Picked up a Coleman 400b - no pressure in tank

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BillHoo
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Picked up a Coleman 400b - no pressure in tank

#1

Post by BillHoo »

Hi folks!

I'm new to the forum and just picked up a Coleman Peak 1 400b.

It was an ebay purchase, untested.

It arrived yesterday and from what I see:
- It does not hold pressure.
- I opened the fill cap and put my thumb over it while I pumped (unlocked the pump and pumped it 40 times. Released my thumb - no pressure
- I removed the pump cover and added a few drops of oil. Pumped again, no pressure.
- I notice after trying to pump, that fuel is dripping into the pump cylinder.

Today, I drained the tank and sprayed carb cleaner into the check valve - I felt some carb cleaner come out the fill hole.

I decided to try an experiment...
- I tightened the fill cap and sealed the tank.
- put the carb cleaner tube into the check valve and did a few quick pumps of of carb cleaner (less than a second in total). Looks like the tank pressurized to a point the check valve closed and carb cleaner started to fill the pump housing a little (to maybe 5mm deep).
- big bubbles periodically glurped from the check valve hole.
- I used a can of Dust-Off in the check valve hole to pressurize further with a few quick bursts.
- the check valve seemed to seal better under higher pressure, and only a few really tiny bubbles came out every few seconds.

So I figured it had pressure.
- I followed lighting instructions and it lit up like a champ. Yellow flames for a few seconds, settling to a nice blue ring.
- With just a bit of carb cleaner and (apparently flammable) canned air, it continued to burn clean and blue for about 1 hour 20 minutes.

I have on order:
- Check valve removal tool
- Check valve (not sure if I got then right kind)
- Universal Coleman pump assembly
- also got a filler cap with schraeder valve to allow pumping with a bicycle pump

Am I on the right track to clean or replace the check valve and pump cup?

I figure I'll replace the check valve and pump assembly to get the stove working, then clean and re-furbished the old chack valve and pump assembly for future reserve.
Last edited by BillHoo on Wed Nov 24, 2021 6:28 pm, edited 1 time in total.
zoomkat
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Re: Picked up a Coleman 400b - no pressure in tank

#2

Post by zoomkat »

"Am I on the right track to clean or replace the check valve and pump cup?"

The stove sounds like it is working good in the end. I suggest you trouble shoot the pump section further before you put any tools on the pump section to ensure you actually have an issue. The burn time seems reasonable so there appears to be little or no pressure loss beyond normal (but I do not have that stove). Note that the pump sections has two pressure sealing mechanisms, the check ball, which can bubble a little as normal, and the shaft needle valve which makes the positive no leak seal. There are simple things you can do to check the pump cup and sealing mechanisms, but there may not be anything really wrong with the pump/check valve assembly.
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arizonacamper
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Re: Picked up a Coleman 400b - no pressure in tank

#3

Post by arizonacamper »

I would put a new leather pump cup on it after rubbing some oil into it and put on a new fuel cap seal these are all available from our sponsor OCP and go from there.
Shawn
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Coldwaterpaddler
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Re: Picked up a Coleman 400b - no pressure in tank

#4

Post by Coldwaterpaddler »

Those came with neoprene pump cups. My first instinct is that the pump cup is your problem. I have 400s, 400As, 400Bs, 442s and a 3024. The pump cup is the most common cause of lack of pressure in these from my experience. Second is the Schrader valve core and third is the fuel cap gasket. You're on the right track.

The B model is when they switched from graphite valve stem packings to O-rings. Once you get good pressure you may find that you'll need to replace those too, although, those are quite easy to replace.

Never seen a bad check valve in any of them, but yours could be dirty with old oil and a chunck of the pump cup.
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BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#5

Post by BillHoo »

Thanks all for the advice and encouragement.

Since it seems to be holding pressure, I'm not too worried about the filler cap for now.

The pump cup does not seem to produce pressure. The pump assembly I have on order from ocp looks like it has a leather pump cup. Also ordered a neoprene cup to refurb the existing pump assembly.

I pressurized it with some more carb cleaner last night and closed the shaft needle. This morning it was still pressurized. Released pressure and sprayed some more carb cleaner in there. to sit a bit more.

btw. The tiny bubbles are coming straight out of the center of the check valve, so I don't think the O-ring is faulty. The ball probably has some gunk on it.

