# I have compression and spark, why won’t my uncle’s chainsaw start?



## AlwaysLimbLeft (Apr 3, 2013)

A relatively experienced sawyer here,

I’m visiting my uncle in rural Nebraska and he asked me to take a look at his saws. He has some craftsman p.o.s. and a Dolmar PS-401. He says he hasn’t run ‘em in a few years and wants to dice up some railroad ties and cut some firewood, but they’re not working. He says he took ‘em to some local "dealer" who said they were toast and recommended buying a new saw, BUT that he’d take the Dolmar as a trade in… My uncle was suspicious and I think reasonable so. Now he’s in luck. I’m in town, I love saws, and I’m fam, so of course I’ll take a look...

Well, the craftsman’s f*cked. Seized like a motherfucker. No loss there as far as I’m concerned.

But the Dolmar… I spent a few hours tinkering with it today. 

Status: Dolmar PS-401, <10 yrs old, ~40hrs of running time on it, *currently non-functional.*

Notes:

filter = kinda oily, but I can see plenty of daylight through it. Frankly, I’ve only run pro saws and am not familiar with these smaller air filters and have no idea how they age
I changed the fuel, the old stuff was rancid and had sat in there for upwards of three years
Spark plug appears new and I’m getting spark, but what seems like a weak shock compared to what Im used to troubleshooting pro saws. More on this further down…
I’m getting at least some compression. When I plug the spark plug port with my finger, it is certainly harder to pull
I can get it to belch fire by holding a lighter next to the spark plug port and pulling the pull starter. Better yet - I can get it to belch fire by pulling the pull starter with the spark plug in its boot, but just dangling next to the port (but not every time). And I do get spark 100% of the time.

My analysis/possible causes:

the gasket that goes between the muffler and the cylinder is missing. The muffler was disassembled and in a gallon ziplock bag when I first laid eyes on the saw. Apparently the “dealer” or whoever gave it back like this.
Dirty carb. I really don’t feel like/have the time to tear it apart, but there was HORRIBLY stale gas left it this little saw. I mean, it was f*cking green when I poured it out. However, with new gas, I’m getting vapor burping out when I pull start without the spark plug in
bad seal somewhere? I haven’t properly ID’d this on a saw before, but (see 7)
dirty spark arrestor. Haven’t checked this yet. *[gameplan for tomorrow]*
simply in need of re-tuning. I’ve tried this a fair bit already, but I am willing to continue to troubleshooting/searching for the right L : Idle ratio… *[gameplan for tomorrow]*
new spark plug. why not? that always works. *[gameplan for tomorrow]*
the cylinder is fouled/damaged. The muffler was left off by the dealer and I see what could be some minor scoring on the pistol. It’s also pretty gunked up in there.
My uncle just needs to buy a new, better saw, preferably Husky or Stihl. They do sell Husqvarna Rancher for $400 in the nearest town.


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## paulr44 (Oct 14, 2008)

Your Notes, my comments:

Fuel rancid - well, then the carb. is probably plugged with gum and/or corrosion.

Belch fire - that means nothing. Sorry, but that's not a viable test at all.

Some compression with your finger - Sorry, but that's not a viable test at all, unless your thumb is a calibrated compression gauge.

If the dealer gave it back like that, it's because it didn't run and your uncle didn't want it fixed. We do this all the time...what' the sense in assembling something that doesn't run, and isn't going to be fixed? We also charge avg. $20 for looking at anything. SEARS charges $29.95 or more, NON-refundable for LOOKING at anything. WE at least will apply the estimate/inspection fee toward the repair or waive it if you buy a new unit. Don't be so hard on someone who took the time to look at it...he didn't punch-out of the time clock to do so. However, there are a FEW less than honest people out there so I can't speak for the dealer in question, but I'd say most are honest. Same with auto shops.

You have to give us more...accurate compression for instance?
Does it run on a prime put in through the intake?
Cylinder "gunked up" vs. "minor scoring" what's that mean? Light scratches are ok, but what's gunked up mean??


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## Rentahusband (Aug 25, 2008)

paulr44 said:


> Your Notes, my comments:
> 
> Fuel rancid - well, then the carb. is probably plugged with gum and/or corrosion.
> 
> ...


I have to agree with Paul.


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