Dies when going into rev/forward and rattles 71 merc 800

[rtpassini]

Tried putting it in the water for the first time. man...how embarassing.


It started up great. idled perfect. could put the warm up lever down almost right away. but when i would try putting it in reverse. it would die. if i tried doing it faster, it would move back a tiny bit then die. i tried putting the warm up lever up to get the idle up but then it would grind/rattle really bad so i stopped that.

i recently replaced the impeller if that makes a different. the most recent time i ran was over a year ago.

 

[Moody Blue]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

Did it only stall in reverse? What about forward?

Most likely the carbs are not set up properly. Have asked this before but not answered yet. Have you performed a sync and link on the motor? It is essential to synchronize the carbs with the ignition.

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

Sorry, i havent responded to that yet.
No i havent. Ill put it on my list of things to do. Everything is matched up at TDC though, should i still do the timing and sync?
I never tried forward. Only a little bit with muffs on (prop BARELY spinning) because i didnt know if i should run the motor much with muffs.

My guess would be carbs too. Is there an easier way i can take the carbs off and clean them without losing my "settings" or having to buy a rebuild kit?

OH! also, when it was idling. it seemd like water was "spraying/misting" from the 2 squares on the back under the cowl. normal?

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

I forgot to add, when i had the warm up lever up a bit to try and get into reverse, it would rev even higher than normal.

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

i tried it today in forward. same thing. it "rattles" and then shuts off. one time it made this clunk noise then shutoff.

could my idle be too high not letting it go into gear?

 

[Moody Blue]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

Well the good thing is that the motor is running. Chances are with properly setup carbs you will have a runner.

One important thing to be aware of is the fast idle lever can ONLY be operated when in neutral. You can (should not be able to) not engage forward or reverse with the fast idle lever up.

For the little time it takes to do the sync and link I would make it a priority. Then at least you KNOW the carbs are properly synchronized with the iginition. Mine was so far off I'm surprised it ran. The max advance timing was 6* off and would have caused piston damage if ran for long and the primary carb pickup was out to lunch, thus poor idling. This is the link that explains both the sync & link and setting up the carbs.

http://forums.iboats.com/showthread.php?t=168855

The two square ports under the cowl are the exhaust relief ports and it is normal (a good sign) to have water exiting there. When idling with the motor in the water, there is too much back pressure for the exhaust to exit thru the prop as normally would happen at speed. Instead the exhaust and cooling water exits thru these relief ports.

 

[tskm2001]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

You mentioned that the engine had not been run in over one year. Did you stabilize you fuel before the enigne sat? Also if the fuel in your area has ethanol in it most fuel stabilizers only work for about 6 months. I have found that the type of problem you are describing works back to gummed up carbs. If you find you have to rebuild them, then a synch and link is part of the standard procedure when reinstalling.

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

i bought it in november and assumed it sat for at least a year. it idles great, nice and smooth. (i put new gas in it)

I called a local dealer and they think its a gear box issue.

when i put it in reverse, i cant spin the prop. when i put it in forward, i can spin in one direction but theres REALLY loud clicks. when i turn the flywheel by hand, it turns the prop....

could i have screwed soemthing up with the impeller install? im 99% sure i lined the splines up correctly.

or is something not adjusted right? it also randomly started peeing really well. it was just a dribble (nothing was blocked, i made sure of that)

 

[cell]

Re: Dies when going into rev/forward and rattles 71 merc 800

Sounds like when you had the lower unit off the shift rod/cam moved.When in forward gear it should ratchet in on direction,and turn the flywheel in the other.When in reverse it should only move a little bit in both directions before it turns in the flywheel.
Or the bearing case needs to be torqued more in order for the clutch dog to engage.

