My new Optimus SVEA 123 stove works well but the flame tends to pulse or surge. I never get the steady roar of an older pump Primus stove. Optimus makes what they call a midi pump which can be used with SVEA 123 or an Optimus 8R stoves. I can't figure out where the pump would fit on the SVEA 123. It seems to go on the fill cap, but there's no room for it with the windscreen on. Anyone have a clue on how this pump works with this stove? and would the addition of a midi pump optimize my Optimus?
Thanks, Doug

Doug,
First lets address the pulsing. Most likely you have a clog somewhere in the stove. I would first try some carburator cleaner or fuel line cleaner product.

The midi pump that you are reffering to is for the 8R etc. If you want to use the pump on the 123 you need to buy the one that has a bend in it.

Chuck

with the pump you should have got a cap with a stem on it..if you got the pump alone you will have to find a cap someplace..the end of the pump fits over the stem which has a one way valve in it..it only
takes a few strokes to get pressure up..i only use the pump to get pressure to run raw fuel out for the
pre-heat and not while the stove is running..there is
no way to pump while the windscreen is on..i don't put the screen on untill the stove is running..thats
not as tricky as it sounds,just keep away from the burner.the running stove can be moved around with no
problems.

Doug,
Below is a picture with both the bent and straight pumps. I have removed the cap from the one of them so you can see what you get when you purchase a pump. The bent one from campmor http://www.campmor.com can be found under backpacking stove accessories.

The pump will increase the pressure for lighting and crank up the btu's. You can then choose to remove after pumping (and before lighting) by just sliding it off the cap. But, your main problem is a clogged jet or wick. You need to clean out the fuel delivery system. The pump will just add presssure but, will not solve the pulsing just because you have increased the preassure.

Chuck

Hi,

I thought I would throw in my two red cents.

I own a 123R that pulses. Its effect is pronounced when the fuel is topped off, leaving less air pocket to pressurize. If I fill the tank less than full, 123R behaves more acceptably. The pulsing effect becomes also noticeable, if priming is not done quite enough (I use alcohol). After the stove itself is fully warmed up, i.e., at the max. pressure, the pulsing becomes hardly noticeable.

I have previously disassembled the stem at least three times--removed the wick, the stuffing nut, spindle, burner, needle, and jet--and cleaned thoroughly. I made sure that the wick was good and free of debris, and put it into the stem all the way, as it should be. I installed everything with care: still the same pulsing.

I just decided to accept it as an annoying quirk and live with it. But who knows, someday, some one may be able to point out the problem.

Thanks for all the good info. I spoke with the tech support people at Brunson who said the stove pulsing was probably due to stove not maintaining pressure. He thought a midi pump would help, but said the stove should not pulse even without one. Some more fiddling with the stove and a longer priming time resulted in a big scarey column of flame!! Something is clearly wrong with this unit. Since it is brand new I returned it for a replacement. I'll let you know what happens.

In the meantime (inspired by Spirtburner.com)I acquired an old Primus 71 which, with a little cleaning and fiddling, works great, way better than the new SVEA 123. SVEA 123 is the stove I had used in the past, and don't remeber this marked pulsing.
Thanks again for your insights, Doug