Fuel spill

[Ian Foster]

2 hours ago, johny said:

possible to clamp the rubber pipe before the filter?

I have fitted an inline tap just upstream of the fuel filter, which allows the fuel to turned off for filter changes.

Ian

[micmak]

Good idea.  At some time in the future, I think I will put a tap/valve at the tank end of the line.  If the line is ever damaged along the length of the car, I can shut off the fuel and replace the line.  It probably would have been a good idea for the tank to have a built-in tap/valve on the supply line coming off it.
Today, I had to deal with trying to slip the line into a section of hose while the fuel was pouring out all over my hands and sleeves and onto the floor.  Messy, but there was really no alternative.

…..Mick…..

[micmak]

21 hours ago, dougbgt6 said:

 Mick,

You display remarkable resilience, my own GT has a number of issues, but will remain untouched in the garage till March/April 

Doug

Thanks for the positive comment, Doug.  I'm not sure if I agree with you;  I often leave the car for days or weeks without touching it, so I am not as dedicated as you suggest! 

Thanks anyway!

.....Mick.....

 

[micmak]

Well guys, I was out playing with the car again today. It started perfectly. It ran with much less choke than before, which indicates to me that it was indeed two lean before. Now that it is running a little richer, it doesn’t need as much choke, and it can run with much lower revs when the choke is on compared to when it was leaner.   So far so good.  I was able to gradually push in the choke as it warmed up. When I reached the point where it was warm enough to run with no choke at all, it idled just beautifully. I let it run for a few minutes. Then I noticed drip, drip, drip, once again. I examined exactly where the drip was coming from and it is indeed from the air filter. I had a good look at the brass jet housing on both carbs, they were both dry.  I turned off the engine, removed the air filter, and took it apart to let the air dry it all out. Then I looked back at the carbs, only to realize that this time it was actually the front or RHS carb that was overflowing. It gave the impression that it was the left-hand side carb, but in actual fact, the front carb was really drenched in fuel all around the air intake port. I guess it was puking out there and trickling down the housing of the air filter to its lowest spot, which is closer to the left-hand side carb, and dripping from there. So, as I said yesterday, I am back to square one with this problem. I started this thread because of an overflowing carb bowl. And here we are back at the same problem again. What is causing this? I wish there was some way to throttle down the fuel pump. Or is it just a matter of turning back the jet screw a tiny, tiny bit again until I reach that sweet spot between running well and overflowing?  By the way yesterday, when I adjusted both carbs, I only opened the brass screw jets, about a quarter of a turn. I suppose logically, I should turn it back the opposite way about an eighth of a turn. Unless some of you have some other solution.

Edited November 28, 2023 by micmak

[johny]

The mixture adjustment should have no relation with the overflowing of the float chambers which is due to the float valves not shutting off the incoming fuel.

We have found on here that mechanical fuel pump output pressure is adjustable by using packers between the pump body and block. The further the pumps operating arm is moved away from the cam that moves it the less the pump internal spring is compressed and as its this that pushes the fuel through the less pressure it will exert. Obviously if you go too far with this process then youre likely to not have enough fuel flow for high demands such as fast up hill runs... 

[Stratton Jimmer]

Johny is right. I had a problem with the mechanical fuel pump overpowering my float valves giving the symptoms that you describe and solved it with 3mm of additional gasket between the pump body and the block. Later, once I had rebuilt the carbs, changed the rubber pipes for Gates Barricade, installed an additional fuel filter just before the carb's "Tee" piece and gotten rid of every last miniscule rubber speck I was able to remove the additional gasket and all is now well.