I think the ball was initially stuck a bit and the carb cleaner has been helping. Seems to be holding pressure better the more I spray it.

The lady I bought it from had not used the stove for a few decades, and there was old fuel in it. Looks like it might have been unleaded gas from the Reagan era. When Saadam Hussein saved us from the OPEC embargoes! She said she never tested it.

I should be getting the new pump assembly and additional parts by middle of this week.

Looking at schematics I would need a shaft and valve part #400-6381. Couldn't find one available, and didn't know the part number at the time, so I ordered a 200-6381. I'm hoping it's the same valve, but maybe a different shaft. I'll hold onto it either way for the next stove I get that might need a rebuild. I have a Peak 1 550b on the way.

Also have a new generator on the way to have onhand as well.
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Re: Picked up a Coleman 400b - no pressure in tank

#6

Post by zoomkat »

"The pump cup does not seem to produce pressure. "

So how are you getting it pressurized? That being said, If you push down on the pump plunger with the needle valve closed (and thumb over the vent hole), does the plunger go down and bottom out, or is it sitting on a cushion of air? I don't want to be a bugger, but it looks like you are just looking for an excuse to work on the stove, which has the real possibility of being damaged beyond repair. It happens, just saying.
BrianP
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Re: Picked up a Coleman 400b - no pressure in tank

#7

Post by BrianP »

What a coincidence...I just picked up a 400B for $15 CAD from a guy who hadn't used it for a long time, judging by the caked on dust.
It wouldn't pressurize, heck, I couldn't even move the pump...
Finally was able to pull the pump out and discovered a bent and twisted valve stem...no wonder the pump couldn't move.
Lots of fuel coming through the check valve too.
All I had was a spare leather pump cup, and this is the only stove that has ever defeated me when trying to reinstall a pump...no way it will get down that tube...I just ordered a check valve tool and a replacement neoprene pump assembly. I hope it works.

How the hell did that check valve stem get so butchered though, guy must have used a torque wrench one day...
There are two types of people in this world...avoid them.



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zoomkat
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Re: Picked up a Coleman 400b - no pressure in tank

#8

Post by zoomkat »

"How the hell did that check valve stem get so butchered though, guy must have used a torque wrench one day..."

Probably had a fuel cap gasket leak and took it out on the pump needle valve. Maybe he had to pump it up more often than he liked and decided to "fix it".
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Coldwaterpaddler
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Re: Picked up a Coleman 400b - no pressure in tank

#9

Post by Coldwaterpaddler »

A couple more notes.

When I said the O-rings on the valve stem might be bad, I was referring to the main valve stem with the red plastic knob, not the check valve.

Leather pump cups are fine for these stoves. My suggesttion there is that neoprene was original and they can develop small cracks on the leading edge, preventing full pressurization. I've had this happen twice, though it's more common for them to get worn or less flexible and fail to pump altogether at the least convenient time.
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BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#10

Post by BillHoo »

zoomkat wrote: Mon Nov 22, 2021 7:42 pm "How the hell did that check valve stem get so butchered though, guy must have used a torque wrench one day..."

Probably had a fuel cap gasket leak and took it out on the pump needle valve. Maybe he had to pump it up more often than he liked and decided to "fix it".
I think I either saw a YouTube video, or a website where some guy described the way to unstick a check valve ball by giving the pump a whack with a mallet. They infer that a sudden compression of air might break the stuck bearing. I'm skeptical
Last edited by BillHoo on Tue Nov 23, 2021 2:20 am, edited 1 time in total.
BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#11

Post by BillHoo »

zoomkat wrote: Mon Nov 22, 2021 7:24 pm "The pump cup does not seem to produce pressure. "

So how are you getting it pressurized? That being said, If you push down on the pump plunger with the needle valve closed (and thumb over the vent hole), does the plunger go down and bottom out, or is it sitting on a cushion of air? I don't want to be a bugger, but it looks like you are just looking for an excuse to work on the stove, which has the real possibility of being damaged beyond repair. It happens, just saying.
As described, I am pressurizing the tank by inserting the spray tube of a can of carburetor cleaner into the check valve hole and spraying for a quick burst or two. This is followed by inserting the red plastic spray tube from a can of Dust Off compressed air into the check valve hole and spraying two to three bursts intoy check valve. So the tank is now pressurized with carburetor cleaner and flammable canned air.

