Need help bad!

[Afrank79@gmail.com]

I have a Miller trailblazer 251. From the label it is somewhere around 1998. I can provide any specific info if it helps!
The welder/generator starts and runs, and idles with no issue. Welds perfectly through the entire range. The problem I am
having is it will not idle up when a load is applied. Doesn’t matter if I am welding or using the generator.

first things first I am not an electrician, engineer, or someone who can diagnose or read the wiring diagrams. I am simply looking for a starting point or directions of what I should do. I know it is absolutely wrong to come and ask experts when I should be more versed, but I’m hoping someone in here can help.

Please help!

[Oldiron2]

I have a Miller trailblazer 251. From the label it is somewhere around 1998. I can provide any specific info if it helps!
The welder/generator starts and runs, and idles with no issue. Welds perfectly through the entire range. The problem I am
having is it will not idle up when a load is applied. Doesn’t matter if I am welding or using the generator.

first things first I am not an electrician, engineer, or someone who can diagnose or read the wiring diagrams. I am simply looking for a starting point or directions of what I should do. I know it is absolutely wrong to come and ask experts when I should be more versed, but I’m hoping someone in here can help.

Please help!

Do you manually increase the engine speed somehow when you need to weld at reasonable amperage?

Do you have the manuals and schematics (in paper form) or do you have links to the right ones for your machine? If so, can you post them? Often the serial number can be used to find the right data on the company's website.

I've never worked on engine-driven welders, don't know that machine, but would think a solenoid would be used to either increase the speed from idle, or possibly decrease it from full speed. Features like that would show up in the schematics, and the manual might even have a troubleshooting section that discusses this problem.

[Afrank79@gmail.com]

I can manually switch it from run/idle to run and it handles any load. I can ditch it to run/idle and it runs and idles down properly. It just won’t idle up automatically when a load is applied.

yes I have access to the manual but doesn’t tell me anything. It gives wiring diagrams and parts diagrams but no troubleshooting.

[52 Ford]

I can manually switch it from run/idle to run and it handles any load. I can ditch it to run/idle and it runs and idles down properly. It just won’t idle up automatically when a load is applied.

yes I have access to the manual but doesn’t tell me anything. It gives wiring diagrams and parts diagrams but no troubleshooting.

I don't have a Trailblazer, but tomorrow or later today, if I have time, I'll look over the diagrams and give it a thinking and try to give you some decent advice (if you haven't already solved the issue).

Sent from my Lincoln Buzzbox using Tapatalk

[Afrank79@gmail.com]

I really appreciate any help I can get.

No I have not solved the problem yet. I cannot figure it out.

[SquirmyPug]

I don't know about that machine but most don't "idle up" with a load other then when welding. When welding it will start at low idle and then go up to welding rpm but rpm shouldn't change much while actually welding.

With the generator side it should hold a pretty constant rpm when a load is applied. Fuel/ air, horsepower/ torque will increase to handle the heavier load but rpm shouldn't change.

Have you checked the rpm to see what it's at before and after a load is applied?

[jpump5]

Finding and visually checking the current transformer, idle
circuit board and throttle solenoid would be a good start.

Current transformer- usually a ring placed around a large wire.
Ring has smaller wire wrapped around it.

Idle circuit board- Smaller than main circuit board. Connected
to current transformer

Throttle solenoid- On or linked to carburetor, powered by idle circuit board.


Current transformer senses rise in current in large wire,
sends signal to idle board. Idle board sends power to
solenoid which throttles up engine.

This is how my Hobart works and from the looks of the
Trailblazer schematic I found , yours should be the same.
If you look at the schematic online you may get help through
wire numbers and other info.

The next step would be checking above components with a
multimeter.

[smithdoor]

I would look at reed sensor switch.
I could be bad or not connected correctly.

Dave

I have a Miller trailblazer 251. From the label it is somewhere around 1998. I can provide any specific info if it helps!
The welder/generator starts and runs, and idles with no issue. Welds perfectly through the entire range. The problem I am
having is it will not idle up when a load is applied. Doesn’t matter if I am welding or using the generator.

first things first I am not an electrician, engineer, or someone who can diagnose or read the wiring diagrams. I am simply looking for a starting point or directions of what I should do. I know it is absolutely wrong to come and ask experts when I should be more versed, but I’m hoping someone in here can help.

Please help!

[duaneb55]

No reed switch on the Trailblazer. My guess is a bad Current Transformer (CT), connection or bad idler module.

I have idler module/CT troubleshooting info but the file size is too large to post to the forum and I'm having email issues and can't send it.

[duaneb55]

Actually, here's some of the information that I can post.


Information on CT troubleshooting from Miller Customer Service originally posted by another member in the past:

The engine speeds need to be set correctly first, as engine speed is very critical for proper system operation. If the speeds are set correctly, and all connections, grounds, and pin terminals appear to be good, then troubleshooting of the CT1 can be done.

With an AC volt meter connected to terminals "G" and "E" at the idle module, start the machine. When applying either an auxiliary power load (such as a 100 watt light bulb) at the receptacles, or striking an arc you should see a minimum of 1 AC volt on your volt meter that is connected to terminals "G" and "E" at the idle module.

If you don't see any AC voltage with a load on the engine, it would be recommended to check for a bad crimp connection at a terminal, corrosion, broken wire or open circuit on the current transformer.

[Afrank79@gmail.com]

I really appreciate the help so far but again, this is not something I am versed in. I can build your house from the ground up but I don’t know these things.

I have a multimeter and can test the ac current but how do I test the current transformer it is round and has wires all around it.

[duaneb55]

From the Technical Manual I can't post due to file size . . .
Current sensing voltage with no weld/power load: 0 volts ac; 100 ampere power load: 11.5 volts ac


These values would be checked for at idler module terminals G and E or CT1 wires #8 and #33 respectively. I do not have a CT1 winding resistance value (ohms) however, if there is no AC voltage at G and E with the recommended test loads then CT1 can be safely suspected of being faulty. A likely open winding would show up as an infinite resistance (OL or 0) reading on the multimeter.

[smithdoor]

Sounds like a current transformer.

What amperage are you weld with

Dave

I really appreciate the help so far but again, this is not something I am versed in. I can build your house from the ground up but I don’t know these things.

I have a multimeter and can test the ac current but how do I test the current transformer it is round and has wires all around it.

[Afrank79@gmail.com]

I have been over a range from 80-150. Haven’t had a need to go higher or lower at this point

[smithdoor]

I would try a high settings and stick a arc.
The sensor may need amperage to activate the engine solenoid.

Dave

I have been over a range from 80-150. Haven’t had a need to go higher or lower at this point

[Broccoli1]

From the manual:

"Place Engine Control switch in the Run position for small loads."

Pretty much any load on the generator side will be a small load so it looks like for Aux power use the 251 should be set to Run.

For welding , I dont have enough experience to know exactly what a small load would be but imma guess 80 is small- dunno about 150