Arrrrgh!, engine full of fuel !!

Discussion in 'Mech Tech' started by redgaz, Aug 25, 2019.

  1. redgaz

    redgaz Supporter

    Bloody Hell !, just been out to the van after doing carb re-build yesterday, i fitted new diaphragms, float valve etc. I was about to remove top of carb (Solex 34 pict 3) to check float level but have fuel dripping out of spindle bush and the dipstick is full to the very top, inches over full mark with fuel !. The fuel tank is full.
    About to go back out and remove top of carb. any advice appreciated.
     
    Merlin Cat likes this.
  2. Don't start the engine. I would clamp the fuel hose below the tank so no more fuel can flow to the carb. Drain the sump of all fuel oil mixture. Disconnect engine battery earth lead so cannot start engine by mistake.

    We assume the carb didn't leak before your refurb? or was their a fuel problem hence your attempt to cure it.

    Leaky carb is a common fault posted on here and the experts will be along to advise about setting float height, renewing spindle bushes and so on.
     
    F_Pantos, scrooge95 and Merlin Cat like this.
  3. Merlin Cat

    Merlin Cat Moderator

    Ooh I had that and followed advice on her to NOT start it. I got it tow trucked to the garage. They couldn’t find what had caused it, maybe because I also followed hit the carbs with a spanner advice :)

    Bits were replaced and hopefully it won’t happen again. Tho I do check dipstick regularly, just in case.
     
    Valveandy and F_Pantos like this.
  4. mikedjames

    mikedjames Supporter

    I expect that either the new valve got a bit of dirt in it or had dirt in it from fiddling with hoses, or you assembled the carb with the rectangular plastic piece under the float pivot rather than placed on top of it, or your new float has moulding flash on it and it wedged on the side....


    If you still have the old float and valve, and it wasnt leaking, use it.


    Rule 1. Only change what is broken, rather than replace what you can buy as new spares.
    Be wary until the EMPI supply chain
    is flushed clean of very cheap EMPI stuff. Buy the expensive stuff, hopefully the new owners will mark the new improved parts packaging differently..

    Dont start the engine, dump all the oil and replace it with fresh.
     
    F_Pantos likes this.
  5. redgaz

    redgaz Supporter

    Thanks all, just took carb off and removed lid, new float valve seems ok blowing down it etc. Fuel level a few mm low but would have to re check that at a later date. I've fitted a 1 mm pacer instead of 0.5 mm spacer because of thick lid gasket.
    Constant drip from squirter at the top of the carb so as you said Mike i'll re fit old diaphragm and leave off 1 mm thick gasket which may have been causing the drip.
    The carb was dripping fuel before rebuild. See my last thread, Accelerator diaphragm gasket.
    Going back out to drain and renew oil.
     
  6. Barry Haynes

    Barry Haynes I dance in leopard skin mankini’s

    What fuel pump have you got, the Weber 34 ict has to have a low pressure fuel pump and can't really handle anything over 2 PCI or it will over fuel
     
  7. also do you have a fuel filter, I would replace with a nice big new one placed under the fuel tank outlet. the carb needle valve is sensitive to bits of rust from the tank or bits of rubber fuel hose and easily sticks open. how old is your fuel hose?

    when you have drained and replaced the oil and started the engine, I would switch off and take lid off the carb and see what fuel level is, and look for crud at the bottom of the float bowl, should be clean and fuel nice and clear.

    also you said the fuel tank was full so the head of fuel would put more pressure on the float valve. Is your van parked front higher than the rear?
     
  8. redgaz

    redgaz Supporter

    It's a Brosol fuel pump, haven't checked the pressure, what if it was too high, what can be done?.
    Fuel hoses fairly new, look ok.
    There is a larger type fuel filter fitted under the fuel tank which was removed and cleaned out a few years ago.
    Drained oil/fuel from sump, about 6.5 litres !!, mainly fuel.
    Wondered if float level can be bench tested by putting fuel into carb with a pipe etc while the carbs off.
    Very wary about re fitting this carb, thought about buying a new one outright . Are any of them out there any good?.
    The van is parked level, maybe slightly higher at the front but not much really.
     
