225 sho blowing fuse. help please

[HarrisonDawgs]

VF225LA (sho 4 stroke) 2010 model recently blew 10 amp electronic throttle valve fuse. After about 12 fuses tried after each attempt to isolate the problem I am back at square one. Thought it was possibly the tilt n trim motor but disconnected it and fuse still blows. Possibly the old ranger (2006) touch keypad but unplugged it and used key pigtail and fuse still blows. No engine wiring with any noticeable damage or shorts. The fuse seems to be blowing each time the high pressure fuel pump activates at startup. High pressure pump is 4 months old and works great. Have had about 30 hours on engine since fuel pump and all fuel filters replaced. I am not real knowledgeable about the electronic throttle or servo it uses. Could the servo be stuck or shorted and draw enough amperage to consistently blow this fuse? Can this problem be tested and isolated by a computer hookup thru certified mechanic or will it be a ghost I am chasing and throwing $ at? Not real excited about throwing $ toward an ECM, sensor, etc if there is a way to correctly diagnose the problem. Any help is appreciated.

[fairdeal]

I can't imagine getting anywhere without the wiring diagram;
try this link

https://tinyurl.com/y9sxxchl

[99yam40]

monitoring the DC current running thru certain wires with a DC clamp on meter(or accessory plugged into DMM) would probably help identify what is pulling too much current and blowing the fuse.

[99yam40]

looking at that wiring diagram, the ETV is a separate 10 amp fuse.
each fuel pump has it's own fuse so they have nothing to do with that fuse that is blowing if it is the (b) fuse in diagram.
I would disconnect the ETV connector to see if that stops it from blowing.
If it still blows then it has to be in the wiring or connectors before it gets to the ETV

[HarrisonDawgs]

99yam40, yes, appears ETV is it's own circuit. Just did further testing. Cleaned all grounds and reconnected. They were spotless before I cleaned, just did so to check. Tested continuity of all grounds on wiring harness at ECM. All grounds fine. Checked continuity from throttle plug back to ECM plug, ground wire fine. Throttle plate moved by hand with expected spring resistance (ie, not stuck to throttle body). Hooked it all back up and decided to say a prayer and power it back up. 10 amp ETV fuse blows the instant the fuel pumps come alive, I think I actually hear it pop. Just for kicks I left fuse out of block, keyed back on and waited until I heard the fuel pump kick off and then installed the fuse for 30 seconds with system powered up ready to crank. In this situation it does not blow the fuse. Fuse only blows when fuel pumps kick on. Unless there is a short in the wiring harness that allows current to flow into the ETV circuitry from the fuel pump circuitry or somehow there is a crossing of currents at the fuse panel, this makes no sense to me. boscoe99 thanks and I'll try some of your suggestions. BTW, thanks to all for the input so far. Much appreciated. This forum is so much better than others I have been on in the past. Thanks guys!

[HarrisonDawgs]

Ok, so this is a 2006 Ranger keyless touchpad. There are basically 2 startups on circuit before the final switch to turn the starter motor. First sequence powers up all internal boat circuits. That would be gauges, lights, etc. The second start sequence powers up the fuel pumps. It may power up some other components as well but this is where you can hear the pumps run. It is at this moment the 10 amp ETV fuse blows every time. The last step of the keyless pad is to hit start and the starter engages. Keypad seems to be fine and all components of the keypad work as expected. Motor will still crank with ETV fuse blown but it is in fail safe mode with 1200 or so rpm limit. (manual says 1500 but I observe 12 on tach)

[HarrisonDawgs]

boscoe, Just tried 2 of your 3 step approach in reverse. Disconnected plug from ETV - fuse blows same as before. I am assuming this would possibly eliminate the TPS or ETV from being the culprit. Move on to your second step. Disconnected plug from ECU (ECM). Powered up and behold fuse DOES NOT blow. Repeated the start up sequence 5 times and still no blown fuse. Final step was to leave plug from ECU disconnected and re-connect the ETV plug (don't ask me why cause I'm not sure) but same result no blown fuse. This being the case, am I correct in thinking the problem is in a wire or ground between the ECU and throttle body? Just checking to see if I am missing something in my thinking. I have not disconnected anything from the fuse/relay panel as it requires more work/time but I am also wondering if there is any way a faulty relay could be causing this. OR, does the second step of this process rule out anything being wrong at the fuse/relay panel? Thank you so much. Feel like I am much closer now.

