could a low battery cause engine to stall at wide open throttle?

[couger300]

had the boat out today and I was cruising along when I heard a change in the sound of the engine then it shut off! then wouldnt restart. I believe because the battery has some issues. the battery measures just over 12v sitting there and while attempting to start the engine it drops to 5v. I was wondering two things. what type of voltage should you see at that battery when cranking and if higher than the 5v mine was seeing could that cause it to shut off at wot? you guys have been very helpful! thank you

 

[Fed]

Re: could a low battery cause engine to stall at wide open throttle?

You should be seeing around 10 or 11 Volts at the battery while cranking the motor over.
If your motor is an old standard 2 stroke with no computer stuff a bad battery won't stop it.

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

thanks for the help! the motor is is a johnson 90hp the boat is a 95 im hoping the engine is the same year! mdl #jt90tleor, ser#g03829797. anyways I wonder what else it could be?

 

[HighTrim]

Re: could a low battery cause engine to stall at wide open throttle?

Does the boat have a tach? If so anything abnormal with it?

 

[boobie]

Re: could a low battery cause engine to stall at wide open throttle?

Your battery charging and ignition are two seperate systems. Check your compression and the spark with a spark tester set at 7/16" open air gap.

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

the spark is good. have yet to do compression test. the tach is not working right now! i just bought this boat and im trying to work out all of the bugs. it will get on plane really well and run wide open for less than a minute then lose power and stall. i recently had a problem with water in the oil tank. i have no idea how it got there or how long it was run like that.

 

[HighTrim]

Re: could a low battery cause engine to stall at wide open throttle?

As I thought, test your rectifier. Check the Faqs for help with this. Do not run the motor again until you have remedied it or sorted it out.

 

[Fed]

Re: could a low battery cause engine to stall at wide open throttle?

it will get on plane really well and run wide open for less than a minute then lose power and stall

You have a fuel delivery problem.

i recently had a problem with water in the oil tank. i have no idea how it got there or how long it was run like that.

This can turn your motor into an anchor.
Be VERY sure it's now fixed and your alarms are working properly.

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

there is not a drop of water in the tank or in the line. after it stalled i drained the bowls to see if there was still water somewhere. nothing. looking back the gas from the bowls didnt seem to have oil in it. it wasnt discolored. should you be able to see the oil in that small amount of gas. as far as the rectifier goes could that in some way cause it to stall? i thought that was just charging system. oh the overheat alarm works per the tan wire test. i would imagine there is some sort of switch in the cylinder head also but i have no idea how to test that or the no oil alarm

 

[Sprky]

Re: could a low battery cause engine to stall at wide open throttle?

What year and model motor?

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

i belive its a 95 j90tleor

 

[RandyJ]

Re: could a low battery cause engine to stall at wide open throttle?

Just a DIY guy here but I've turned oodles of wrenches on boats & cars & toyz. I wouldn't do a thing to that engine before I checked the compression first.

 

[Sprky]

Re: could a low battery cause engine to stall at wide open throttle?

That ignition makes it's own voltage. Your problem is else where.

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

well did the compression test today with horrible results. first plug i pulled had metal flakes welded to it. that cylinder wouldnt even get a reading. called our local johnson service shop. their guy told me its junk and i was better off trying to find a used engine. i have yet to pull the heads cause its raining like crazy here. but id inagine its pretty bad and there is probably a bunch of metal in the crank case. i really dont even know what to look at when i do take it off. anyone have any ideas on my next move.

 

[BonairII]

Re: could a low battery cause engine to stall at wide open throttle?

Pulling the heads is the ONLY move at this point. I don't imagine it's gonna be pretty.

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

thats what i figured. as soon as it stops raining im on it. knowing my luck i will snap every bolt on there!

 

[daselbee]

Re: could a low battery cause engine to stall at wide open throttle?

Your problem was very likely due to the piston swelling in the cylinder as you were running lean. It happens in an avalanche style...running good, then all of a sudden, loss of RPM, and engine shuts down. The piston has seized in the cylinder due to the swelling, and as soon as it cools a bit, the engine will turn over again. Your voltage drop at the battery was due to the locked up motor, the non turning starter (because the motor was locked up), and some pre-existing resistance somewhere in the battery cables.

 

[gjmsd]

Re: could a low battery cause engine to stall at wide open throttle?

If it runs a short while at WOT then stalls, it sounds like a fuel delivery problem. At WOT, you are running from the bowl and the fuel system is not pumping in enough to keep up the level and it stalls. Check the fuel pump (they need rebuilding occasionally) and the rest of the fuel lines. Maybe try a test of someone squeezing the bulb while you are at WOT and see if that helps.


*** Whoops, just refreshed and saw all the additional posts about the piston and cylinder. Probably not the fuel

 

[couger300]

Re: could a low battery cause engine to stall at wide open throttle?

that is probably what caused this whole mess in the first place! who knows right now.