71 merc115 no power in water

[2ndboat]

hello all ,
Ive read lots of your posts and they seem very helpfull.
heres my problem.
I have a 1971 merc 115 6 cyl that ran super 2 months ago lots of power and lots of throttle on the water. took it out yesterday and gets no rpm or power on the water but runs perfect in the yard with hose connected.
the middle carb was flooding then it stopped and the bottem carb was flooding through the overflow but ran great in the yard. I took the bottom carb of and found the float sticking so replaced it with a spare used one . now it has no fuel over flow problems and just wont get any rpm in the water but great at home. the distributor appears to advance . has good spark on all cyinders and has 120-140 comp between cyinders.just paid a tech to change the plugs and comp test it .he said to do the carbs ? it just bogs on throttle.
I tryed sqeezing the ball for more fuel while on the water and made no difference, so I dont think its fuel starving. The tech tells me he can change the trigger mechanizim for around 800.00 new but no garantee thats it and cant really test trigger? sounds kinda funny he cant test it but can selll me a new or used one. My question is can it be truly tested? Or does anyone have any ideas where to start? I'm automotive mechanically inclined and new to outboards but can take anything aprt and put it back together correctly.
any suggestions appreciated.. this thing used to fly two months ago.... Lou

 

[bootle]

Re: 71 merc115 no power in water

$800.00 Bucks?

 

[Chris1956]

Re: 71 merc115 no power in water

Since it fires, the trigger is good, as is the switchbox. Use a timing light to test for spark to all plugs. If you have spark on all six, and no arcing to ground, the carbs are the likely suspects. You might do a comperession check to rule out damaged rings.

 

[CharlieB]

Re: 71 merc115 no power in water

Find a new mechanic.

Order a manual and a DVA Meter and learn to test yourself, it is NOT difficult.

Use this forum to ask question just as you did this time. You CAN DO this and SAVE BIG $$$$$$$

Test the stator with a DVA Meter, you may have a bad high speed winding.

DO NOT buy ANY electrical parts until tested and PROVEN bad.

 

[emckelvy]

Re: 71 merc115 no power in water

'71 115 stator only provides charge to the battery, nothing to the ign. Here's the correct test for a CDI distributor ign:

MERCURY BATTERY-POWERED CDI TEST
FOR DISTRIBUTOR MODELS, Courtesy of Clams Canino

This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.

This test assumes your coil is good (most all are).

DISCONNCT BATTERY

1. Turn off ignion
2. Disconnect all 3 wires on the distributor side of the switchbox.
3. Remove the HV lead from the coil to the center cap (remember it unscrews
from cap)
4. Reconnect that HV center lead to the COIL side only.
5. Position that HV lead about about 3/8" from ground (block, shrouds etc)
and find a way to hold it there.
6. Jumper the brown and white terminals on the dist. side of the switchbox
together.

RECONNECT BATTERRY

7. Check that you have +12 V at red terminal.
8. Turn on ignition and verify +12V at white terminal (on red terminal side)
9. Touch the black terminal to ground - unit should cause spark each time
you touch ground.

If that passes and it won't fire at all, suspect the trigger.

 

[2ndboat]

Re: 71 merc115 no power in water

I did do all three carbs today .... seat and needle and gaskets ....
went for a test run and same thing booooooooggggs in the water but runs great at home on hose hookup?
full throttle in gear and only reachs 2000 rpm on tach.
compression test 120- 140 lbs between all six cylinders
6 brand new plugs just installed
nice blue spark at plugs
............................................i have two new fuelpump kits gonna try next........update to follow

 

[cb950]

Re: 71 merc115 no power in water

have you tried to run it at night on the hose? spray the electrical with a mist from a water bottle, and watch for anything is arcing to ground.

 

[gregpro50]

Re: 71 merc115 no power in water

The fuel pumps are a good idea and I would also check the timing just to be sure.

 

[Chris1956]

Re: 71 merc115 no power in water

What pitch prop do you have on it? What kind (weight of) boat do you have. If those motors are overpropped, they will behave like that.