175 black max trigger and stator failed? having a heck of a time...

[chris71167]

ok heres the deal my grandfathers 1985 mercury 175 black max blew last sept(oil pump gear on crank shredded) i rebuilt it (im an ASE master tech in automobiles so i have alot of mechanical experience) i also removed the oil pump and everything with the oil injection. He ran the boat for a month maybe 4 or 5 trips out. When it blew again seems rod bearing/rollers cage had broken/cracked whatever broke a cap etc. well i rebuilt it again. Heres where im having trouble. It wont sounds like it wants to but wont start. Well it starts if held 1/4 throttle or above wont run under 2k or above 3k sounds like hits rev limiter at 3k. Plugs are new fuel pump rebuilt, engine is all redone, carbs gone through were fine, idle box removed, all filters replace, all fuel lines replaced, removed bayonet fuel line fitting all plugs/coils firing, link and sync checked/adjusted according to factory mercury manual. timing is at 11 atdc at idle cranking. Well im running out of crap to check. i tested the stator according to the manual blue red wire from stator spec is 5400-6200 ohms reading 2300 same with blue/red with white stripe red lead to ground spec 125-175 reading 51.8 soooo according to mercury the stator is bad ok well i test more test the trigger brown to white spec 1100-1400 my reading 2300 etc on the trigger my readings are not close to spec soo my grandfather has bad luck or something else is going on, is it common to have several electrical parts go out at once, i know his battery was stinking and leaking and his starter had to be rebuilt from arcing to block. but all this crapwas working a fewmonths ago before it was installed any ideas at all im running out of stuff to test.... thanks chris

 

[nbnewbie]

Re: 175 black max trigger and stator failed? having a heck of a time...

Wow! Sounds like you have a "head-scracher" I would suggest sort of going back to square one and assume nothing from previous tests. At times it is hard to see the forest because of all the trees. A couple of things are not mentioned in your post what is the max timing at cranking speed? Have you done a compression test since the last rebuild? Did you obtain your timing pointer position as suggested by the manual with a dial indicator. Have you done a spark gap test? From your description of the trouble it does sound like possible timing issue you say it won't start unless held at 1/4 throttle and does not run above 3k. What is the crank timing spec at 1/4 throttle and what is the max timing spec at 3k. I don't think I would call it "common" for several electrical parts to fail at once, but certainly not impossible. Good luck! When you do figure it out please post the solution.

 

[jigmister]

Re: 175 black max trigger and stator failed? having a heck of a time...

got the same engine and found out that the merc ohmes test is not reliable. Get a DVA and check the stator and trigger that way.

I have a trigger that merc says is junk. It runs top notch. DVA says the trigger is good.

Check to see if all the cylinders are geting spark. Simple way would be pulling plug wires off as it runs and look for the arc and see if it stalls out.
My engine was running and idling with only 2 cylinders getting spark. How I dont know but it WAS.

 

[CharlieB]

Re: 175 black max trigger and stator failed? having a heck of a time...

You mentioned starter and battery problems, minimum cranking speed is 300 RPM or the stator will not reliably generated enough to power the ignition.

11 ATDC craning? Should be more like 4, Check WOT timing cranking then readjust idle timing closer to 4 just to get started, final idle speed is adjusted with base timing.

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

Yes all cylinders have spark and good too can jump 1/2 gap with ease. compression is good boat hasnt been put in water since rebuild hasnt idled yet. pointer is right on 0 at tdc #1 spark does not seem to be cutting out on any cylinders with timing light. 11 atdc is what the mercury manual says to put it at it seems not right to me. i would guess 4-7 so your telling me the factory mercury manual for this engine (80 or so bucks i dont remember) is incorrect. Im frustrated becuase i have vast amounts of mechanicall knowledge and experience but with boats it seems the biggest downfall is lack of information or good information and a good mechanic cant do anything with out that.... also noticed last night if throttle sits at about 2k it will run for about 30 seconds fine then slowly come down by itself throttle staying in position and die but if reved back up same thing. it seems to be timing/stator or electrically related doesnt seem mechanicall or fuel but im not an expert on outboards just rebuilt/worked on a handfull. also starter is new batterys replaced cranks just fine. and trys to start sputters sometimes backfires this is why i think its timing either set wrong(book and timing light say its right?) or and electrical component screwing with the ignition.

