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0540 Requires 2 Batteries to Start ????


Well-known member
My dad's 0540 will start cold on one battery. After a little running, I have to use both batteries to start it. Both batteries are brand new and fully charged. What's the deal?? Thanks in advance........
check battery terminal clamps for corroded or loose condition.
if good then its your starter needs replacing
already covered that.....all new cables. been through two new starters. same problem. its like none of the starters are getting enough juice to turn the prop over. it even has a high torque starter with some type of gear reduction component in it. i'm thinking it has some type of alignment problem that is putting a strain on the starter but i don't even know where to start!!!
Morning...1)does the engine turn over when hot with mag's off.
2) Ground....is the bat. ground directly to the engine? not to the boat trying to go thru the engine stand rubber.
3) Do the teeth on the ring gear look ok? cause youve replaced the starter.
Ive got a 10 to 1 hemi head that starts with a small dyno-bat battery, so somethings wrong.
If it turns over hot, -but is hard to start the timing could be to far advanced, or the inpluse couplers might need to be 30-deg, for additional retard. timing should be 25 deg.
I woould try (with mags off) pulling it thru when hot by hand, hopeing you dont have a bearing problem insinde the engine or something serious.
Since it starts cold OK I think I would check the timing first. If thats OK then you could pull the plugs and spin it to check for any misalignments. I'd check that cold and hot just to make sure. (don't cuss me when you pull the plugs on a hot engine). Let us know what you find. Good luck.
Make sure the batteries are for cranking and not deep cycle. I hade two boats from the University of Alabama that did the same thing--replaced the deep cycle batteries with cranking batteries and they started just fine.
I would do some voltage tests. you will need someone to help you with it first I would check the voltage at the battety terminals just sitting, should be 12.5+ volts. Then with it cranking. Check it at the lead terminals not on the cables. If the voltage drops down to 6-8 volts then you either have battery problems or excessive draw from the starter, which would include starter binding or engine binding. If the voltage stays at 11+ volts, that most likely is a connection problem. Time for voltage drop tests on the cables to the starter. If you need help with the voltage drop tests let me know and I will run through them.
Good Luck
thanks for all the advice. where to start? i crank the boat like this: all mags off, turn it over a few times and then turn on the impulse mag. as soon as it cranks, i turn on the straight mag. the order of mag activation does not effect the difficulty of turn over, ie; it is just as hard to turn over with the impulse mag on. when i try to turn the prop by hand it is very tight. i have a 200 with high compression cylinders. the 260 has low compression cylinders. i know its a bigger motor but it is 10X harder to turn by hand. hand cranking is out of the question while i can hand crank the 200. i think it has some type of alignment or bearing problem. which makes sense to me; heat causes bearings to swell, making it tighter and harder to turn over.......right? how do i check for this? or do you think it is something else.

they are cranking batteries as well.
the ring gears have been fine on the previous starters. just attempted to fix the easiest problem first!
I would pull the starter out and try to turn it by hand. If it is still tight you have engine problems.
Whats your oil pressure like hot and running at idle, and at 2000 rpm?

Sounds like internal engine problems though.....I can hand prop my 10 to 1 hemi head,,if i HAVE to....
don't quote me but i think about 40 psi at 750 and 80 at 2100. temperature is always between 140 - 160.

i can turn the prop by hand but it would be impossible to hand crank it. it takes two hands move the prop any distance. not like its bolted down but it is considerably hard to turn compared to my 200 high compression engine.
How many hours are on the engine? Did the problem just start? Run the engine till it hot, pull the plugs and turn the engine through--this will tell you if it is a mechanical issue or compression related. Check the engine screens and filter for metal.