My old Whisperlite stove pump developed a leak at the valve body where it has a few small craks. It's old so I figured I'd get a new replacement.
I expected the new pump would be an imporvement over the old one, instead it was much worse. It has a weak flame unlike the famous weld position we brag about so often. Absolutely no flame control and imposable to get it to a simmer.
I took it back to EMS and of course the lady tried telling me Whisperlites never had a simmer or even a flame control and how many of these she personally owns and different types of stove that can... etc etc. Now she is telling me about a stove I use every weekend during the extream upstate NY winter conditions. So I invited her outside to show her what my stove can do using a borrowed old style pump like mine.
Fired it up and did it's magic from weld to simmer in a smooth 1/2 turn of the wheel. Now I put her brand new out of the box pump I bought and it was embarrasing. The flame was like an old man with prostate problems, no where near weld. Couldn't even get a hint of flame control no matter how hard you try to tweak it. She of course ran in and got another one saying it might be a bad one... same thing. I got my $37.50 back.
When I got home I got a replay from MSR about the pump, this is what they said....
Thank you for contacting Cascade Designs Inc.
The current design doesn’t simmer like the older style pumps .
We are working on getting this changed but it’s going to take sometime.
The current model pump has one setting of high and it should work on this setting even in the frigid temperature that you were experiencing.
Part of your problem may have been that white gas contains paraffin which starts to solidify at these low temps and can hamper performance.
You should try exposing your white gas to this low temperature then pour it through a coffee filter to help strain out any solidified paraffin.
So I think you may have been experiencing the flame performance problem due to the paraffin.
As far as the various flame control levels that you were trying to achieve goes, this is a problem with the newer pumps that we are working to resolve.
Nathan Hamm
Cascade Designs Inc.
4225 2nd Ave. South