2000 Johnson 150 - Only 1800 RPM Under Load

[Jose67]

Where in the wiring harness would I find the "blocking diode"? Could I have damaged it as I was pulling it thru the conduit under the floor? Or is this diode located on engine harness and not the control box to engine harness?

 

[Jose67]

Rectifier/Regulator Question- 2000 Johnson 150

If the Rectifier/Regulator were overcharging or putting out too much voltage would it be possible for it to damage the diodes? I get 14.5 volts at idle (900 rpm) have not checked voltage at any RPM's above idle. I would assume the more RPM's the more voltage the Rectifier/Regulator would put out to a certain point.

 

[GA_Boater]

If the regulator is working properly, the max output will be around 14.5 volts at all RPMs. The output may increase slightly when revving above idle RPM.

Are you having a charging problem?

 

[Jose67]

Not having a charging problem that I know of as I have not checked voltage above idle rpm range so don't know if it is putting out above 14.5 volts. Was just curious if too much voltage could damage the diodes. I have checked the diodes and the voltage drop indicates a good diode in the diode check setting of the meter. When I switch to the ohms settings I get no resistance forward or backwards. I read where bench testing a diode does not always 100% tell if the diode is bad. To answer your question on what type of problem I am having it is that I can not get the engine to rev past 1,800 rpm in gear under load. I have disconnected the temp sensors, shift switch and VRO plugs one at a time all with the same results. I am trying to eliminate an electrical issue before I move to the fuel/induction system.

 

[racerone]

Contacted the seller of this motor ??

 

[racerone]

Perhaps ask the seller if he rebuilt it him self or a pro shop ?----Perhaps pistons are in upside down / wrong pistons.-----Hard to tell from 1000 miles away !!

 

[F_R]

You cannot test a diode with the Ohms function on most digital multimeters. That is because the meter does not apply enough voltage to make the diode function (takes about 0.7 V).

Your regulator probably is working fine at 14.5V.

 

[GA_Boater]

I think you're barking up the wrong tree.

Have you checked compression and spark? Fresh fuel?

 

[Jose67]

I have not as of yet. I will send him an email to see if he give me more info on this engine such as if he is original owner or somehow acquired it with no knowledge of it's history other than it needing a rebuild.

 

[GA_Boater]

I combined your two threads and re-titled. If you noticed, the new thread was getting the same answers as the first thread.

Please keep your questions in this one thread. Thanks.

 

[Jose67]

Got it, I will keep questions to this thread. I did check compression, 105 psi each cylinder on a cold motor all spark plugs removed, have not checked spark on each cylinder but prior to changing out shift switch the port side spark plugs and head were noticeably cooler than starboard side and not receiving any spark and fuel is fresh and treated with Startron fuel treatment every time fuel is added to tank. I emailed the PO/seller for more history on the engine as Racerone suggested.

 

[racerone]

What side of the engine has the momentary spark loss from the shift switch ??--------What colours are the orange striped wires going from powerpack to the coils ?----List them from #1 to # 6.-----# 1 is the top cylinder and #6 is the bottom.

 

[Jose67]

Per CDI's Troubleshooting Guide 1998 and newer the shift interrupter switch cut power to the port side cylinders which is what was happening before I changed out the switch. I will check on the orange powerpack wires when I get home from work weather permitting, we have mist and light rain here in the Galveston area.

 

[Jose67]

Wires coming from power pack to coils- starboard side #1 orange/blue #3 orange #5 orange/green, port side #2 orange/blue #4 orange #6 orange/green.

 

[racerone]

That is correct.-----The mystery goes on.-----

 

[Jose67]

It sure does, lol. I know for a fact that at idle all cylinders are getting spark. My next step is to verify if spark is dropping out at 1,800 rpm when the motor starts to shake and not rev any more. Once I eliminate anything in the electrical system I will look at fuel/induction.

 

[racerone]

Looking in manual for earlier models .--------Look at the 2 timing sensors.-.-----Spark timing could be way off.

 

[Jose67]

Low and high spark timing was set using the Johnny Rude Easy Timer, which per their instructions seems as if it works opposite of the OMC Timing Analyzer. With the Easy Timer timing is set when CYL light comes on as opposed to when the CYL goes off with the OMC analyzer.

 

[Jose67]

Does diode repair kit 0583898 replace either of the two diodes in the wiring harness? The diode with the tan wires going into it is smaller than the diode with the black/yellow, black/orange wires. I only find the 0583898 diode repair kit which comes the smaller diode. The small diode with the tan wires was completely removed and will have to be replaced with the kit but did test good at .5 voltage drop, the other larger diode was not removed and tested good as well with a .6 voltage drop.

 

[Faztbullet]

It sure sounds lie its going into slow...could be a bad pack or eye..