Starting engine blows breaker

[henryj2]

We have a 1978 '44 Gulfstar twin engine Perkins. Recently starboard starter circuit breaker blows whenever starboard engine started. Will not restart until circuit breaker re-set by hand. Our mechanic has traced every wire, replaced starter, solenoid, disconnected every related electric device, reset breaker both with engine running and not running but no luck, start engine, breaker blows. Any ideas?
Thanks for all (or any) suggestions.
Jim H.

 

[Larry M]

Does the starting circuit go through the neutral switch on the running gear? There may be a relay in the circuit, a Bosch type, that has failed.

 

[henryj2]

Thank you Larry M. We are checking that out right now.

 

[rwidman]

I suggest a new mechanic. If he can't figure it out in person, it's going to be pretty hard to figure it out on the Internet.

BTW: I hope he didn't make you pay for the new parts that didn't cure the problem.

 

[Lou_tribal]

Stupid question but did you try to change the breaker itself?

L

 

[hmason]

Stupid question but did you try to change the breaker itself?

L

+ 1

 

[Lepke]

Stupid question but did you try to change the breaker itself?

L

Exactly. When breakers get old or have tripped several times they get weak and trip at lower amps.

Switch the breakers between the engines.

 

[Xsbank]

What exactly in the starter circuit has a breaker? The starter to battery connection should not have a breaker. The starter-to-solenoid is probably all that’s fused. Have you tried starting it by eliminating the stater switch? Is it a push-button or a key-type switch? Does it have any other circuits that become live when you turn the key? Need more info.

If we fix it, you better give the money that you would have paid the “mechanic” to hurricane relief!

 

[tiltrider1]

As xsbank said. It would not be normal to have over current protection between the battery and the starter.

 

[boomerang]

Jim, be sure to check your ground connection points on the block. A loose ground will drive the amperage draw up & cause the breaker to open.

 

[High Wire]

This is the exact reason cruisers should have a clamp-on DC Ammeter in their toolbox. It will tell you if the breaker is tripping false or due to a real fault.
The breaker is to power the control, alarm, and gauge circuits.

 

[rwidman]

Jim, be sure to check your ground connection points on the block. A loose ground will drive the amperage draw up & cause the breaker to open.

Nope, not correct.

 

[rwidman]

This is the exact reason cruisers should have a clamp-on DC Ammeter in their toolbox. It will tell you if the breaker is tripping false or due to a real fault.
The breaker is to power the control, alarm, and gauge circuits.

It's a reason a "mechanic" should have a meter in his tool box. This guy is not trying to fix it himself, he is paying someone who calls himself a mechanic to fix it.

 

[Larry M]

Here’s an example of fused circuit with a rely.

 

[Xsbank]

That diagram doesn’t make any sense to me - what’s the point of that other, smaller solenoid?

 

[Scary]

Neutral safety switch

Neutral safety switch controls relay.

 

[LarryM]

That diagram doesn’t make any sense to me - what’s the point of that other, smaller solenoid?

Actually, this additional relay/solenoid in starter circuits is very common. It has many names: aux. mag. switch, aux. starter relay, remote starter relay, Ford solenoid and others. Its purpose is to provide more current to the starter solenoid.

With this relay installed, a very small current from the starter/ignition switch contacts can activate the starter solenoid, which on larger starters can be substantial.

Here is a Perkins wiring diagram that shows the relay as an 'optional relay'.

A fuse or circuit breaker when fitted will be located somewhere between the battery and the ignition switch. Cummins B-Series diesels I have owned had 10A engine-mounted breakers, and were referenced in the troubleshooting section of the owners manuals relating to starting.

I agree with other posters, check the circuit breaker as they can definitely fail and become 'weaker' with age.

 

[what_barnacles]

Yeh so when I disconnect the power lead from the battery to the starter on my genny, and forget to reconnect it, I blow the breaker every time when trying to crank it.

Try looking for a poor battery to starter connection.

 

[MYTraveler]

As xsbank said. It would not be normal to have over current protection between the battery and the starter.

Really? Every electron coming out of my batteries goes through a fuse of some sort. And wouldn't it be extremely dangerous not to limit the current to the wiring capacity? I must be missing something.

And to the OP, if voltage goes down (for example, by reduced battery capacity), amperage will often go up, sometimes to the point of blowing a fuse / circuit breaker that would not have popped with proper voltage.

 

[Capecodder]

My starter was blowing a fuse when starting, turned out to be the one year old 8d battery. It took a few mechanics figure it out, i was tool it tested fine....... twice....

 

[tiltrider1]

ABYC Standards do not require overcurrent protection between the battery and the starter. By the time the fuse or circuit breaker’s rating was high enough to handle the temporary load of a starter motor it would be to high to provide any usable protection to the wire.

 

[Xsbank]

Thanks for explaining the neutral switch, I couldn’t understand why the relay wiring diagram does not show a power source. The one on the Perkins diagram does.

Starter inrush current can be well over 1000 amps, which would be a problem for most fuses. Ergo bingo, no cable protection for starter motor circuits.

 

[diver dave]

Mechanic needs to stop replacing things and to use an ohmeter and clampon dc current meter.
Did we establish what size breaker is tripping? And does it blow during crank or just after?