Air leak or vacuum leak? I only ask because if they are the same next step is to get the vacuum test. If they aren’t the same any suggestions on where the leak might be? Ok thanks much appreciated.
Husqvarna 435 won’t stay running
- Thread starter kur1j
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Air leak or vacuum leak? I only ask because if they are the same next step is to get the vacuum test. If they aren’t the same any suggestions on where the leak might be? Ok thanks much appreciated.
I mean a vacuum leak. Since you have it running you can spray some brake or carb cleaner around the seals, cylinder base and carb boot and if theres a change in rpm you have a vacuum leak.
Saw Fixr
ArboristSite Operative
Video is kind of short, but looks like something might be limiting the carb from opening all the way. If you were to disconnect the throttle rod, could you move the throttle farther than with the linkage connected?
Saw should be able to start with the throttle linkage disconnected. Can you fully rev it without the linkage?
Another suggestion:
If linkage is all correct, are you sure the carb adjusting screws were reinstalled in the correct hi/low positions?
Saw should be able to start with the throttle linkage disconnected. Can you fully rev it without the linkage?
Another suggestion:
If linkage is all correct, are you sure the carb adjusting screws were reinstalled in the correct hi/low positions?
Well it revs to like half throttle without touching the throttle (even without the high idle when you engage the choke), if I try to pull the throttle it will just bog down and die.
I did not think to try it with the throttle linkage disconnected. I’ll try thst tomorrow. I feel it’s moving back all the way (less throttle) but not sure if it’s enternally set wrong or something or adjusted incorrectly.
Saw Fixr
ArboristSite Operative
FWIW... I always take a pic of the linkage and throttle trigger springs whenever I take a saw apart. Saves a ton of time Later... I know... backseat driver, but maybe for next time, now that your hooked
I did do that. I wasn’t the first to open the saw unfortunately. Was given to me through another guy that got it from his FIL thst couldn’t get it running. I put it back together as I got it, I just don’t know how much he dickered with it (if at all).
I checked mine and it looks the same as yours. I took a video of it so you can compare
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Your throttle rod appears to not have full movement, is it connected correctly to the trigger in the rear handle?
I think y’all are right that there is some type of air leak somewhere.
I took this video. I am making progress with it I feel. I finally got it to crank up and stay running long enough to warm up.
I could crank it with chain brake on and it would “idle” without choking it. It would stay “idling” for awhile. I cut it off after a few minutes. However, if I took the brake off (no choke) it would just run like a bat out of hell. No amount of adjusting the idle, H,L jets would do a damn thing. Based on this I feel like y’all are right and it’s sucking air in from somewhere.
So at this point I still think y’all are right that it’s a vacuum (air leak issue). I called around and couldn’t find anyone that knew what I was talking about when I asked for a “vacuum test”.
So I either buy a vacuum testing kit...or...if I was a betting man...the leak is between the carb and where the carb meets the intake (e.g. it didn’t seal properly?). If that’s the case buy the carb/carb kit with that seal and give it a try?
If you recommend the former and pinpointing the leak, can you recommend a vacuum kit from amazon?
I took this video. I am making progress with it I feel. I finally got it to crank up and stay running long enough to warm up.
I could crank it with chain brake on and it would “idle” without choking it. It would stay “idling” for awhile. I cut it off after a few minutes. However, if I took the brake off (no choke) it would just run like a bat out of hell. No amount of adjusting the idle, H,L jets would do a damn thing. Based on this I feel like y’all are right and it’s sucking air in from somewhere.
So at this point I still think y’all are right that it’s a vacuum (air leak issue). I called around and couldn’t find anyone that knew what I was talking about when I asked for a “vacuum test”.
So I either buy a vacuum testing kit...or...if I was a betting man...the leak is between the carb and where the carb meets the intake (e.g. it didn’t seal properly?). If that’s the case buy the carb/carb kit with that seal and give it a try?
If you recommend the former and pinpointing the leak, can you recommend a vacuum kit from amazon?