The check valve ball is doing its job by sealing the carburetor cleaner and canned air in the tank. Though it leaks a little bit. I can see bubbles coming out of the check valve hole in the little pool of carburetor cleaner at the bottom of the pump well.

I then turned the valve to the on position, and ignited a mixture of carburetor cleaner and canned air. The pressure from the carburetor cleaner propellant and canned air in the tank seem to keep the stove burning for over an hour with a nice blue flame.

It leaks a little, but I immediately seal it by screwing in the check valve rod. I learned to do this quickly because a small bubble of gassified carb cleaner floated out of the check valve and became a small fireball!

Now back to the pump. No, the neoprene pump cup rides straight down to bottom. There is no cushion of air.

I have a new pump assembly coming in a day or so. I think it is the kind with leather pump cup. I also have a neoprene cup on order as well.
Ene
BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#12

Post by BillHoo »

Coldwaterpaddler wrote: Mon Nov 22, 2021 8:49 pm A couple more notes.

When I said the O-rings on the valve stem might be bad, I was referring to the main valve stem with the red plastic knob, not the check valve.

Leather pump cups are fine for these stoves. My suggesttion there is that neoprene was original and they can develop small cracks on the leading edge, preventing full pressurization. I've had this happen twice, though it's more common for them to get worn or less flexible and fail to pump altogether at the least convenient time.
Thanks! I'm looking forward to replacing the neoprene pump cup with a leather one to see if it pressurizes better.
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Re: Picked up a Coleman 400b - no pressure in tank

#13

Post by zoomkat »

"Now back to the pump. No, the neoprene pump cup rides straight down to bottom. There is no cushion of air."

Have you re-oiled the cup and pump tube after using carburetor cleaner and similar in the pump tube and assembly? Making sure the cup sides are clean and then a good oiling might make the cup seal gain. A little Vaseline might work too.

Edit: Have you previously removed the cup from the pump shaft?
BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#14

Post by BillHoo »

I have not had a chance to play with it since Sunday, other than spraying more carb cleaner in it as I walk out the door to work.

My current pump assembly is intact. Cup sides are clean. I have not yet attempted to remove the cup.

When I first broke the ball free with the first spray of carb cleaner, I reinstalled the pump assembly, but did not re-oil it. Gave it a few pumps, but no pressure.

Note: when I first got it out of the shipping box, first thing I did was apply generous glop of 2 stroke motor oil to the pump assembly. No pressure at that point.

I'll try putting the pump assembly back in and giving the cup a smear of Vaseline (good idea!) and a few drops of oil tonight.

UPS tracking shows my OCP delivery should be in tonight also! So, if I cannot recover the existing pump cup, I've got a new neoprene cup, and a whole new pump assembly (with leather cup) at my disposal.

I will also get in the same delivery, a filler cap with bicycle pump schraeder valve on it. Mayre test that out too. I think I'd have to be careful about over-pressure of the tank with that. I would think only a third of a stroke of a bicycle pump would be more than enough to pressurize the tank.

I just got the new generator delivered last night. Since the stove seems to be operating once pressurized, I don't think I need to replace the generator. Will just keep that in my pack for emergency repair.
BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#15

Post by BillHoo »

zoomkat wrote: Tue Nov 23, 2021 2:47 am "Now back to the pump. No, the neoprene pump cup rides straight down to bottom. There is no cushion of air."

Have you re-oiled the cup and pump tube after using carburetor cleaner and similar in the pump tube and assembly? Making sure the cup sides are clean and then a good oiling might make the cup seal gain. A little Vaseline might work too.

Edit: Have you previously removed the cup from the pump shaft?
I see in another site/thread someone mention you can "flair" out the neoprene cup a little to make it seal better. I didn't know that was possible.
https://bushcraftusa.com/forum/threads/ ... 901/page-2

I'll give it a shot when I tinker tonight.
BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#16

Post by BillHoo »

I got the new pump assembly with leather pump cup, a neoprene cup, and a fill valve with schraeder valve on it last night.

Took another look at the neoprene cup on the pump that the stove currently has. Compared to the new one, the old cup is really stiff, almost brittle. The "skirt" of the cup is shorter and fits real easy in the pump well. Slides down with almost no effort. I also noticed two cracks in the edge of the pump skirt.

