40hp Evinrude WOT Issues

Ultrium

Seaman Apprentice
Joined
Dec 10, 2009
Messages
40
I have had this boat/engine model# E40TLCCS for a few weeks now and here these are the symptoms of the engine.

Starting/Idling - Excellent
Idling - 75% throttle - Excellent
75% - 100% throttle - hit or miss. Sometimes the engine will come alive and pick up about 1500 rpm's and run like a scalded dog. When the engine is cold, I can leave the no wake zone and go to 100% throttle and it will run wide open for about 15 mins then when I back the throttle down it will start to ? (sounds like detonation but isn't) I have checked the plugs numerous times and they look good.

I have replaced the spark plugs and used a spark tester to make sure they are firing, compression is fine, replaced fuel lines from the tank to the VRO, new fuel filter, new primer bulb. Everyone I have spoken to, sounds like its the high speed jets, but if that were the case, wouldn't it act this way all the time? The pee stream coming from the motor is strong and consistent, so I know its not over heating. Could it be the coils, going out and not producing enough spark at WOT to burn the fuel.

I am at a loss on this thing. I don't have the money to take it to a mechanic at 150 an hour for something simple that I could have done. Any help would be greatly appreciated.

Thank you!!
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 40hp Evinrude WOT Issues

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP.

Check for this type spark while moving the timer base under the flywheel from its idle position clear up to its full spark advance position. To do this, you may need to have the engine in gear.... and if this should engage the neutral safety switch (electric starter wouldn't work) use a small jumper from the battery cable terminal of the starter solenoid to the small 3/8" nut terminal that engages the solenoid.

If the spark remains strong as I've stated above, it is possible that something is floating aorund in a float chamber and is getting drawn into the high speed jet at times (I encountered this once in my 30+ years in the marine line).

Have the carburetor face plate removed. When this problem takes place, have someone stick a couple fingers into the carburetor throats (one carb at a time). If the engine picks up rpms, you've found an offending carburetor.

Since the engine runs for 15 minutes before this problem takes place, there is a strong possibility that you have a fuel restriction problem. If the fuel primer bulb has a tendency to go flat, suspect the anti siphon valve, as follows.

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anteutrali siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.
 

hidef

Lieutenant
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Aug 22, 2009
Messages
1,465
Re: 40hp Evinrude WOT Issues

Could be the thermostat is sticking causing the outboard to go into SLOW mode. There should be a warning horn in the controls but if that has been disconnected or is not functioning that could be hiding the issue. The pee stream indicates the water pump is working it does not indicate that the thermostat is opening. Have you checked the temperature of the heads and block with a thermometer when the engine starts to act up?
 

Ultrium

Seaman Apprentice
Joined
Dec 10, 2009
Messages
40
Re: 40hp Evinrude WOT Issues

Thanks for the response guys. I will give your suggestions a shot and see if that works. If anyone else has any suggestions, please post them up.
 

Ultrium

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Joined
Dec 10, 2009
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40
Re: 40hp Evinrude WOT Issues

Also what temp should the head and block be when I check it?
 

hidef

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Aug 22, 2009
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1,465
Re: 40hp Evinrude WOT Issues

After running the outboard at over 3000 RPM for five minutes and then idling back to 900 the heads should be 140 degrees plus or minus 15 degrees. They should never go over 160 degrees if they do you have serious problems.
 

Ultrium

Seaman Apprentice
Joined
Dec 10, 2009
Messages
40
Re: 40hp Evinrude WOT Issues

I went out last night and checked the temp after the recommended procedures and the hottest it got was 138. I also noticed that it started making the noise and not running right, right from the start when I went WOT, so I don't think its the thermostat. I left the controls at WOT and after about 30 to 45 seconds, the motor came alive and ran great until I backed the throttle down. When I got home, I pulled the plugs and they looked ok, so I have completely ruled out detonation. I guess my next course of action, is to pull the carbs and somehow test the coils when at WOT. If anyone has any helpful tips on testing the coils, please let me know.
 

hidef

Lieutenant
Joined
Aug 22, 2009
Messages
1,465
Re: 40hp Evinrude WOT Issues

Get a spark tester and set it for 7/16 inch as per Joe's post above
 

Ultrium

Seaman Apprentice
Joined
Dec 10, 2009
Messages
40
Re: 40hp Evinrude WOT Issues

hidef,
Thanks for pointing out his post. I will test tonight, weather permitting, and post results. Thanks again for the help.
 

Ultrium

Seaman Apprentice
Joined
Dec 10, 2009
Messages
40
Re: 40hp Evinrude WOT Issues

After testing the spark, both were able to jump the 7/16" gap. I talked to a outboard mechanic (on the side) yesterday and he said it might be the VRO going out, putting the engine in slow mode or the power pack going out. I would rather not remove the VRO unless it is absolutely necessary b/c I really like not having to mix the oil and gas. Is there any way to test and see if it is the VRO before I completely bypass it for good? Thanks for everyone's help!!
 
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