Stihl 045 AV Electronic Starting Problem

[Fredward]

Hi from New Zealand,

A friend asked me to take a look at his 045 which someone gave him - all I was told is that he had it running briefly at some stage, it just spluttered and died. I'm have some experience with small engines, but I'm a bit stuck.. I checked that it had spark, noticed that quite a bit of fuel would pour out the back of the carb when I had the air filter off.. Took off the exhaust too see if it was clean and cear, had a little look at the piston which looked o.k.. I haven't got a compression tester but feels like there is plenty, hard work on the shoulders!.. It seemed like 'some' fuel was making it in to the cylinder, the plug was coming out with a bit of fuel on after trying to start, there was a strong smel of fuel but mainly what spilled out the bacl. I put a little fuel in to the cylinder through the plug bore and she started up with a bit of throttle and ran for about 10 or so seconds.

I wound in the H/L screws on the carbie and set them to the specifications I found in the manual. It still wouldn't start.. I'm guessing the fuel is making it to the carb but seems like a lot of it is coming back out. I took the carb and tank off.. Checked the rubber intake hose and the impulse hose which both look okay.. So I hooked out the tank hose, the filter looked clean (I don't know what else to do to it?!). I've taken the carb off but don't know where to go from here.. I'm scared of all those little parts and don't know what I'm looking for! I've got the parts list and manual so just need a little straight forward information on what I'm looking for..

I own a small Echo with an 18" bar but would love to buy the Stihl off him and get it going! More than that would just be great to see it running again

 

[rmh3481]

Fred,
Chances are that since the unit has been sitting, the carb diaphragms have hardened up. Because of this the inlet needle is stuck in the open position allowing the intake to flood. You can remove the carb from the intake and then take the four screws out of the metering side of the carb to see what things look like. If the diaphragm is hard/stiff it will need to be replaced.

Here is a link to the Walbro service and aftermarket website. Look up the carb which will give you the replacement kit number for the replacement parts. There should be a couple of numbers on the side of your carb to get you started. Its not a difficult job to do, just pay particular attention to the order of the gaskets and diaphragms from the metering side of the carb to the pump side because they are reversed in order.

Select a Manufacturer [Frontstep Customer Center 5 Frontstep, Inc.]

Here is a vid that may also help you with the order of things;
HOW TO Disassemble Poulan 2150 Chainsaw Walbro Carburetor - YouTube

 

[Fredward]

Thanks for the reply.. I've opened up the carb, the metering diaphragm seems still quite flexible and the needle underneath seems to move freely.. I will replace these if I can get the kit here in N.Z., but it looks pretty clean and tidy so far.. What else do I need to check?

 

[redunshee]

Thanks for the reply.. I've opened up the carb, the metering diaphragm seems still quite flexible and the needle underneath seems to move freely.. I will replace these if I can get the kit here in N.Z., but it looks pretty clean and tidy so far.. What else do I need to check?

I'd get a new Kit in any event. Also check the level of the metering lever. If its set too high, the saw will flood.

 

[Fredward]

I'd get a new Kit in any event. Also check the level of the metering lever. If its set too high, the saw will flood.

The metering lever is set dead level with the carb body, I saw in a video that the lever was a bit higher than mine?

Also, I didn't pay much attention when I took it off, but is it possible that the diaphragm wasn't correctly sotted into the lever? What effect would that have?

 

[hotshot]

The metering lever is set dead level with the carb body, I saw in a video that the lever was a bit higher than mine?

Also, I didn't pay much attention when I took it off, but is it possible that the diaphragm wasn't correctly sLotted into the lever? What effect would that have?

It would allow "un-metered" gas to overflow out of the carburetor, just like what you're seeing.

You may have found the problem there. Does the metering diaphragm have a slot in the stud? or is it just flat?
If it's slotted, then you have to slide it in from the side to engage the fork in the metering lever...else it floods badly.

 

[Fredward]

It would allow "un-metered" gas to overflow out of the carburetor, just like what you're seeing.

You may have found the problem there. Does the metering diaphragm have a slot in the stud? or is it just flat?
If it's slotted, then you have to slide it in from the side to engage the fork in the metering lever...else it floods badly.

