Testing Power Pack vs Stator

[Captquin]

Hello! I'm new to the site and already really like it. Lots of good information!

Here's my issue: I have an 85 Merc 150 XR2 that is only firing on one bank of cylinders.

Last night I ran a compression test and all cylinders are above 100 and within 10% of each other. I then followed the trouble shooting guide which reccommended I remove the black and yellow kill swich wire and then swap the stator leads on the power packs - (red with red/white and blue with blue/white). The notes said "If the problem moves (the oposite bank of cylinders now only fires) then the stator is bad. If the problem stays (same bank of cylinders now only fires) the power pack is bad."

I first switched only the red leads and the problem stayed the same, BUT when I switched both the red & blue leads NONE of the cylinders fired. The notes only said if the problem moved or stayed, nothing about not firing completely.

Looking for ideas on what to do next. Are the power pack & stator both bad? The trigger?

Thanks in advance for the help!!

 

[SparkieBoat]

Re: Testing Power Pack vs Stator

the best way to test it with a DVA adapter, they are cheap enough, link for trouble shooting guide and DVA adapter is in my sig below. a cheap investment and you will use it many times if you own an outboard.

 

[Faztbullet]

Re: Testing Power Pack vs Stator

Its a stator or pack,its not the trigger....

 

[CharlieB]

Re: Testing Power Pack vs Stator

First, reconnect the stator wires correctly paired, the ones with stripes must be on the same switchbox, the plain ones on the other switchbox. You can switch the PAIRs between the switchboxes but each pair MUST BE together.

Now, recheck for spark. If no spark on one switchbox, switch the stator pairs and retest for spark, if spark switches sides then the stator is suspect.

If no change, next disconnect the white Bias wire that connects the switchboxes together, recheck spark. If now you have spark on all cyls then the switchbox that always had spark has a bad Bias circuit and that switchbox must be replaced.

Merc recommends that switchboxes be replaced in PAIRS. If you already have CDI switchboxes you can replace only the bad box.

 

[Captquin]

Re: Testing Power Pack vs Stator

Thanks for the replies, specifically about the bias wire. I had heard that term, but didn't know what it was.

We switched the red & blue wires in pairs, so we should be good there. We did not have a DVA meter, so we just tested each wire (disconnected from the packs) with the multimeter. Both reds showed resistance, but only one blue one did - the one for the side that was working.

That led us to believe it was a possibly a bad pack AND stator, but since we didn't have the DVA tester or a flywheel puller, we brought it to the local Bass Pro Shop who said they'd test it for free.

Based on what they say we'll either let them do it, or buy the part and do it ourselves. I'll keep y'all updated so anyone else with the same problem will have a record.

 

[CharlieB]

Re: Testing Power Pack vs Stator

It IS possible for a bad switchbox to overload and take out a stator.

HOWEVER.....................since there is NO RETURN on electrical parts, and switchboxes and stators can add up to a pretty good sized bill, you want to be absolutely certain what parts you need before spending your hard earned cash.

DVA testing is THE most reliable indicator and is a very necessary part of diagnosing ignition problems.

With the Bias wire removed, and no change in spark, then switching stator leads between the switchobxes cause no spark anywhere, then confirm with DVA tests, a bad stator AND one bad switchbox. It is highly recommended to replace Mercury switchboxes in pairs. CDI stators and switchboxes are very high quality parts and often priced far better than Merc parts.

 

[SparkieBoat]

Re: Testing Power Pack vs Stator

someone mentioned that ...I think it might be in post #2..which seemed to have gotten ignored...I can not figure out why anyone with a outboard would not spend $25 on a DVA adapter and download a FREE troubleshooting guide and just do it right...takes all the guessing out of the situation. best $25 I ever spent.

 

[Captquin]

Re: Testing Power Pack vs Stator

Sparkie - Let me know where I can find a $25 DVA adapter. I'd appreciate it.

Update: got the boat back from the shop. They said the stator was shot, so they replaced it. They also said a switchbox was bad, but since they wanted $200 PER SWITCHBOX, I ordered them to install myself. For some reason, I decided to check the spark before installing the new switchboxes. Low and behold every plug fired.

Assuming they weren't lying, why would the shop say a switchbox was bad when all cylinders are firing? Would a DVA tester that they have and I dont reveal a weak spark or something? No since replacing the boxes if I dont have too, but I also dont want to get stranded somewhere.

 

[Faztbullet]

Re: Testing Power Pack vs Stator

They didnt test it ..they where covering their arse.

 

[SparkieBoat]

Re: Testing Power Pack vs Stator

a lot of times they figure it is best to replace stator and switch boxes in case there is a short or intermittent problem with them..It probably would not be a bad idea to replace both switch boxes, even though you MAY be ok with the old ones. the DVA adapter is available in the link in my sig below.

 

[CharlieB]

Re: Testing Power Pack vs Stator

A switchbox CAN function and spark all cyls yet still have excessive current draw on the stator, contributing to an early failure of the stator.

Many shops elect to error on the side of caution and replace switchboxes to ensure the new stator does not overload and melt.

DVA testing of the stator output DIS-connected from the switchboxes, then DVA tested again CONNECTED to the switchboxes to see if there is a great difference in the stator outputs. A switchbox going bad will give a very noticably lower stator voltage readings and should be replaced.

 

[Barnacle_Bill]

Re: Testing Power Pack vs Stator

Or google "direct voltage adaptor" and get the instructions for making a DVA. Its a very simple circuit.

 

[CharlieB]

Re: Testing Power Pack vs Stator

Check out this thread, it lists the parts and a diagram for a cheap, easy to make DVA adaptor

http://forums.iboats.com/showthread.php?t=374544