Spray some carb or brake cleaner around all the points I said earlier while it's running a listen for a rpm change and you will know where the leak is coming from. If you want to buy one Mightyvac is a good brand and they sell it on Amazon
Thanks for the help. So I did this tonight. I sprayed the **** out of the carb and couldn’t get it to really change in RPM. I sprayed half a bottle of carb cleaner over the carb, the carb boot and the cylinder base but it wouldn’t change in rpm.
The only time it changed slightly was when the carb was almost drowning in carb cleaner. It only changed slightly and for not very long. Engine slowed down and then started picking up speed again pretty quick. Based on this there might be a leak around the bottom of the carb seal(?)/gasket(?). But it wasn’t much and I was only able to get it to do it twice before i ran out of carb cleaner.
It certainly wasn’t obvious. I think there might be a leak but obviously not 100% sure. I think I’m going to replace the gasket that mates between the carb and the cylinder intake but it’s just a guess still at this point.
On the plus side, your carb is clean ( on the outside ).
I know this is going to drive you nuts, but buy a carb kit for it and find a diagram online for the carb and make sure it’s put together correctly, making sure to remove the screen and blow it out. A friend of mine was having this same issue after I told him how to rebuild a carb he did, and didn’t get it back together tight enough...the gasket and diaphragm were backwards and it was sucking air. 10 min fix and it makes you feel stupid as hell. Other than that fuel lines, or it’s sucking air around the crank seals....or Exhaust is clogged. Since this is a clamshell motor you can take the flywheel off and clutch to get a visual. A lot of times if the seals are shot you can see it.
On the plus side, your carb is clean ( on the outside ).
All this without checking to make sure the throttle butterfly is actually closing, it appears not but instead of checking this simple thing out just keep on worrying about an air leak. More than one saw I have worked on had a linkage problem preventing the butterfly from closing tight enough, thus the biggest air leak a saw can have.
I have a 435 to work on which has the same symptoms except for the fast idle, I'm thinking maybe fuel line or carb. This one runs only when you put some fuel mix into the sparkplug hole or the intake. I guess it's also possible someone mixed up the fuel lines but not sure about that one..
As pioneerguy says, check the throttle plate. Back the idle adjust screw right out and if the linkage isn't interfering, the plate should be completely closed and the engine should not run. If it still does, THEN you have an air leak somewhere else.
Going under the assumption that you have compared your linkage movement to the video I posted and ruled that out, and that you also sprayed the carb cleaner behind the flywheel and clutch on the seals and didn't have a change in rpm then you probably don't have an air leak and the linkage is working like it should. The only thing I can think of is that you have your idle screw turned to far out, try turning it out far enough that it's not pushing on the throttle, or you need to rebuild the carb.
Just so you know for the future, it doesn't take a lot of carb cleaner to find a leak. If you have a leak as soon as the carb cleaner hits the leak you rpm will change, you don't need to drown whatever your spraying.
I took the throttle linkage off which would allow the spring to close the butterfly as much as it could. I cranked it up and it did the same thing (super fast idle).
The top butterfly on the carb looks completely closed to me when no throttle is applied or the linkage is taken off.
I’ll double check this again though to make 100% sure though.
Yeah I compared the linkage and they look to be the same.
I didn’t spray any on the clutch side only on the fly wheel side. I’ll try to spray some on the clutch side of the motor. I’m honestly not 100% sure where i’m spraying is the correct locations, i’ll take a video of it to make sure. But I only sprayed some on the carb the carb/engine intake boot, and the flywheel side of the motor. Didn’t do any on the clutch side of motor.
Good to know I don’t have to spray an entire bottle haha. I wasn’t just spraying areas mentioned above and nothing was happening. So then I assumed it might be sucking air and it needed to be basically coated “sealed” so it wouldn’t suck air. Obviously that was wrong assumption.
The idle screw is only two turns out. The way I understand it is that the further I back the idle screw out the slower it should idle correct?