[Pete Lewis]

on the side under the air piston diahragm casting is a lifting pin ,has a small return spring  on it 

you need filters on for this test

while idling you carefully raise the pin till it just feel it touch the piston 

then raise it 2mm

if there is a hint of increase idle its rich

if it faulters a little  its lean 

if nothing happens its about right

do not expect any radical change  more like a 50 rpm shift up or down 

if you yank the pin up fully it will just stall   so its a touchy feely job

as Jonny says mixture adjustment and settings have no effect on fuel levels and flooding 

good place for pictures and how to is Mechanical Tech Articles — Buckeye Triumphs  carbs 

this is aimed at TR but the basics are all relevant

 

[dougbgt6]

As already said mixture adjustment has no effect on fuel in the reservoir. The pump sends the fuel and the needle valve and the float regulate the level of fuel in the reservoir. If it's only happening on one carb I would suspect the valve and/or float.

The float could be stuck down leaving the valve open. OR the valve is stuck open. Is the float moving freely? Is it on the right way up? This can happen very easily during re-build and not be noticed.

I only discovered recently floats are solid, I had previously though they were hollow and could be punctured. I'm still not sure there aren't some hollow ones about, a puncture would of course stop the thing working.

The valve could be stuck open with debris. OR it's just no longer any good at it's job. This last happened to me a long while back, I changed them both - not expensive.

Doug

Edited November 28, 2023 by dougbgt6

[Iain T]

If you take the float chamber off to clean or change the valve measure the float height which should be 18mm.

Iain 

[johny]

This has been happening since early August so hopefully everything spotless now and reducing fuel pressure last resort...

[daverclasper]

Could a hose be partially clamped somewhere (before, or after?) along the fuel line to temporarily reduce fuel pressure/amount of fuel to carbs. If the car then runs ok  (at higher rpm as well) with no leaks, then maybe pump providing too much pressure?.

I assume?, a needle valve not sealing well would leak as the the pump works harder, so could be better with line clamped, though still providing enough fuel for running, even if the pump was providing usual pressure?

I'm no expert, so maybe BS?  

[Peter Truman]

Not micmaks problem but I’ve had similar issues with the front carb on my Mk2 Vitesse dripping but my issue has been the lack of car use and the gummy nature of modern fuels even 98 octane here in Aus the float valve sticks (push it up and it stays there) and needs cleaning through with carby clean then all’s OK.

I’ve got a dab hand at removing the float bowl and unscrewing the float valve insitu I’ve replaced the float bowl screws with Allen headed bolts and have a  modified small friction ratchet to make the float bowl removal easier

[Pete Lewis]

Doug mentions upside down floats    yes 

if the float has two valve operating arms they can be fitted upside down 

there are pictures in the buckeye site to show these and which way up they  should fit 

Pete

[micmak]

OK Guys, it seems to be everyone’s opinion that the fuel mixture has no impact on the overflowing problem.  As the mix seems pretty nice now, I will leave it and look elsewhere for the cause of the problem. 

The floats are moving freely, on both carbs.  They were when I had the carb bowls off a couple of months ago.  A couple of months may sound like a long time ago, but it is only about 10 or 12 miles ago!  Everything seemed ok at that time.  When this originally happened, it was the LHS carb that was overflowing.  Today it is the RHS carb. When I had both bowls off before, they were spotless.  The mesh in the fuel pump is spotless.   And, if there was dirt keeping the valves open, surely they would leak 100% of the time that the engine is running?  But there is only a leak when the choke is pushed off and the engine is warmed up to normal running temperature.  

It seems to me that when the choke is pushed off, there is less need for fuel.  But the pump is still supplying the same volume of fuel as when the choke is calling for an excess amount.  So, could it not be that the pump is supplying too much fuel for normal warmed-up operation, resulting in spill over? 

If I were to add gaskets between the block and the fuel pump, where would I get them?  Rimmers or one of the other suppliers, or can you make them up yourself?  How do I decide how much of a “space” I need between the block and the pump to reduce the pressure? I am guessing its matter of trial and error?  

Maybe, before I go down that road, I might take the bowls off again and measure the float height.  Maybe I should eliminate that before I go messing with the pump.

[micmak]

2 minutes ago, Pete Lewis said:

Doug mentions upside down floats    yes 

if the float has two valve operating arms they can be fitted upside down 

there are pictures in the buckeye site to show these and which way up they  should fit 

Pete

I will check for that tomorrow too.

