Testing Fuel Enrichment Valve

[ssherbundy]

The idle on my 95 Johnson 50hp is just terrible. The engine runs terrific at full throttle and accelerates without hesitation. I suspect that the fuel enrichment solenoid (cold start solenoid) may be leaking and flooding the engine when in the normal or run position (valve turned toward the solenoid body). I want to test it on the engine. The solenoid does work and fuel enters the hoses to the carb(s).

If I understand correctly, when the the valve is turned to the "run" position it should not pass fuel to the carb(s) without the solenoid being energized by the start/ignition key being depressed. And when the control valve is in the opposite or fully or partially open to the manual position (pointing toward the toward the hose fittings opposite the solenoid body) it should pass fuel through the hoses to the top of the carb(s).

Will it be a valid test to remove the hoses that enter the top of the carb(s) while cranking the engine with the kill switch in the "kill" position to note if any fuel flows past the valve and its diaphragm and to the hoses with the solenoid not energized by the key position?

 

[racerone]

Remove the wee primer hoses at the carburetor with engine running.-----No fuel should come out.-----What other trouble shooting was done ?----Did this problem show up suddenly ?

 

[ssherbundy]

Remove the wee primer hoses at the carburetor with engine running.-----No fuel should come out.-----What other trouble shooting was done ?----Did this problem show up suddenly ?

Not a new but a worsening problem. The engine is not new to me but has not been used much by me and certainly not by the former owner. The idle has always been terrible and I'm trying to get to the bottom of it. It seems to idle better in with the control level of the valve in something toward mid-way but frankly I've not tried it in the position that should shut off the fuel. I did have to remove and shorten one of the hoses that feed from the valve to the carb because it had cracked at the carb fitting and once trimmed back and replaced things improved but it still is not as I think it should be. I've had other older OMC 50 hp twins in the past and they idled far better than this engine. It smokes at idle quite a bit and occasionally runs better, then will stall and ultimately die. Mid range and full range power is great so I suspect the carbs are likely ok.

I really think it's flooding and thus also over-oiling as the exhaust at the prop would indicate so and the hub is wet with oil as well. I'll try your suggestion. If I don't find the problem to be the enrichment valve it's time to pull the carbs and rebuild them. I have the parts but it's so darned hot here in Alabama I'm not enthusiastic about undertaking it right not. Not to mention those danged "no-see-ums" around my house here in the mountains. They eat you alive and you don't even know you've been bitten....until later.

Do you think the engine will continue to run with the hoses removed? It seems to me the removal would create a massive air leak created that would stop it cold. Maybe I need to remove the and substitute a plugged hose to stop the air. That's why I planned to crank it with the ignition disabled by the kill switch.

 

[racerone]

When you pull the hoses off the motor will continue to run !------The holes in those fittings are really small and it would not bother the engine.----Why would you say it is a " massive air leak" ----You suspect the carburetors are OK but then you say you think it is flooding.------So I would take the carburetors off right now for cleaning.----Especially the high speed jet that screws into the very bottom of the bowl.

 

[ssherbundy]

When you pull the hoses off the motor will continue to run !------The holes in those fittings are really small and it would not bother the engine.----Why would you say it is a " massive air leak" ----You suspect the carburetors are OK but then you say you think it is flooding.------So I would take the carburetors off right now for cleaning.----Especially the high speed jet that screws into the very bottom of the bowl.

Not trying to be argumentative here. I do need assistance and highly value your input. Pulling and rebuilding the carbs without fully exploring other causes would very possibly be premature. I am prepared to pull the carbs and clean them ultrasonically and rebuild them if it comes to that. I also have the parts on hand for that and for rebuild of the solenoid valve we're discussing. I just enjoy troubleshooting and especially if I can save some work and money in the process. (Too much engineer in my DNA and not enough mechanic I guess).

Here's my logic.

1. As regards the air leak assumption, as I mentioned in my post, one of the hoses from the valve was cracked where it attached to the carb. In that state the engine was very hard to start and would not idle at all. That condition was corrected and starting is not an issue now.

2. As regards the assumption of flooding, my thinking is that an overly rich mixture is created by the excess fuel drawn into the engine if the solenoid valve is not stopping the fuel flow. My assumption is that the impact would be at idle but not necessarily at high speed. I have no issue at high speed in fact it's excellent. I can't imagine that the engine will turn 5500 RPM with fuel supplied from the solenoid valve.​

I am a bit puzzled by your emphasis on the high speed jets. I would think that a problem there would dramatically effect the acceleration and high speed function.

I haven't had time today to try the test but will tomorrow. I will post my results.

 

[ssherbundy]

racerone you are correct the engine doesn't die with the hoses removed; it just runs a little rougher. If I cover the hose fitting at the carb it smooths somewhat but I still can't get it to idle well. I am cleaning and rebuilding the carbs at this time. I do note however a peculiarity with the carbs that varies from what the Evinrude website parts list shows. My carbs do not have the slow speed jet. They appear to be perhaps 95+ carbs rather than that shown for the 94 model I have. I have verified the model number to be certain. That seems really peculiar. I have looked and checked the location where the jet should be per the diagram but it simply isn't. The 95+ model carbs appear identical to mine; again per the diagram. Very frustrating.

 

[GabrielleSimpsonC]

Perhaps I will give you a very trivial advice now, but first check the carburetor jet. It is possible that they just got clogged and now you have problems with idling because of this. I had a similar problem with my irrigation system. I thought that the problems in the pump, which pumped all the water, also thought that there were problems with the valves and even replaced them. It took a very long time to look for a quality valve manufacturer usa. As a result, it turned out that due to heavy rain, dirt got into the sprayers and they did not water well. In short, just check all the pipes and everything around them if they are not dirty. (by the way, there may still be a problem with the gas pump. Its performance can be checked in any car workshop). Good luck!

 

[flyingscott]

What is your compression? Have the low speed screws been adjusted at any time? Link and sync done? Do you have a factory Manual? That motor should not idle terrible far from it.