Bad Voltage Regualtor or Stator????

Drewd · Feb 4, 2017

8 hours on engine post rebuild,about 1 mile from trail head after 5 hours of riding today, lost headlights, all gauges (no rpm, no speedometer) and engine dies 30 seconds afterwards or when trying to increase rpm. It won't restart immediately

Allow sled to sit for about 15 minutes and sled starts easily and everything works again only for the above issue to repeat itself not too long afterwards.

I noticed that my brake light bulb is burned out but not sure if that is a coincidence or not.

I was thinking voltage regulator that seems to short out internally when it gets hot.

Thoughts and suggestions appreciated.Chassis has about 100 hours on it and I'm thinking that the IQ VR's don't seem to last much longer.

volcano buster · Feb 5, 2017

That's where I would start.

Seems like when they go out they can show several different problems and you are likely showing many of them.

Dazzler · Feb 5, 2017

Definite symptoms for a faulty voltage regulator.

XCaSSAULT · Feb 5, 2017

Also check the back of the ecu and make sure there is no bubbling or "heat" looking damage. I've read a lot about how the ecu goes down after the voltage reg. Especially if u try and make the thing run on a bad volt reg to get back to the truck. Hope this isn't your case but check out for sure as u could replace the volt reg and if ecu is bad it could lean u out and make motor damage.

Dazzler · Feb 5, 2017

XCaSSAULT said:
Also check the back of the ecu and make sure there is no bubbling or "heat" looking damage. I've read a lot about how the ecu goes down after the voltage reg. Especially if u try and make the thing run on a bad volt reg to get back to the truck. Hope this isn't your case but check out for sure as u could replace the volt reg and if ecu is bad it could lean u out and make motor damage.

Typically the sled is on a rope if the ECU is burnt up. If you continue trying to run the motor with a bad voltage regulator you will likely fry it.

Drewd · Feb 5, 2017

Thanks for the great feedback, much appreciated!

Sled runs and sounds great when the VR is cold. It seems to cut out when it warms up a bit. Will have to take sled off of trailer and put it in garage. Gonna try to winch it in with ATV in garage so as not to risk damaging the ECU. Sled fires up on first and sometimes second pull when cold.

I'm buying 2 VRS. One is a used good one from a vendor and second one is brand new. Will keep it on me as a spare as I can't spare losing an engine many miles from trail head.

XCaSSAULT · Feb 5, 2017

As a precaution on my sled, I removed the capacitor from the top of the volt reg and zip tied it to the top of the plastic belt holder/electronics cover and put a couple washers under the volt reg mounts for better air flow. I read a post where guys were saying that the volt reg was running 200 plus degrees! And after mods I mentioned was down around 130. Having a clean ground and a extra ground ran to the motor mount isn't a bad idea either.

Drewd · Feb 12, 2017

Got new (used) VR installed, and it fire up on first pull. I put all electrical devices on high such as grip/thumb throttle warmers and ran engine for about 10 minutes. Boy, that VR sure does get warm quick.

I read that folks have been moving the capacitor and placing a 70mm computer cooling on top of them to promote airflow and cooing really extends their life. Gonna try it when I get some extra time.

Dazzler · Feb 12, 2017

Just a note, there have been a couple "updated" VR's since 08/09 due to early failures, so your used VR you purchased may be of the earlier production.

Drewd · Feb 12, 2017

Thanks, I did buy a new VR also but the used one was shipped from a local vendor who got it to me the next day. I'll keep the new VR as a backup and carry it with me.

HalfBrit · Feb 21, 2017

I just picked up an 08 d800. It has a new VR and ECU. I remember reading a year or so ago about someone putting a 2 wire universal VR on as well as the factory one. The spare universal one takes some load off of the factory one. Has anyone else heard this and can verify? I ordered one off ebay for $15. Seems like cheap insurance.

Drewd · Feb 22, 2017

Not sure about a second VR to reduce the load on the factory one. If I were to put a second VR, it would on the power going to the ECu so that if a failure caused voltage to go high, it would shunt the excess voltage to the ground.

HalfBrit · Feb 22, 2017

Drewd said:
Not sure about a second VR to reduce the load on the factory one. If I were to put a second VR, it would on the power going to the ECu so that if a failure caused voltage to go high, it would shunt the excess voltage to the ground.

That's what I was thinking. I just wasn't sure if one would fight the other or one would help the other? It seems as if they would both have to have precisely the same voltage cutoff to work together. Otherwise, one would do all the shunting until it burned out then the next highest voltage one would take over.

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Bad Voltage Regualtor or Stator????

Drewd

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volcano buster

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Dazzler

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XCaSSAULT

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Dazzler

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Drewd

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