 

[CharlieB]

Re: 175 black max trigger and stator failed? having a heck of a time...

Does it have the 'Idle Stabilizer Module'? When these go bad they ground the Bias to alter timing, and WILL destroy an engine. Take it OFF and THROW IT AWAY, set WOT timing at 23 BTDC, initial idle timing at 4, final idle timinng is used to set idle speed once in the water so's to have full water backpressure in the midleg/exhaust.

 

[j_martin]

Re: 175 black max trigger and stator failed? having a heck of a time...

Simple doctrine, but hard to swallow.

If you rebuild an engine, and it soon blows up, it's something you did.
If you assemble an engine with parts that were good, and it doesn't run, you put something together wrong. (pistons in wrong bank, maybe.)

You may be a mechanical master and genius, but this one's got you for now.

Idle timing late, it'll start with the lever up, just won't idle.
Back firing, something mechanical, or wired wrong.

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

Not exactly it blew cause a rod cap broke, apparently there is updated rod bearing/cage assemblies and was told you should replace the rod bolts so second time around i did replaced the bolts and cage/bearings. timing spot on double checked it. well i started rechecking stuff sprayed mix fuel into carbs would start and idle for a couple seconds. so since fuel system is all redone and mixed a little tank of gas no help well its got a clear filter assembly after the bulb when i would get it running i noticed it sucked fuel dry after the bulb tried pumping but wouldnt come thru unless engine was not running then fuel would go thru bulb. it seems the simplest thing is the culprit i really hope thats it but also hope i didnt waste all my time chasing crap when its a cheapy bulb. Btw i wouldnt put pistons in wrong bank im not a retard i have the factory manual, i also do this sorta thing every day for the last 10 years i never had something blow up after i rebuilt it. it blew after a month and prb 15 hours of use. yea i didnt have the right info didnt know about the cages and new rod bolts . So not my mechanical ability just un informed theres a difference. Dont mean to come off a little harsh but trust me i get what your saying i already double checked everything i did first. I may be a master mechanic but everybody makes mistakes thats why i always double check my work and certainly if theres an issue after my work. If i can rebuild new mercedes engines i can do a 2 stroke boat motor ive already done a handfull with no issues thanks for all the help guys.

 

[j_martin]

Re: 175 black max trigger and stator failed? having a heck of a time...

Serious blockage between bulb and tank. Possibly pick up screen in tank.

And it's common knowledge that you don't re-use rod bolts.

I'm not saying you're not a crack Mercedes mechanic, but you did something wrong on this engine. It's what you did. You won't find it till you can overcome your pride enough to double check your own work.

I truly hope it helps
John

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

Well i didnt know about the rod bolts everyother engine in the world does reuse them unless stated in the service information...so my bad. fuel pump cant be assembled wrong it ran last time perfectly. I rechecked it and rebuilt it just in case the diaphram had a pinhole in it. I appreciate the help why do you think its the fuel pump? I know now its starving for fuel when the throttle linkage is moved no fuel comes out of jets( i already cleaned them) when pumped up and cranked fuel comes out of lines from fuel pump. when running starves out does not go past bulb.


Serious blockage between bulb and tank. Possibly pick up screen in tank. ( i already stated used a seperate gas tank same result)

And it's common knowledge that you don't re-use rod bolts.

I'm not saying you're not a crack Mercedes mechanic, but you did something wrong on this engine. It's what you did. You won't find it till you can overcome your pride enough to double check your own work.

( ive already stated i double checked my own work) could not find anything....soo something has changed either something i did has to be minor or something with the boat...ive checked every wire every connection EVERYTHING tens times over so i dont know something or ive missed something 10 times over. Thanks for the help. i will figure it out i just dont want to spend forever and find something stupid.

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

Ok the boat seems to be only getting fuel in midrange 2-3k for 30sec to 60 seconds Ive already tried to bypass the fuel pump and use the bulb as a pump in a seperate tank no help. ive cleaned carbs also rebuilt fuel pump(this was all fine and running great before) ive checked fuel quality and ran new gas replaced all filters and lines. the only thing is the bulb seems to be the culprit. engine will not pull gas past it while running pumps fine when engine off. with engine running bulb is hard and will not push gas to filter.... Im goin to try to find a mercury bulb and recheck. thanks for the help any other ideas.

 

[CharlieB]

Re: 175 black max trigger and stator failed? having a heck of a time...

