spark, gas, compression, but still won't start, what next??

[a. palmer jr.]

You really don't have to use a plastic gap gauge between the coil and flywheel. I loosen the screws on the coil to a little less than snug, insert the steel gap gauge and let the magnetism pull the coil into the gauge and flywheel, tighten up the screws and pull out the gauge.

 

[homelitejim]

my most valuable tool for setting gap is a business card, I get these free all the time. All you really need is a screwdriver, pliers, a few wrenches, and a good hammer, which can be bought for cheap at a pawn shop, second hand store, or even a yard sale.

 

[LoggingEngineer]

Fixed a 044 that had fuel spark and comp the other day that never would 'pop'. The flywheel key had sheared, timing was off, pulled the nut and could see the key, looked fine, but puled the flywheel and saw it was sheared, put in a new key, broke that one when it fired. Had to put in another key and a different flywheel since the other was wallowed out, trying to be cheap with a marginal flywheel sot me another key and a few minutes time. The brother in law was happy when I got it goin with used parts for him though.

 

[a. palmer jr.]

I had a Poulan 25DA once that had compression, spark and gas and wouldn't run. Turned out to be a busted crankcase that I didn't see until I'd done everything else to it.

 

[cityboy]

You do not need all the tools. checking spark is easy, first pull the plug from the cylinder then plug the spark plug back into the wire lean the base of the spark plug against the cylinder or one of the fins so u can see the diode, pull the cord and look for bright blue spark and listen for crackle. If this is impossible then grab the spark plug with bare hand and pull the cord, no crying because it only hurts for a second and u saved some money. If the spark is yellow or orange or u did not pee yourself then it is not getting enough spark and your problem will lie in the electrical side of the saw. on the gas side open up your needles about 2 turns pull choke and set throttle lock, if after a few pulls gas is not visibly leaking out of the muffler you have a fuel flow problem, start from the tank and work your way to the carb. This is not rocket science just seems that way until u get your hands dirty a few times.

I guess I didn't mention all that I've tried so far, because I've covered some of them in previous threads. I've covered the basics like you mention.

Have spark at the plug resting on the cylinder, but don't know if I have a strong enough spark. Hard to say exactly what color it is, its kinda yellow, orange, blue, depending on the lighting at the time I test it. Don't have a spare coil handy to rule out that option, or anything to measure how strong the spark is, so can't really say if its good or not. It didn't look weak to me, but I don't have enough experience to tell by appearance.

Have fuel getting into the cylinder, but can't tell if its too much, too little or just enough. The plug gets wet after pulling several times, and the choke lever is working normally. Also, since saw was running normally last time, I have no reason to start tweaking the H/L screws, they should be at the correct settings already. I've rebuilt small carbs before, so I would consider doing that, but not sure it would make any difference, I'd expect it to at least start but maybe run or idle lousy if the diaphragms were getting old.

Have compression, which gives a nice pop when I put my finger on the hole and pull, but again this is not very conclusive. Saw ran normally two weeks prior to this problem, so I have no reason to believe my compression went from normal to crap when the saw was running normally. Don't have compression gauge, so can't conclude anything here either.

I pulled the flywheel bolt, expecting to be able to see the woodruff key underneath, but there's nothing to see that I can tell. I rotated the flywheel with an artist paintbrush handle in the spark plug hole on top of the piston and the timing appears to have the magnet and coil aligned at or just prior to TDC, so that seems like it isn't totally out of whack, but again, I can't tell if its exactly right without having a flywheel puller to remove and replace so I can see the keyway.

Oh yeah, I replaced the plug and that didn't help either.

So at this point I've tried all the simple things with no luck, and have no experience with troubleshooting saws, so I'm taking it to someone who knows what to look for and can diagnose the problem faster than I can. My time is worth more to me than the few bucks I'm going to be charged to have it diagnosed by someone who knows what to look for and has the ability to conclusively test various systems (or has spare parts to swap out).

 

[macj]

don't dispair

Citiboy, recently I was in the same space you're in.
Compression OK, fuel OK, spark appeared OK.
However I did read here(somewhwere) that while you can have a spark when the plug is rested on the cylinder, it maybe insufficient to fire the mixture in the cylinder.
Bearing in mind there seems to be no easy way of testing coils, I did a swap from another saw, and hey presto away she went!
Also there is a thread or two here that will tell you which Husqy saws have interchangeable coils.

 

[angelo c]

Like a good realtor would say...

Pressure

pressure

pressure(i.e. location)

test it....check for leaks. Pressure and vac test the case, hoses, lines tank .

I'm not understanding the refusal to purchase minimal tools for a guy who said he is now interested in owning OPE. Most OPE can and will need attention. Spread out the purchases of said tools but buy the darn things. Once you learn how to fix these machines they just show up at your garage door. Trust me it happens. Broken machines always find good mechanics...eventually.

A

 

[Fish]

Like I said, you need to read post #2, and of course follow it........

