21 replies to this topic

[dansnyderECE2010]

So, took my 89 mini out for a drive to work.  Longest distance I've driven so far!  Made it to the parking lot and BAM, car cuts out after going over a bump.  Try to start her up again and the battery gets drained...  After work I charged the car up and started it up.  Took a bit to get the car running and the engine speed was all over the place.  High then at some point it would cut out unless I gas it throttle.  Give it some more choke and the engine starts racing.

 

I then notice the smell of gas.  I look and there's a decent amount of it on the ground.  I traced the source to the second metal line on the top of the carb fuel reservoir (HS4).  This line sortof just opens up into the air after following a metal line to, more or less, the front of the car.  What is this line and why would it open up into the air?  Should I assume that because gas is getting spit out of it that my needle valve is probably not working right?

Edited by dansnyderECE2010, 04 March 2014 - 06:25 PM.

[DomCr250]

I think you are 100% correct, it's probably your needle valve, it's a quick job that only requires three screws, a spanner to replace the valve (if I remember correctly) and maybe a gasket for the float chamber top.

 

Only concern would be the cutting out after the bump incident ...maybe that was just enough to push a worn out valve to it's breaking point.

[robminibcy]

very common particularly on cars that have been sat. Your float is either broken and full of fuel so has sunk or the needle has dirt and or excessive wear preventing it from closing. Take the lid of the float of (3 screws) and check the float for damage and any fuel inside it. If that's fine take the needel out of top and clean it up as well as the seat. If you don't already have one id suggest fitting a fuel filter as it really does help stop the needle being forced open by and dirt

Edited by robminibcy, 04 March 2014 - 06:26 PM.

[stefan5417]

I had the same problem the other week, cleaned the needle valve up with some scotch pad and everything was fine

[dansnyderECE2010]

Interesting, well, I know for a fact that my needle valve has a groove worn in it (I dissassembled the carb a while ago).  I think it's time to get a new one.  Anyone have any thoughts of the minispares superflow valve?  Looks pretty different from the standard ones I've seen.

 

As for the fuel filter, can you suggest a part to do this?  I see some inline fuel filters on minispares however this seems like something I could buy anywhere.

[RedRuby]

Not familiar with carb set up, mine is injection, but could the second line be a return fuel line and the bang you heard was something hitting your car and damaging the fuel line. If so you are probably suffering fuel starvation and I would advise not to drive the car until the line has been repaired.

[dansnyderECE2010]

This is what I was thinking originally when I saw the open end of a metal line dripping gas.  In my dads 72 merc there is a return line back to the gas tank (this is an injection car too) however this line literally empties into air.  Seems a bit wacky to me but I checked my friend's Mini and its setup the same way.  Perhaps this is meant mainly for gas vapors?

[A-Cell]

This pipe is an overflow pipe from the HS4 carb. It's function is to direct fuel to the ground rather than onto the hot exhaust manifold when there is an overfill of the fuel bowl due to faulty needle valve.

[robminibcy]

any filter will do, its not critical like on injected engines where even a spec can cause issues. The pipe is purely an overflow and does not go back to tank. Its only there for emergencies(like this) so wouldn't normally have any fuel coming out whereas injection usually have excess coming through for cooling and lubrication properties.

 

as for the minispares valve i fitted one briefly and it justs did not want to seal. In the end fitted a standard new one and been fine since. I might have just had a dodgy one though.

[tiger99]

Always use a Viton (a kind of hard rubber-like material) tipped needle valve, as they work a lot better. They were specifically introduced to solve this problem. As far as I know, the Minispares one is metal tipped, and they invariably leak slightly.

 

For some reason which as far as I can tell, no-one understands, some needle valves stick in the open position, or even the closed position, occasionally. It is not just the plastic part being too tight in the bore of the brass body. Some never give trouble, others do, so perhaps it is best to always keep a spare.

 

This link may help:

 

http://sucarb.co.uk/...s-needle-valves

[dansnyderECE2010]

Okay, I'm on the same page with ya'll now.  I understand the function of the overflow line (still seems a bit wacky).  I ended up fitting the minispares valve just to give it a go and it seems to be sealing fine.  I believe it isn't coated with anything special so maybe this will be my short term fix.

 

So, my problem ended up being that I fitted my friend's needle valve with MY needle valve's housing, choosing the two that looked to be the best (he replaced his with the new one I was testing with).  BIG MISTAKE.  Turns out after 25 years a needle valve and the needle valve housing (the hole the needle seals up) wear the same...  So if you mix and match after they've been worn down they don't match up anymore.  So yeah...  You live you learn.  Anyway, the minispares valve seems like a nice design, but I will be adding a filter as suggested.  

Edited by dansnyderECE2010, 15 March 2014 - 11:27 PM.

[tiger99]

The Minispares valve does not have a Viton tip, and so it will give all the same problems as the original design, with metal to metal sealing. The only "improvement" is that there is more cross-sectional area to allow a greater flow rate, which is not needed unless the engine is in a very high state of tune. It is a typical amateurish Minispares design, best avoided.

[dansnyderECE2010]

Okay, good to know.  My next order will include a Viton tipped valve for when the superflow goes bad.

[dklawson]

Consider this another vote to follow Tiger's advice and buy a Viton tipped float valve.  If the Superflow valve is working for you, great.  Leave well enough alone but carry a spare Viton tipped needle with you in the car so you will have one when/if it becomes necessary.

 

As you discovered, the needle and seat do wear together.  Anytime you suspect a float valve issue and find witness marks (wear rings) on the tip of the needle it is time for a replacement.

 

As for the overflow, on some cars where the overflow has a tubing nipple (not all do) it is not uncommon to run a length of fuel hose from that nipple to a safe location away from the carbs and exhaust manifold so any leaked fuel can safely reach the ground.

[dansnyderECE2010]

So far so good.  Viton tipped needle on its way for the future!  One thing I have noticed with the superflow valve is that the float closes much earlier (seems that the housing is longer that the standard one), which means that the fuel level is lower at the jet.  I always have to pump the gas a little now that the new valve is in when starting the car.  That seems like it makes sense if the level in the reservoir is too low.  Is this the expected result of the fuel level being too low?