Unich mini floor pump won't work - faulty?

[TPMB12]

OK I've used pumps of many types without any issue. I'm not normally clueless about using a pump but this one has me stumped. Has anyone used one before?

Let's start at the beginning. It's a nice looking portable pump with hose, tiny folding foot stand, integral gauge and bleed valve button. The hose head can convert between Schrader and presta valves by unscrewing, turning it around and screwing it back in. This creates a narrow or wider hole for the appropriate valve so it's obvious which way round to have it for your valve.

I use presta valves so I undid the screw on the end like I've always done. Pushed the hose head with it the narrow hole way around. I screwed it onto the valve like I believe I should with this pump. Then pumped away. Nothing happened. Pressure did not build up, no air seemed to be leaking and nothing seemed to be happening.

What's going on? What am I doing wrong? Could it be faulty?

http://www.unich.tw/product_description.php?PNo=3

http://road.cc/content/review/187526-unich-mini-floor-pump

[PaulF]

If you block the hole with your thumb and pump does pressure build up?

[TPMB12]

Yes, pressure seems to build up.

I've just put it on my son's bike, flat tyre but quickly pumping sees the pressure gauge needle move.

Could there be something wrong with the valve? It was a while ago now that I tried it. When I couldn't get it working I just switched to the track pump. I've changed tyres again today with the old inner tubes (changed from 32mm to 38mm tyres so changed inner tube sizes). New tube = new valve, wonder if it works now?

I really can't see it being a valve issue so I'm doing something wrong.

[Brucey]

apologies if this is obvious but

a) presta valves often jam themselves shut; as well as unscrewing the little nut, it is always a good idea to push the valve in to make sure that the thing is unjammed and will move when you pump and let air through OK. Also,

b) when converting pump heads it is normal to also invert the chuck insert part immediately below the rubber seal, so that the valve is accommodated in the best way.

The latter point means that a Schrader valve is help open by a central pip in the chuck insert; the same part when inverted usually presents a deeper bore that allows a presta valve to be fitted properly.

This is a typical chuck insert



cheers

[TPMB12]

I'm aware of the presta jamming but I might not have checked it at the time. I'll have another go on a spare inner tube.

The second point I'm not sure about. First off with the presta side set the head looks just like all my other presta heads including the one on my race rocket pump which you loosen the head to convert from Schrader to presta.

Secondly I can't see any way to easily remove the chuck. Plus the instructions never said anything about it, just turn the head around to switch to the different valve. In some ways that's similar to other pumps I have owned. The head changes by a very simple action. My race rocket just slightly unscrews the head so it's loose but still contained (won't come off without serious effort to break it). That's too convert to the presta valve. I'd still be using it if my hand wasn't too big for the handle (gives me a nasty blood blister every time I use it).

The whole head comes off and you screw it one way or the other to fit the different valves. One way presents a kind of small, fat, flathead screwdriver to push the Schrader pin in. The other is a small bore hole with just a rounded end to it.

Of course I could be totally wrong but I can't see how to get the chuck out of the head.

[T42]

I can imagine the bloke at my LBS explaining "well, sir, you're using the wrong kind of floor".

IGMC

[Little Jim]

If you have to screw it on to the valve is it also screwing the Presta valve shut at the same time?  I've had this problem occasionally with the little Toepeak mini pump I occasionally use.  The only way round it that I've found is to turn the little Presta valve fully open and then apply a bit more pressure to try and lock it open on the thread (if that makes sense)

[Brucey]

The whole head comes off and you screw it one way or the other to fit the different valves. One way presents a kind of small, fat, flathead screwdriver to push the Schrader pin in. The other is a small bore hole with just a rounded end to it.

Of course I could be totally wrong but I can't see how to get the chuck out of the head.

that does sound as if it is different to the sort that I posted a picture of; apologies if that was a red herring.

cheers

[TPMB12]

It's all good information, let's me rule out something else that could be wrong that I didn't know about.

I appreciate your help everyone. Got a few things to check out when I get home. I'll sit down with a few inner tubes and try a few things out based on your replies. I want to rule out any issue due to a particular inner tube too. I can't think why but I wonder if it's just an issue with the one inner tube.

BTW it works with Schrader valve. Is there any reason why I can't use that valve type instead? Is road / gravel running 38mm tyres. I'm used to presta but Schrader fits the valve hole so why not?

[Kim]

BTW it works with Schrader valve. Is there any reason why I can't use that valve type instead? Is road / gravel running 38mm tyres. I'm used to presta but Schrader fits the valve hole so why not?

No.  The main advantage of Presta is that it fits narrower rims (and tends to be easier to come by in longer lengths).  The secondary advantage is that standardising on one valve type means less arsing about with pump heads, and if you have road bikes Presta tends to be the lowest common denominator.

Most of the issues I've had with Schrader valves were down to them being cheap and nasty inner tubes, particularly in small-wheel sizes (they're for children's bikes, aren't they?).  Decent Schwalbe Schrader tubes have nice metal threaded valve stems, just like the Presta ones.

[Brucey]

fundamentally a Presta valve is probably a better valve for a bicycle than a Schrader valve.

Given the current circumstances this may sound a little ironic, but one of the reasons I'd cite as to why Presta is better is that the pump is more likely to work more of the time with Presta than Schrader. The seal has less load on it, there is no need for a valve-opening pip or a check valve in the pump head, and small leaks are better tolerated. The valves don't fill up with crud if you leave the dustcap off, it is easier to completely deflate a tube.... I could go on.

But the fact remains that your pump presently does one valve well and the other one badly, so that may dominate your choice. I'd be a bit worried that there is some kind of lurking fault in the pump and that it may stop working altogether, though....

cheers