Stihl 028WB won't start w/o adding fuel thru carb

[Geneb]

Hi all,

First post and a shade tree DIY'er here so please bear with me. Ran across this site while searching for help on problems relating to the saw starting but would not stay running. I ran across several threads that talked about this type of condition and after eliminating some of the other possible causes, installing an electronic ignition module took care of the problem.

As my saw is 30 years old and has never had the points or condenser changed, I decided a weak spark could be the cause of my problem also and installed a NAPA ignition module #7-01749. Leading up to this I had already replaced the spark plug and did a complete teardown and cleaning of the carburator body and needle valves which did not help. I had been using the saw for several days before having any problems. Last years repairs included installing a carburator kit and replacing the fuel filter and line from the tank to the carburator after which time the saw ran great. It turned out the fuel line had rotted off inside the tank.

Now, after installing the module, the saw did not start until I added fuel thru the carburator. It started and kept running pretty good while I adjusted the carburator L and H idle screws. Ran better than it has in years and started right up after shutting it off. So adding the module to replace the function of the points and condenser definitely worked. However after the saw sat a while, I couldn't get it started. After a small shot of starting fluid in the carburator, it took right off and stayed running. I tweaked the adjustment screws some more and the saw accelerated and ran great. However, each time it cools down, it won't start without first adding fuel of some sort.

I just checked the tank vent hose for a kink or blockage and it was good and the fuel line from the tank is passing fuel freely. Just seems as it can't pull the initial slug of fuel to get started though but after it starts, it's fine.

Suggestion of what to try next in order of the most likely cause would be appreciated.

Thanks for reviewing and for your input.

Gene

 

[DeAvilaTree]

I have had the same problems, turned out to be clogged fuel ports on the carb

 

[jockeydeuce]

The 028 has the choke built into the air filter.....I've seen many of them, that the flapper in the filter doesn't close off completely or the parts fall out of place and don't close at all....That choke has to completely close off to work properly for cold starting.

I ended up buying an 026 recently, because the guy that owned it was completely fed up with having to prime it every time he wanted to start it cold......Turns out the choke flapper was completely missing from the air filter.

 

[Geneb]

Thanks to both for your replies. Since posting the other day, I spoke with a local technician and explained the condition. He indicated a gumed up fuel pump diaphram or the metering diaphram or possibly a leak in the impluse tube could the carburator not to get an initial slug of fuel to get it started. So I took the carburator apart again and cleaned the metering diaphram with carburator cleaner and reassembled.

I then proceeded to try to start the saw but just continued to keep on pulling. I probably pulled a dozen times at which time it indicated it may start and after a few more pulls, it did start and ran very strong. Now I'm not sure if I helped anything by cleaning the metering diaphram or if I just did not pull it often enough before. It used to start every time with 3 or less pulls.

Well because I had to get some wood cut up, I decided to reassemble the saw and put it to work even if it wasn't completely right.

No here comes the "I had a brain fart" moment:msp_confused:. After I reassembled everything, it started up with less than 3 pulls of the starter rope and ran strong all afternoon. Now after reading jockeydeuce's input I realize that during this whole time of it not wanting to start was caused by me not putting the air cleaner back on. So when I was choking it, I really was not choking it therefore taking a lot more pulls before it would feed in enough fuel to start:bang:. I was just lucky that it was warm here today when I tried to start it. Other wise I may never have put two and two together.

Again, thanks for taking the time to respond. All is well now.

Gene