32 replies to this topic

[mkw]

Hi, 

 

As above, the last time I was out with the car I came back with the AA due to fuel leaking out of the overflow and the engine cutting out.

 

When i got back i removed the float chamber lid and examined the needle which was quite worn, I replaced it with one of the Minispares CA90 updated needles. That didn't seem to make an difference, i then replaced the float itself even though mine appeared fine, this also didn't cure the problem.

 

Oddly when i remove the lid and run the car with my fingers holding the float closed there doesn't appear to be any fuel forcing it's way out so i assumed the float/needle combo is working fine.

 

Oh, i also cleaned out the float lid with carb cleaner. 

 

I've looked at various posts on this topic and most people say to try what i've already done.

 

The car is a 1991 998cc, Single HS4 carb with stage 1 kit. Everything else is standard.

 

Cheers in advance.

[Tamworthbay]

Did you check the hole where the valve sits? I am wondering if it's is sticking and causing it not to cut off. I can't see how it could wear as such but could be some dirt perhaps.

[mkw]

Well i cleaned it all down before i put the new needle in so that side of things should be ok, i'm really stuck on what else to try to be honest.

[nicklouse]

Fuel out of overflow is the valve not closing or being forced open by exesive fuel pressure.

You say standard. Even the fuel pump?

[lawrie124]

And if you blow into the fuel inlet and lift the float up and down does it work?

[Tamworthbay]

Well i cleaned it all down before i put the new needle in so that side of things should be ok, i'm really stuck on what else to try to be honest.

do you have a decent inline filter in place? Otherwise it could be muck being pumped through.

[mkw]

Fuel out of overflow is the valve not closing or being forced open by exesive fuel pressure.
You say standard. Even the fuel pump?

Yes, even the fuel pump. Could that be the issue? I was told that there is basically nothing to go wrong with the mechanical fuel pump on that engine so I've not thought about replacing it.

[mkw]

Well i cleaned it all down before i put the new needle in so that side of things should be ok, i'm really stuck on what else to try to be honest.

do you have a decent inline filter in place? Otherwise it could be muck being pumped through.

I don't have one on the car but I do have one in the garage so I can stick it in and see what happens. Do you think the problem would start straight after cleaning everything just by mucky fuel? Would it not need time to build up is what I mean.

[mkw]

And if you blow into the fuel inlet and lift the float up and down does it work?

It appears to work as it should, it was a little dodgy before which is what made me look closer at the needle.

[carbon]

 

 

Well i cleaned it all down before i put the new needle in so that side of things should be ok, i'm really stuck on what else to try to be honest.

do you have a decent inline filter in place? Otherwise it could be muck being pumped through.

I don't have one on the car but I do have one in the garage so I can stick it in and see what happens. Do you think the problem would start straight after cleaning everything just by mucky fuel? Would it not need time to build up is what I mean.

 

Only takes a small spec of dirt under the needle valve seat. Last time I had problems it was soon after a rebuild, I have been running with one of the cheap plastic inline filters ever since and no recurring problems.

 

Looking at my filter it is now dark brown... so has been catching quite a lot of rust and other dirt, probably coming from the inside  of the petrol tank.

[Tamworthbay]

As said above it only needs to be a tiny bit of dirt and if it's in the fuel line it only takes a couple of seconds to get pulled into the carb. Also it's a very cheap job (approx-£1-£2) to fit a filter and could do with being there anyway so you won't be losing anything by fitting one.

[mkw]

Well i cleaned it all down before i put the new needle in so that side of things should be ok, i'm really stuck on what else to try to be honest.

do you have a decent inline filter in place? Otherwise it could be muck being pumped through.

I don't have one on the car but I do have one in the garage so I can stick it in and see what happens. Do you think the problem would start straight after cleaning everything just by mucky fuel? Would it not need time to build up is what I mean.

Only takes a small spec of dirt under the needle valve seat. Last time I had problems it was soon after a rebuild, I have been running with one of the cheap plastic inline filters ever since and no recurring problems.
 
Looking at my filter it is now dark brown... so has been catching quite a lot of rust and other dirt, probably coming from the inside  of the petrol tank.

  

As said above it only needs to be a tiny bit of dirt and if it's in the furl line it only takes a couple of seconds to get pulled into the carb. Also it's a very cheap job (approx-£1-£2) to fit a filter and could do with being there anyway so you won't be losing anything by fitting one.

In that case then, I'll fit it and clean the chamber then have another go and see what happens.

[mkw]

Ok, so I've fitted an inline filter and stripped the carb completly for cleaning. Put it all back together, started the car and within seconds fuel poured out of the overflow and enine cut out.

Any more ideas?? I'm stumped...

[Tamworthbay]

Did you check the float height when you fitted the new one?

[mkw]

Did you check the float height when you fitted the new one?

Followed the manual to the letter yeah, tried various heights as well to see what happened but no difference.