2004 vz300 ecm fuse blows at high rpm

[david2014]

I have a vz300tlrc that blows the 20a ecm/fuel pump/ignition coil fuse above 6700 rpm. Runs good at idle to 6700, and the amp load is 8a, at 6800 it spikes this fuse at 79a, then replace the fuse restart and stay below 6800 rpm. There are no trouble codes. The local dealer wants to install a new $ 1451.50 ecm to see if the problem goes away. Has anyone heard of this problem.

[boscoe99]

I have a vz300tlrc that blows the 20a ecm/fuel pump/ignition coil fuse above 6700 rpm. Runs good at idle to 6700, and the amp load is 8a, at 6800 it spikes this fuse at 79a, then replace the fuse restart and stay below 6800 rpm. There are no trouble codes. The local dealer wants to install a new $ 1451.50 ecm to see if the problem goes away. Has anyone heard of this problem.

Please confirm that you are seeing the problem above 6700 RPM?

Please confirm that you are seeing 89 amps through a 20 amp fuse. What are you using to measure current flow?

Since the redline (not to exceed) RPM is 5500, perhaps if you just kept the motor under control you might not be blowing fuses.

[99yam40]

I wonder if this thing has been modified some how to get that high of RPM

[david2014]

2004 vz300 ecm fuse blows at high rpm

Tach on boat was set to the wrong pole #. Rechecked the rpm with a scan tool. The fuse blows at 4500 rpm. I have pulled all the wire connectors to inspect for moisture or burning, found none. Have also checked the harness where is touches metal parts for a short, removed and cleaned all harness grounds. The engine history showed zero hours run time for 6000-6500rpm, and rev limit is 6200 rpm. 277 hr total run time, 207 hr 0-1000rpm. Sorry for the bad rpm info.

[99yam40]

In case you have never looked before the Owners manual says full throttle operation is 4500-5500.
You should be propping to get there

Have no idea why the 20 amp fuse is getting a heavy draw at higher RPM.

Maybe Rodbolt17 will give you some idea

[david2014]

2004 vz300 ecm fuse

vz300tlrc engine specs full throttle range 4500-6000 rpm, 300 hp at 5250 rpm Someone mentioned it could be one of the injection driver computers. This motor still spiking the ecm fuse at 79 amp surge 9 times now. Testing peak current with an Amprobe digital amp clamp.

[boscoe99]

You might want to check your source of information. A VZ300TLRC has a 5500 RPM red line.


Are you saying that you have a data recording amp meter that is showing that 79 amps are being seen across a 20 amp fuse before that fuse can blow?

[boscoe99]

vz300tlrc engine specs full throttle range 4500-6000 rpm, 300 hp at 5250 rpm Someone mentioned it could be one of the injection driver computers. This motor still spiking the ecm fuse at 79 amp surge 9 times now. Testing peak current with an Amprobe digital amp clamp.

The ECM gets its power from the ECM fuse/relay. A separate fuse/relay powers the injector driver. I am not seeing how an injector driver issue can be over loading an ECM fuse.

Only thing that comes to my simple mind is a chaffed wire that is shorting to ground causing excessive current flow.

[boscoe99]

Another thing that comes to mind is that there was a bulletin issued for 2003 - 2004 HPDI's that called for repositioning and securing of the main wire harness to avoid wire damage. Has you motor had that bulletin performed?

[rodbolt17]

very carefully inspect the main harness where it passes under the stbd cyl head.