Mysterious problem Stihl 038 AVS

[spudulike]

It would be a nice challange, the same old same old can get a bit repetative - thats why I started porting....for a bit of fun:thumbup:

 

If you get stuck, I will take a look at it, my cash is still on fuel which can be verified with the carb strip I mentioned earlier. Once you know where there is no fuel, you can find out where the issue is.

 

If you look at the vid, the saw falters and dies then doesn't start on the first pull but takes a few pulls as if fuel needs to be pulled through the carb.

 

Personally I would do a vac and pressure check with the carb boot and impulse line in place, rotate the crank and push and pull on the crank end float to make sure those crank seals are 100% and all rubber parts are good although the only part that I think would cause this issue is a cracked impulse line - the rest would lean the mix and cause other issues like racing or bad idle and over revving top end. Always a good starting point.

 

Next step is to take a good look at the carb and drill down on faults in that area.

[Charles Ekin]

Thanks to all of you. I'll get back to you asap and when I've gone through the extensive check list you have provided me with. Many thanks again.

Charlie

[Charles Ekin]

Thanks Spud. The impulse line is also brand spanking and not kinked!

[oldnwrinkly]

.....The impulse line is also brand spanking and not kinked!

 

But have you checked to see if it distorts when the saw is on its side? I am not familiar with the saw so don't know if this is a possibility or not.

Are the AV buffers in good condition?

 

Dave.

[Ricbob]

One last thing and then im out of ideas. Does the crank shaft move or wobble as if the crank bearings are worn? Just thinking under load in the felling cut could worn bearings cause the oil seals to leak?

 

Ric

[Charles Ekin]

Jamie

Your Carb arrived today. Thanks so much. It could have been one of two and it turned out to be the right one. Can't wait to try it out later on. It will help eliminate several posibilities. You're a star. Thank you very much.

Oldnwrinkly

The front AV buffers were slackened off and the rear ones removed when I pivotted the tank housing forward to get at the carb boot. They were all in good nick. The rear left near the ignition module which seems to cause the most problems, was fine. Thanks for the suggestion. I'll check out the impulse line later on.

Ricbob

I'll throw the idea of the crank bearings into the mix but unfortunately I'm not clued up enough about the stuff right down in the bowels of the engine. By comparison to the 038 I had before from new and which worked a treat for 20 years, it doesn't seem to behave any differently when it's working!

Thanks again to all.

Charlie

[Charles Ekin]

I'VE GOT MY SAW BACK!

Although I haven't managed to put my finger precisely on the culprit, the saw is now running perfectly after putting in the replacement carb supplied by Jamie. Thank you so much. Fortunately I didn't need to replace crankcase seals or bearings or anything else more serious.

For those of you who like "whodunnits", the carb that was in it when I bought the saw was missing the high and low adjustment screw o rings and also the main gasket where it connects with the boot. Can't help feeling some botch recon or replacement job had been carried out. The replacement diaphragm and gasket set which I used was not Stihl but made by some Italian outfit supplied by L&S Engineers. Whatever, it didn't change anything about the behaviour of the saw by comparison to when I first got it. When I stripped the carb down everything else seemed clean and correct but who knows. What might shift inside a carb when you turn it on its side?

All I can say is that this whole experience has restored my faith in human nature! You have all been so willing to spend time sharing your thoughts and experience with me and I'm really grateful. I look forward to returning the favour, probably not directly to you because you know so much and I know so little, but to someone else.

Thanks Lads very much.

Charlie

[Rich2484]

Let's see a vid of it running perfectly then! I take it you never noticed the ring seals were missing before in the carb?

[Stubby]

I'VE GOT MY SAW BACK!

Although I haven't managed to put my finger precisely on the culprit, the saw is now running perfectly after putting in the replacement carb supplied by Jamie. Thank you so much. Fortunately I didn't need to replace crankcase seals or bearings or anything else more serious.

For those of you who like "whodunnits", the carb that was in it when I bought the saw was missing the high and low adjustment screw o rings and also the main gasket where it connects with the boot. Can't help feeling some botch recon or replacement job had been carried out. The replacement diaphragm and gasket set which I used was not Stihl but made by some Italian outfit supplied by L&S Engineers. Whatever, it didn't change anything about the behaviour of the saw by comparison to when I first got it. When I stripped the carb down everything else seemed clean and correct but who knows. What might shift inside a carb when you turn it on its side?

All I can say is that this whole experience has restored my faith in human nature! You have all been so willing to spend time sharing your thoughts and experience with me and I'm really grateful. I look forward to returning the favour, probably not directly to you because you know so much and I know so little, but to someone else.

Thanks Lads very much.

Charlie

 

Pleased for you Charlie . Well donr bud !

[JAMIE1]

Glad i could help. it was just sat doing nothing on the shelf as i dont have a 038 anymore.