# Stihl TS510 won't run



## niagara transom (Jan 28, 2019)

Hi All, I have read some of the other posts on this forum and can't quite dial in my issue. I have 2 Stihl ts510's.
The first one leaks out the fuel cap. I changed the O ring, but I can see it leaking out the set screw for the vent. Do I adjust the screw or change the cap? It is a black cap. I bought the saw, cleaned the carb, fuel filter and repaired the impulse line. This think starts and runs like a champ, very low hours. Carb and filter were a waste of time but I like things that start and run.

Saw #2 had compression. Bought it a year ago, poured gas in it and cranked till I couldn't breath anymore. It will start and run briefly like it is starving. I bought another carb and rebuilt it. Same thing. The saw will start every day 1 time cold and stall. It will NOT run again that day. I checked spark. It has plenty. Fuel filter done, lines done, impulse checked with grease. I tried with gas cap loose for venting issue. At wits end I bought a seal kit and was going to split the saw and reseal thinking possibly the erratic behavior was vacuum leaks. Black fuel cap. Run time under 30 seconds before dying. Compression was great.
I haven't split the case yet but did go over the carb and intake spacer gaskets. Bought saw #1 to help me figure out saw #2. I figured that one out but stumped on #2 stihll -pun intended.

I just thought before I split this open is there something I missed?
Thanks in advance for any input!


----------



## paulr44 (Oct 14, 2008)

First, the older STIHL fuel caps will allow fuel to spurt out, as cap venting was simpler then. Fill the tank up less.

Second, the starting once a day and not again is bad, and we'd need more info. When you say compression is "good," that's subjective to your arm being calibrated. So, we'd need a compression reading. What you're describing though, could be fuel or spark, so all I can do is speculate.

If it's wetting the plug, that can be a sign of an ignition problem, or a worn piston and cylinder. It could feel good when pulling over (trust me, your arm can lie to you), but I've seen it first hand many times and it'll fool you. Scoring, or so worn that the intake is no longer being closed off properly (piston-ported engine as opposed to reed valve) that will not start, or if does go nowhere near idle.

If it's spitting a lot of fuel back through the intake, it's worn out.
A worn cylinder doesn't transfer the charge properly, and ends up wetting the plug.

A proper ignition test requires a tester with a gap of about 0.150" to subject it to a heavy load. A spark plug against a cylinder is NOT a valid test of an ignition system.

Now, as to re-sealing it. A qualified STIHL dealer, and perhaps many OPE dealers, can perform a crankcase pressure/vacuum test, indicating whether or there's a leak. A pressure leak indicates gaskets, a vacuum leak alone indicates crank seals.

You need to do more testing...let us know.

Paul
STIHL Silver Certified Tech.

Edited...P.S. Most older TS units like this have a compression release. To do a proper compression test that port should be plugged. A STIHL dealer should have one on hand.


----------



## mongo37 (10 mo ago)

paulr44 said:


> First, the older STIHL fuel caps will allow fuel to spurt out, as cap venting was simpler then. Fill the tank up less.
> 
> Second, the starting once a day and not again is bad, and we'd need more info. When you say compression is "good," that's subjective to your arm being calibrated. So, we'd need a compression reading. What you're describing though, could be fuel or spark, so all I can do is speculate.
> 
> ...


is the ts 510 its a chop saw or concrete saw is it not.check the fuel and breather hose configuration and also if nyou have a bad vent it could be the oil tank vent i had one filling up the oil tankn with gas.the fuel lines and vents for the tanks all are sealed because its a concrete saw so no dust ges in the system,


----------

