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Electrical issue need help

Luke Lapham

Well-Known Member
Messages
13
Reaction score
4
Points
52
Boat Make
Yamaha
Year
2013
Boat Model
SX
Boat Length
19
I have a 2010 242 limited and I just got back from Bimini on vacation a few months ago and the boat has performed great, however the other day we took it out and when we got back and I pull it on the lift the port engine would fire then stall as if it wasn’t getting gas. Did the usual tests and found she has spark, compression but the fuel pump is not turning on. So to check off what it could be I swapped fuel sending units, no change, I swapped relays no change and I swapped ecm and no change, however even with the swaps the starboard ran fine with each swap of each part. Sooo brings me to my last test which I found that the running engine is getting 12.6 volts on the plug that hooks to the fuel sending unit... the engine that is not running only getting 10.4 volts to the fuel sending unit. Obviously that is not enough to activate the pump, but I don’t know what that means ... wether a new wiring harness or I have a ground issue somewhere and I don’t know how to fi
 

Neutron

Jetboaters Captain
Messages
1,888
Reaction score
2,222
Points
227
Location
New Bern, NC
Boat Make
Yamaha
Year
2016
Boat Model
AR
Boat Length
24
If you think its a ground issue. Add a temp ground wire from battery to the ground to the pump..
But when you see lower voltage it usually means something is robbing some voltage. Like corrosion, resistance, poor connections. Etc
 

Jimmers

Active Member
Messages
2
Reaction score
0
Points
40
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
I had a somewhat similar problem a couple of days ago. Of course it was just a a few days before a holiday weekend with company on the way. Both engines fired up, although slowly. Each one worked good separately, reved up fine but when both engines were running, port engine would not get up to rpm. Dash said check engine and voltage was 13.1. Get a new battery. Running great now!
 

3 green tornados

Active Member
Messages
58
Reaction score
34
Points
27
Boat Make
Yamaha
Year
2015
Boat Model
X
Boat Length
21
I don’t work with automotive/marine batteries often but deal with grid tied and backup batteries often.
Battery voltage drops while under load as it is discharging. “Minor” corrosion or build up between plates in the cells of batteries can cause internal shorts that are expressing themselves when not under a load. Ohm’s law says that the larger the current (amperage) that is being drawn the lower the resistance. Once the amperage increases to run/operate more electrical loads it naturally finds the path that has the least resistance and more current will flow by that channel. the “minor” short within the battery will typically have just a slightly higher resistance than when just one or two loads are applied but once more loads are applied it then provides less resistance than the path through the loads applied and the electrons use the new path within the battery.
This is why a battery voltage may test well under no or minor loads but then fail when trying to handle more.
 

rand01tj

Member
Messages
7
Reaction score
1
Points
10
Boat Make
Yamaha
Year
2008
Boat Model
SX
Boat Length
23
I have a 2010 242 limited and I just got back from Bimini on vacation a few months ago and the boat has performed great, however the other day we took it out and when we got back and I pull it on the lift the port engine would fire then stall as if it wasn’t getting gas. Did the usual tests and found she has spark, compression but the fuel pump is not turning on. So to check off what it could be I swapped fuel sending units, no change, I swapped relays no change and I swapped ecm and no change, however even with the swaps the starboard ran fine with each swap of each part. Sooo brings me to my last test which I found that the running engine is getting 12.6 volts on the plug that hooks to the fuel sending unit... the engine that is not running only getting 10.4 volts to the fuel sending unit. Obviously that is not enough to activate the pump, but I don’t know what that means ... wether a new wiring harness or I have a ground issue somewhere and I don’t know how to fi
Luke did you ever sort this out? I have the EXACT same issue on a family vacation right now and am hoping I can get it resolved to salvage my trip.
 

rand01tj

Member
Messages
7
Reaction score
1
Points
10
Boat Make
Yamaha
Year
2008
Boat Model
SX
Boat Length
23
Luke did you ever sort this out? I have the EXACT same issue on a family vacation right now and am hoping I can get it resolved to salvage my trip.
I was able to sort it out. Bad connection to the earth plate on the back side of the engine. A little contact cleaner and it fired right up!
 
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