  9. Check your new carb lid gasket.
     
    paradox likes this.
  10. redgaz

    redgaz Supporter

    Gasket is ok, checked float level with carb in vice, correct height with 0.5 mm spacer.
    The thing i don't get is that the accelerator pump does not squirt fuel out of the top nozzle when activated with carb full of fuel, am i missing something?.
     
  11. Is the inlet hole at the bottom of the float chamber bunged up? The acc pump should give a healthy jet of fuel straight down the throat of the carb if you operate the throttle/pump by hand.
     
  12. redgaz

    redgaz Supporter

    Inlet hole?, not sure what you mean. I'll have a look.
     
  13. mikedjames

    mikedjames Supporter

    There should be a little hole feeding into the pump from the bottom of the float chamber.
    Maybe some dirt has wedged in the galleries feeding the pump, I think theres meant to be a ball bearing rolling around in one of the channels that acts as a one way valve. It should rattle..
    Also there needs to be a spring in the accelerator pump to push the diaphragm back against the lever. Miss that out, fit diaphragm, wont leak but wont pump either.

    Despite everything, the original carburettor is likely to be better than any new copies of it.

    Sometimes these leaks are one off because of dirt. What I did on recommendation from Scott at SGS Aircooled was to fit a fuel shutoff solenoid under the bus so that the fuel pump feed was blocked with the ignition off. Then it gets almost impossible for a carburettor to leak onto the oil even when it has a problem.
    That was because I use a Weber progressive carburettor which are even more prone to leaking because the Weber needle valve seems more prone to wearing with vibration.
     
    Faust likes this.
  14. At the bottom of the float chamber there’s a brass plug. From memory, near that there’s a teeny hole, the inlet for the accelerator pump. The plug in theory is removable, but I wouldn’t try it. Blast some carb cleaner in that hole, or better still take the acc pump diaphragm off and blast it from the other side.

    The pump should shoot a solid jet of fuel straight down the carb (mind your shoes :)), just missing the opening throttle plate if the nozzle’s correctly positioned.
     
  15. While the carb is off, I would spend time cleaning the crud out of it. Re the fuel filter. I would replace the in line fuel filter under the tank. I have a Meyle big plastic filter they are cheap and you can see when they get crudded up. I replace mine every 2 years minimum. Its an important component.

    Even if fuel hoses look ok, they don't seem to last, I would replace them while you are at it. Lots of advice on here as to best fuel hose.

    It seems to me your original problem could have been crud in the fuel which has clogged up the carb and some stray bigger bits caused the float needle valve to stick open causing flooding. Its all a common problem on here.
     
  16. redgaz

    redgaz Supporter

    Mike, Snotty, i'm going from bad to worse !, tried blasting it with carb cleaner , diaphragm on and off several times to no avail, i think maybe that ball bearing is sticking, so carb wise i think i'm stuffed.
    I've drained the oil which was mainly fuel and have left it to drain/ air off overnight.
    I'm beginning to think that with that much fuel in the sump maybe the fuel pump is faulty.
     
  17. redgaz

    redgaz Supporter

    The carb has been on and off and a few times recently, engine had new barrels, pistons and heads only 400 miles ago.
    As i said i'm beginning to suspect the fuel pump more and more after much research but who knows . :(
    And now the carb is unusable as is. Hey Ho.
     
  18. Don't worry many of us had same issues, you will get it sorted.

    I wouldn't assume its the pump. Your fuel pump, is it a mechanical one sat next to the distributor? Original ones last a very long time but they are known to get perished diaphragm which would leak fuel down into the sump and oil. The stock mechanical pump may be delivering too much pressure, not likely though but can be adjusted via the push rod and gaskets. Electric pumps can deliver too much pressure and folks then have to fit a pressure regulator, more complication.
     
  19. redgaz

    redgaz Supporter

    I think i'll fit a new pump as a matter of coarse and check the pressure when i can get the thing running again.
    My real problem though is the carb !, i cannot get the accelerator pump to work whatever i try, shame because the carb re-build itself went quite well.
     
  20. Try filling the bowel with carb cleaner and leaving it overnight. There’s nothing really in there apart from as I recall a small ball bearing. Hard to imagine it’s truly stuck.
     
    mgbman likes this.

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