175 Mariner fell on its face all of a sudden

[Jmr1974]

Updated report. Got the two new switch boxes installed Friday night and all cylinders have spark now. Yesterday test run motor in barrel of water. It was hard to start, back firing and popping but finally started. It kept running once it started but sounded rough and seemed to smoke more than normal. I decided to take it to the nearest boat launch to test run it, boat starts right up, put it in reverse and it dies, starts up again, put it in forward and it dies. I did this probably 6 times and it died every time I put it in gear, I gave up and trailered the boat before I floated to the other end of the lake. So the motor has a new stator and two new switch boxes. Also I have removed both black boxes as suggested earlier in this thread, the one labeled advance module on top of the motor behind the flywheel and the one on the side of the motor that must have something to do with the oil injection. The only thing I have not done yet is adjust the timing from the factory setting after removing the boxes, I was just happy when I had everything back together and was getting spark on all cylinders and figured things could be fine tuned after seeing how it would run on the water. What I’m having a hard time understanding is how the motor can even run after removing those two boxes that were put there from the factory and unplugging the wiring that goes to them... I thank all of you that have helped me along to this point and hope you guys can bear with me till I can figure out what the hell im doing right or wrong.LOL. I know it has been suggested I need to adjust timing after removal of the two boxes but would the motor be this far out of wack until I do? I have no clue how to time an outboard. So basically the only thing the motor will do now is start up and run but once put in gear it will die. Before I put the boat on the trailer I tilted the motor up till the prop was half out of the water and it would go into gear and stay running but dies under the load of the boat. I’m stumped...

[Jmr1974]

I pulled the plugs to see what they look like today. They all look similar except cylinder#3, second one down on the right is all black. Even the other 5 plugs have wet black residue around the perimeter of them but not all blacked over like cylinder#3. I don’t recall the plugs looking like this in the past when the motor ran correctly, they all looked nice and clean. Strange thing is cylinder3 is the one I had no spark on when this problem began. When you guys look at these plugs what symptoms do you see?

[Jmr1974]

I pulled the plugs to see what they look like today. They all look similar except cylinder#3, second one down on the right is all black. Even the other 5 plugs have wet black residue around the perimeter of them but not all blacked over like cylinder#3. I don’t recall the plugs looking like this in the past when the motor ran correctly, they all looked nice and clean. Strange thing is cylinder3 is the one I had no spark on when this problem began. When you guys look at these plugs what symptoms do you see?

I also just snapped a pic of the lower unit and exhaust, you can see the black oil residue leaking down the skeg. Its hard to see in the pic but there’s a black ring around the two exhaust ports where it comes out in the upper part of the mid section also. This motor has never looked like this, always nice and clean.

[Merc 2.5]

I think i said this b4 but u need check fuel pump diaphragm is the pump on starboard side?

[sizzler]

Updated report. Got the two new switch boxes installed Friday night and all cylinders have spark now. Yesterday test run motor in barrel of water. It was hard to start, back firing and popping but finally started. It kept running once it started but sounded rough and seemed to smoke more than normal. I decided to take it to the nearest boat launch to test run it, boat starts right up, put it in reverse and it dies, starts up again, put it in forward and it dies. I did this probably 6 times and it died every time I put it in gear, I gave up and trailered the boat before I floated to the other end of the lake. So the motor has a new stator and two new switch boxes. Also I have removed both black boxes as suggested earlier in this thread, the one labeled advance module on top of the motor behind the flywheel and the one on the side of the motor that must have something to do with the oil injection. The only thing I have not done yet is adjust the timing from the factory setting after removing the boxes, I was just happy when I had everything back together and was getting spark on all cylinders and figured things could be fine tuned after seeing how it would run on the water. What I’m having a hard time understanding is how the motor can even run after removing those two boxes that were put there from the factory and unplugging the wiring that goes to them... I thank all of you that have helped me along to this point and hope you guys can bear with me till I can figure out what the hell im doing right or wrong.LOL. I know it has been suggested I need to adjust timing after removal of the two boxes but would the motor be this far out of wack until I do? I have no clue how to time an outboard. So basically the only thing the motor will do now is start up and run but once put in gear it will die. Before I put the boat on the trailer I tilted the motor up till the prop was half out of the water and it would go into gear and stay running but dies under the load of the boat. I’m stumped...

