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Thread: 45 DCOE Unexplained Leak

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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    45 DCOE Unexplained Leak

    After running my Pinto I noticed a pool of petrol under the engine. On investigating I could see drips hanging off the bottom of the carbs just behind the rubber soft mounts. As the car had not been run for a long time I decided to pull the carbs off, replace the needles and check the float levels just in case. Float levels were bang on. I reinstalled and without even turning on the electric fuel pumps one of them started to leak (gravity filled the float bowls). Upon looking I could see the rear most carb was leaking alot of fuel from the auxillary venturi bolts on the rearmost cylinder only. ahhhhhh

    It is leaking on one choke only so I am very confident I do NOT have a float level issue (gravity pressure only, floats set correctly and new needles).

    I have read through my Weber book but cannot identify any reason. The aux venturi bolts were both snug but there is no fuel flowing there anyway.

    I did think about connecting a gravity fuel feed into the carbs on the bench so that I can see if I can ID where the fuel is exactly coming from.

    I did not use any of the other parts from the rebuild kit other than the needles and top cover gaskets so maybe there are other worn parts (although these are only 5 years old and not very used).

    Can anybody help me as I have an event coming up FAST!
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Been sitting researching and thinking. The one thing that I have changed between no leaks and leaks is the cold start system. I have added a cable to the 2 cold start levers that can be operated from inside the car. I am yet to work out how but maybe this is causing it? I know that the lever on the carb that is leaking is not returning completely back to the stop although is extremely close. Maybe coincidence? Just thinking out loud.........
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Have you checked that the needle valves cannot "drop" too much?
    If it does it can stick keeping the valve open.
    Bending the tap on the float mechanism stops the float from dropping too much.

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    Re: 45 DCOE Unexplained Leak

    I adjusted the droop to the recommended setting (25mm) but will take a close look at things. As only 1 barrel has a leak I doubt that is the answer though but will look.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Just to close this thread off and prevent me having to talk to myself more, I fitted a few more rebuild parts and there are no leaks now.

    One of the aluminium washers on the #4 (the leaky cylinder) pump jet was doubled over meaning the jet was not sealing. This probably accounted for alot of the fuel leak. I also think that when I tested the throttle opening it must have pumped alot of fuel into the barrels that eventually leaked out.

    I rechecked the float drop Miniliteman and all was good on that score.

    Anyway, problem solved.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    OK I may have spoken too soon. The carbs are again leaking but this time it is coming out of the filter bottoms only. My suspicion is that as the shed has warmed from 12 degrees to around 26 degrees the fuel in the bowls has expanded and raised the bowl height enough to cause a leak. There were definitely no leaks evident for an hour after reinstalling them and the leak is only enough to soak the filters and not to drip on the floor yet. I have deliberately not opened the throttles since installation.

    I had the floats set spot on previously but when I now remove the main jets and measure down to the fluid level I am seeing around 23mm which seems a long way from the 29mm I expected. These are Spanish 45 DCOEs so not sure that the 29mm figure is correct. Thoughts??
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Hi mk 1 oz check if the float bowls have holes in them and makes them more heavy causing high fuel level in carbys weber proformance web site has the weight of the float hope that helps cheers Mario. Spanish webers have plastic float they can absorb fuel get heavy.

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    Re: 45 DCOE Unexplained Leak

    What presure are you running?

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    Re: 45 DCOE Unexplained Leak

    I have a pressure transducer that shows 3 - 3.5psi and an analog gauge showing 2.5 - 3psi. The Holley 1-4psi regulator is screwed as low as it will go so I am confident the pressure is low. However, all these issues seem to have started since I 1) rebuilt the Holley blue fuel pump and 2) LOWERED the pressure by adjusting the regulator. It is possible that in changing the reg that I damaged it/it broke. I plan on using a third gauge (if I can find it) to measure the pressure once more. Testing the carbie needles with the tops off the carbies shows that the needles both will take a high amount of pressure (= me blowing into the fuel inlet).

    I decided to take the manifold and carbies off the engine and I am so glad I did. Inlets # 2 & 4 were FULL of raw fuel but by some will of Allah or some other the inlets were closed. If I had cranked the engine it may have been a sad day!

    I have now mounted the carbs/manifold to an old stock Pinto I have. I connected the fuel line and watched what happened when the fuel pump was turned on. Fuel FLOWED out of the #2 & #4 aux venturi!!!

    I measured the fuel height down the main jet tube whilst the pump ran and lo and behold it got higher and higher. When I turned the pump off it settled to a slightly lower level. 100% the fuel leak is via the aux venturi and this can ONLY mean that the fuel is somehow flowing past the needle. I have 3 situations that I can think of;
    1. the fuel pressure is too high (and would need to be significantly high)
    2. the needle is not seating correctly
    3. the floats are getting caught on something and holding the needle open

    I will have to test the heck out of things until I find the answer. Getting very annoyed with having contradictory hypothesis and results grrrrrrrrrrr
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    hi mk 1 oz

    holley blue fuel pump have to much fuel pressure

    you need a holley red fuel pump and reg

    a holley blue reg is nogood thats why you got it screw down all the way

    you need to run a pump with no reg like a carter fuel pump thats what i use

    cheers mario.

