My solenoid seems bad, so i am jumping that. When i turn the key i get 10.3V to the solenoid which should be enough. Anyone have a PN? 99 carbed 351W

Getting around 9.6 to the + of the coil when key is in run, and it drops to 9.4 while the starter is running.

Is there something else i should be checking?

ETA: Battery is at 12.8V. Will hook it up to jumper cables and see if that makes a difference.

ETA2: Hooking up jumper cables did it, so assuming the battery isnt good enough. Still looking for a PN on a solenoid if someone has it.

ETA: So hooking a separate battery to the coil, and using a main to start it works. Back to one battery, the coil wire has 12.6 in run. When the starting is running it drop to 10.4. Again i am doing this jumping the solenoid, so it isnt the ignition. Is that normal for it to drop when the starter is running?

What kind of ignition system is in the boat? Being a 99, most likely electronic and depending on the brand, some really don't like low voltage

Original Prestolite electronic module, Pertronix module, or you talked previously about getting a DUI, or maybe you have something else.

Since it was good last year, maybe cleaning all the connections in the supply to the ignition system will help.

All the connections on the key switch, the 8 plug connector at the back of the engine are some likely suspects.

You can show good voltage with your meter but have corroded  contacts that affect the currents ability to flow.

What type of battery?

Based on here i got an everstart maxx group 65 from walmart

What is the best way to clean the connection? The pins i can scrub with a brush, what about the female end?

Back to one of your earlier questions, here's a link to a PCM solenoid/relay or you can cross reference it to a whole bunch of stuff

Or go to your local auto parts place and ask for a Standard Motor products SMP5598 solenoid or equivalent .

Post a picture with the cap off would be the best if you're unsure

Contact cleaner etc and anything that fits in the hole will probably be good if you don't have some small wire brush type cleaners.

Good choice. 

They can be sensitive to voltage high or low

It works with electronic or points.

brantb wrote: Any issue with having two 12v sources at the coil

The extra wire Ken mentions is from the same source. 

Just much more direct so the coil gets the most voltage it could during starting. "I" terminal to the coil is a couple of feet at the most.

The way it's wired now, the power goes from the back of the engine, through the 8 plug connector, down through the bilge to get up to the dash, through the ignition breaker, to the key switch and then it goes from the key switch back down through the bilge, back through the 8 pin connector and then to the coil. An extra 20 feet or so of wire

It's a long and winding road that has a number of places to lose small amounts of voltage due to corroded contacts etc causing extra resistance. and the length of the wire run causes some voltage loss also due to extra resistance of the long length of wire..

The direct wire from the "I" terminal only powers the coil when the key is in START( in parallel with the normal long winding path) and when the key is released to RUN, the coil gets it's power from the long winding path  but the alternator is now putting out about 14 or so volts and the ignition system is happy.

If you were to check the "I" terminal with the engine running without the bypass in place you'd have 0 volts.

With the bypass in place, you'd find the 14 or so volts from the alternator at the "i" terminal but it's coming "backwards" from the coil positive connection and not being supplied internally from the solenoid.

Hope all that makes sense to you, some applications use it as standard wiring, 

Like said in the other thread, "there's no down side to using it"

The piece of wire for the jumper is the 1 dollar thing to try.

The DUI and a new set of plug wires is the 400 plus dollar fix that still depends on having good wiring and a good voltage supply.

I know what I'd try first 

Whatever you do, don't try and use the "S" terminal to do the same thing, it won't work. (funny things happen).

The solenoid shows up, and wasnt what i ordered, but it does have the 4th 'I' terminal. I put it in and it is now doing its job so i dont have to jump it. The boat turned over a little slower than when i was jumping it, but it did fire and start. I still might put a jumper wire in there just so i dont have to deal with it again. This weekend i am going to look for some small brushes and pick up contact cleaner and clean up the connection at the motor and behind the dash.