Stu
Posted a lot
Posts: 2,913
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Hello All, I appear to have messed something up on my Mk1 Golf with twin Dellorto 40's on it. I took the carbs off the manifold so I could drill out the vacuum take off on the manifold for the brake servo. That went well and I was very careful to place the carbs to one side, just disconnected the fuel pipe but left the accelerator linkage attached and didn't adjust any settings on them. Anyway, I put it all back together and turned the ignition on to prime them so I could have a look for leaks. The car has an electric fuel pump fitted and what normally happens is that you turn ignition on, hear the pump prime (presumably fills float chambers? I know nothing about carbs!), pump the accelerator a bit and then it'll start. Well, now you turn ignition on and the carbs fill up with petrol and then excess petrol pours out of the trumpets (is that what they're called?) on the right hand carb as you look at the engine bay. If you look with a mirror down the trumpets then the left carb is ok but the right one seems to keep spraying fuel and overflowing, that's just with the pump running, not the engine started? What have I done? Is there some sort of valve that should cut off fuel when float chambers are full or something? Everything looks in order and I didn't adjust any screws/linkages/cables or anything? The throttle linkage seems to sit where it should against it's stop so it's not holding the butterflys open or anything? Help!  Pic for reference....  By the way, haven't tried starting the car as there was too much petrol around, didn't want it to go bang!  Cheers Stu |
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Last Edit: Apr 10, 2006 14:36:14 GMT by Stu
'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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have you got a return on there?
are you still using the high pressure injection fuel pump?
have you got a pressure regulator fitted?
sounds like your putting too much pressure into the carb and/or youve knackered the stop cock type thing inside the float chamber
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Nathan
Club Retro Rides Member
Posts: 5,649
Club RR Member Number: 1
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If you look insode the trumpets you will see a plate this should be fully closed, I know I took mine of the MG before but it back on and I had the same issue. It was due to this plate getting stuck in the open position and releasing fuel out of the jets. Give it a look see
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Sounds to me like you either have to much fuel pressure (unlikely as both carbs would be effected)
or
The float valve is playing up. What id do is strip down the carb that has the problem so you can get to the float valve and check its not stuck open. Its most likely that the float valve has simply got jammed open and that means the pump is pumping fuel straight through!
If thats not the problem i would suggest you back off the fuel pressure (surely it must be regulated?) If it dose have a fuel return check its not blocked.
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Sounds to me like you either have to much fuel pressure (unlikely as both carbs would be effected) or The float valve is playing up. What id do is strip down the carb that has the problem so you can get to the float valve and check its not stuck open. Its most likely that the float valve has simply got jammed open and that means the pump is pumping fuel straight through! This sounds like the most obvious possibility. I have known it happen if the carbs are not regulated or the regulator is set too high as well |
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yeah, but what i was thinking is that one of the valves might be weaker than the other one -therefore it only curse word out the one carb
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If it all worked fine before then that rules out the fuel pressure etc. It's almost sure to be a stuck float holding the float needle open that's causing your problem. Best (easist) thing to try would be to give the offending carb a couple of taps to see if that re-sets the float - if not then it's a case of spripping down the top of the carb and freeing it off.
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Stu
Posted a lot
Posts: 2,913
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Wow, lots of replies! Yes, the fuel pressure was ok before I started messing today and I haven't changed anything in that area so hopefully that's not the issue. It does sound like a valve is stuck in just one carb as the left one is alright, just the right one is overflowing itself. I will check that out - will it be obvious how it works if I just take the top off the righthand carb? I'll try giving it a tap first though to see if that frees it up. Thanks for all the advice so far, much appreciated! Carbs are a mystery to me, ask me a Bosch k-jet question and I might have some idea!  |
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'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Its pretty obvious how they work when you take the top off, The float goes up and down which pushes a little valve closed when its at the top. Its quite common for them to get stuck open and get blocked by curse word in the fuel.
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Mr K
Posted a lot
Posts: 2,993
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nothing to do with the problem but:
could you not turn the banjo around on the left carb... so that the rubber fuel pipe can go strait to it rather than bending through 180 first?
