Problems with Coleman 424 Unleaded Double Burner Stove

Hi all, really hoping you can help us out. Sorry for the long post but I thought I’d try include as many details as possible to start with.

We are having issues with our 424 unleaded stove. I have no heat control at all and a constant yellow flame on the main burner.

When we turn the aux burner on both burner run close to how they should, blue flame with flickers of orange in the main, but not heat control atall.

I have cleaned the mixture chamber well, took apart the generator and cleaned components the best I can in the field as we are currently camping!

One thing I did notice is that at the end of the thin piece that goes through the coil it does not have a point on the end as I have seen in other pictures. Is this correct?

Also when I turn the stove off it continues to spit fuel in for a few minuites after causing it to flare up.

Any help would be great.

Harry

 

The pricker rod needle absent, sounds like.

Symptoms point to a restricted (partially blocked) jet orifice, to be expected with the pricker gone. Without a full-on efflux of vapourised fuel you’re probably barely vapourising what’s trickling through, hence the yellow flames.

Fuel tank and assembled generator and valve away from a flame, priming lever down, pressurising the tank then turning on the fuel briefly will confirm. A steady stream of fuel would result if the jet were clear. No or little fuel emerging if not.

Even if the jet orifice temporarily cleared, without a working pricker it would soon fail.

A replacement pricker would be hard to come by here in the UK but a new generator with pricker not so.

Regards,

John

 

You need a tapered point on that generator rod. Without it, as you are aware, you have no control. The" pricker" meters the flow of fuel. Can you see where it broke off?
You need a new generator.

 

The pricker looks to be broken off right at the end of the rod. No sign of it in the assembly when stripped down.

We are camping in Italy for the next 3 weeks. Could anyone point us in the direction to get hold of a new generator? I assume these come with a new pricker as well?

 

Generator comes with pricker (more aptly called metering rod)

In the USA most sporting goods and some hardware stores have em.....good luck

The pricker/metering rod threads out of the valve, you might be able to unthread it a bit, and file a crude taper on the end, and make it work. Sounds like something I would try. when desperate for hot coffee.

 

No, it’s the taper on the valve spindle mating up to the valve seat that controls fuel.

Coleman don’t refer to a ‘metering’ rod.

 

Old Coleman Parts > 424 > Valve and Generator - C35

 

John,

When I do as you said in the first post I get a stream of fuel come out but it’s on and off with a lot of spray around it as well.

The jet at the end of the generator is clear at present, as I unblocked it the other day but still suffering the same symptoms.

Would a missing pricker cause me to have no control over the flow of fuel.

Obviously being 2000 miles from home and trying to find parts for one of these in a country that doesn’t speak your language is challenging. Is there anything I could do temporarily?

Harry

 

Thanks,

Was hoping it wouldn’t cost that much to fix up!

 

New stove.
Duane

 

@presscall I disagree. The needle meters fuel. It is not a pricker as we would think in an 8R. As the OP has noted, without it there is no fuel control. Basicly on or off.

They may not have called it a metering rod, but is a more accurate term, in this case, than "pricker"

 

That’s not how it reads. Output is poor. Partially blocked jet. So you say the valve on a Coleman suitcase is simply a fuel on/off control with no metering function. Really?

Were that the case, in creating their 431 Easi-Lite, which unquestionably meters fuel at the valve, Coleman Canada would have broken with decades of ‘suitcase’ tradition other than merely creating a valve incorporating O-rings.

 

The easy lite is a whole different valve, and not what we are talking about. The OP stated " I have no heat control at all and a constant yellow flame ". which is what you get without a needle/pricker/metering rod in a Coleman stove. No mention of a blocked jet. No mention of low output.
The taper on the seat is too short/abrupt (I struggle for the right term here) to do a decent job metering fuel flow.

Looking forward to going home tonight and removing a needle/pricker/metering rod from one of my stove. Will report back. Really!

 

Sounds logical to me.
It kind of looks like the throttle needle in most old moped or small motorcycle carburators with its almost invisible taper considering its length. If so, It's there to meter the fuel/air ratio.
And as you say - the taper on the actual seat can hardly meter the fuel with that steep angle.
It's probaly there just for the regular shut on/shut off function for the fuel.

 

Use the stove as is.
Find a stove to supplement.
Fix it at home.

 

Not too much steeper than an Optimus burner’s so I believe you’re wrong Christer - and Keith.



John

 

I've been wrong a lot......and will happily admit it (OK, maybe not "happily") but methinks we have down this road on CCF before. Looking forward to playing with a stove tonight.

On that 8r valve, how far can you turn that to go from shut off to full on? A half a turn or so I think. The Coleman valve you open multiple turns. Looking at that Coleman valve, the moment you have it open at all it is gonna provide more fuel then that the generator tip can use, any further turns open would be ineffective. Which is the case for the OP, he has no control, just full on, yellow flames. If he runs bothburners, he says it runs "close to how they should" , which is what you would expect, as with the valve wide open and the needle/ pricker/metering rod retracted all the way, now the tip is providing all the fuel it can.

 

Got home and drug my 417B out of the basement. Before I took it apart I noted that it takes over 1.5 turns of valve to retract needle visibly from tip. Hard to see though, tiny wire down a hole...

Took needle out, reassembled, lit. I expected more yellow flames, was not bad, but no flame control at all, other than off and on. Bet if I moved the valve just fractions of a turn when close to off I could get some control, maybe tonight when it's darker out.

 

@HGW088 I Lit my stove again (no needle) let it get warm, and turned it off...it continued to burn for a 20 seconds or so...and just as it was about to go out I cracked the valve just a few degrees. And it stayed with a real low flame. So you should be able, with a little care, get it to simmer a bit. Anything more that a few degrees and it's full-throttle.

 

Firstly, apologies to @HGW088 for having this on the back of your post requesting advice. I hope you manage to resolve your holiday cooking arrangements.

I removed the pricker rod from my Coleman (Canada) 6H valve.






The pricker needle.




A couple of videos, pricker rod removed from the control valve spindle, then spindle re-installed in the valve and the tank pressurised.

Fuel/air lever down, so neat fuel.




Installed in the stove.



Conclusion, the same degree and characteristics of burner control without the pricker rod installed, only I would expect the generator tip/jet to block - even if only partially - without the pricker function of course.