motor sputters??

[macojoe]

Hi guys been a while!!

Ok I have a new to me 1985 Merc 175, 2.4 motor. SS# 6619813 Oil injection dis connected, running 50:1

When I start the motor it is fine, when I troll for hours on end it is fine, but when I take off and are going 4500 rpm it starts bogging down? all lines from the tank are new this season, along with the ball, and the ball does stay hard. I have replaced the filter and there is no signs of a restriction any were.

What I have done so far, rebuilt the fuel pump with a new kit and gaskets, but not the ck vales.
Tested the Stator and it was bad, replaced with another used stator that tested good with a meter and was with in spec according to the book.
Replaced rectifier as it had a hole in the resin looked melted?
Replaced one bad wire and one coil as the plug wire was rotted into it.

The carbs were taken off and cleaned, all floats were cked for settings, then all put back together.

I was told that when the motor is acting up to push they key in, if it bogs down then it must be electrical, if it speeds up then it must be a fuel problem?
Well when I do this test it bogs done. So must be electrical??


Non related issue maybe?? I just replaced Tstas, it did not have any in it before. Motor seems to run hot at idle and at troll speeds with very hot water till you speed up, then it cools down, I was told this is nothing to worry about, it is normal for a merc?? I have no temp gauge install at this time.

Ok you know what I know now, I hope I was detailed enough for you guys. So what you say??

thanks

 

[hamit59]

Re: motor sputters??

Hi.
I have seen stators, when they get hot go out of spec. I would run your motor until it's hot like you would when trolling. Recheck the stator then
as will as a spark test hot. As for the temp of you motor it should not be any hotter than when your running at idle as wot. I would look for a restriction or a failing cooling pump. Check with a temp stick or Ir temp meter. Tstat should keep your motor at 140 or so.

 

[CharlieB]

Re: motor sputters??

"when I troll for hours on end it is fine, but when I take off and are going 4500 rpm it starts bogging down"

"I was told that when the motor is acting up to push they key in, if it bogs down then it must be electrical"

Your first statement is half the clue, the second solved the puzzle.

A choke bogging an engine isn't ALWAYS proof of an electrical problem, most of the time, just not always.

You simply have an oil overload.

When this occurs again, immediately pull the plugs and take a hard look at them. I'd be willing to bet that they are seriously oiled to the point that they will NOT fire under a heavy load such as put on the motor at 4500 RPM.

There is also an amount of pure oil in the recirc system, patiently waiting for engine speed to increase sufficiently to get it airborne and burnt off and let the spark plugs burn clean enough for the engine to get up to full power again.

The factory oiling systems lighten the oil mixture at low engine speeds to prevent this oil overload and hesitant throttle after long periods of idling and/or trolling.

Possible cures are;

1. install a small trolling motor and NOT idle the big motor

2. install spark plugs one-step hotter than the factory specified plugs (also, if piston clearance is adequate, change from surface gap to standard electrode or extended electrode plug)

3. if carb'd, readjust idle mixture to leanest idle possible and still not have any hesitation on rapid acceleration in gear.

 

[macojoe]

Re: motor sputters??

Thanks guys!!

Today I went threw the whole fuel system. from the tank to the motor all is new, I replaced the fuel filter also.
Then we took the fuel pump apart, one of the ck vales were stuck and we replaced them also. Other then that the pump was rebuilt only a few trips ago.

Also found a hose that was getting hit by the throttle linkage and had a small pinch in it.
The Carbs were taken off cleaned and floats set reassembled with new gaskets just 2 trips ago.

I replaced the plugs today and they were oiled up as you say, but this was running this way before I ever did any trolling. So I am guessing this is not the problem??

Motor stared right up and ran fine on the hose, we will see in the next day or so what it does in the water??

I think if the issue is still there it will have to be electrical?

So what you think??

Thanks everyone!