Any Carburetted - Fuel On The Roof

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Mon 5 Aug 2019 08:13
Any Carburetted - Fuel On The Roof - edlithgow

Good name for a trendy South Bank restaurant? Perhaps it already is.

GF's thesis is finished so phase one of the (probably 5-Year) Plan to Catch my Kangaroo, I'm bypassing the fuel pump with gravity feed.

Have 2 cans of Guinness and 2 of Lager as extinguishants, but I'm thinking I should perhaps get more Guiness, which I think will work better.

I had the fuel pump delivering into the fuel can, but (presumably due to a lack of back pressure), it seems rather fast and would probably overflow the can if run for very long.

I assume its OK to completely block off the fuel pump (assuming I can)? There is a return pipe to I presume it'll all just go back into the tank.

Bit of trouble getting it to syphon, but that never seems to go like it does in the movies.

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Mon 5 Aug 2019 08:44
Any Carburetted - Fuel On The Roof - paul 1963

Sorry Edith you've completely lost me.....

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Mon 5 Aug 2019 08:55
Any Carburetted - Fuel On The Roof - Oli rag

I'm confused by the kangaroo part?

I would be surprised if you managed to get a syphon to work as the fuel tank is normally lower than the carb. If the can is some kind of header tank, you will still struggle to get a consistent flow from one to another without a pump or negative pressure in the line.

I know you seem to love a challenge and Heath Robinson / lateral thinking ways of getting around problems, but suspect you're on a wasted journey with this latest one. Good luck!

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Mon 5 Aug 2019 08:57
Any Carburetted - Fuel On The Roof - Bolt

Good name for a trendy South Bank restaurant? Perhaps it already is.

GF's thesis is finished so phase one of the (probably 5-Year) Plan to Catch my Kangaroo, I'm bypassing the fuel pump with gravity feed.

Have 2 cans of Guinness and 2 of Lager as extinguishants, but I'm thinking I should perhaps get more Guiness, which I think will work better.

I had the fuel pump delivering into the fuel can, but (presumably due to a lack of back pressure), it seems rather fast and would probably overflow the can if run for very long.

I assume its OK to completely block off the fuel pump (assuming I can)? There is a return pipe to I presume it'll all just go back into the tank.

Bit of trouble getting it to syphon, but that never seems to go like it does in the movies.

Lost me as well, but would suggest not playing around with fuel system as the vapour is a killer if not CAREFULL, but then you already know that, as for extinguishants, they are more likely to make a fire worse than put it out!

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Mon 5 Aug 2019 10:37
Any Carburetted - Fuel On The Roof - skidpan

I suspect that Edith has been drinking the petrol instead of the Guinness and Lager.

If he is being serious I am mighty pleased I am 12,000 miles away. Having a Molotov cocktail on the roof seems just about the daftest idea I have heard (if I have interpreted his post correctly.

Keep taking the tablets.

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Mon 5 Aug 2019 13:04
Any Carburetted - Fuel On The Roof - Bolt

I suspect that Edith has been drinking the petrol instead of the Guinness and Lager.

If he is being serious I am mighty pleased I am 12,000 miles away. Having a Molotov cocktail on the roof seems just about the daftest idea I have heard (if I have interpreted his post correctly.

Keep taking the tablets.

I think most of the posts are like that, but you need a comedian here sometimes lol

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Mon 5 Aug 2019 13:23
Any Carburetted - Fuel On The Roof - Oli rag
Ed Lithgow NOT Edith!
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Mon 5 Aug 2019 15:35
Any Carburetted - Fuel On The Roof - edlithgow
Ed Lithgow NOT Edith!

Thanks. Inclined to ignore those other people. Girls names huh?

Rather politicallly incorrect playground this.

It might not work, of course, but I have heard of it being done successfully in emergencies, one of them being the Japanese invasion of Malaya. Admittedly it didn't fix that.

A fuel can lashed to the roof isn't going to win any HSE awards but a "Molotov cocktail" it aint. Most likely hazard is a leak within the engine compartment, where there are ignition sources.

