Why is my fuel pump roasting its 20 amp fuse?

[Skicoop2]

2001 310 Sundancer with 2012 v-drive 5.7 mpi mercruiser engines.

Drove the boat 10 hours straight. It ran perfectly. Right after I throw the dock line the starboard engine stalls. Help here led me to a 20 amp fuse that was blown. Replaced the fuse and it started and ran great as I moved it a couple slips over. Got in the slip tied the back line and it did it again.

Definitely not complaining, the timing has been perfect. I would like to figure out why it's blowing the fuse.

Any ideas?

Thanks!
John

 

[Juliery]

2001 310 Sundancer with 2012 v-drive 5.7 mpi mercruiser engines.

Drove the boat 10 hours straight. It ran perfectly. Right after I throw the dock line the starboard engine stalls. Help here led me to a 20 amp fuse that was blown. Replaced the fuse and it started and ran great as I moved it a couple slips over. Got in the slip tied the back line and it did it again.

Definitely not complaining, the timing has been perfect. I would like to figure out why it's blowing the fuse.

Any ideas?

Thanks!
John

It's clear it needs replacing.

 

[Skicoop2]

It's clear it needs replacing.

Not sure if you're joking about replacing the blown fuse to make it work or not. Is the blown fuse a sure sign the fuel pumps need replacement or could something else cause it to blow(example: Clogged filter)?

 

[hughespat57]

Not sure if you're joking about replacing the blown fuse to make it work or not. Is the blown fuse a sure sign the fuel pumps need replacement or could something else cause it to blow(example: Clogged filter)?

Most likely the pump is failing

But as I mentioned in your other thread
The relay contacts can burn up
And the relay sockets are known for melting connections

so check them carefully first
High resistance can cause issues
Cheaper to confirm these first

 

[Skicoop2]

Most likely the pump is failing

But as I mentioned in your other thread
The relay contacts can burn up
And the relay sockets are known for melting connections

so check them carefully first
High resistance can cause issues
Cheaper to confirm these first

Is this damage to the relay something I can see? I visually inspected all of the relays and they look fine. I also replaced the IAC valve. The engine runs great for five min or so and then stalls. After that it's a little hard to start and then stalls. Let it sit and it runs great at idle and 1000-1100 for a few again and the stalls/repeat...

Thoughts?

 

[scoflaw]

Inspected the outside of the relays or the contacts?

Relays are cheap and they don't last forever.

 

[Skicoop2]

Inspected the outside of the relays or the contacts?

Relays are cheap and they don't last forever.

Both. They are clean and the metal is shiny. No signs of heat or damage. I already have a set in case I needed one.

 

[Skicoop2]

So I swapped the relays and it didn't change a thing. Port runs great and starboard stalls when it hits about 150 degrees. Starboard sounds great until it stalls.

Any addition thoughts prior to fuel pump replacement?

Thank you!

 

[techmitch]

2001 310 Sundancer with 2012 v-drive 5.7 mpi mercruiser engines.

Drove the boat 10 hours straight. It ran perfectly. Right after I throw the dock line the starboard engine stalls. Help here led me to a 20 amp fuse that was blown. Replaced the fuse and it started and ran great as I moved it a couple slips over. Got in the slip tied the back line and it did it again.

Definitely not complaining, the timing has been perfect. I would like to figure out why it's blowing the fuse.

Any ideas?


Thanks!
John

So I swapped the relays and it didn't change a thing. Port runs great and starboard stalls when it hits about 150 degrees. Starboard sounds great until it stalls.

Any addition thoughts prior to fuel pump replacement?

Thank you!

What are you loosing? Spark or fuel when it stalls?

 

[Skicoop2]

What are you loosing? Spark or fuel when it stalls?

Not sure how to test that. The fuel pump fuse blew the first time and each time there after it's stalled the same but no blown fuse and starts back up. Stalls pretty quick once warm. Seems like fuel and no one has made a case for spark. What would I look for on the spark side that would make it stall when warm?

 

[techmitch]

Not sure how to test that. The fuel pump fuse blew the first time and each time there after it's stalled the same but no blown fuse and starts back up. Stalls pretty quick once warm. Seems like fuel and no one has made a case for spark. What would I look for on the spark side that would make it stall when warm?

You will need an encapsulated (ignition protected) spark tester and a good quality fuel pressure gauge with the correct adaptors for your engine.