But now you have a loose flywheel nut you need to retighten so you won't shear the key when it finally hits and runs. You should do the rope method there.

But DRAIN the fuel tank, remove the plug, get a new one too, pull the rope a bunch with the plug removed, let it sit an hour or two, then put in the new plug and pull the rope a dozen or two times more with the trigger squeezed.

Then, when you are sure all of the old fuel is gone, get some FRESH gas mix, and pour a dribble, or use carb spray, and put a squirt in the Carb throat {air filter removed}, and pull some more with the trigger squoze and it should fire then die, then you know that it was either flooded or the gas in it was so old it wouldn't burn.

 

[Fish]

Please try that like I said, and tell us what you found.

 

[chainsawcircus]

Just from me but I have seen spark plugs that fire great out in the open, but when under pressure ina cylinder they really dont get it done. It does happen, may not be your case but I have chased my tail for hours and then found this.

 

[a. palmer jr.]

Citiboy, recently I was in the same space you're in.
Compression OK, fuel OK, spark appeared OK.
However I did read here(somewhwere) that while you can have a spark when the plug is rested on the cylinder, it maybe insufficient to fire the mixture in the cylinder.
Bearing in mind there seems to be no easy way of testing coils, I did a swap from another saw, and hey presto away she went!
Also there is a thread or two here that will tell you which Husqy saws have interchangeable coils.

You can test coils with an ohmmeter or an oscilloscope...much harder to check modules in electronic ignitions. I usually just replace with a known good one.

 

[cityboy]

Citiboy, recently I was in the same space you're in.
Compression OK, fuel OK, spark appeared OK.
However I did read here(somewhwere) that while you can have a spark when the plug is rested on the cylinder, it maybe insufficient to fire the mixture in the cylinder.
Bearing in mind there seems to be no easy way of testing coils, I did a swap from another saw, and hey presto away she went!
Also there is a thread or two here that will tell you which Husqy saws have interchangeable coils.

Yes, I am fully aware of the fact that you can have spark at ambient pressure, but it might not be strong enough at cylinder pressure. I even mentioned it in several of my posts. Since I only have one saw, and don't know anyone else with a Husky that will let me swap coils, I don't have that option available to me, otherwise I'd have already tried it.

 

[cityboy]

Like I said, you need to read post #2, and of course follow it........

But now you have a loose flywheel nut you need to retighten so you won't shear the key when it finally hits and runs. You should do the rope method there.

But DRAIN the fuel tank, remove the plug, get a new one too, pull the rope a bunch with the plug removed, let it sit an hour or two, then put in the new plug and pull the rope a dozen or two times more with the trigger squeezed.

Then, when you are sure all of the old fuel is gone, get some FRESH gas mix, and pour a dribble, or use carb spray, and put a squirt in the Carb throat {air filter removed}, and pull some more with the trigger squoze and it should fire then die, then you know that it was either flooded or the gas in it was so old it wouldn't burn.

My flywheel nut is no longer loose, I tightened it (with a torque wrench BTW).

I drained the tank, removed the plug, got a new one too. Let it sit for hours, days, etc. All the old fuel was gone. Put fresh fuel in, no difference.

 

[cityboy]

Like a good realtor would say...

Pressure

pressure

pressure(i.e. location)

test it....check for leaks. Pressure and vac test the case, hoses, lines tank .

I'm not understanding the refusal to purchase minimal tools for a guy who said he is now interested in owning OPE. Most OPE can and will need attention. Spread out the purchases of said tools but buy the darn things. Once you learn how to fix these machines they just show up at your garage door. Trust me it happens. Broken machines always find good mechanics...eventually.

A

Simple economics. I can pay a guy $20 to diagnose the saw for me, or spend $40 on a compression gauge to make sure my compression is good, another $60 on a new coil (just in case the old one is bad), another $50 or so on pressure and vac testers, $20 or so on a flywheel puller to verify my timing is OK, and then MAYBE figure out why it doesn't run after spending $150-200 on special tools and parts swapping. I'm not planning on fixing a different saw every month for the rest of my life. Maybe where you live they just show up at your garage door, where I live you can't even find them if you actively look. I still have a bunch of special tools that I bought over the last 35 yrs. ago for a one-time motorcycle or auto repair that haven't been picked up since I used them for that first job. The difference there was the cost of the tools was minimal, and the cost savings by doing it myself were many times the cost of the tools. And, I knew how to finish the job once the tools were purchased. In this case its the opposite, the cost of the tools is several times the cost of having someone else do the work for me, and I don't actually know exactly what's wrong with the saw. If I did, I'd buy the one tool I actually needed and finish the job myself.