 

[Pete Lewis]

as a trial  cut  some packing   gasket from an cornflake packet or similar 

anyone you can borrow a low pressure gauge from ????

rubber sliver pests wont get in the float bowl they hide in the supply pipe and float about in the flow and 

find their way into the back of the needle valves   small orifice.

crafty little sods ,cause havoc  

if the pump looks newish then excess pressure are a well known headache 

Pete

[micmak]

8 minutes ago, Pete Lewis said:

as a trial  cut  some packing   gasket from an cornflake packet or similar 

anyone you can borrow a low pressure gauge from ????

rubber sliver pests wont get in the float bowl they hide in the supply pipe and float about in the flow and 

find their way into the back of the needle valves   small orifice.

crafty little sods ,cause havoc  

if the pump looks newish then excess pressure are a well known headache 

Pete

The pump does indeed look new.  The car had a full restoration and has only done just a few hundred miles.  I will take the bowls off tomorrow and check once again for slivers around the needle valves.

If making gaskets out of cornflake boxes will suffice, then that will be my next step after tomorrow’s sliver search!

.....Mick.....

[Iain T]

Am I right in saying around 3mm thick packer is a good start? Frosties packet must also work but if you want a low sugar option try Quacker Oats😂

I gave up and fitted a Huco low pressure electric pump. Primes the bowls nicely. 

Iain 

Edited November 28, 2023 by Iain T

[johny]

2 hours ago, daverclasper said:

Could a hose be partially clamped somewhere (before, or after?) along the fuel line to temporarily reduce fuel pressure/amount of fuel to carbs. If the car then runs ok  (at higher rpm as well) with no leaks, then maybe pump providing too much pressure?.

I assume?, a needle valve not sealing well would leak as the the pump works harder, so could be better with line clamped, though still providing enough fuel for running, even if the pump was providing usual pressure?

Nice idea Dave and its basically what a fuel pressure regulator does but cant when the float valve closes because its impossible to reduce pressure when theres no flow. The pump spring gets compressed by the cam lever and then when released tries to push fuel against the shut float valve so the pressure depends on the strength of the spring. No matter how much you restrict the pipe the pressure will be the same all its entire length... 

[dannyb]

Are the fibre washers in place on both valves. As fuel can get past the threads and it also affects the float hight if missing.

I've also had a new mechanical pump in the past intermittently putting out high pressure.  Found this when fitting a pressure gauge to test it. The pressure fluctuating between 2 and 9 pounds.

Danny

[Pete Lewis]

the spec is normally around the 2.5psi     

so at 9 you will certainly overtake the float and valve 

doesnt surprise me there have been so many reporting new pumps being silly high pressures 

down to eastern promise copies with no regard to any specification 

i guess if you can swap the spring from the  old unit .

Pete

[micmak]

16 hours ago, Pete Lewis said:

as a trial  cut  some packing   gasket from an cornflake packet or similar 

anyone you can borrow a low pressure gauge from ????

rubber sliver pests wont get in the float bowl they hide in the supply pipe and float about in the flow and 

find their way into the back of the needle valves   small orifice.

crafty little sods ,cause havoc  

if the pump looks newish then excess pressure are a well known headache 

Pete

Pete, will cardboard  really work?  I just looked at a cereal box a moment ago, and I measured the thickness with a calliper.  I will need about 5 or 6 pieces sandwiched together to get between 2 and 3 mm. Surely that will allow a serious leak down the side of the engine block?

.....Mick.....

 

Edited November 29, 2023 by micmak

[johny]

yes this is just a trial and if it works youll need to get some proper gasket material...

[micmak]

28 minutes ago, johny said:

yes this is just a trial and if it works youll need to get some proper gasket material...

OK, thanks Johny.  I will check the float valves first (to be totally sure they are not upside down) and also try to make sure there are no slivers in the line to the carbs. 

Thanks.

.....Mick.....

[dougbgt6]

And as Danny says check the washers are there between jet and carb body. the jets will only properly seal with washers.

 

Doug