Re the negative pressure thing, I think that's how carburettors work, but it is a very weak negative pressure and won't be enough to start a syphon. i'll try that with a hypodermic syringe tomorrow. If I can't get that to work I'll give up. I'm not sucking on any petrol syphon tubes. Done that before and didn't like it.,

I rather doubt the fuel pump is responsible for the kangaroo-ing anyway, but I'd like to eliminate it if possible without too much agro. It gets mentioned on Internyet ""Ït could be" lists, but they are mostly these days talking about fuel injection, where the fuel pump is probably more critical.

I'll try the question again, as I'm here

Is it ok to block off delivery by the fuel pump, or is this likely to damage it?

My assumption is the fuel that would be pumped is instead diverted back to the tank through the return line. If I have to collect it things get more complicated and less safe.

Alternatively is there an easy reversible way to disable a mechanical fuel pump? Can't just take it of because that creates an oil leak. Remove the internal piston?

Edited by edlithgow on 05/08/2019 at 15:51

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Mon 5 Aug 2019 18:09
Any Carburetted - Fuel On The Roof - paul 1963

Firstly humble apologies, I browse this forum on my phone and I honestly thought your user name was "Edith Gow"!!!.

why exactly do you want to do this? seems a little odd tbh....

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Mon 5 Aug 2019 20:28
Any Carburetted - Fuel On The Roof - Bolt

if its the old lever type pump off the cam shaft it should be ok to disconnect the feed from tank assuming its not got a pump in the tank which I doubt

how many pipes has it got ie feed from tank and feed to float chamber only or has it a fuel return as well? ie 3 pipes, even then it should be ok if not left off too long as some used petrol to lubricate the valves, so if left dry too long they went brittle and broke

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Tue 6 Aug 2019 02:27
Any Carburetted - Fuel On The Roof - edlithgow

if its the old lever type pump off the cam shaft it should be ok to disconnect the feed from tank assuming its not got a pump in the tank which I doubt

how many pipes has it got ie feed from tank and feed to float chamber only or has it a fuel return as well? ie 3 pipes, even then it should be ok if not left off too long as some used petrol to lubricate the valves, so if left dry too long they went brittle and broke

Thanks.

There is what appears to be a return line, as I mentioned above.

TBH I hadn't actually considered disconnecting the feed from the tank.

DUH!. That'd be safer, but I assumed ithe pump would need the fuel for lubrication.

Yesterday I had it pumping back into the air bleed hole on my petrol can, but it seemed to be pumping dangerously fast, since the can is only 3L, with about 2L of fuel in it initially.

The syphon feed to the carb (from the fuel can spout outlet) wasn't established so it only ran briefly, presumably on the fuel in the float chamber.

I'll try blocking off the pump outlet and seeing if the return line will take full pump output without leaks. If that doesn't work I'll disconnect the fuel feed.

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Tue 6 Aug 2019 06:14
Any Carburetted - Fuel On The Roof - Bolt

if its the old lever type pump off the cam shaft it should be ok to disconnect the feed from tank assuming its not got a pump in the tank which I doubt

how many pipes has it got ie feed from tank and feed to float chamber only or has it a fuel return as well? ie 3 pipes, even then it should be ok if not left off too long as some used petrol to lubricate the valves, so if left dry too long they went brittle and broke

Thanks.

There is what appears to be a return line, as I mentioned above.

TBH I hadn't actually considered disconnecting the feed from the tank.

DUH!. That'd be safer, but I assumed ithe pump would need the fuel for lubrication.

Yesterday I had it pumping back into the air bleed hole on my petrol can, but it seemed to be pumping dangerously fast, since the can is only 3L, with about 2L of fuel in it initially.

The syphon feed to the carb (from the fuel can spout outlet) wasn't established so it only ran briefly, presumably on the fuel in the float chamber.

I'll try blocking off the pump outlet and seeing if the return line will take full pump output without leaks. If that doesn't work I'll disconnect the fuel feed.

Not certain what you mean by syphon feed to carb as float chamber is vented so you wont get a syphoning of fuel from above, the float chamber would have to be full without a vent to syphon any fuel but doubt volume of fuel would be enough even then

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Tue 6 Aug 2019 07:39
Any Carburetted - Fuel On The Roof - edlithgow

Worked fine (so far)

Got the siphon started with a 30 ml hypodermic. I'm initially relying on the tube self-sealing round the needle hole, which is a bit dodgy, but there didn't seem to be any seepage.

