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1983 Mercury 50 HP 4 cyl starting issues

J

JasRam

Contributing Member
Hello all.
I bought a boat with a Mercury 50hp 1983 4 cyl last year. I went through the entire thing and replaced the stator and trigger as well as rebuilding the carbs and syncing things up. It ran excellent for about 25 trips last year and 5 this year so far. The first 3 times I had it out this year, it started as usual. The last two times out were hard starts, requiring about 6-7 cranks to get it going. Once running, I could turn off and it would start with one turn of the key every time. I decided that try to crank it over in my drive way before I went out yesterday. I could not get it to turn over at all. I noticed a leak in the fuel filter (cartridge type), and I couldn't find a gasket, so I went to the dealer and got an inline filter to see if that was the issue. It still won't turn over.

Things I checked to day below

I've checked spark to each plug an all are strong
Tested each coil and they test within range
Switched tanks to try different gas- I used gas from last year but I had since run through that tank and new gas is now mixed in with the new tank. The fuel was stored with Stabil and there were no issues on the first times out with the old fuel
I'm not sure if this is an issue but I can't seem to get the fuel filter to fill, it goes about 3/4 of the way and it feels like I'm fighting against something. The bulb stays somewhat firm.
One other detail- when I try to start it, I get a definite pop like it's igniting but it's only a single pop and it won't do it again after the initial tuen of the key.
Any ideas?
 
.."It still won't turn over."

What does that mean to you? The starter won't turn it over, or it won't start?

I'd try some ether (starting fluid).

Jeff
 
Hi , sorry about that, I should have worded that differently. The starter turns the flywheel as it should and it cranks fine, I'm just not getting ignition other than the brief noise I mentioned in the original post. It will sould like it wants to start for about a second and then it doesn't do it for me again unless I let it sit and then try in an hour or so.
fastjeff said:
.."It still won't turn over."

What does that mean to you? The starter won't turn it over, or it won't start?

I'd try some ether (starting fluid).

Jeff
Click to expand...
 
Get battery load tested,----Pull starter apart for ohm check , inspection.---Check battery cables .----Clean connections.----Check operation of choke system.
 
I checked the starter and battery and they're good, as the starter spins the flywheelas it should. I cleaned both carbs and I did find that the jet under one of the needles was clogged. I put the carbs back on and it's still doing the same thing. I'm wondering if it might be a faulty mercury micro switch, but would I still get a spark if that were faulty?
 
JasRam said:
I checked the starter and battery and they're good, as the starter spins the flywheelas it should. I cleaned both carbs and I did find that the jet under one of the needles was clogged. I put the carbs back on and it's still doing the same thing. I'm wondering if it might be a faulty mercury micro switch, but would I still get a spark if that were faulty?
Click to expand...

I re-rested the plugs tonight to be sure I didn't miss anything. They all look good but a strange thing happens when I take a plug out and let it arc to metal on the motor, the motor wants to start and run. Does anyone know why this would happen? I had to kill it with the key twice as this happened with two plugs in a row. Any ideas? I'm sure I'm missing something here
 
The starter needs to turn the motor over to at least 300 rpm for the stator to create enough voltage to operate the plugs/CDI correctly. Get out your DVA and start checking the voltage levels.
 
FishinLite said:
The starter needs to turn the motor over to at least 300 rpm for the stator to create enough voltage to operate the plugs/CDI correctly. Get out your DVA and start checking the voltage levels.
Click to expand...

Thanks for the input! I let it charge overnight and tried starting this morning and it started right up. I had no idea that it wasn't getting enough voltage, since the starter seemed to be turning the flywheel as it should. Do folks typically charge the starting battery after evey outing? That battery has the fishfinder and the livewell pump/bilge/ and lights hooked to it. I really only every use the fishfinder and the livewell pump occasionally. I know that the stator generates the charge for the battery. I have a new stator and trigger and I'm wondering if there's something else that could cause it to be low?
 
My experience is with a '85 - 60hp, but I am guessing that your stator feeds a rectifier that is connected to your battery. A rectifier is not a voltage regulator and the design is meant for a lead/acid battery not one of the more exotic agm batteries. The internal resistance in the lead/acid battery absorbs the voltage fluctuation caused by the unregulated voltage to charge the battery and supply your accessories. If you monitor the voltage applied to the battery it should vary from about 13 volts at idle to over 18 volts at full speed. 13 volts will keep it from discharging but you need about 14.5 volts for it to charge. If you don't run your motor at about 1/3 throttle or higher for some period of time you will not make up for frequent starts.
 
FishinLite said:
My experience is with a '85 - 60hp, but I am guessing that your stator feeds a rectifier that is connected to your battery. A rectifier is not a voltage regulator and the design is meant for a lead/acid battery not one of the more exotic agm batteries. The internal resistance in the lead/acid battery absorbs the voltage fluctuation caused by the unregulated voltage to charge the battery and supply your accessories. If you monitor the voltage applied to the battery it should vary from about 13 volts at idle to over 18 volts at full speed. 13 volts will keep it from discharging but you need about 14.5 volts for it to charge. If you don't run your motor at about 1/3 throttle or higher for some period of time you will not make up for frequent starts.
Click to expand...