I have a 71 115,and had the same problem.I don't know if it shifts the same as yours but ......

http://forums.iboats.com/showthread.php?t=306705

 

[Karl_Childers]

Re: Dies when going into rev/forward and rattles 71 merc 800

Yeah man, you got your shift cable/rod/linkage all out of adjustment. Make sure your cable isn't frozen up too. Like others have said, be sure to do a sync and link too. Read the proccedure in the manual at least twice if it is your first time, after that it should be pretty easy. Good luck, Rob

 

[rtpassini]

Re: Dies when going into rev/forward and rattles 71 merc 800

i dont suppose anyone has a good picture shift rod...all the parts pics ive seen are really bad...i think mine may be broke. im not sure.
you dont mean the drive shaft right? is it that little part thats in front of the drive shaft? also which bearing case?

when in both gears, its very difficult to spin the flywheel from the prop. and im a big dude. haha

 

[cell]

Re: Dies when going into rev/forward and rattles 71 merc 800

when in both gears, its very difficult to spin the flywheel from the prop. and im a big dude. haha

Take the plugs out


The shift shaft is in front of the drive shaft.The bearing case is where the.......crap hang on and ill look for a pic.

heres a vid of the internal workings.Ill get more...

http://www.youtube.com/watch?v=vuAcrDFvApA

 

[cell]

Re: Dies when going into rev/forward and rattles 71 merc 800

Well I can't find a blown up pic of the lower unit.Id just worry about getting the shift mechanism right for now.

The bearing case basically holds all the gears and bearings on the prop shaft.If you take the prop off you will see a big nut behind it.Take that off,and then all the guts will come out....at least on mine it does.But I wouldn't worry about that just yet.Just concentrate on the shift rod.If mine is like yours(i have no idea)Then the first link I post gives you a good idea on what needs to be done.

 

[Moody Blue]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

I called a local dealer and they think its a gear box issue.

I'm no expert by any means but what you described with the prop and gear selection is normal. Neutral - prop spins freely both directions. Fwd - prop spins one direction only. Rev - prop is locked. If a dealer can diagnose a problem over the phone without ever looking at the motor they are pretty amazing . I would not start tearing your lower unit apart without very good cause unless you have lots of time and money on your hands.

My best guess is that your problem is carb related

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

i agree with you guys too. i think its something with the carbs. but im going to take my lower off, because when i did it, i thought the shift shaft didnt look right. basically, where the lower seperates, so did the shaft.

ill post pics today sometime. im wondering if the broken shift shaft just cant handle going into gear under load.

after i double check that. then carb work comes

 

[rtpassini]

Re: Dies when going into reverse 71 merc 800

Re: Dies when going into reverse 71 merc 800

im pissed...

so apparently the tq amounts for tightening the water pump housing in the manual are not correct. i starting crushing the housing.

great. anyone know some "safe" tq numbers.

 

[cell]

Re: Dies when going into rev/forward and rattles 71 merc 800

Till its tight....

 

[Moody Blue]

Re: Dies when going into rev/forward and rattles 71 merc 800

Yep, like Cell says, till its tight but not over tight. Sorry can't be more specific. Never used a torque wrench for those fasteners. Have heard of that happening to those housings.

Are you saying you have a broken shift shaft?

 

[rtpassini]

Re: Dies when going into rev/forward and rattles 71 merc 800

i thought i did. but it looks like its okay.

itll be a good week before i get a new housing. but im going to try the reverse idea and see what happens.

is it pretty easy to adjust the shifter?
im going to start there because adjusting carbs and all that makes me a bit nervous.

the housing is supposed to be tq'd down to 20,30, and 40 ft lbs. I dont think i was even close. i just dont want to have it too loose and have it leak everywhere.

 

[cell]

Re: Dies when going into rev/forward and rattles 71 merc 800

The carbs are easy.....tighten them up,unscrew 1 1/2 turns.Hit the throttle if it fails unscrew the top one 1/4 out.hit the throttle.If it fails turn the next one 1/4 out,and so on.

You might be able to get away with 2 turns out on all of them till you get out from the launch.Then follow the carb tuning when your out safe to test.


To adjust the shift cable.......take the cable off the engine side.Manually shift the the outboard into neutral.(if it isn't.)Now put the throttle lever in nutrual.Adjust the cable to fit in the shift linkage on the engine side.

When you do all this take note on how everything jives with each other.You can actually do fine adjustments if your having shifting problems.