Hey Jmr1974,
I've got a 1986 v135 black max that was running strong, very strong, last night for about 7 miles...we stopped, started, moved around a bit sniffing out surface activity...noticed the motor stuttered a bit on accelerating....and then...no accelerating...different engine sound, hit the throttle and tach won't go above around 1800 but it doesn't feel good there at all, my son said it sounded like it was being suffocated, wondered if the prop hub was spun (no), shut down, restarted ok but won't get going and sounds not good. Sounds like there's a t-shirt caught in the pistons or something. Reminds me too of my childhood minibike when the air filter became clogged - hit the thottle but no hp. Anyway...We went about 1/2 mile at 1000 rpm and then I switched to the kicker for the 6 miles home. I'm a freak about fuel and filtration, and the kicker ran well so I'm sure its not fuel. I've never overheated, so don't know how that plays out....but the stream out the back was always good and no smells of any sort....could be a clogged t-stat on one side only? I've decided it must be electrical - excited to see your thread here, until getting to the end here seeing that new stator and new switch boxes didn't fix it. Perhaps removal of the timing stuff screwed up timing so once that's addressed, you will screamandfly? Could it be the voltage regulator? Could it be a bad wire connection beyond all that you obviously cleaned up? Someone said their flywheel (magnet) was the problem on their motor...? Please keep us posted...I'll let you know what I discover.
Mike

[Merc 2.5]

I also just snapped a pic of the lower unit and exhaust, you can see the black oil residue leaking down the skeg. Its hard to see in the pic but there’s a black ring around the two exhaust ports where it comes out in the upper part of the mid section also. This motor has never looked like this, always nice and clean.

That pic is raw fuel. If fuel pump is on starboard side (switchbox side) then thats gonna b least part of the issue

[Jmr1974]

Hey Jmr1974,
I've got a 1986 v135 black max that was running strong, very strong, last night for about 7 miles...we stopped, started, moved around a bit sniffing out surface activity...noticed the motor stuttered a bit on accelerating....and then...no accelerating...different engine sound, hit the throttle and tach won't go above around 1800 but it doesn't feel good there at all, my son said it sounded like it was being suffocated, wondered if the prop hub was spun (no), shut down, restarted ok but won't get going and sounds not good. Sounds like there's a t-shirt caught in the pistons or something. Reminds me too of my childhood minibike when the air filter became clogged - hit the thottle but no hp. Anyway...We went about 1/2 mile at 1000 rpm and then I switched to the kicker for the 6 miles home. I'm a freak about fuel and filtration, and the kicker ran well so I'm sure its not fuel. I've never overheated, so don't know how that plays out....but the stream out the back was always good and no smells of any sort....could be a clogged t-stat on one side only? I've decided it must be electrical - excited to see your thread here, until getting to the end here seeing that new stator and new switch boxes didn't fix it. Perhaps removal of the timing stuff screwed up timing so once that's addressed, you will screamandfly? Could it be the voltage regulator? Could it be a bad wire connection beyond all that you obviously cleaned up? Someone said their flywheel (magnet) was the problem on their motor...? Please keep us posted...I'll let you know what I discover.
Mike

From your description it sounds like your motor did the same thing as mine. My motor would run perfect up to 1500-2000 rpms anymore throttle than that and it would just bog until I let off. From idle up to that rpm range you wouldn’t know anything was wrong. Now after putting new parts on and pulling boxes off it runs worse now than It did with the initial problem. It idles for crap now and dies at the thought of being put in gear under the load of the boat. I. Think if I would put all the original parts back on I would be back to the initial problem. Something got more messed up between adding new parts and removing the two boxes.

