91 XR4 150

[kkelley]

I have a 91 XR150 ser# oc267202

This question is from a beginner, working on my own motor but from the past experience i have had from a local repair shop i cant do any worse. The question i have do the switch boxes work independent of each other. I know there is a jumper on the white-black wire connecting the boxes on the top left lug. The reason i ask this is the idle stabilizer should hook to the outer box via a white-black wire and red-white stripe. After looking at mine the stabilizer is hooked to the outer box and inner box would this pose a problem. This all started b/c my boat would bog under a load at 2000 rpm. After doing some reading it would appear the high end of the stator is not doing its job. So i have decided to replace the 40amp stator along with both switch boxes. The fuel pump rebuilt, carbs cleaned and a compression test on all 6 cylinders at 90. The motor will crank and idle on muffs and does fine in the water until i reach 2000 rpms. I would appreciate any thoughts on this. Thank You in advance.

[JOE54]

black white wire does conn,to inside box,unhook both wires going to idle stab and try it, would not replace both boxes and stator without testing all componenets, nope

[kkelley]

I will try that tonight. But do the boxes work separately of one another being each box controls 3 cylinders each.

[JOE54]

yes sir

[kkelley]

I tested the stator with multimeter and it passed the ohms test, The trigger passed the ohms test as well. But the boat still bogged at 2000 rpm. Reading the service manual they can pass on ohms test and still not push correct voltage. What i don't have is a dva adapter.

[kkelley]

How do you test a switch box ? Any suggestions would be appreciated.

[JOE54]

dva would be nice,normally if you have voltage going in and none coming out box is bad, unless you have bias problem

[kkelley]

so that's on the white/black stripe wire going into switchbox if I am corrrect

[Dejecting]

DVA Adaptors are pretty cheap and easy to make, you can do a quick youtube search for how to make one. Dangar Marine has a good video on it.

You might also check your throttle, make sure there's no issues with the linkage, timing advance, or carb synchronization.

90 psi on your compression test seems a little low doesn't it? The manual I have (which covers the XR4 up to 1989, so take this with a grain of salt) states "While minimum compression per cylinder should be no less than 100 psi, actual readings are not as important as the differences in readings when interpreting the results. A variation of more than 10 percent between 2 cylinders indicates a problem with the lower reading cylinder, such as worn or sticking piston rings and/or scored pistons or cylinders. In such cases, pour a tablespoon of engine oil into the suspect cylinder and repeat the compression test. If the compression raised significantly (by 10psi in an old engine) the rings are worn and should be replaced."

[EuropeanAM]

Really need to test inputs and outputs with a DVA to have any real accurate reflection of where in the ignition (or IF) the problem really is.

IF a switchbox has failed, then it's wise to replace both of them as the "mate" is often damaged via the bias circuit.

Also, make sure you've pulled any advance/stabilizer modules OUT of the system to rule them out as potential causes (common problem point- engine can be setup to run just fine without them).

[kkelley]

I am replacing both switch boxes as a pair. I also have a new stator arriving. I tested the stator and trigger they both passed the ohms test but my boat still bogs under load at 2000 rpm. I have read they can pass ohms test but get hot under load and not put out the correct voltage. So i should remove the idle stabilizer for good and not hook back up.

I really appreciate the guidance from you gurus on this site. I have worked on motocross bikes when my son raced and now my grandson. But this is my first on outboards once again thank you

[JOE54]

well that should cure it for sure, wish my customers would say just replace it all, and yes remove module , would set max timming at 23 and roll on

[kkelley]

Well tonight i finished replacing the switch boxes and replaced the stator and buttoned her all back up. I have not removed the idle stabilizer as of yet. I plan too tomorrow night and re adjust the max timing to 23. I will report back on this keeping the ole fingers crossed. Thanks for all help and advice.

[JOE54]

make sure spark arm moves freely

[kkelley]

Well i put her in the water tonight. she cranked right up idled like a dream put her in gear and she eased out no problem through the no wake zone. As we got past the no wake zone i hit the throttle we got around 3 to 4k on the tach and she just bogged down throttled back and she ran fine just would not get on plane. So as of now we have replaced the stator and both switch boxes. The only thing left is the trigger. she runs fine on the muffs in the yard. In the water under a load just wont get on plane and open up just shuts down. Anyone have any thoughts. Ser # 0c267202

[kkelley]

Saturday morning after the Friday night failure. I went out and got back to basics pulled the carbs off the boat and found trash in the bowls, cleaned the carbs again it cost nothing but time. So checked fuel coming from fuel pump looks like it has shredded rubber. Now we are changing fuel lines out all the way through from tank to engine. Checked the vent from the tank good to go. As the afternoon rolled around everything buttoned back up and the wife says to me you ready to test? I said heck yeah nothing to lose but time. The boat cranked right away idled smooth put her into gear and like Friday night she purred like a kitten. As we approached the channel and engaged the throttle she tore out like she use to jumped on plane and we were gone.

Once again to the members Joe54 Dejecting EuropeanAM I thank you for your insight and wisdom. As i was once told KISS= Keep it simple stupid.

[JOE54]

test and verify,DEJECTING ???????