Stalls at Idle

[TonyD20]

Hi! I have a '92 Johnson 175 - I have been having a hard time trohnleshooting this problem - engine spits and finally stalls at idle but if I run the RPM's up (or in gear with speed) everything is fine.

Oddly enough though, I have found that if I run the engine with the mufs on, the engine runs just fine.. but once I place the boat into the water, with the engine submersed, I begin to have idling problems...

I had two different theory's mentioned to me..
one was that it was a VRO failure.. is this possible?

OR, there is something called back pressure in the exhaust that is cauing this... ??

Any ideas, anyone??

Tony D.

 

[airframer]

Re: Stalls at Idle

engines need a little back pressure, thats why cars have mufflers. but it does put a small load on the engine, just enough to kill yours. i'd check your carbs/ fuel mixer and quality

 

[TonyD20]

Re: Stalls at Idle

engines need a little back pressure, thats why cars have mufflers. but it does put a small load on the engine, just enough to kill yours. i'd check your carbs/ fuel mixer and quality

Okay, so this could be a VRO issue then? OR oil quality?

Tony D.

 

[ezeke]

Re: Stalls at Idle

You need to set your idle speed with the boat in the water and the engine warmed up. If you set it on muffs, it will be too low. If you try to set it while on the trailer, you may have the motor too low in the water, so do it at the dock if possible.

 

[TonyD20]

Re: Stalls at Idle

You need to set your idle speed with the boat in the water and the engine warmed up. If you set it on muffs, it will be too low. If you try to set it while on the trailer, you may have the motor too low in the water, so do it at the dock if possible.

ohh.. so you are saying that my idle speed should be adjusted? But then why would it spit on me like it does, almost like it is mis-firing. That would be grat if it were just an idle adjustment, which would bring me to a new question: I am not sure I know where the adjustment screw is for this engine, there are 6 carbs on this motor..

 

[ezeke]

Re: Stalls at Idle

If you want to troubleshoot, start with a compression check and then a spark test. Use a screw in compression tester, engine warm, all plugs removed and the emergency kill lanyard pulled to supress firing. Test each hole and record the results.

The spark test should also be done with all plugs out, using a tester capable of a 7/16 gap.

 

[TonyD20]

Re: Stalls at Idle

ezeke, I had the compression tested, all was good in that area. I don't have the numbers in front of me though.

originally, I brought this problem to the mechanic and what he found was an o-ring squashed between the gas filter and the engine. They said they ran it and everything was fine (with muffs on). They also ran a compression test and all looked good in that area...

 

[ezeke]

Re: Stalls at Idle

If everything was fine, you should just need to adjust the idle. Do you have a manual for your motor? Do you have a tachometer?

 

[TonyD20]

Re: Stalls at Idle

Yes, I have both.. but reading through the manual, it doesn't show me where the idle screw is - just goes over basic maintenance for the most part. The tach is on the dash of my boat.

 

[tashasdaddy]

Re: Stalls at Idle

it is on the throttle linkage. look at the link and sinc part of the manual, it will show you.

 

[TonyD20]

Re: Stalls at Idle

it is on the throttle linkage. look at the link and sinc part of the manual, it will show you.

I don't have a link and sinc section in the manual.. it's a very small man., I am not even sure you can call it a manual, it's all of 20 pages, and then another 20 for spanish. I think I might have to buy one.

What rpm should I be idling at?

 

[ezeke]

Re: Stalls at Idle

General synchronization and linkage instructions are usually in section 1 of the OMC factory service manuals. They are usually in section 2 of the Seloc Manuals and Chapter 5 of the Clymer manuals.

You will want to have your engine idling at around 650 RPM in gear unrestrained on the water, so you might start at around 900+ on muffs with the engine warmed up. Then when you get on the water you can make the final adjustment.

 

[TonyD20]

Re: Stalls at Idle

650, wow.. I doubt I am running lower than that now, I'd imagine it would be a bad thing to run a higher than normal idle to keep me running.. ?

Let me check my manual at home tonight and see what I can find, maybe I overlooked it...

 

[ezeke]

Re: Stalls at Idle

The manual you have is just the owner's manual. You would need a service manual. You can often find a factory service manual for your year and model on Ebay. http://cgi.ebay.com/ebaymotors/NEW-...016QQitemZ260092460967QQrdZ1QQsspagenameZWD1V

The parts manuals show the linkage and they are free and on-line:

http://epc.brp.com/default.aspx?brands=ej&lang=e

Navigate to your motor, then enlarge the diagram for the "Cylinder and Crankcase"

 

[TonyD20]

Re: Stalls at Idle

okay, thanks guys! The link you provided doesn't seem to open up the part of the engine I want but I suspect it's a java thing going on here on my work cpu, I'll have to try it at home.

I'll let you know how it all plays out.. should be interesting..

 

[tashasdaddy]

Re: Stalls at Idle

this one will work follow prompts to your motor.
http://shop2.evinrude.com/ext/index.aspx?s1=c6d575184c39a9353cbc049e378606f9

 

[TonyD20]

Re: Stalls at Idle

this one will work follow prompts to your motor.
http://shop2.evinrude.com/ext/index.aspx?s1=c6d575184c39a9353cbc049e378606f9

Yep, that one works! Thanks!!

 

[TonyD20]

Re: Stalls at Idle

So, still trying to figure this problem out and so far, this si what I have found...

While running the engine, I started to pull the wires off each plus to see which made a difference and which did not. To my surprise, all 3 cylanders on the left side of the motor made no difference at all with the wires pulled from the spark plug. the other side (other 3) certainly made a difference and started to choke a little when wire removed from plug.

I then began to make sure that those 3 clyanders were getting gas by half covering with my hand, the carbs, then realeasing. Gas came out...

I also checked the spark getting to the plug from the wire.. almost a 3/4" of an arc.. real good spark...

So now at this point...
compression is good
cylanders are getting gas
there is spark.. plugs are NOT fouled.

???

Could there be a timing issue here? What could this be? I did get a service manual for this engine from e-bay. There are no idle adjustments on the carbs and the overall idle adjustment is a timing adjustment but could it be that off to shut down 1 whole side of the engine?

Tony D.

 

[skynyrdcat]

Re: Stalls at Idle

So, still trying to figure this problem out and so far, this si what I have found...

While running the engine, I started to pull the wires off each plus to see which made a difference and which did not. To my surprise, all 3 cylanders on the left side of the motor made no difference at all with the wires pulled from the spark plug. the other side (other 3) certainly made a difference and started to choke a little when wire removed from plug.

I then began to make sure that those 3 clyanders were getting gas by half covering with my hand, the carbs, then realeasing. Gas came out...

I also checked the spark getting to the plug from the wire.. almost a 3/4" of an arc.. real good spark...

So now at this point...
compression is good
cylanders are getting gas
there is spark.. plugs are NOT fouled.

???

Could there be a timing issue here? What could this be? I did get a service manual for this engine from e-bay. There are no idle adjustments on the carbs and the overall idle adjustment is a timing adjustment but could it be that off to shut down 1 whole side of the engine?

Tony D.

How good is the spark on the 3 cyl that DID NOT MAKE A DIFFERENCE when you removed the wires?

compare spark on all 6 cyl

 

[TonyD20]

Re: Stalls at Idle

How good is the spark on the 3 cyl that DID NOT MAKE A DIFFERENCE when you removed the wires?

compare spark on all 6 cyl

Yep, spark is the same on all 6.. very good spark in fact.