I took out the needle and metering lever and they looked O.K, when I put them back in it sat on a slightly different angle, a few degrees higher at the back (more like the one I had seen in a video). Then I slotted in the diaphragm and put the cover back on. I checked the H/L needles were the right way around and set them to 1 1/8 turns out and 1 turn out respectively. I checked the inlet and impulse lines and both were nice and air tight. Reassembled the saw and she ran for a while with a bit of fuel in the bore. Then I can't start it again and fuel is pouring out the back of the carb unless the throttle is wide open. A couple of times I got it to 'cough' like when you start a good saw up with the choke on, but still wouldn't run.

I know I need to replace al the diaphragms and gaskets but getting parts over here could take some time - if I can get them at all. The diaphragm seems quite flexible and the whole carb looks very cean (compared to the one I saw in the video). Would this really stop it from running?

I don't know what else to check.. Should I take it apart again and squirt carb cleaner through the holes in the body, then bow out with compressed air?

Thanks for everyones suggestions..

 

[Fredward]

Hi guys I'm still battling with this saw. Went over the carb for a 3rd time, cleaning, checking diaphragms and needles etc.. I'm starting to think that the carb is maybe not the issue.. O.K the carb leaks fuel out the back, but on this saw it slopes away from the cylilnder inlet, so when I'm cranking it would be normal for some fuel to escape out the back if she's not running and drawing the air inwards at high veocity?

I just pulled the plug again and I'm struggling to get a spark. This was my original diagnosis, becuase usually I can get machines to spark easily, this one I played around with for a few hours, trying different plugs etc and eventually saw a spark..Obviously it did get a decent enough spark at one point, because it managed to run for a little bit - on the original plug it came with. But would a coil really be intermittent? I've heard of intermittent coils which stop when they get hot, but the saw hasn't run enough for it to get hot. Is this more likely to be an HT lead? I shouldn't be able to earth the side of the plug on the top of the cyclinder case, holding it with my fingers without getting a shock? I can't see a spark of any description currently.

Please help this is screwing with my brain!!!!

 

[Fredward]

Had this thing sparking with different plug.. Tried to start.. Nothing.. Took plug out again and no spark?

I don't know if the ignition is the only problem but I'm sure it doesn't seem right to me.

Also noticed when I tired to start it fuel came through the exhaust so must be getting adequate fuel?

 

[Fredward]

Appologies for dredging this thread but I'm not making much progress with this saw so thought I'd update and see if anyone can help..

So after checking the carb/spark/fuel and coming to the end of my thether, I phoned my local Stihl dealer and asked if he could do a leakdown test. I explained to him what I'd done and he was sceptical that it would need a pressure test and told me to put it back together and bring it in. I did so, and funnily enough - before I took it in, it ran for maybe 4 seconds, the first time without having to put fuel in the bore. Needless to say I couldn't get it to fire again so I took it in and he proceeded to re-cover all of my work (he was a nice enough about it and let me come in the shop and watch him go over it.) I'd already had the saw on a spark tester at another shop, as a result he said there was 'enough' spark - although it's hard to see in daylight, but he reconfirmed there was spark in his darkroom (thought they'd have a tester at a Stihl dealer?!). Put a new plug in for good measure. He went over the carb and cleaned it AGAIN, he said the diaphrams were good and put it back together.

He eventually did a leakdown test and it held pressure. Weirdly enough after looking again (I'd already taken it off and checked it), we'd missed a split in the impulse hose. He couldn't get hold of the exact same one but we found one very similar just maybe 1.5cm longer. I replaced this but the saw still doesn't start. When he was looking it over he noticed a tiny bit of brown marking on the piston on the exhaust side - so I took the jug off and checked it today. There is no 'scoring', just burn marks as such, the piston and jug are pretty mint, no vertical play in the piston and rod. The only nastyness is a bit of carbon deposit on the top of the piston.

I'm waiting for a gasket before I put the cylinder back on - if anyone can think of something stupid why this thing will only fire up on rare occassions, I'm open to any suggestions. I couldn't get it to go at all with the new impulse hose on, not even when I put some fuel in the bore. I can post pictures of things if it's any help. I'm still not confident of the spark, even though it's there it doesn't seem bright...