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Davenger
Club Retro Rides Member
It's only metal
Posts: 7,272
Club RR Member Number: 140
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Like ScotsDave said, sounds liike the float is stuck in the down position and letting far too much fuel in
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Philj
Part of things
Posts: 898
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Did I miss the pictures of your golf? Gonna have a quick look for em, looks sweet as.
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nothing to do with the problem but: could you not turn the banjo around on the left carb... so that the rubber fuel pipe can go strait to it rather than bending through 180 first? It looks like it would foul the throttle linkage though. |
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Stu
Posted a lot
Posts: 2,913
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Apr 10, 2006 10:59:06 GMT
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nothing to do with the problem but: could you not turn the banjo around on the left carb... so that the rubber fuel pipe can go strait to it rather than bending through 180 first? It looks like it would foul the throttle linkage though. Yes, I looked at that so I could tidy up the way the fuel pipe runs but it would indeed foul the throttle linkage unfortunately. The previous owner who fitted the carbs had looked into a variety of options apparently but that was the only linkage he could get to work so the pipe has to be that way. Pesky 8v non-cross flow head puts the carbs at the back of the bay... a nice VW 16v engine would have them sticking out the front instead... ;D Phil - pics of the Golf in readers rides here, assuming this link works: retrorides.proboards29.com/index.cgi?board=readersrides&action=display&thread=1137865309I will check out the float valve thingymajig today, hopefully the stench of petrol has aired from the garage overnight, I was quite light-headed in there yesterday!  |
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'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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street
Posted a lot
6.2 ft/lbs of talk
Posts: 4,662
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Apr 10, 2006 11:46:34 GMT
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When you take the top off the carb, be very gentle. The floats are very easy to bend and upset the amound of 'droop' the floats should have. That means the distance between the the carb top and the floats resting position. They should be at 25mm (measured with the gasket in place) But if you take the top off carefully you wont have to worry about any of that. The bit your interested in is in the carb top, and its a spring-loaded needle valve attatched to the float. Just check to make sure its moving freely, give it a squirt of carb cleaner if is really gunked up. If it looks really worn and looks like its going to keep fouling up, I have a good second hand one you can have for nowt  |
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Stu
Posted a lot
Posts: 2,913
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Apr 10, 2006 14:32:19 GMT
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Thanks for all the help everyone, I think it's sorted now! I carefully took the top off the right hand carb and the two floats are on a mechanism attached to the carb lid, as described by a few people above. Anyway, all seemed to look ok so I just operated the float mechanism by hand a little bit and then carefully put it back together. It must have just got trapped or stuck somehow from my messing around. Turn on the ignition, pump primes but no excess fuel spraying everywhere, jobs a good 'un I think, starts up fine and back to normal... well, as normal as a 30 year old 3-speed auto hatchback with two whopping carbs is ever going to be... ;D There does seem to be a little leak from the manifold or carbs somewhere as when you rev it there is a bit of smoke/steam/exhaust gas (?) flying around in that area but I wonder if it's just spilt oil and petrol burning off the exhaust manifold? I will check everything is tight once it's cooled down. Also, still not very impressed with the brakes (remember, the brake servo is where this all started), the servo is now getting a very stong vacuum to it but the brakes are still rubbish so will need to investigate further. I will give the discs, pads, fluid, handbrake adjustment etc a once over and see how that goes.  |
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Last Edit: Apr 10, 2006 14:33:59 GMT by Stu
'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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Apr 10, 2006 14:51:18 GMT
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Have you checked the adjustment of the bell crank linkage (assuming the car is RHD)?
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Stu
Posted a lot
Posts: 2,913
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Apr 10, 2006 15:45:00 GMT
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Have you checked the adjustment of the bell crank linkage (assuming the car is RHD)? Yep, RHD. I did have a look at the cross linkage from the pedal box to the master cylinder and it looks alright, no play in it but I've not tried to adjust it or anything like that. What effect would adjusting it have, reduce pedal travel? I'm probably worrying about nothing, the brakes seem about as good as the ones on my Mk1 Polo were when first got that, before changing pads, fluid etc. I think it's just 'cos it's an auto it seems harder to make it stop! |
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'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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