HELP! 462 won’t rev up

[furb]

Picked up a 462, starts and idles but won’t rev up. It’s getting fuel, spark screen is clean, new plug, no air filter but it doesn’t look like it was run without. Is it worth throwing a carb at it? I don’t have access to plug this in. I do have solenoids off of 261s that might swap over. Carbs are $150 for a new take off

 

[SawAddictedFarmer]

Picked up a 462, starts and idles but won’t rev up. It’s getting fuel, spark screen is clean, new plug, no air filter but it doesn’t look like it was run without. Is it worth throwing a carb at it? I don’t have access to plug this in. I do have solenoids off of 261s that might swap over. Carbs are $150 for a new take off

I've heard it said that a new solenoids fix a lot of issues. You can always take it back off and keep it if it doesn't change anything. Also spray around for a air leak with carb cleaner.

 

[singinwoodwackr]

Picked up a 462, starts and idles but won’t rev up. It’s getting fuel, spark screen is clean, new plug, no air filter but it doesn’t look like it was run without. Is it worth throwing a carb at it? I don’t have access to plug this in. I do have solenoids off of 261s that might swap over. Carbs are $150 for a new take off

Pull the the fuel filter and try to blow through it…

 

[furb]

Pull the he fuel filter and try to blow through it…

I was planning on getting a new one with an air filter tomorrow. I will try that later tonight if I clear a bench spot

 

[furb]

Pull the he fuel filter and try to blow through it…

I had a new one, installed and same thing

 

[furb]

I don’t think anything looks too bad in here. The one diaphragm seems a little stiff but I’ve seen worse in better running saws

 

[TX_Welder]

Like won't rev at all ? Falls on it's face? Spits and sputters or what ?

I will say that mine is fuel filter sensitive. The only saw I've ever had that I've changed one. Fuel line on mine split one time also. Would run awesome for half a tank and then start acting goofy. Sounds like you already explored that option though.

 

[cuinrearview]

If this were mine, I'd swap a solenoid and kit the carb. But everyone knows I'm just an unskilled hammer donkey.

 

[huskihl]

Clean/rebuild the carburetor and put a new fuel solenoid on it like mentioned. If that doesn’t do it, it’s more likely that it’s electrical. Either the harness, plug wire or a coil.
There’s less precision jetting inside these mtronic carburetors than there is in one with needles. Aluminum holes rather than precise brass jets. Not much to go bad.

 

[Coupe]

Check you haven't semi pinched your fuel line.

 

[Stump Shot]

I don’t think anything looks too bad in here. The one diaphragm seems a little stiff but I’ve seen worse in better running sawsView attachment 486955View attachment 486956

The fuel pump looks to be worn out as well, could not be good in combination with the stiff metering diaphragm. All the above recommendations are good, the only thing I could add is to check the fuel inlet screen, these can film over and the only way you can see it is to take it out and hold it up to a light source. Thought I would mention that in case just a G & D kit is installed.
I'm really not sure just what causes this other than maybe it has to do with some plastic from modern fuel cans coming into solution with the fuel and settling on the screen possibly?

 

[furb]

Clean/rebuild the carburetor and put a new fuel solenoid on it like mentioned. If that doesn’t do it, it’s more likely that it’s electrical. Either the harness, plug wire or a coil.
There’s less precision jetting inside these mtronic carburetors than there is in one with needles. Auminum holes rather than precise brass jets. Not much to go bad.

I swapped a white solenoid to see if anything changes, nothing. How to you diagnose the other electrical parts? It has spark and fuel to some extent. Someone was already in here judging by the mismatched hardware

 

[huskihl]

I swapped a white solenoid to see if anything changes, nothing. How to you diagnose the other electrical parts? It has spark and fuel to some extent. Someone was already in here judging by the mismatched hardware View attachment 486973

I would test them for continuity with a multimeter. Try bending and twisting them to see if there is a break. Also check from red to yellow to confirm they aren’t touching each other

 

[furb]

I would test them for continuity with a multimeter. Try bending and twisting them to see if there is a break. Also check from red to yellow to confirm they aren’t touching each other

I’m getting a carb kit whenever it gets here and I’ll check out the wiring before them. If it revs and restarts is it safe to assume the coil is good? It doesn’t break up or act like it has a limiter

 

[huskihl]

I’m getting a carb kit whenever it gets here and I’ll check out the wiring before them. If it revs and restarts is it safe to assume the coil is good? It doesn’t break up or act like it has a limiter

All I know is I’ve seen a half dozen mtron and autotune coils go bad but never a carb itself other than diaphragms. After buying a few new carburetors because that’s what it sounded like, and then actually fixing it with a new coil, it leaves a sore spot

 

[furb]

All I know is I’ve seen a half dozen mtron and autotune coils go bad but never a carb itself other than diaphragms. After buying a few new carburetors because that’s what it sounded like, and then actually fixing it with a new coil, it leaves a sore spot

How did you diagnose the coil. In the good old days they were interchangeable and I had multiple saws to swap parts around. These dumb things are saw specific and $150

 

[huskihl]

How did you diagnose the coil. In the good old days they were interchangeable and I had multiple saws to swap parts around. These dumb things are saw specific and $150

I didn’t really. Don’t actually know if it can be diagnosed without the SDS software. The brain is in the coil. Many of the issues we associate with fuel problems are actually issues with the coil communicating to the carburetor.
My main gig is port work, not repair. Rather than spend hours or sometimes parts of multiple days trying to diagnose something, it’s often easier for me to replace a carburetor or coil and try it. I have ended up purchasing a few new carburetors that didn’t fix the issue and then replacing the coil in the end. Still sitting on a couple brand new carburetors because of it.

 

[Stump Shot]

I didn’t really. Don’t actually know if it can be diagnosed without the SDS software. The brain is in the coil. Many of the issues we associate with fuel problems are actually issues with the coil communicating to the carburetor.
My main gig is port work, not repair. Rather than spend hours or sometimes parts of multiple days trying to diagnose something, it’s often easier for me to replace a carburetor or coil and try it. I have ended up purchasing a few new carburetors that didn’t fix the issue and then replacing the coil in the end. Still sitting on a couple brand new carburetors because of it.

Interesting, I wonder if something like a simple voltage check would tell anything or not?

 

[Stump Shot]

Interesting, I wonder if something like a simple voltage check would tell anything or not?

That is if it can run at all. Otherwise maybe a resistance check if it is not running maybe?

 

[huskihl]

Interesting, I wonder if something like a simple voltage check would tell anything or not?

I don’t think so. It’s computer code *s-word I believe. Had a 572 that would start and idle like it was in the choke position on at3. Pull the throttle and it would not rev up at all, could hear the air being sucked through the carburetor, but no change in RPMs. Put a new coil on it and it ran fine