Still very determined to get this thing going, parts are very expensive over here which is why I'm reluctant to throw in a carb kit.

 

[Phil_C]

I'd already had the saw on a spark tester at another shop, as a result he said there was 'enough' spark - although it's hard to see in daylight, but he reconfirmed there was spark in his darkroom

Chances are if you have to be in a dark room to see the spark then the spark is not strong enough. A spark in atmosphere is not the same as a spark under compression. If you do not have a good strong blue spark in atmosphere then you will find the spark is too weak to jump the electrodes under compression. Yes a coil can display the characteristics you describe although it is unusual. Normally they simply die or they break down when hot. It could also be the electronic ignition module causing the issue. There are several threads on AS about 045/056 ignition repair or replacement. Alternatively you could look on eBay for a S/H one or a new aftermarket one.

Regards

Phil

 

[sefh3]

While you have the cylinder off, mic the piston skirts. If they are worn too thin it will cause fuel to come out of the carb. Also, search on AS and you'll see these saws are known for ignition failure. They are under the flywheel and get hot and shut down. Bad thing is they produce spark when cold and nothing when hot.

 

[Fredward]

Thanks guys for the help. I wil get the shop to look at the piston, but skirts seem fine to me - piston seems in good condition. Am hunting for a 045 electronic ignition/056 as I've heard they fit as long as you have the correct flywheel. Might not be easy as N.Z is a small place with a limited amount of saws! Looks like a mission to take it all apart aswell...

Is there a possibility that it could be a timing issue? I haven't taken off the flywheel, only the fan part helld on by three small screws, but the saw was not running when given to me so someone else could have done something?

 

[Fredward]

I remembered a friend has an 041 which died a glorious non-ignition related death under a bobcat bucket Would I be able to swap over the ignition modue (not sure if it's electronic or points style)?

 

[maico490]

As others have said my guess would also be the Bosch ignition is on it's way out which is a common problem with these saws. There is some interesting stuff in this thread: http://www.arboristsite.com/chainsaw/153271.htm
Here is what I did with my 056 when the module gave out: http://www.arboristsite.com/chainsaw/62401.htm.
German ebay has new modules for points,Bosch and SEM ignitions. Use either Google or Bing to translate if your German isn't up to scratch

 

[Fredward]

Thanks,

It looks like the Bosch ignitions are unfortunately twice the price of the SEM modules.. If anyone has info regarding swapping the 041 ignition please let me know. I can't find any second hand 045 or 056 ignitions thus far.

 

[Fredward]

I went into the Stihl dealer today to see about the '$26' part blind hog listed in his very informative thread. He looked it up and told me it was over $300NZD - I can't remember the exact figure as I lost interest after he said 'three hundred and...'!!!!!

ANY info regarding a 041 ignition compatability would be great as the dealer said it comes up the same on his parts list..

 

[Phil_C]

According to my IPL's the 056 shares the ignition with the 08S and the 045 shares the ignition with no other saw. Both the 056 and 045 are almost identical so you should be able to swap between the two.
There is a module on ebay at the moment. There are also the cheaper version on eBay that may or may not work.

Most likely though a genuine 041 ignition if it is still available is going to be pricy. They are far less common on eBay than 045/056 ignitions.

Regards

Phil

 

[Fredward]

ROYALLY pissed myself off now!!!

Got the electronc 041 AV from my mate - striped it and removed coil, looks very similar to the 045.. Repaired kill switch lead, fitted to 045, but I made the novice error of putting too long bolts through the fanwheel into the flywheel and through into the ignition. Now the 041 ignition looks utterly stuffed, can see lots of shiny copper.. :'( Needless to say it has no spark!!

 

[Phil_C]

ROYALLY pissed myself off now!!!

Got the electronc 041 AV from my mate - striped it and removed coil, looks very similar to the 045.. Repaired kill switch lead, fitted to 045, but I made the novice error of putting too long bolts through the fanwheel into the flywheel and through into the ignition. Now the 041 ignition looks utterly stuffed, can see lots of shiny copper.. :'( Needless to say it has no spark!!

Ouch. Been there done that many years ago. Luckily though when I did it the screws only broke the wire on top of the coil off. Brand new ignition.

Regards

Phil