I pried off the retainer and installed the new neoprene pump cup. Greased it with two-stroke motor oil. I had to carefully, yet forcefully push the pump assembly down the pump well. The new cup almost doesn't fit.

I sprayed a bit of Mil-spec CLP down the well on top of the pump.

Installed the D-retainer and gave it a few pumps. It was really hard at fiurst, but after a few pumps it got easier, but still much harder to pump than the old pump cup.

I don't think I got it more than 25 pumps before it got really hard, and I didn't want to force it.

Turned on the valve to the light position and sparked her up. Wooosh! a big yellow flame for a few seconds that settle down to a nice blue ring. The bowl around the burner rings started to glow red. Turned it down a bit, but it went out.

Waited a few minutes. Gave it a few more pumps and it lit up, getting to the blue flame a bit faster. But this time, it wasn't a nice circle. Looks like the flame jets coming out the 3 to 5 o'clock position shoots out a little further, making the circle of blue, more like weird oval.

I let it burn tthat way for about half an hour, and the circle never straightened out. Turned it off and let it cool for a few hours.

Came back and repositioned the grate. Also lightly tapped the burner cap a bit with back of a screwdriver handle. I notice the cap and rings beneath are not perfectly aligned. I might try loosening the screw later to re-positioned and align everything.... or not.

Depressurized. Then pumped again to 25 strokes and lit it up. A quick initial yellow flame, followed by a nice, perfectly round ring of blue!

I'm satisfied for this $50 eBay stove plus additional $3 for a new pump cup.

The check valve tool, spare pump assembly, and spare generator will just go into my emergency spares pack, until I need them.

NEXT - I have a 550-b coming in the mail in a few days. Got it off a guy who got a bunch of them from a municipal auction. Wonder what that'll need to get up and running?
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Re: Picked up a Coleman 400b - no pressure in tank

#17

Post by BillHoo »

video of stove operation.

NOTE: for some reason, there is no audio. But it sounds like a train chugging around.
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Coldwaterpaddler
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Re: Picked up a Coleman 400b - no pressure in tank

#18

Post by Coldwaterpaddler »

Well, there you go. Fixed! Congratulations!
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BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#19

Post by BillHoo »

arizonacamper wrote: Mon Nov 22, 2021 1:21 am I would put a new leather pump cup on it after rubbing some oil into it and put on a new fuel cap seal these are all available from our sponsor OCP and go from there.
Shawn
Shawn,

Do you find that leather is better than neoprene?

Does it last longer? Or provide better seal?
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Re: Picked up a Coleman 400b - no pressure in tank

#20

Post by adamshepherd »

BillHoo- just some friendly notes on your 550B build if you wish. The valve, F/A set up on those stoves are sealed entirely with o-rings and not the usual brass fittings. The o-rings are quite specific (and vastly different from each other although the parts list just says "2", all available at OCP). Every one I have worked on, regardless of age, needed a complete o-ring replacement for safe operation. This is in addition to the usual pump cup/cap gasket issues like everything else. I think these stoves are made this way for quick conversion between CF and 1-K, and they run great on either. I'm sure there is plenty of help here from members, and you are welcome to send me a message if you need something- Good Luck!
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arizonacamper
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Re: Picked up a Coleman 400b - no pressure in tank

#21

Post by arizonacamper »

The neoprene cups don't last that long and if you use them in colder weather they sometimes wont pump at all. use the leather cups. all it takes is a little bit of oil every now and again they last half a forever. Be sure to oil the cup before installing.
Shawn
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BillHoo
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Re: Picked up a Coleman 400b - no pressure in tank

#22

Post by BillHoo »

arizonacamper wrote: Wed Nov 24, 2021 7:46 pm The neoprene cups don't last that long and if you use them in colder weather they sometimes wont pump at all. use the leather cups. all it takes is a little bit of oil every now and again they last half a forever. Be sure to oil the cup before installing.
Shawn
Good to know! Thanks!

Since I just put in a new neoprene cup, AND have a full pump assembly with leather cup on standby, I will let the neoprene cup wear out naturally and switch to leather from there on.

I saw a nice YouTube video where a guys shows how to make replacement leather cups out of scrap leather.
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