I'm using a cut-up renal dialysis set. These have injection ports in them, so if there was a problem I could probably cut up another. to get an injection port in the right place.

I put a line clamp that came with the set on the pump outlet tube to give control of its output, so I can use it to top-up the fuel can, which I put in front of the windscreen rather than on the roof, so Il'll be able to see whats going on.

Started it on butane since the float chamber was probably dry. Purred like an (OK, slightly bronchial) kitten, and revved ok,, but it doesn't turn kangaroo until its been driven for a bit.

That (which is obviously more difficult and dangerous) is next, once I've figured out how to secure the can. Safer to run it without the air cleaner since it wont get so hot and I can see better, but that is another variable, plus I don't actually LIKE running it without an air filter.

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Tue 6 Aug 2019 11:02
Any Carburetted - Fuel On The Roof - bathtub tom

Not certain what you mean by syphon feed to carb as float chamber is vented so you wont get a syphoning of fuel from above, the float chamber would have to be full without a vent to syphon any fuel but doubt volume of fuel would be enough even then

I don't see why it shouldn't work. The float needle valve should shut off the flow which would then continue once the float level drops. This system worked fine on old cars with gravity feed fuel supplies and they all had vents in the float chamber.

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Tue 6 Aug 2019 11:18
Any Carburetted - Fuel On The Roof - Bolt

Not certain what you mean by syphon feed to carb as float chamber is vented so you wont get a syphoning of fuel from above, the float chamber would have to be full without a vent to syphon any fuel but doubt volume of fuel would be enough even then

I don't see why it shouldn't work. The float needle valve should shut off the flow which would then continue once the float level drops. This system worked fine on old cars with gravity feed fuel supplies and they all had vents in the float chamber.

My point was, I didn't think or not sure if gravity fed fuel flow would have enough pressure to fill the float chamber as the fuel pump is a higher pressure, but as I`ve never tried it I don't know

but I doubt pressure will be high enough to keep revs up as it needs more fuel but will depend how high the container is from float chamber and its capacity

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Tue 6 Aug 2019 14:14
Any Carburetted - Fuel On The Roof - edlithgow

Got interrupted. Back at the car couple of hours later the siphon had gone dry and there was some seepage of petrol from the hypodermic hole in the hose, so I replaced that setup with one with a capped and tapped side branch (perhaps a sample port?) that I could more sustainably use to re-start the siphon

About 20 mins run up and down a quiet road, air filter off, max speed 80kph. No misbehaviour.

Put the airfilter back on for maybe 10 mins of similar (interrupted when I left the line clip on the fuel supply closed, which stopped the engine. Restarted OK from when clip opened).

Then it started to rain, no good because water will get in the petrol and the can is tied to the windscreen wiper, so I stopped under a bridge.

.Short burst of Kangaroo on driving away. I'd have liked to drive for longer to see if I could get iit to do it again, but a hefty incoming thunderstorm (typhoon) stopped me.

So not conclusive but looks like it isn't the fuel pump.

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Fri 9 Aug 2019 02:49
Any Carburetted - Fuel On The Roof - edlithgow

Weathers been unsuitable for further test drives (getting clipped by Lekima. Nothing extreme round here so far but too unpredictably windy and rainy).

Got nervous about leaving the tubing exposed to petrol long term. (Really don't want dissolved plastic in that carb, which has clog-tastic sintered metal bits in it. Amazed they put it in Landcruisers.). Tubing seems OK apart from some discoloration but there was embrittlement of harder threaded plastic parts like sampling ports, Even Scotty Kilmer doesn't have 98 octane in his veins.

So I took iit all off. Just have to stay inconclusive for now.

I did note when using the fuel pump to top-up the gravity feed can that there were a lot of bubbles in the line, though this could be the ole Heisenberg Principle at work.

If there's a next time, I might just replace the feed from the pump with some transparent tubing, rather than the full gravity-feed monty. See-through air filter housing could also help see whats happening if I can score some thickish perspex.

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