3.7 wont start

[blueagletalon]

i have been reading and have been checking it out. when i first turn the key on i have 11.67 volts to the coil. then when i try to start it i only get 5.65 volts. the wires coming from off the electric choke are getting hot and so is the one going to the coil. what do i have to check out next? my boat is the 1987 Thompson cutlass 185 with the 3.7 470 165hp

 

[stonyloam]

Re: 3.7 wont start

You either have too much draw on the battery (bad starter), or you have a bad battery, or you have bad connections on the battery cables. So charge your battery, clean an tighten all of your connections and give it a try. No luck take the battery in and have it load tested (wal mart or any auto parts store can do it). Good luck.

 

[blueagletalon]

Re: 3.7 wont start

i check the voltage on the battery and i have 12.23 then i have 11.8 when i try to start it. i just dont know why the electric choke wires are getting so hot. after i start it have a constant 5.65 volts to the coil.

 

[stonyloam]

Re: 3.7 wont start

The wire going from the choke to the coil is a resistance wire which drops the voltage, so it might be getting warm. With the key on coil + will be significantly less than 12V, when starting, the coil + should be the same as battery voltage. The draw from the starter will drop the battery voltage some.

 

[blueagletalon]

Re: 3.7 wont start

i dont have battery voltage at the coil. what do i check? i ran a wire from the + of the battery to the coil and it started. so is it the switch?

 

[blueagletalon]

Re: 3.7 wont start

anyone?

 

[Eric 3.7LX Alpha 1]

Re: 3.7 wont start

Here is a link to the factory wiring which I'm sure you have, but so we can reference. The original set up has two wires to the (+) side of the coil, each are powering the coil at different times. One from the elect. choke which is a purple resistance wire, and another wire from the starter solenoid which is a purple/yellow wire.

The starter solenoid gives the coil full 12v while you are cranking the engine over to start it. when you release the key, that wire (purp/yellow) is now dead and the coil is now getting "reduced power" thru the resistance wire (purp) from the choke.

The choke has 12v as long as the key is in "run" position, but the resistance wire reduces it to the coil.

 

[scv76]

Re: 3.7 wont start

FYI..
While trouble shooting/investigating the electrical system of my 470 engine, I discovered the resistance wire from the choke to the coil was very hot; so hot I thought the insulation was going to melt. I put a current meter in line and measured something like 8 amps!
It so happened that the points just happened to be closed while I was taking my measurements..Since then, if I trouble shoot the electrical system, I put a small piece of paper between the points...no more problems measuring coil voltages or super heating the resistance wire.
Hope this helps someone

 

[natemoore]

Re: 3.7 wont start

I think stony explained it already. You won't have battery voltage at the (+) terminal of the coil if you have a resistance wire installed. My resistance wire drops 3 volts off, so I have 9 volts at the coil.

We had an alternator/choke/coil symposium over the weekend. That discussion that I started would be informative to you.

http://forums.iboats.com/showthread.php?t=507183