1990 mercury 135 ignition problem

[eaglejax]

I have a 1990 mercury 135 v6 with only one bank firing, Ser.# falls between OA904646 and OC100860. My son got this boat and was told that the motor needed a stator and trigger. Picked up both along with one switch box used. Prior to swapping, we had fire on the right engine bank. After swapping we now have fire on the left bank only. Tried swapping the original switch boxes that we had but no change. Wondering where to go next; such as the mercury switch or voltage regulator or maybe weak flywheel magnets. Have ruled out coils since it fired on #1,3,&5 at first and #2,4,&6 now. Have no reading on the mercury switch but thought that if it were bad there would be no fire at all. A little input would be much appreciated.

 

[sam am I]

Re: 1990 mercury 135 ignition problem

http://forums.iboats.com/mercury-ma...issues-running-3-cyls-633874.html#post4436891

 

[eaglejax]

Re: 1990 mercury 135 ignition problem

http://forums.iboats.com/mercury-ma...issues-running-3-cyls-633874.html#post4436891

Thanks for the reply. I have manuals to reference and I work on all engine types but like like to get feedback from others who've had simillar situations so I can see if I missed anything. I believe The used trigger is the culprit since I had fire on one bank bofore and after swapping to this trigger now have fire on the opposite bank only. Disconnecting stator wires at the voltage reulator and the black and yellow stop circuit wires at the mercury switch and switch boxes has no affect, so now I'm back to checking continuity on the trigger again. Also have no reading when checking resistance on both the mercury switch and voltage regulator.

 

[Chris1956]

Re: 1990 mercury 135 ignition problem

Eagle, That motor has two switchboxes, three triggers and a single stator. I would recommend you see what components map into the cylinders with no spark. I doubt it is a trigger as they fire two cylinders each, and you have three non-sparking cylinders. That would mean that you have 1 and a half, non working triggers.

 

[Dukedog]

Re: 1990 mercury 135 ignition problem

stator or switch box more than likely..........Your case its leanin' more towards tha switch box. Replace in pairs (new). They share tha bias circuit so one can take out tha other.

 

[eaglejax]

Re: 1990 mercury 135 ignition problem

stator or switch box more than likely..........Your case its leanin' more towards tha switch box. Replace in pairs (new). They share tha bias circuit so one can take out tha other.

Thank you; Will check into new ones. I did switch the boxes, inner to outer to see if i could get the opposite bank to fire but still fires on the same three. Strange to me since it fired on the other bank before swapping stator and trigger

 

[Faztbullet]

Re: 1990 mercury 135 ignition problem

Swap the stator wire thats firing to the no firing switchbox,if it starts firing check you stator wiring or new stator was bad out of box...

 

[eaglejax]

Re: 1990 mercury 135 ignition problem

I beleive the opinions about the switch boxes hit. Though I checked before, I rechecked the bias this morning. One box good and one bad. Waited a few minutes and checked again;both bad (.55 volt). specs show 1-6 volts. Checked one more time to be sure and both bad.
Thanks

 

[Faztbullet]

Re: 1990 mercury 135 ignition problem

You should have 14,000 ohm on bias +/- 100..

 

[eaglejax]

Re: 1990 mercury 135 ignition problem

You should have 14,000 ohm on bias +/- 100..

14,000 at terminals from box to box or each terminal to grnd? I also have no reading on the red & blue stator wires on the affected box now so I've told my son to return the stator and buy new.
Thanks

 

[Faztbullet]

Re: 1990 mercury 135 ignition problem

From terminal to switchbox case

 

[eaglejax]

For the maritime gurus: I don't post questions that often and can't figure out how anymore so I thought I'd send by reply. Someone just brought a boat over and told me it started running rough and wouldn't idle, also wouldn't run any faster than 5mph at wot. He wanted the carbs rebuilt. Checked him out and 1st thing I see is blue milky mixture in the fuel filter. 2nd the oil reservoir was only 1/3 full. I told him that low oil will restrict the motor to 3000 rpms and that he had bad fuel. I then told him to drain the fuel, change the water/fuel separator and put in a fuel stabilizer. He said he just put two bottles of seafoam in the tank. Bingo!!!!!!! Only had 40 gallons of fuel. There's the milky mixture. He said rebuild the carbs anyway. Now after the drawn out symptoms. This is a 00 mercury 125EXLPTO Ser.# OT074494. I've rebuilt all 4 carbs and everything's working good. Link&synced but I didn't have the model specific manual for this motor meaning I don't have model years 98-00. When I rebuilt I put the mixture screws in #3 and #4 carbs and didn't plug the backdraft holes on all 4. Just found info. in an olderclymer manual that shows no Mixture screws in the bottom carbs because it idles on the upper two only. Not a problem but do all 4 carbs use or not use the backdraft vent plugs? Carb models are WME I believe. Sent the guy out to test the boat but called him to return so I can correct

 

[Faztbullet]

I told him that low oil will restrict the motor to 3000 rpms

Thats incorrect as motor has no such feature....sorry

 

[eaglejax]

Thank you sir for the reply and info.! You would think they would keep that feature as the older models restrict rpms to 1600-2000. Maybe if I don't tell him any different he'll make it a habit to check the reservoir. Haha. I've got the manual ordered for the model years that I don't have but do you have the info. on the backdraft vent plugs for this model? The motor came to me with one of the upper 2 carbs plugged and one of the lower 2 carbs plugged. I didn't think they used the but installed anyway. Removed the upper two carb plugs because it wouldn't idle but not sure about the lower two carbs.

Thanks again for the reply
​I still can't figure out how to put a new post on this site anymore

 

[eaglejax]

Got it. Water tested and could not get on plane. Pulled the vent plugs on the bottom two carbs and everything's good. Bottom two starving.
Thanks