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    Re: 45 DCOE Unexplained Leak

    i have a holley blue pump with a holley 1-4 psi regulator. has been working for 6 years.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Needle and seats must be worn out then if running at 3 psi cheers mario

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    Re: 45 DCOE Unexplained Leak

    brand new needle/seat. I have alot of investigating to do.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    If all parts are good shape the DCOE can cope with high fuel pressure.
    We used to run a set of twin Webers straight off a Facet Red Top pump on the dyno.

    Maybe replace older / replaced parts back into carbs and try again.

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    Re: 45 DCOE Unexplained Leak

    The fuel should stop soon as the float makes contact with the ball bearing,

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    Re: 45 DCOE Unexplained Leak

    Do you have a small washer behind the neddle valve housing nut?

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    Re: 45 DCOE Unexplained Leak

    I thought maybe Rick was on the money as i did not put a new aluminum washer under the needle. The old one was still there although not in good condition. I put the new one in with big hopes but no change.

    To totally eliminate needle and seat issues i took the carb top off and connected the fuel line. The electric pump was NOT over powering the seat i.e. no fuel flow so i am happy the issue is not there.

    I have now decided to stuff the stated float heights as measured with a ruler from gasket to float. I am trying to move the floats to whatever position gets me 25mm as measured down the main jet tube. Anybody see an issue with that???

    Question: are the 2 sides of the float chamber linked i.e. can the float heights for adjoining main jet tube be changed independently?? The reason i ask is that there seems to be little correspondence between the 2 heights. My carbs are sat at the max forward/ backwards angle of 5 degrees with similar side to side angle. If the float chamber is one big one then i would expect #2 and 4 to be slightly higher than 1 and 3.

    I really am over this now. It appears i have narrowed the issue down to pure float height.......
    Last edited by MK1_Oz; 12-10-2018 at 03:17.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Main jet tubes 13mm apart with 5 degree angle => fuel height difference in tubes 1.14mm (Tan(5) x 13). Useful info.

    Just looked harder and the float bowl acts as one large bowl.

    Why I am seeing bigger differences in float height is unexplained - could just be variations in measurement by me.
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    hi mk1 it can leak fuel through the cold start unit. the choke unit you can buy kits to deleate it, if car starts ok with out choke cheers mario.

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    Re: 45 DCOE Unexplained Leak

    Pretty sure it is not the cold start unit as the outlet for that is the engine side of the butterfly and I have watched the fuel leak out of the aux venturi. However, I have considered a deletion kit just in case but it looks like the kits requires drilling and taping so not keen just at the minute.

    I appear to have found the issue. Although I cannot be 100% sure it appears that both the floats have been hanging up at times resulting in either an open seat (float not rising) or a closed seat (float not falling). This was why I was getting such random results when measuring fuel levels. I managed to work this out by poking some solder wire through a slit in the top cover and physically pushing the float a little. Maybe when driving the vibrations are enough to force the floats to move.

    Anyway, I now have carbs that don't leak but I do now have a car that coughs and jerks when driving. I have set the floats to 25-26mm so doubt it is them causing it. The float level is only critical for the main circuit operation anyway which is not used until high revs or WOT.

    Off to fix the next issue.............
    1970 Mk1 Escort Tarmac Rally Car

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    Re: 45 DCOE Unexplained Leak

    Main circuit comes into play around 2500rpm

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    Re: 45 DCOE Unexplained Leak

    Quote Originally Posted by Erikmex View Post
    Main circuit comes into play around 2500rpm
    what he said the main circuit comes into play way before WOT or high rpm, what do you think supplies the fuel once you get past the progression holes?

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    Re: 45 DCOE Unexplained Leak

    hi mk1

    what size mains and emuslion tubes and idle jets are you using may be able help you will your fault cheers mario.

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    Re: 45 DCOE Unexplained Leak

    Righty-oh. Fixed the spluttering issue. Nothing to do with the carbies but rather the digital controller that operates the EWP and engine fan. It is allowing rogue signals into the ground circuit that it causing all sorts of issues - the tach needle swings wildly, the electric fuel pumps come on when they should not and the car splutters. All narrowed down to all the faults occurring when the EWP was being powered. I took a look with the Picoscope and sure enough the ground is very dirty. The tachometric relay on the fuel pumps was receiving a signal everytime the EWP operated and put the pumps on even if the engine was stopped. Talk about a wild goose chase!!!!!!!!!!

    Fitted the old controller and the car is perfect again. Part sent off for warranty........
    1970 Mk1 Escort Tarmac Rally Car

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