I acquired a stihl 026 that I'm trying to get back into service. I removed the carb and cleaned it and replaced the diaphragms, but left the old needle valve, Welch plug, and screen in place because they looked clean. I pressure checked the carb, and the needle valve is holding pressure ok. I pressure checked the fuel line and the impulse line, and they don't seem to be leaking. I have not pressure checked the seals on the engine. I'm just getting into working on saws, and haven't rigged a set up to do seal pressure check on an engine yet. I've gotten the saw to the point where it will start, run for a couple seconds, but won't rev up cleanly and dies after maybe 2-5 seconds. Any tips on where I might look next to try and trace down the problem?
Runs for a couple seconds
- Thread starter Hosocat
- Start date
Rob Stafari
Participating member
- Location
- Cincinnasti
Is it flooding it self out or leaning itself out to die?
Rob Stafari
Participating member
- Location
- Cincinnasti
Check plug as that could help point you in the right direction. Ultimately with an old saw, pressure and vacuum test is going to be the best coarse of action with a saw that age. Although, if you can get it running right within normal specs without, not entirely necessary. What are the carb needles set at? May be worth going back in and checking metering lever height even though you didn't replace it. Perhaps replace it and set it right while you're in there. Springs do go bad with use. Absolute first place to start is making sure the carb needles are close to factory spec. If they are way off you don't stand a chance and likely points towards other issue someone else was trying to compensate for.
Barc Buster
Branched out member
- Location
- The land shaped like a hand
Did you do anything with the fuel filter and fuel line besides pressure test? The filter could be plugged or the line could be old and collapsing. As others have said a vac test may help you find air leaks that the pressure test missed.
Rob Stafari
Participating member
- Location
- Cincinnasti
Vacuum test is more important for crank seals. Some of those smaller stihl seals will only leak under vacuum from the way they are designed, not pressure. Make sure you rotate the crank by hand while testing. That can also uncover a hard to find leak.
A saw that old, just replace the line and filter(with OEM). Cheap insurance for an expensive top end. Even if it isn't bad yet, it will be soon if somebody hasn't already replaced it. If they replaced it with aftermarket, it will be soon anyways.
A saw that old, just replace the line and filter(with OEM). Cheap insurance for an expensive top end. Even if it isn't bad yet, it will be soon if somebody hasn't already replaced it. If they replaced it with aftermarket, it will be soon anyways.
Ok, I still haven't pressure checked the crankcase, but I was able to get it running roughly at idle. Won't rev up. What I'm noticing is that it is blowing smoke from under the clutch drum. A lot. Would it be safe to assume I have at least one blown seal? I will do a vacuum and pressure check when I can find something suitable to seal off carb and exhaust, but just kind of feeling my way into this project. This is the first saw I've tried to do anything beyond maintenance, so I'm learning.
