In my experiance Peak I 4xx stoves throttle exceptionally well - we have my old one, two of our sons have 442 versions, my Dad has one like mine, my brother has a 400A - all of them throttle exceptionally well. They are basically a miniature verson of the ubiquitous Coleman box stove - same type of burner, generator, and throttle.

Are you certain you have an older 400 stove? The 400 and 400A stove has two control levers - a little red "choke" lever much like on a green box stove and a large black lever positioned lower that moves thru a horizontal arc to throttle the burner - see part 8 below:



The newer model 400B stoves, as well as the 442 dual fuel stoves only have the little red lever. See below:



The older version is far easier to throttle while a pan is on the stove. Coleman probably saved 9 cents a stove by changing the design...

Perhaps there is something mechanically amiss with yours? At a guess, depending on the exact version, the wire is not connected in your generator tube - have you ever had it off? Coleman does not have great QC on these small stoves or their propane lanterns IMHO - good designs sometimes poorly assembled.

My old Svea had the pump conversion (more like a syringe). I also carried a circular bit of 1/8" plywood about 1" larger in diameter than the stove base with a scrap of ensolite on the bottom. On the top I had 3 tiny round head brass screws arranged so that the seam on the tank was a snap fit. It made the stove more stable and provided some insulation from the ground in winter. Performance-wise, I'll take any of my other stoves. Nostalgia-wise, I'd love to have the stove back... you're helping me talk myself into buying a new one for fair weather cuppas.

EDIT: A Svea without pump only saves 5 ounces weight over a 400 Featherlite (which also has a much larger fuel tank, far better simmering, nearly twice the max heat output, better stove and pot stability, and works better in cold weather). I see they have modified the pump - added a little angle fitting to the end. Take a look at some other stoves, too. A JetBoil is awesome. MSR Simmerlite or WindPro - heck there are tons of neat stoves out there now that beat a Svea hands down. Sveas don't make sense from a performance standpoint. Ya just gotta love those little Sveas to use one! END EDIT

Regards,

Tom