[HarrisonDawgs]

All harnesses connected EXCEPT high pressure fuel pump still blows fuse, so I suppose I can rule out HP pump drawing too much current as well. When the "a" plug from the ECU (ECM) is disconnected, no fuse blows. Can I assume the problem is in the wiring harness from the ECU to the throttle body? Unfortunately it is the plug with the most wires lol. Posting this as my previous post indicated it was blocked due to spam...not sure why.

[99yam40]

high and low pressure pumps have their own fuses, does no make sense to me how the pumps would blow the ETV fuse.
pull those fuses and then see if the ETV fuse blows still.

Too many wires for me to follow thru that print, so I am not much help
hope you bought a lot of 10 amp fuses

[HarrisonDawgs]

yep, real booger with so many wires. Ok, so pulling fuse 10 amp fuel feed pump AND 15 amp fuel pump fuse results with 10amp ETV fuse still blowing at startup. Only way I have started up without blowing 10 amp ETV fuse is with the top connector from ECU (ECM) unplugged. Again, with this top connector unplugged and everything else in normal position, no fuse blows. I am beginning to think the problem is at the fuse/relay panel and being caused by some sort of voltage coming back into the fuse panel from the ECM via the top wiring harness connector. Maybe some sort of feedback voltage ?? but I haven't had time to really study the wiring diagram. Thanks to all with input. Still no conclusion but I feel I am much closer than I could have gotten with my own brain. Next step is to pull the fuse/relay box and check everything as best I can.

[HarrisonDawgs]

I have also checked continuity from the ETV plug back to the ECM plug and all wires check out good. Checked every single wire in connector to see if there was any chance of a short between 2 wires in the bundle and continuity test does not show any problems with wiring harness.

[rodbolt17]

you guys are killing me.
chasing ghosties.
hunting wabbits.
maybe sasquatch will appear.
why hunt a circuit that has nothing to do with the fuse that is blowing?
the 10A ETV fuse is simply a protection device.
something in the ETV OR the ETV circuit is simply asking for more amperage than the fuse allows.
remember the ETV is an electric motor. shafts bind.
if the fuse wont blow with the ETV unplugged you know the answer.
if it blows with the ETV unplugged simply find the short to ground in the harness.
we already know it is not an ECU issue cause the ECU is not involved in the 10 amp side.
the ECU simply closes the relay to allow current to the device.

[boscoe99]

you guys are killing me.
chasing ghosties.
hunting wabbits.
maybe sasquatch will appear.
why hunt a circuit that has nothing to do with the fuse that is blowing?
the 10A ETV fuse is simply a protection device.
something in the ETV OR the ETV circuit is simply asking for more amperage than the fuse allows.
remember the ETV is an electric motor. shafts bind.
if the fuse wont blow with the ETV unplugged you know the answer.
if it blows with the ETV unplugged simply find the short to ground in the harness.
we already know it is not an ECU issue cause the ECU is not involved in the 10 amp side.
the ECU simply closes the relay to allow current to the device.

The wiring diagrams show the ETV fuse providing power to the ECU and the ECU providing power to the ET valve. Are the diagrams incorrect?

[boscoe99]

you guys are killing me.
chasing ghosties.
hunting wabbits.
maybe sasquatch will appear.
why hunt a circuit that has nothing to do with the fuse that is blowing?
the 10A ETV fuse is simply a protection device.
something in the ETV OR the ETV circuit is simply asking for more amperage than the fuse allows.
remember the ETV is an electric motor. shafts bind.
if the fuse wont blow with the ETV unplugged you know the answer.
if it blows with the ETV unplugged simply find the short to ground in the harness.
we already know it is not an ECU issue cause the ECU is not involved in the 10 amp side.
the ECU simply closes the relay to allow current to the device.

The wiring diagrams show the ETV fuse powering the ECU. The ECU is shown as powering the throttle valve.

Are the diagrams wrong?

[panasonic]

I have not followed this post much. But if you are thinking it's a harness problem...you may want to purchase one of these to track down that short.

https://www.amazon.ca/gp/aw/d/B00KD3...ID=61XBaN15IRL

I don't know how good these cheap meggars are, but the good ones are invaluable in chasing down shorts, especially partially shorted wires in bundles with hundreds of wires (all white wires in a airplane) Our avionics techs use them all the time...the mechanics just use them for shocking others for fun.

For god sake if you try one make sure the wires are disconnected on both ends from anything you don't want fried. I don't think your ECU will like 1000 volts coursing through its veins....