3.7 no crank

[Dschaffer]

Hi all. I am new to this forum. I’ve been looking around a bit and found some items I can rule out as being the issue but have yet to find the solution. I have power at the gauges, 12v at the igntion switch in run. When turned to try and crank it drops to 5.6 volts at ignition. Also, only 5.6 at the positive terminal on the coil in run position. The choke resistance wire (from coil to choke) gets hot. New batteries, ignition coil and slave solenoid. It will crank when I jump from the battery to the slave solenoid. I tried bypassing the neutral safety switch but no dice. The hot choke wire is a “newer” discovery and has me thinking there must be a short somewhere but I’m not much with electrical so I thought I would ask here first. Any help is appreciated. Thanks
Edit: I put on another slave solenoid with no positive results. I tried jumping the new slave solenoid directly from the battery and it cranked for half a second but then nothing. Did I fry the new solenoid? What the heck is going on??

 

[Bt Doctur]

bad ground connection?

 

[Dschaffer]

bad ground connection?

Not that I can find. I’ve cleaned all the grounds I’m aware of. All looked pretty good even before giving them the wire brush.

 

[QBhoy]

Quite a delicate charging system on these. They have a system not unlike an outboards. As in like a stator idea and a rectifier from AC to DC. Some guys swap it out for a regular alternator set up usually.
Hopefully your issue isn’t because of the usual 3.7 trick of frying the cylinder head after a water pump failure and letting coolant into the bores to hydro lock it up or worse. Fingers crossed

 

[Dschaffer]

Quite a delicate charging system on these. They have a system not unlike an outboards. As in like a stator idea and a rectifier from AC to DC. Some guys swap it out for a regular alternator set up usually.
Hopefully your issue isn’t because of the usual 3.7 trick of frying the cylinder head after a water pump failure and letting coolant into the bores to hydro lock it up or worse. Fingers crossed

Pretty sure that’s not the case. It ran great before winter and never overheated. I’ve got to think its a short somewhere or bad ground or ???

 

[QBhoy]

Pretty sure that’s not the case. It ran great before winter and never overheated. I’ve got to think its a short somewhere or bad ground or ???

Likely right. Is this the first time you’ve ran it after winter ?

 

[Dschaffer]

Likely right. Is this the first time you’ve ran it after winter ?

Yes. First attempt to fire it up since last October, when I winterized it. There was a no crank situation in August that ended up being the ignition coil. Other then that, no issues. Maybe there is a ground I am missing?

 

[achris]

Pull the spark plugs and see if it cranks. If it's still got a voltage dropping problem, use my 'voltage drop' testing procedure to find out where you're dropping that voltage.

https://forums.iboats.com/forum/eng...ives/10259654-how-to-perform-a-volt-drop-test

Chris........

 

[Scott Danforth]

pull the plugs, then try turning it over. if coolant comes out of the spark plug holes, you need to go from there.

 

[QBhoy]

Ok so, the reason asked and the couple of posts above are along my thinkings. You need to look for signs of water and take the plugs out. How was the AF mix strength in the FW cooling system ? Was it all good and checked before winter ? Did you drain the raw water side ?

 

[Dschaffer]

Pull the spark plugs and see if it cranks. If it's still got a voltage dropping problem, use my 'voltage drop' testing procedure to find out where you're dropping that voltage.

https://forums.iboats.com/forum/engi...volt-drop-test

Chris........

I pulled the wires to the plugs and a couple of the metal connections stayed with the plugs. I tried cranking with just the wires off and nothing. Then I remembered that my new slave solenoid might have gotten fried so I put the old one back on. With the wires off, the starter turns and rumbles? Not really a cranking sound like when I was jumping from the battery to the solenoid with the wires connected but at least it something. What does this mean?

UPDATE: I turned the perko switch to all and it cranks much better but still seems week. This is with 2 brand new batteries. I’ve got the main starting battery charging right now. There must be a big power draw somewhere to be draining the battery so quickly.
I pulled the back two plugs and see no signs of water. Defiantly in need of an oil change though.

