At the launch the other day I put my battery switch to #2 it turned over fine but would not fire. After a few tries I switched to #1 and it started right up. I installed both new battery's a few months ago, I'm not sure I ever tried to start on the #2 Bat. before. I'm thinking there may be a wire that I failed to hook up but I'm not seeing one. Any thoughts?
Won't start on #2 battery
- Thread starter Pighunter
- Start date
Check your crossover between the two batteries. I had a similar issue and thought it was a bad battery but the ground connecting the two batteries was not connected..
Then start looking at the cable to the switch to see if properly connected and no resistance issues.
Then start looking at the cable to the switch to see if properly connected and no resistance issues.
Yes it turns over strong just no fire. Battery's are both brand new (4 month old interstate battery) I checked voltage night before leaving, both were just under 13 volts. The number 2 battery will power everything on the boat it just won't create spark at the engine.
Lt.Mike
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I’d say there’s a corrosion issue somewhere In #2’s cables. Could be as simple as in the connections where a good cleaning will correct it or the cables themselves are needing replacement.
SkunkBoat
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That is a very strange symptom...cranks but doesn't run. Cranking implies that there is a good connection and ample power thru the motor's starter cable. Do your gauges come on with the key when on Bat#2???
So you turn the key and hear the starter cranking but engine doesnt run? Did you try again after getting it to run on battery #1?
Before going crazy, I would swap the batteries and see if battery 2 in the first battery’s location works and try #1 in 2nd battery’s location.
You can then start checking volts and resistance from there if no issue with #2 when you swap it
Before going crazy, I would swap the batteries and see if battery 2 in the first battery’s location works and try #1 in 2nd battery’s location.
You can then start checking volts and resistance from there if no issue with #2 when you swap it
Lt.Mike
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There enough juice getting thru to turn the starter but it produces a weak spark or being weak the computer doesn’t let the injectors work properly.
check your plugs and see if their wet when that happens. Not wet, no fuel to the cylinders. A weak battery or low voltage to the computer will definitely cause problems. Either the battery is weak or it can’t get it’s full potential to the engine.
Hookup1
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Can you flip the batteries using your battery switches? See if the problem follows the battery or the motor.
Not sure how the MOB kill switch wiring works. I know it will kill the engine but not sure if it will prevent cranking.
Not sure how the MOB kill switch wiring works. I know it will kill the engine but not sure if it will prevent cranking.
The symptom is odd but I have seen it on Mercs.
Normally the battery switch feeds the motor directly. That juice is then fed back to the helm for the start switch. If the motor cranks normally, I would expect it to also fire up.
On some Mercs like my Optimaxes, the ECU is very picky about voltage. Just a tad low and the motor will crank over but won't start.
The motors usually start when batteries set to BOTH. Very strange but true.
The question about the gauges powering up when the ignition is turned on is an important piece of data.
Also I need to know if this is a single or twin motor setup
Normally the battery switch feeds the motor directly. That juice is then fed back to the helm for the start switch. If the motor cranks normally, I would expect it to also fire up.
On some Mercs like my Optimaxes, the ECU is very picky about voltage. Just a tad low and the motor will crank over but won't start.
The motors usually start when batteries set to BOTH. Very strange but true.
The question about the gauges powering up when the ignition is turned on is an important piece of data.
Also I need to know if this is a single or twin motor setup
Single ox66 225, battery has 12.8 volts yesterday. All electronics, gauges, radio, horn and lights work with number 2 battery. Motor cranks fast and strong just no spark or fire. My battery's are on each side the number 2 is on port side with the 2 stroke oil tank and it's a very tight fit in there.
All connections are clean.
All connections are clean.
Ryhlick
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I had something very similar to what you are having on the same exact motor. Everything worked fine on #2 but the engine would not fire. I ended up replacing my battery switch and all is good now. Never figured out what the problem was but for me replacing the switch worked. Good Luck
SkunkBoat
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If replacing your switch, check to see if you have an Aux wire. If so, go with the 5511e battery switch. Huge fan of it since installing to have two seperate circuits on boat. Otherwise, look into the kit with ACR
Honestly, this problem makes no sense based on the info stated. There is either low voltage or no voltage to the ignition. There has to be some additional factor(s).
As a next step, I would measure the voltage at the #2 battery terminals while the motor is being cranked to see if there is a large drop. If not there, I would next measure voltage at the main engine terminals and then finally at the main engine relay ( a bit harder to do).
As a next step, I would measure the voltage at the #2 battery terminals while the motor is being cranked to see if there is a large drop. If not there, I would next measure voltage at the main engine terminals and then finally at the main engine relay ( a bit harder to do).
If the #2 battery is turning to motor over strong I don't see how that would create low voltage at the ignition? Do you know if there should be any other wires hooked up to the battery besides Pos. & Neg. cable?
On battery #2, turn the ignition "on" but not to "start". You should hear the fuel injection pump energize for a few seconds. Do you? And, check for spark on #1 plug. For good measure, check around the #2 battery for a smaller gauge wire that you missed putting back on.
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Some engine control units (ECMs or ECUs) are very sensitive to voltage. I have seen engines that appear to turn over fine without spark due to the voltage drop at the ECU that seasick mentioned. I'd check the voltage drop while starting on each battery and I think you'll find the #2 has a higher voltage drop. The cause for that could be various reasons: higher resistance in the circuit or simply a weaker battery. I'd test the batteries with a cheap load tester and compare and watch the voltage drop during the start cycle before buying a new switch or battery. It is always a good idea to disconnect and clean all connections as well. That alone might fix the problem.