Enrichener Circuit

[jethro]

On my side console boat with 150 Merc, it's very hard to start. When I push the key in to activate the electric choke (enrichener) it kills the starter immediately. Like it's grounding out the enrichening circuit somehow. I verified the solenoid functions correct and isn't the problem, but I can't figure out what it isn't working? Any ideas what to check next? Maybe it's the ignition switch itself? How would I test that?

 

[DaleH]

The OEM Manuals can be had on-line for free to $20, but I believe and/or recall they are very limited to troubleshooting connections to this degree needed. But remember, DC power will ALWAYS try to find the fastest way to ground, so I'm guessing you may have a poor, loose or corroded connection or a bad/worn switch internally.

And yes, I have seen plenty of key switches go bad in my life, from over-use and then more so from people who hang a TON of keys (weight) off the ignition switch key ring, especially when in RUN mode. This wears them out internally.

First - One of the first things I do is to check ALL connections and terminations, even from back at the motor. Might also want to check operation of the start-in-neutral circuit, even throw some lube onto the switch activator if you can easily get to it. Now 90% of my experience is with OMC motors and their older pre-Ficht models used a large red amphenol connection to connect the harness from the OB to the harness from the helm/key switch. But I once took apart such a harness connector and had to clean up the contacts and regrease with dielectric grease. Then all was well! I was getting a phantom overheat alarms, even with the OB not started, but key switch to RUN.

Ask - Do you have the older 10-wire switch or the newer 6-wire one? The Choke (primer enrichment) connector is typically adjacent to the Starter connector, so check them out. Confirm this is your switch layout BEFORE doing any tests ...

Try this, battery switch OFF (or disconnected), key switch to RUN, DVM leads to Choke & Starter connectors on switch, DVM set to continuity ... push IN on key while turning switch to crank ... and I don't think you should hear the continuity 'tone' that they are connected in a circuit or talking to each other.

Other - In the mean time try this! On my OMC motors, I prime the bulb hard, turn key switch to ON, press IN on the choke and slowly count to 4 or 8 ... as your motor will tell you which she prefers. Then release the key from IN and turn to CRANK. I do not flood the carbs when cranking, ever! And they start right up on the 1st turn of the key!

Let me know ... as I have a mid-90s vintage Merc harness/switch I can send you to try out.

 

[richg99]

Dale H....what a guy!

 

[jethro]

Dale H....what a guy!

I know, I was hoping he'd be the one to respond!! Was considering sending him a PM but I didn't want to seem to pushy, LOL!

The OEM Manuals can be had on-line for free to $20, but I believe and/or recall they are limited to troubleshooting connections to this degree needed. But remember, DC power will ALWAYS try to find the fastest way to ground, so I'd guess you may have a poor, loose or corroded connection or a bad/worn switch internally.

And yes, I have seen plenty of key switches go bad in my life, from over-use and then from people who hang a TON of keys (weight) off the ignition switch key ring, especially when in RUN mode. This wears them out internally.

First - One of the first things I do it check ALL connections and terminations, even from back at the motor. Might also want to check operation of the start-in-neutral circuit, even throw some lube onto the switch activator if you can easily get to it. Now 90% of my experience is with OMC motors and their older pre-Ficht models used a large red amphenol connection to connect the hardness from the OB to the harness from the helm/key switch. But I once took apart such a harness connector and had to clean up the contacts and regrease with dielectric grease. Then all was well! I was getting a phantom overheat alarms, even with the OB not started, but key switch to RUN.

Ask - Do you have the older 10-wire switch or the newer 6-wire one? The Choke (primer enrichment) connector is typically adjacent to the Starter connector, so check them out. Confirm this is your switch layout BEFORE doing any tests ...

Try this, battery switch OFF (or disconnected), key switch to RUN, DVM leads to Choke & Starter connectors on switch, DVM set to continuity ... push IN on key while turning switch to crank ... and I don't think you should hear the continuity 'tone' that they are connected in a circuit or talking to each other.

Other - In the mean time try this! On my OMC motors, I prime the bulb hard, turn key switch to ON, press IN on the choke and slowly count to 4 or 8 ... as your motor will tell you which she prefers. Then release the key from IN and turn to CRANK. I do not flood the carbs when cranking, ever! And they start right up on the 1st turn of the key!

Let me know ... as I have a mid-90s vintage Merc harness/switch I can send you to try out.

So I have the newer 6 wire switch. I looked at that last night and all checks out pretty good. I couldn't find a short but that doesn't mean there isn't one. I am horrible with electrics! I'd rather the motor needs a new flywheel or even has a spun crank to deal with.

I was wondering if the choke solenoid should engage when the motor isn't cranking? It sounds like on your OMC it does if you engage it first, but I always figured the choke circuit only gets power when the switch is turned to "crank". I will see if the solenoid activates tonight when the switch is just in "run" mode. I will also test the switch as you say above, Dale.

Regarding the "start in neutral" circuit... is that switch usually on the throttle lever itself, or on the linkage in the motor?

I am hunting today for a factory shop manual for this motor. I know they are usually big money but for me it will totally be worth it.

 

[DaleH]

So I have the newer 6 wire switch. I looked at that last night and all checks out pretty good. I couldn't find a short but that doesn't mean there isn't one.

You might want to try that DVM continuity test I posed before, but 'rock' the key up and down (or side-to-side in whatever orientation it is in) as the key is pushed IN and or turned to CRANK (same deal, battery switch off). As I am still best guessing that the previous owner either wore out the switch and/or with it out with had heavy keys on that key ring. I have seen more bum key switches that I believe were caused by excessive weight hanging off the key, whilst turned to the ON position.

I was wondering if the choke solenoid should engage when the motor isn't cranking? It sounds like on your OMC it does if you engage it first, but I always figured the choke circuit only gets power when the switch is turned to "crank".

On OMCs it works either cranking or not, engaged 1st or not, as I would presume a Merc switch would/should work too ... at least by looking at that wiring diagram.

Regarding the "start in neutral" circuit ... is that switch usually on the throttle lever itself, or on the linkage in the motor?

Usually in the control box. This can be a simple check, just try to start when not in neutral.

 

[jethro]

Well, tonight I was able to get the piece of fuel line I needed for the enrichener circuit and put it on. That was definitely cracked and could have been a contributor to why my motor was so hard to start in the first place. It still looks like I can't choke when I am cranking because the starter just stops turning instantly, but the same thing happens on my smaller Mercury. However, the enrichment works when you just click it to run just like you said Dale. So after I put the fuel line back on and put it all back together I tried the method you said, Dale, of pumping the ball to hard, opening up the enrichener for about 8 seconds, and then cranking it and wouldn't you know... it started right up quicker than it ever has!

It may be possible that the way you describe your starting routine is how I'm supposed to do it?

Thanks for the help Dale, I think I'll have a much easier time at the launch!

Oh, also thank you for that wiring color chart. That's going to come in handy...