A few quick questions - blown fuse 350 Mag

[SC_Regal]

2002 Crownline with 5.7 350 Mag serial# 0M290622

new boat (project) for me. Using Manual #36 I have been troubleshooting fuel pump issue, no power with turning key.

I found a blown 20a fuse which leads to Fuel Pump Relay. It is the middle fuse in the fuse holder - I believe it is fuse 107

My questions:

What else runs through that fuse? I can't figure it out from the wiring diagram

What would cause the fuse to blow? The fuel pump runs when I bypass the fuse (12v directly to FPR) but does not sound smooth - could the blown fuse be a symptom of a failing fuel pump?

Thanks, I have been searching but could not find answers

 

[achris]

Re: A few quick questions - blown fuse 350 Mag

By 'fuel pump' fuse I assume you mean the middle fuse in the rack of three. That fuse also carries current to the Alternator (sense wire) and the power wire on the CAN bus connector. Do you have any smart gauges?

I'd put an ammeter in the circuit and see how much current is being drawn.

Chris.............

 

[SC_Regal]

Re: A few quick questions - blown fuse 350 Mag

Thanks Chris

Yes it is the middle fuse in rack.

No I don't have any smart gauges.

Put ammeter on which circuit? How much current should I be looking for?

 

[achris]

Re: A few quick questions - blown fuse 350 Mag

Put ammeter on which circuit? How much current should I be looking for?

Ammeters get put IN circuit, voltmeters get put ACROSS a circuit.... The easiest way to put the ammeter in the circuit would be to remove fuse and stuff the ammeter leads into each fuse leg hole. I suspect that's where you have your shorting wire, yes?

How much current? There was a 20A fuse so I guess, less than 20A... I would expect probably in the order of 6 or so amps.

Chris......

 

[SC_Regal]

Re: A few quick questions - blown fuse 350 Mag

So - put ammeter in circuit then disconnect the feeds one at a time?

 

[achris]

Re: A few quick questions - blown fuse 350 Mag

So - put ammeter in circuit then disconnect the feeds one at a time?

That's what I'd do...

 

[SC_Regal]

Re: A few quick questions - blown fuse 350 Mag

Thanks

will try tomorrow. This forum is the best

 

[nolalake]

Re: A few quick questions - blown fuse 350 Mag

I have a similar problem with my 35' Chaparral with two 2006 Mercrusier 6.2 MPI. I was having problems with my starboard engine stalling at slow speeds. However it would restart and run fine. My mechanic said it might be the Air Intake Valve that was not in stock and would have to order. Took the boat out and starboard engine died again but would not restart. Drove boat in on port engine and found a replacement Air Intake Valve at another dealer. Replaced part however boat did not start.

Mechanic said check fuses in same compartment mentioned above and middle 20 amp fuse was blown. Changed fuse and boat ran fine. (Note: Fuse had small blow and no black markings.) Ran boat for 3 hours straight no problems to first destination and stopped for the night. Started up fine and ran another hour. However we underestimated the fuel burned in first trip and ran out of gas. Once we were able to refuel bout ran fine for 20 minutes and starboard engine stopped. Checked middle fuse and it was blown with a 1/4 of the inside having black soot markings. Replaced the fuse again and turned the key but would not start. This time the inside of the fuse was completely blown. Took boat in and rented a slip.

After speaking to mechanics they said it might be the fuel pump. Purchased two new fuel pumps for the starboard engine and a fuel filter for each engine. After purchasing the pumps the mechanic said before changing the parts to change fuse, take power off of fuel pump, and start the key. This way if fuse does not blow then it is the pump that is bad. Did that and the element inside the fuse was completely gone.

Not sure if the Air Intake Valve or running out of gas had anything to do with the fuse blowing. Was hoping you could help because I am having a problem finding a mechanic in this small town. And the boat is an hour away so I wanted to be able to try a few different trouble shooting procedures when I return.

I will try what you mentioned above. In addition I read in this forum that it could be the fuel relay switch? Or is there a manual I could purchase to help with the troubleshooting?

Thanks for time and consideration.

 

[Tomw2]

Re: A few quick questions - blown fuse 350 Mag

By 'fuel pump' fuse I assume you mean the middle fuse in the rack of three. That fuse also carries current to the Alternator (sense wire) and the power wire on the CAN bus connector. Do you have any smart gauges?

I'd put an ammeter in the circuit and see how much current is being drawn.

Chris.............

Chris, I am having a very similar problem. Blowing the B fuse. What have been the popular causes? Thank you for any insight!
-Tom