[Jmr1974]

That pic is raw fuel. If fuel pump is on starboard side (switchbox side) then thats gonna b least part of the issue

Merc, here’s a pic of the fuel pump. It’s on the switchbox side of the motor right in front of the starter. When I pulled the plugs after the initial problem they looked normal even tho the motor wouldn’t go past 2000 rpm, this new plug condition only happened after replacing both switch boxes, the stator and removing the two black boxes. I have created a new problem along with the old one... the motor runs piss poor now, before it ran great until it hit 2000ish rpms. I think I should’ve left the two boxes on even tho the wires were exposed and seen how it ran with the new stator and switch boxes. Only thing I gained was spark on all cylinders, before the new parts I had no spark on cylinder #3. Would the timing be this messed up after loosing those two black boxes?

[Merc 2.5]

Yes but won't b off that bad. Find the hose that feeds the pulse to the pump. If its hooked to number 3 then diaphragm is bad. It will flood the cyl thats feeding it the pulse
I say this as I've had more than 1 pumlp go bad and pour fuel out the lower

[Jmr1974]

Yes but won't b off that bad. Find the hose that feeds the pulse to the pump. If its hooked to number 3 then diaphragm is bad. It will flood the cyl thats feeding it the pulse
I say this as I've had more than 1 pumlp go bad and pour fuel out the lower

Merc, what hose am I looking for that gives the pulse? The two black boxes have been eating away at me so I went ahead and hooked them back up. Back to the launch I went only to discover nothing changed. At least that won’t keep me from pulling any more hair out. Also is it possible I installed the stator clockwise or counterclockwise by one screw hole? I thought I did but anything is possible and would it matter? I checked my before and after picture and the wires look like they come out the same place. When the motor is running and I give it some throttle it almost sounds like the plug wires are on the wrong cylinders if that makes any sense.

[Merc 2.5]

Yes it makes sense and stator needs b clocked rite but thats no reason at all for raw fuel to run out the prop. Ur so rich its flooding itself on #3 which prob provides pulse to pump and 1 and 5 little fatter also than port side. Really need least look at the pump diaphragm a pin hole will cause this issue. The stator wires need come out just behind the starter
There should b a fuel hose runnin from the pump to the block

[Jmr1974]

Yes it makes sense and stator needs b clocked rite but thats no reason at all for raw fuel to run out the prop. Ur so rich its flooding itself on #3 which prob provides pulse to pump and 1 and 5 little fatter also than port side. Really need least look at the pump diaphragm a pin hole will cause this issue. The stator wires need come out just behind the starter
There should b a fuel hose runnin from the pump to the block

first pic is old stator wire location, second pic is new stator wire location. I’d say there close to the same spot but pic angle could be a hair different. The only hoses I see for the fuel pump is one feeding it from the fuel tank and then a 3 way splitter which go to each carb. These hoses are around 3/8” dia. There are other smaller I’d say 1/4” hoses that route to nipples on the front side of each cylinder in the engine block but do not come out of the fuel pump. These little hoses are black with a yellow or white stripe on them. I looked up the diaphragm on iboats and it’s only like $15, it comes with some other pieces and parts. It almost seems like a mini rebuild kit. Does that seem correct?

[rgsauger]

Yank the boxes back off. Theres a reason we all do it. It might be worth replumbing your hoses, too. It's nearly free. Tygon.

Yep, fuel pump rebuild is 4 screws

[Merc 2.5]

first pic is old stator wire location, second pic is new stator wire location. I’d say there close to the same spot but pic angle could be a hair different. The only hoses I see for the fuel pump is one feeding it from the fuel tank and then a 3 way splitter which go to each carb. These hoses are around 3/8” dia. There are other smaller I’d say 1/4” hoses that route to nipples on the front side of each cylinder in the engine block but do not come out of the fuel pump. These little hoses are black with a yellow or white stripe on them. I looked up the diaphragm on iboats and it’s only like $15, it comes with some other pieces and parts. It almost seems like a mini rebuild kit. Does that seem correct?

Those r bleed hoses shouldn't have to mess with those.Stator looks to b rite

[tlwjkw]

Yesterday test run motor in barrel of water. It was hard to start, back firing and popping but finally started. It kept running once it started but sounded rough and seemed to smoke more than normal. .

ya have something wired wrong with switch boxes ta coils.. it only takes one.................. or timin' could be WAY, WAY, WAY off but doubt it..