Dolmar 421problem

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excessive hissing and pressure in Gas tank *might suggest vapour lock, but usually only on a very hot day.

I had vapour lock on my EA4300(dolmar 421) last summer after bucking hardwood non-stop in heat, prior to removing the cat! Saw would not start and run properly until I let it cool down for 20 minutes.

These little saws with the cat still in get pretty warm if you run them with no mercy.

Just a thought.
 
I appreciate the input . It's not that warm here and I hadn't even used a tank of gas. I cut all day with it this past fall when it was pretty warm with no issues. As far as the cat goes I'd like to get rid of it ,,I'm glad I didn't now. Maybe after we get this cleared up. Maybe I should wait until the warranty expires. Thanks again for the input!!
 
I appreciate the input . It's not that warm here and I hadn't even used a tank of gas. I cut all day with it this past fall when it was pretty warm with no issues. As far as the cat goes I'd like to get rid of it ,,I'm glad I didn't now. Maybe after we get this cleared up. Maybe I should wait until the warranty expires. Thanks again for the input!!
Ya if you've got unsolved problems, I'd wait to remove the cat while the warranty is still valid.
 
Well I'm taking the 421 back to the dealer tomorrow. Hope we get this squared away soon! It's 45 min one way . Question for those of you in the know. Is it common to turn out the high 3/4 turn and not change the low?? Seems like my other saws required a little tweaking on both. Here's one more thought ! If you have an air leak on an auto tune saw will it keep adjusting until you scorch the piston? Anyway I'll keep you all posted on the 421. Wish me luck!
 
My 421 always hisses when I open the fuel cap by the way.
 
Dropped the saw off at the dealer again this morning. I showed them a short video I made of the saw idling too fast while in the woods. They were scratching their heads???? Said a B&S rep that hooked them up with Dolmar 10 years ago would be there today they were going to quiz him. Told me not to worry they would figure it out.
 
According to the dealer the Briggs rep is a small engine guru hopefully he was able to provide some insight.
 
While searching for info on the 421 on this site I ran across a thread 'replacing my 421' it seems a member ' gearjunkie' had three 421's all with high idle issues. Anyone here familiar with this member I would like to know how / if they resolved those high idle issues. It appears I'm not the only one I wonder how many more out there are plagued with this problem!!!!
 
I've had this on mine in the last year. Bought it from an auction. Just keep running it, that's my MO. I am going to try and remove the CAT myself to see if this helps. Mine is definitely not under warranty. LOL
 
Just got an email from the dealer . He said the B&S rep called a "huge dealer who sells over 200 saws a year" they said they had it happen 1 time, it was the internal fuel line that runs from the filter to the top of the tank. My dealer said he has some ordered will have them next week. I'm hoping this fixes it. We shall see! I ran a whole tank of gas through the saw with no issues the day before the past episode??
 
I've had this on mine in the last year. Bought it from an auction. Just keep running it, that's my MO. I am going to try and remove the CAT myself to see if this helps. Mine is definitely not under warranty. LOL
Part no. for the fuel line is 195 114 050 maybe this will help you.
 
Apparently they think this is the problem because it only happens with under 1/2 tank of fuel. But... it also only happens when it has been run for 45 min or so , and is warm, which burns fuel . After the saw sat for an hour or so ,after the first episode, it started and idled fine. I'm hoping they are right and the fuel line works but I'm somewhat skeptical.
 
Apparently they think this is the problem because it only happens with under 1/2 tank of fuel. But... it also only happens when it has been run for 45 min or so , and is warm, which burns fuel . After the saw sat for an hour or so ,after the first episode, it started and idled fine. I'm hoping they are right and the fuel line works but I'm somewhat skeptical.

hmmmm ... did they say the fuel line collapses/pinches under heat or ..... ?

Replace-FuelLine.jpg
 
I just point the girl in a safe direction and keep cutting. I try and treat the bar as always live when I cut or carry, etc. Kinda like the business end of a gun barrel.
 
If the fuel line were cut or broken off in the tank it would begin running out of fuel if held in the normal orientation. I can see that it might cause a lean idle and make the idle rpms go up, but how would it work properly when cutting?
 
It's definitely not broken off I changed the fuel filter when it first started acting up. There was no obvious damage. I didn't do a cluster we inspection but nothing noticeable. I don't know why it would run right after cooling down.
 
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