut down and disconnected both thermostat tan wires in case a temp sensor was bad - same problem - I just installed new stats & water pump all is working fine - I am assuming a shut dowm (turning key off) will clear any SLOW activiation from any prior overheats that activated SLOW
 

Walker

Captain
Joined
Jun 15, 2002
Messages
3,085
Re: 95 Johnson 130 WOT Loss of RPM and power

Are you sure the throttle plates are opening up fully perpendicular to the throats?
When you disconnected the temp sensor wires you disconnected the sensor end of the SLOW. You can still have a bad powerpark that is staying in SLOW.
 

Striper500

Seaman
Joined
Nov 20, 2005
Messages
52
Re: 95 Johnson 130 WOT Loss of RPM and power

Walker said:
Are you sure the throttle plates are opening up fully perpendicular to the throats?
When you disconnected the temp sensor wires you disconnected the sensor end of the SLOW. You can still have a bad powerpark that is staying in SLOW.

I emailed CDI electronics about that - that's an interesting possibility - I think the tan wire from the VRO is also in that circuit but they say the VRO cannot cause a SLOW state - and yes the throttle plates are fully perpindicular to the throats
 
Top