Strange weber problem, idles then dies leaking fuel.
Turbo Mini Forums

Hi guys, i've got a crazy problem with my weber 45DCOE, and I'm at a loss to what's causing it.

I had problems with a fuel leak caused by split misab plates, which i fixed today, with new misab platse and thackray washers gapped at 20thou as per weber instructions.

The car's running perfectly, starts on the button and drives wonderfully, and appears to idle fine too for a while.

After 3-4 minutes on idle, the car starts to judder for a few seconds, then stutters badly, backfiring out of the carb once or twice before dying. I watched this happen a few minutes ago, and as it died, seemingly loads of fuel poured out of the carb and dripped down onto the manifold!

It looks like the fuel is coming from the front of the carb, around the choke area, although it's pretty hard to tell. it's definitely not coming from the float chamber top gasket, as that's bone dry still.

When I fitted the air filter earlier and held the carb on end (filter to the sky) it did seem to ooze a tiny bit of petrol from around the front choke area, but I assumed this was due to it being held basicly upside down.

Any suggestions would be great! is there a seal around the choke area that could have perished?

I don't really want to risk driving it again as fuel leaking onto a hot manifold doesn't sound too safe to me!

I know this is perhaps not the ideal place to post about n/a issues, but there's SO much more technical knowledge on here compared to (dare I say it?) tmf.

Cheers for reading the essay!

Nick

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

I would start by checking the Fuel Presure sounds like the FP is over coming the flot valve.

interesting thought Paul, I hadn't thought of that! could this explain why it's stalling (perhaps choking itself?) and fuel is pouring out?

I have noticed today that the bowl on my filter king pressure reg/filter is full to the brim, when it usually sits about 2/3rds of the way downwards.

Fuel pressure hasn't been altered at all since it was running fine a few months ago. could it perhaps be a problem with the float valve?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

this should be 3psi

rather than fuel pressure, could it be the float height?

are you using the rond brass floats of the later plastic angular ones

i only mention it as you need to use a different figure to get the valve to shut correctly, and i had a similar issue (i sorted mine by trial and error)

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

cheers Phill, I spoke to a friend about it earlier today and he also suggested it sounded like fuel pressure too high.

interestingly, it starts perfectly, and whilst warming up it doesn't have any problems. the problem only occurs once it's warmed through.

I've also noticed that my throttle linkage doesn't want to naturally return to it's complete stop, instead is sits maybe 0.5-1mm from it's stop and idles fine at 1100rpm. if I push the linkage back to a complete stop the car stutters and dies straight away.

i've not got the gear to check fuel pressure here at the moment, and I need my timming checked after replacing the points with an electronic module, so I'll book it in at the rollers sometime this week.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

here's an idea.....

I've just found a profuel 1-5psi AFPR in the garage, is it worth me bashing that on after my filter/king inline set at 3psi and see if it cures the problem?

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Hi,
I always used on of those on my 45 never a problem :)
Cheers,
Gavin :)

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well I just chucked the pro fuel regulator in set at 3psi, and it still seems to have the stalling issue when it warms up. Perhaps Joey's idea of the float being at fault is my next thing to look at!

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

OK, so I went for a drive, and it's still running well, but still idling like a bag of shite with the profuel regulator set at 3psi.

I noticed it's been pushing out water a fair bit, to the point where the level is JUST below the bottom of the top rad tank, half a pint always fills it again. it's got a brand new 15lb rad cap on it, and it's only running at 80-90 degrees, so I don't quite understand why it's pushing some out.

I did a compression test, just for interest, and it got 162-170-180-175 from 1-4 respectively.

Running ever so slightly lean on #4 I'd say, and generally a tad richer on 1&2 compared to 3&4, with the outers being more lean than inners as you would expect.

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Edited by Prawn on 14th Jun, 2009.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.