1988 Mercruiser 3.0L - starting issues. Time for a new battery?

eavega

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Apr 29, 2008
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Hi all
So, I have a 1988 Mercruiser 3.0L 135 HP I/O with some strange or unexpected behavior when starting up. If the boat has been sitting for a time (usually about 6 days, Sunday to Saturday), If I turn the key from the off position to start, I get nothing. No clicking, no attempt to engage the starter, nothing. If instead I turn it to the run position and leave it there for about 30 seconds, then try to start, kicks right off. Observing the Voltage gauge on the dash, I see that by leaving it in the run position, the voltage slowly crawls up to just past 12 V. Once initially started and warmed up, then there is no hesitation to engage the starter. I've learned to not try to start the motor until the needle on the voltage gauge stops moving. Is this a symptom of a battery starting to let me know that its time has come? I don't have a history to the battery other than it came with the boat when I purchased it almost two years ago. I know the battery should have a marking indicating date of manufacture, but I can't find it. The only other thing I can think of is that there would be some component that puts a load on the system immediately upon being engaged, and until that component is not "charged", then there is not enough juice from the battery to turn the starter. I did put a new Pertronix coil and electronic ignition module to replace the points last year. I don't recall the ignition behaving this way when it had points, but then again I think I only went out on the boat 3 or 4 times before doing the conversion. Any thoughts or observations would be greatly appreciated.

Rgds

Eric
 

stonyloam

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Sounds like the battery is just fine, it starts right? Something is preventing full battery voltage from reaching the start terminal of the switch til something heats up??? Try this: check your grounds, and try removing the wire from the bat terminal of the switch, and running a jumper directly from the terminal to the battery + and see if it works. If it does you have a wiring problem.
 

alldodge

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Hi all
So, I have a 1988 Mercruiser 3.0L 135 HP I/O with some strange or unexpected behavior when starting up. If the boat has been sitting for a time (usually about 6 days, Sunday to Saturday), If I turn the key from the off position to start, I get nothing. No clicking, no attempt to engage the starter, nothing. If instead I turn it to the run position and leave it there for about 30 seconds, then try to start, kicks right off. Observing the Voltage gauge on the dash, I see that by leaving it in the run position, the voltage slowly crawls up to just past 12 V. Once initially started and warmed up, then there is no hesitation to engage the starter. I've learned to not try to start the motor until the needle on the voltage gauge stops moving. Is this a symptom of a battery starting to let me know that its time has come? I don't have a history to the battery other than it came with the boat when I purchased it almost two years ago. I know the battery should have a marking indicating date of manufacture, but I can't find it. The only other thing I can think of is that there would be some component that puts a load on the system immediately upon being engaged, and until that component is not "charged", then there is not enough juice from the battery to turn the starter. I did put a new Pertronix coil and electronic ignition module to replace the points last year. I don't recall the ignition behaving this way when it had points, but then again I think I only went out on the boat 3 or 4 times before doing the conversion. Any thoughts or observations would be greatly appreciated.

Rgds

Eric


I wouldn't initially think it was the battery because there was no mention of turning over slowly or other problems once it would first crank. Could be as simple as weak contacts inside the key switch of corrosion. My first thought would be some kind of corrosion. Corrosion acts like a resistor and could cause what your seeing. With the new ignition did you change the coil to a 12V model and remove the in line resistor?

Next, Check and clean the battery cables, change the battery and then load test it just in case.
 

eavega

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I wouldn't initially think it was the battery because there was no mention of turning over slowly or other problems once it would first crank. Could be as simple as weak contacts inside the key switch of corrosion. My first thought would be some kind of corrosion. Corrosion acts like a resistor and could cause what your seeing. With the new ignition did you change the coil to a 12V model and remove the in line resistor?

Next, Check and clean the battery cables, change the battery and then load test it just in case.


I did, in fact, change the coil to the recommended oil-filled coil, and I did remove the resistor wire.

stonyloam said:
Sounds like the battery is just fine, it starts right? Something is preventing full battery voltage from reaching the start terminal of the switch til something heats up??? Try this: check your grounds, and try removing the wire from the bat terminal of the switch, and running a jumper directly from the terminal to the battery + and see if it works. If it does you have a wiring problem.

I guess I'll start troubleshooting the wiring from the switch back and look for any obvious corrosion.

Thanks.

Eric
 

Starcraft5834

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wire issue.......break in wire, gummed up? one or both.. these boys above hit it on the head I think............
 
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airshot

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Jul 22, 2008
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I agree with the other posters, sounds like an electrical issue but......why not take your battery to most any battery outlet and have them run a battery test, it usually costs nothing and you would know for sure to cross that off your list. They should do a complete battery test not just voltage
 

eavega

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I agree with the other posters, sounds like an electrical issue but......why not take your battery to most any battery outlet and have them run a battery test, it usually costs nothing and you would know for sure to cross that off your list. They should do a complete battery test not just voltage
Quite honestly, I've never taken a battery to be load tested that didn't test bad and supposedly need to be replaced. I don't trust them not to tell me my battery needs to be replaced as that translates directly into a sale for them.

-E
 

Bondo

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I did, in fact, change the coil to the recommended oil-filled coil, and I did remove the resistor wire.



I guess I'll start troubleshooting the wiring from the switch back and look for any obvious corrosion.

Thanks.

Eric

Ayuh,.... It ain't so much the Obvious Corrosion, it's the Hidden Corrosion that's causin' yer problems,....

The Corrosion, 'tween the connector, the terminal, washer, 'n nut,....
Inspect the crimped areas for Obvious corrosion,...
Take 'em All apart, sand, clean to Shiny metal clean, 'n reassemble,...
Greasin' 'em helps keep 'em that way,....
 
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