 

[Dschaffer]

Ok so, the reason asked and the couple of posts above are along my thinkings. You need to look for signs of water and take the plugs out. How was the AF mix strength in the FW cooling system ? Was it all good and checked before winter ? Did you drain the raw water side ?

The coolant is good and I did drain the raw water side. I see what y’all are thinking but I don’t understand how that would make the system not crank via ignition but crank when jumped from the battery?

 

[QBhoy]

The coolant is good and I did drain the raw water side. I see what y’all are thinking but I don’t understand how that would make the system not crank via ignition but crank when jumped from the battery?

If it was hydrolocked...it would struggle to turn over without some real serious help. Dead easy to take plugs out and see what happens. Will get you further along the road on the way to solving your issue, for sure.

 

[Scott Danforth]

I pulled the wires to the plugs and a couple of the metal connections stayed with the plugs. I tried cranking with just the wires off and nothing. Then I remembered that my new slave solenoid might have gotten fried so I put the old one back on. With the wires off, the starter turns and rumbles? Not really a cranking sound like when I was jumping from the battery to the solenoid with the wires connected but at least it something. What does this mean?

UPDATE: I turned the perko switch to all and it cranks much better but still seems week. This is with 2 brand new batteries. I’ve got the main starting battery charging right now. There must be a big power draw somewhere to be draining the battery so quickly.
I pulled the back two plugs and see no signs of water. Defiantly in need of an oil change though.

you have to pull the plugs out of the motor..... this will allow any coolant in the cylinders to shoot out the plug holes.. the issue is if coolant is in the cylinder bores, no amount of power will crank it over if its hydro-locked.

Now, do like we tell you and pull the @!#$R!@#$!@#%$@# spark plugs prior to cranking the motor, not just the wires.

 

[Dschaffer]

you have to pull the plugs out of the motor..... this will allow any coolant in the cylinders to shoot out the plug holes.. the issue is if coolant is in the cylinder bores, no amount of power will crank it over if its hydro-locked.

Now, do like we tell you and pull the @!#$R!@#$!@#%$@# spark plugs prior to cranking the motor, not just the wires.

Ok. Weird that it cranked with the wires off though, right? I did pull two plugs and it was the same. I will pull the other two when the battery is done charging and report back. Thanks for the help

 

[Dschaffer]

you have to pull the plugs out of the motor..... this will allow any coolant in the cylinders to shoot out the plug holes.. the issue is if coolant is in the cylinder bores, no amount of power will crank it over if its hydro-locked.

Now, do like we tell you and pull the @!#$R!@#$!@#%$@# spark plugs prior to cranking the motor, not just the wires.

Plugs pulled and it cranks. Not as fast as I would think a new battery should but its probably enough to make it fire, if that were possible. Nothing shoots out of the pug holes. What does this mean?

 

[Dschaffer]

Any thoughts what’s going on? Cranks with the plugs out but no signs of water/coolant? No crank when plugs are in.

 

[Scott Danforth]

could be rust in the bores

could be bad battery cables or connections

could be bad battery

could be drive is toast and putting a bit of drag on the system

time to do some troubleshooting.

pull the drive and test. if no improvement, move on to the battery cables and connections.

 

[Dschaffer]

could be rust in the bores

could be bad battery cables or connections

could be bad battery

could be drive is toast and putting a bit of drag on the system

time to do some troubleshooting.

pull the drive and test. if no improvement, move on to the battery cables and connections.

Thanks. What is the drive? Batteries are new and the cables look great.

 

[Dschaffer]

You are probably referring to the outdrive, thinking maybe its a bit “frozen” up.
At this point, I should probably try and get it into a shop. I’ve spent many, many hours trying to figure this thing out. I have more time on my hands then usual but i don’t really know what the hell I’m doing. I’m mechanically inclined but gas motors, especially on boats, are not something I’ve spent much time on. Thanks again for the help. If anybody has any “Ah-ha” moments or further thoughts on diagnostics, please do share. Thanks again.