Hi Fishinlite
So, after it started for me yesterday, I decided to take it out on the water today. It started right away and idled for around 3 minutes. I then turned it off just to see if it would start again, this time, it stayed running for about 15 seconds and then would not restart after that. I left the boat ramp to have the battery tested, it load tested as a "good" battery at Autozone. I went ahead and bought some new plugs and 3 brand new gallons of gas just to rule out bad gas. I installed the plugs and also checked the rectifier and it tested fine. I tried to start it several times earlier today after I changed all of this, and it wouldn't start.

3-4 Hours later, I finally had time to check for spark again, I did this by setting my gap tester to 7/16. All 4 plug wires bridged the gap. Here's where it gets strange.. I tested the spark with the plug left in and the tester grounded to the plug. Each time I turned the key, it really wanted to start like it hadn't done all day. It nearly started like this on each of the 4 plug/spark tests. After doing the spark tests, it started right up. It would run at a high idle but dies when I tried to bring lever back to neutral position. After it died when I tried to put it in idle, it wouldn't start again.

I'm wondering if there could be short in the starter? Maybe it just chooses to work sometimes? That doesn't explain the fact that it won't idle. I took the carbs apart to clean them but I didn't touch the idle screws because I didn't want to move their setting. Should I have taken those screws out and cleaned behind them?
 
Post #4 recommends taking starter apart for inspection and ohm check.----Very easy to do.----If starter is 37 years old it could probably use new brushes..
 
racerone said:
Post #4 recommends taking starter apart for inspection and ohm check.----Very easy to do.----If starter is 37 years old it could probably use new brushes..
Click to expand...

Hi racerone. Any tips on how I would do this? I Or are you aware of any tutorials I could take a look at?
 
Google ----Mercury outboard starter repair or Johnson outboard starter ( nearly the same starter ) repair.----Lots of useful information.
 
I maybe talking out of school again, but my stator has two sets of ignition windings and two charge circuits in the CDI block. One is for High speed and the other is for low speed. Here is a link to the CDI Troubleshooting Guide.

https://www.cdielectronics.com/wp-content/uploads/2016/12/7th-Edition-Troubleshooting-Guide_RS.pdf

It will help eliminate any ignition type issues. You will need a DVA to do all the testing....

https://www.amazon.com/Electronic-S...t=&hvlocphy=9020145&hvtargid=pla-449403286482
 
racerone said:
Google ----Mercury outboard starter repair or Johnson outboard starter ( nearly the same starter ) repair.----Lots of useful information.
Click to expand...

Thanks, I pulled the starter and cleaned the commutator with contact cleaner, I also cleaned the grooves out with a pick. Two of the brushes were stuck due to a bit of crud in the seating area. I cleaned all of that out and they moved smoothly after that. I put the starter back on after putting it back together and it once again started right away. I let it idle with the throttle advanced and neutral switch engaged, it idled fine unitl I brought the lever back to normal idle. It then died and would not restart. Any ideas? The only thing I didn't check in the starter was the ohms, as I didn't see a mention of it in the videos I found. The brushes looked to be in good condition and the springs were pretty strong.
 
JasRam said:
Thanks, I pulled the starter and cleaned the commutator with contact cleaner, I also cleaned the grooves out with a pick. Two of the brushes were stuck due to a bit of crud in the seating area. I cleaned all of that out and they moved smoothly after that. I put the starter back on after putting it back together and it once again started right away. I let it idle with the throttle advanced and neutral switch engaged, it idled fine unitl I brought the lever back to normal idle. It then died and would not restart. Any ideas? The only thing I didn't check in the starter was the ohms, as I didn't see a mention of it in the videos I found. The brushes looked to be in good condition and the springs were pretty strong.
Click to expand...


Sorry for the multiple posts, I've been working on this thing for 5 days and I think I'm making progress. I just went out this evening and did the spark check again. I figured I would check them just like I did yesterday. I hooked my gap tester up to the second plug and had my daughter turn the key. The motor fired up instantly, it continued to do this with each plug tested. After testing all 4, I started it up right up and had no issues. I let it run for about 4 minutes, I then turned it off and it wouldn't restart. Would the starter need to do less with a plug wire disconnected? Is this why it would want to start ? Could the plug wire that's off be shorting something out and making it work? Any help is appreciated.
 
JasRam said:
Sorry for the multiple posts, I've been working on this thing for 5 days and I think I'm making progress. I just went out this evening and did the spark check again. I figured I would check them just like I did yesterday. I hooked my gap tester up to the second plug and had my daughter turn the key. The motor fired up instantly, it continued to do this with each plug tested. After testing all 4, I started it up right up and had no issues. I let it run for about 4 minutes, I then turned it off and it wouldn't restart. Would the starter need to do less with a plug wire disconnected? Is this why it would want to start ? Could the plug wire that's off be shorting something out and making it work? Any help is appreciated.
Click to expand...


Issue resolved- I think... After the starter rebuild didnt help, I inspected the gas lines once again. I found a plastic hose clamp that allowing a tiny bit of gas and air to leak when I pumped my ball. I went ahead and replaced this with a metal hose clamp and the motor started without issue. It's hard to believe that was that big of an issue. This was the hose that hooks into a T to feed each carb. I took it out today for 5 hours and had no issues.
 
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