1997 Evinrude 150-HP CHK ENG Alarm

[kladd]

[Please give me] any ideas [you have on how to remedy the continually occurring CHK ENG alarm that is described below in detail].

BACKGROUND ON ENGINE
A 1997 Evinrude 115-HP model E115SXEUC is now 28-years-old but has less than 250-hours run time, and most of that on fresh water. The engine still has the original . In 28 years the motor has less than 250 hours on it. Almost exclusively on fresh water. The engine is still running the original VRO system although I vaguely remember replacing a VRO pump more than ten years ago.

[Moderator's note: I have used 1997 as the engine model year in this thread because the model designation given above decodes to 1997 as the model year.]

[Moderator's note: a c.1997 engine would have what at that time was called the OMS or oil mixing system, which was an improved version of the original VRO or Variable Rate Oiling system. The second-generation VRO was also called the VRO1. See more about the VRO system in the REFERENCE section article VRO Story--The Myth of the Mixer, by well-known OMC authority Bill Grannis. In the article, Bill mentions that in c.1993 the name of the oil-mixing system was changed to be OMS or oil-mixing system from VRO or variable-rate oiling.]

ONSET OF PROBLEM
In 2025 after taking out the engine from storage, the engine started without hesitation, but soon after the CHK ENG lamp signal would illuminate and an aural alarm signal would sound; this behavior eventually occurred at every start.

On turning the ignition key switch to RUN, the Check System [tachometer or annunciator gauge] would do its normal thing: cycling all four indicator lamps and momentarily sounding the alarm horn. But sometimes the CHK ENG lamp illuminates and stays on after its [start sequence or boot-up] even without starting the engine.

Q1: how does the System Check gauge remember to show a CHK ENG lamp without the engine even having been started?

My research indicates the CHK ENG signal indicates an obstruction in the fuel system. This alarm condition is activated by a fuel [line] vacuum-switch sensor. This alarm has me worried about the engine running in a too-lean condition.

REPAIRS MADE
First, I installed a new fuel-water separator filter, but there was no change to the alarm

Second, I removed the white in-line fuel filter under the engine cowling. It looked great, but I cleaned the filter anyway, and re-installed it; no change.

Third, I ran a 3/8-inch-ID fuel hose from a 5-gallon tank sitting on the cockpit deck of the Dauntless straight into the white under-cowling in-line fuel filter input. Now the engine runs and does not throw CHK ENG right away. In fact it seemingly idles happily forever. But when I increase the engine speed to about 1500-RPM, the CHK ENG lamp illuminates in about five to ten seconds, and does this consistently.

INFERENCES
I feel I have proven that at least part of the problem is on the engine side of the fuel line. I'm not much of a boat mechanic. From reading the service manual the ENG CHK is solely due to excessive vacuum on the suction side of fuel pump.

My next step is to acquire a fuel vacuum pressure gauge.

ASIDE
In digging around under the engine cowl I found a few fuel leaks from distorted plastic carburetor parts. I fixed those with JB-WELD epoxy resin and Black RTV sealant, which stopped leaks but made no difference on CHK ENG.

But maybe that situation would be a screaming hint to an experienced boat mechanic?

[kladd]

I just read my post and wondered if my ancient Evinrude carburetor engine has no microprocessor and no memory, how can it "remember" a CHK ENG fault.

Q2: would the cause then be the vacuum sensor switch is sticking, or otherwise messed up?

[jimh]

[Please give me] any ideas [you have on how to remedy the continually occurring CHK ENG alarm that is described below in detail].

Regarding what conditions cause the CHK ENG alert to be illuminated, the source of that signal is from a vacuum switch that is attached to the fuel line via a T-connection. If there is too much vacuum in the fuel supply to the engine--that is, the engine is experiencing too much resistance to the flow of fuel from the tank toward the engine--the vacuum switch is supposed to close to alert the operator about this problem.

If the CHK ENG alarm occurs prior to actually starting the engine, there are a few possible circumstances that might create that situation:

• for some reason the fuel system is still experiencing the high vacuum in the supply hose, and the vacuum switch properly signals this is occuring;
• there is no problem with the level of vacuum in the fuel supply hose, but the vacuum switch has failed in some way that it is stuck in the alarm mode;
• there is some damage to the wiring on which the alert signal is being carried, and that conductor is shorting to ground (which is what the switch would do if it were in the high-vacuum condition).

However, the behavior you describe (in which the engine runs without the CHK ENG alert at idle speeds, but when the engine accelerates to 1,500-RPM or more the CHK ENG alert is initiated) tends to match the normal operation of the system which is detecting a restriction in the fuel flow at higher throttle settings. This tends to suggest the vacuum switch is operating nornmally.

I think your plan to insert a pressure gauge into the fuel supply line is a good test. You could also set up a test of the vacuum switch to see at what actual vacuum pressure the switch operates. Connecting an Ohmmeter to the switch and perhaps using a primer bulb to pump-up the vacuum on the switch hose input would be one way to test the operation.

Of course, knowing what the criterion was for too much vacuum would be very helpful. I can't offer advice on that.

[jimh]

Q2: would the cause then be the vacuum sensor switch is sticking, or otherwise messed up?

Yes, a faulty vacuum switch is a possibility. See my remarks above where I offered that as a possible cause.

[jimh]

ERRATUM
In some posts the model year of the engine has been changed to conform to the model year indicated in the actual engine model number coding ("EU"). I am sorry this post contained any ambiguity (between 1996 and 1997) about the engine model year.

The originator contacted me to indicate this ambiguity was a result of something I changed, and that the content of his posts in this thread were (in his description) "butchered." I disagree with that notion, as I do not believe that any information was lost in this thread, other than a confusion about the model year, and that any changes made were with the intention of clarification. Again, the model year now being used is in agreement with the model year as deduced from the model code for the engine as given in the first thread. I will now stop participation in this thread, as the originator seems to be very upset with me.

ASIDE: information on how to decode an Evinrude (or Johnson) outboard engine model code is give in an article in the REFERENCE section:

Evinrude-Johnson Model Codes
https://continuouswave.com/whaler/refer ... Codes.html