Motor Runs On Muffs But Not In The Water

[CEBall]

Ive got a 1973 johnson 65hp. the motor runs strong when you have the muffs hooked up to the hose and there is no load on the motor. when you put the motor in the water it starts right up and idles fine but when you put it in to gear in stalls. i just bought the boat and motor and have had only limited time to mess with it, i was just wondering if anyone had any suggestions on where to start. thanks, CEB

 

[tashasdaddy]

Re: Motor Runs On Muffs But Not In The Water

set your idle speed higher. there is not backpressure on the exhaust when on muffs. your idle should be set at 600-750rpms, IN THE WATER, AND IN GEAR.

 

[jtexas]

Re: Motor Runs On Muffs But Not In The Water

cylinder drop test:
Engine idling on muffs, pull then replace the spark plug wires one at a time.
RPMs should drop noticeably; if they don't, that cylinder's not making power.

Use a plastic or insulated tool to avoid electric shock (or ask your mother-in-law to help out).

Your motor will idle all day on 2 cylinders and sound happy doing it, until you put a load on it.

Let us know what you find out.

welcome to iboats!

 

[CEBall]

Re: Motor Runs On Muffs But Not In The Water

havent tryed yet but waht do you do if one cylinder is not making power?

 

[tashasdaddy]

Re: Motor Runs On Muffs But Not In The Water

you find out why, it takes 3 things, compression, spark and fuel.

 

[markhamilton]

Re: Motor Runs On Muffs But Not In The Water

i had the same problem on my motor although mines about a '93. the problem was the high speed jets in the carburator. we removed them soaked the carb's in a bucket of carb cleaner overnight and blew air through the highspeed jets with an air hose. worked fine eversince

 

[cmuman]

Re: Motor Runs On Muffs But Not In The Water

I had the same problem. My idle jet was clogged right in the bottom of the float bowl. I went through much more trouble than I needed to. A good carburetor cleaning goes a long way.

 

[CEBall]

Re: Motor Runs On Muffs But Not In The Water

I have determined that it must be a fuel problem. I did the cylinder drop test and all the cylinder were hitting very well. then a compression test, all three were right around 120#. so it looks like the carbs are next. they look like they are extreamly hard to remove. anyone have a link to directions or any tips on how to remove the carbs. what all do I have to remove to get the carbs off. I am only a college student and working on a limited budget, is soaking the carbs enough or do I need to buy a rebuild kit. if I just soak them do they need to be re linked and syncked?

 

[jtexas]

Re: Motor Runs On Muffs But Not In The Water

do you know whether it sat idle for awhile since it was last used?

all three are hitting, you can check the idle speed before doing anything drastic. have a tachometer?

best investment you can make is the factory service manual, available at kencook.com or marineengine.com - it'll save you $400 first time you use it.

 

[CEBall]

Re: Motor Runs On Muffs But Not In The Water

hey, the boat has sat for awhile since it was last used. i do not have tachometer. whats the easyest way to adjust the idel speed

 

[tashasdaddy]

Re: Motor Runs On Muffs But Not In The Water

your motor has a idle stop screw. move the linkage, you will see it hit the stop. turning clockwise speeds up the idle.

 

[jtexas]

Re: Motor Runs On Muffs But Not In The Water

the longer the boat sits unused, the more likely carbs will be clogged

 

[CEBall]

Re: Motor Runs On Muffs But Not In The Water

is there any to clean to carbs with out removing them?

 

[wildmaninal]

Re: Motor Runs On Muffs But Not In The Water

is there any to clean to carbs with out removing them?

I have '78 85hp evinrude that was doing the same thing. I started by doing a coil/spark check, found out that the coils were firing fine. I decarbed the motor and replaced the spark plugs. I did another compression check and found out all cylinders were fair/decent compression (you want to see 100 or above for decent compression). I rebuilt the fuel pump in the past. I cleaned the carbs (in carb cleaner), ran 120psi air through the all ports and holes in the carbs, and rebuilt them and from there I had to tinker with the linkage (link and sync the carbs), this straightened the motor out and it now runs like a scalded ape. Just thought I would run that by you.

Other things to check or try out is:

Air leak (leaky line)
Fuel pump (you may half to rebuild it)
Use a fuel injection cleaner or sea foam (not both) with a gallon of mixed gas and hook a hose up to this gallon and run the mix through the motor.

 

[HighTrim]

Re: Motor Runs On Muffs But Not In The Water

is there any to clean to carbs with out removing them?

Short and sweet, no.

 

[jtexas]

Re: Motor Runs On Muffs But Not In The Water

is there any to clean to carbs with out removing them?

no, but...these carbs are remarkably simple devices, you can do it.