Aftermarket primerbulbs and bayonet fittings are highly suspect, these are two parts that OEM are highly recommended.

 

[j_martin]

Re: 175 black max trigger and stator failed? having a heck of a time...

Yer right on. It's either the bulb itself, the hose between the bulb and the tank, or the fittings. What you're describing sounds like what happens when the inner tube in the hose collapses. Slow volume it works, collapses when volume increases. If the hose de-laminates, the inner tube can collapse and the hose looks normal. BTW, you came on claiming bad electrics, and it's coming down to fuel.

 

[sschefer]

Re: 175 black max trigger and stator failed? having a heck of a time...

Did you do the link/sync procedure per the Merc Manual? I think your only problem is that one of your carbs is opening early. It's usually the center carb that opens back up when you tighten down the screw. The symptoms all fit.

Also the rod bolts were probably fine. It's more likely that you accidentally reversed a rod cap. The caps are freeze broken not machined so they only go on one way. If you get one on wrong the cap will skew and break the rod bolt.

Replacing rod bolts is the norm for a shop and performance builders but I've seen them used over without any adverse consequences many times.

 

[CharlieB]

Re: 175 black max trigger and stator failed? having a heck of a time...

Hi Steve, haven't seen you post in a while.

Still would like to know if this poster has the idle stabilzer removed BEFORE it hurts his freshly rebuilt motor, and if he has replaced ALL fuel hoses with good quality rated alky-resistant line.

 

[j_martin]

Re: 175 black max trigger and stator failed? having a heck of a time...

Hi Steve, haven't seen you post in a while.

Still would like to know if this poster has the idle stabilzer removed BEFORE it hurts his freshly rebuilt motor, and if he has replaced ALL fuel hoses with good quality rated alky-resistant line.

Claims he did in his initial post.

 

[CharlieB]

Re: 175 black max trigger and stator failed? having a heck of a time...

Claims he did in his initial post.

D'oh!

O.K., I'd suggest looking into that timing again anyway.

Disconnect the throttle cable and make SURE that the timing lever is not sticking anywhere, that it moves smoothly with the throttle lever, up to the max timing set screw and that the throttle continues to open against the spring pressure of the timing level.

With the throttle lever held WOT recheck cranking timing at 23 and idle timing near 4 with a smooth advance throughout the movement.

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

Yes idle stabilizer was removed, link and sync per manual. timing when cranking is 4 WOT is 23 spot on installed a new(aftermarket bulb...i made it real clear to him i wanted mercury several times. Ok heres new results....its definantly fuel. really is trying to start runs sometimes for 2-3 seconds. with a seperate tank and new bulb its runs better and will run down to 1200 rpm but will die 10-30 seconds....with the primer solenoid disconnected and capped will not start. when pumping bulb kills engine. and still seems to be sucking filter dry/near dry. Im thinking its pulling air/incorrect volume. i also noticed the NEW fuel lines i put on last sunday some are rock hard and some are soft and loosening. i think he got cheapy non fuel lines. SO im goin to get quality fuel lines mercury bulb and mercury filter...it seems im running in circles. So with that stuff put on i should get some better results i hope. i think im just dealing with cheapo crap... i know those aftermarket filters and bulbs flow different volumes than OEM and these boats dont run on much fuel pressure so im thinking the fuel system needs to be spot on right flow and no leaks since it runs on vacuum/pressure, thanks for the help guys do you agree im on the right track?

 

[chris71167]

Re: 175 black max trigger and stator failed? having a heck of a time...

i was outside writing the list of crap to get and noticed with the engine off when i pump the bulb up and fill the filter its bleeding back down dry back into the tank....the cheapo bulb im guessing. but im hoping with the correct fuel lines bulbs and filters and tight connections i have a feeling it will be just fine....

 

[nbnewbie]

Re: 175 black max trigger and stator failed? having a heck of a time...

I've been following this out of interest. I hope your "feeling" is correct and the next round of parts fixes it. Just something to ponder, everyday on lakes and rivers all over this country there are outboards of many makes and models running on what some might call "cheap aftermarket s!#@*t". This is not a suggestion that you shouldn't use quality parts, just something to think about. From your last post "i pump the bulb up and fill the filter its bleeding back down dry back into the tank" certainly not the best situation. When you run the outboard can you see the same thing happening the filter not staying full?