40hp Evinrude 1968 or 67 will not turn over

[grieshop]

I have recently aquired a 40 hp evinrude "Big Twin". Its either 1967 or 68. When i take the plugs out it spins over feely. With plugs in, it will not turn over. It acts like it has to much compression. I even tried starting with two batteries with no luck.

Any ideas what might cause it to not turn over?

2 new batteries
new starter

 

[racerone]

Never encountered one of those with too much compression.---Battery cables tested ?----Tried using a set of booster cables directly from battery to the starter ?----Factory new starter / aftermarket / Chinese made ??

 

[grieshop]

OMC brand new out of box starter. U.S.A. made.
by passed all wiring with new jumper cables straight to starter.

 

[F_R]

Are they quality jumper cables, or ---er, shall we say "cheap junk"? There are a lot of them out there with like 10 GA wire. Some even have aluminum wire. Good heavy copper cables are expensive.

You may also be getting high resistance connections with the pointy cable clamps.

 

[kbait]

I bought 4 gauge jumper cables (amazon $14.95) to test outboard starters.. my cheap set wouldn’t carry the amps to spin a 40 like yours.. sometimes not even an 18.. new cables give a definitive starter motor test.
Good luck!

 

[oldboat1]

Not sure what your testing sequence was, but did you by accident double the voltage by running the two batteries in series? (could damage the starter)

 

[grieshop]

Problem solved! I relaced the cavles with 2 gauge, cleaned all the connections and it fires up just fine. Thanks for all the advice.

 

[SuperCap]

OzCharge America has a great Super Capacitor Jump Starter you never have to plug in the wall. Will jump your boat off it's own dead battery, 3 volts minimum. Lasts for 500,000 jumps,10 years. Leave it on the boat. No charging. www.ozchargeamerica.com