 

[homelitejim]

the 357xp is a nice saw and more economical to repair than replace. Why did you replace the decomp valve, did it not function or was it stuck partially open? Was this the only problem with the saw that you know of? I re read your initial post and for the life of me can't figure out why it won't run if all you did was replace the decompression valve. If you have compression, spark, and fuel but no fire I would say flip the switch to the on position, but since you have tested for spark and got some that would rule that out. The next best thing is to start ruling out things, start by rebuilding the carb, carb kits are usually under $20, replace your fuel line and filter usually under $20, replace the coil, not sure how much they cost but I bet it is cheaper than a new 357xp. Pull the muffler, check not only the exhaust side of the piston but also the back and sides of the cylinder, any lines up and down that are unmistakeably visible are a sign of trouble. When pulling the flywheel leave the nut on the crank but flush with the crank and tap with a hammer, you can use a flat screw driver as a pry bar on the back with a little pressure usually pops them right off, if this saw is that old usually saws made after the late 70's have electronic ignitions which means everything is in the coil. If that does not work then maybe it is time for expert opinion, if it does work then sell the thing and get a Stihl.

 

[angelo c]

Simple economics. I can pay a guy $20 to diagnose the saw for me, or spend $40 on a compression gauge to make sure my compression is good, another $60 on a new coil (just in case the old one is bad), another $50 or so on pressure and vac testers, $20 or so on a flywheel puller to verify my timing is OK, and then MAYBE figure out why it doesn't run after spending $150-200 on special tools and parts swapping. I'm not planning on fixing a different saw every month for the rest of my life. Maybe where you live they just show up at your garage door, where I live you can't even find them if you actively look. I still have a bunch of special tools that I bought over the last 35 yrs. ago for a one-time motorcycle or auto repair that haven't been picked up since I used them for that first job. The difference there was the cost of the tools was minimal, and the cost savings by doing it myself were many times the cost of the tools. And, I knew how to finish the job once the tools were purchased. In this case its the opposite, the cost of the tools is several times the cost of having someone else do the work for me, and I don't actually know exactly what's wrong with the saw. If I did, I'd buy the one tool I actually needed and finish the job myself.

Ok then, pay the man his $20 and lets see what he says is the problem.
What's a guy like Fish and the rest of us yahoos know anyway. Besides, most of the tooling Im talking about can be "rented" from your Autozone for the grand sum of $0 dollars if you return them. I'ld like to visit this country called California some day. I hear its a hoot. Best of luck, or as the Southern contingent would say..."bless your heart".

 

[cityboy]

Ok then, pay the man his $20 and lets see what he says is the problem.
What's a guy like Fish and the rest of us yahoos know anyway. Besides, most of the tooling Im talking about can be "rented" from your Autozone for the grand sum of $0 dollars if you return them. I'ld like to visit this country called California some day. I hear its a hoot. Best of luck, or as the Southern contingent would say..."bless your heart".

First of all, I have never disagreed with or disrespected any of the advice I've received here, so the 'yahoo' comment makes no sense to me, and suggests I am not taking the advice here seriously, which is completely untrue. I appreciate all the help suggested so far, so please don't suggest that I'm ignoring what's being said to me.

Where I live, nobody gives you anything for free, or at least I haven't found any evidence of it yet, so the Autozone approach probably wouldn't work either. But thanks for the idea, I think I'll call them anyway.

 

[avason]

I would pull the kill switch to see if it fires up. Someone mentioned it before it happened on my 353. pretty easy to do. I pulled the contacts and put electrical tape around the terminal so it wouldn't ground out. if you did this already i must of overlooked it. Good luck.

 

[Fish]

If you have done as I have said, then take off the muffler and look at the scored up piston, as that is all that is left, probably burnt up by the
decompression button leaking, a scored up piston can mimic compression.
I always suggest the simple and cheap things to check first, as I hate wasting time and money, mine and other's.

 

[cityboy]

If you have done as I have said, then take off the muffler and look at the scored up piston, as that is all that is left, probably burnt up by the
decompression button leaking, a scored up piston can mimic compression.
I always suggest the simple and cheap things to check first, as I hate wasting time and money, mine and other's.

Here are a few pics of the piston. One to show the ring, another the skirt, and the third is a closeup of the skirt to show some extremely fine scratches.

From a distance the piston surface looks good to me, but I have no idea how perfect it has to be for optimum compression. The scratches are barely visible, but are there, so I suspect them to be primarily cosmetic, no? The closeup shows they are maybe not quite as deep as the machining lines on the piston.

when I pulled the muffler it had more gas in it than the fuel tank. At some point would that keep the saw from starting? I'm drying it out now, and will try again after its dried out.

I've been suspecting a marginal coil all along, and so far I'm not seeing any indication of fuel delivery or compression problems, so the coil/timing are still the chief suspects. I'm going to call the guy on Monday and see if he has either a) a spare coil to swap out, or b) a conclusive way to test my coil. If not, I think I'll gamble the $60 on a new coil from Bailey's and see what happens. None of the repair shops around here I've talked to even have a coil in stock, its a non-returnable special order.

Regarding muffler re-attachment, is it a good idea to put a dab of anti-seize on the bolts?

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