HIF6 carbs. petrol overflowing on Princess 2200

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Dave289
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HIF6 carbs. petrol overflowing on Princess 2200

Post by Dave289 » Sat Jul 13, 2019 12:21 pm

It started with petrol pouring out of the overflow tube on the nearside carb. on my Princess 2200.

I dismantled and cleaned both carbs., and noticed that on both carbs., the float level was set much lower than it should be, so I set it correctly.

Then I had petrol pouring out of both overflow pipes (within 5 to 10 seconds of starting the engine) :-(

Dismantled again, reset float levels to where they were, still perol pouring out of both carbs. overflows.

Although neither of the floats appeared to be faulty and the needles valves & seats appeared to be clean (there was a small amount of dirt in the float chamber, cleaned out on the first attempt), I invested £50 in a set of brand new floats, needle valves and seats and fitted these yesterday - but petrol is still pouring out of both overflows, both with the float levels set correctly and with them set very low (so the floats hardly move upwards before the needle valve is shut off).

On the Burlen SU web site, they say "Assuming that the float height setting is correct, the normal cause of flooding is a small amount of dirt (i.e. rust) lodging in the float needle valve, preventing it from closing. Fuel continues to fill the float chamber, eventually overflowing or ‘flooding’. The cure is to remove the float lid and clean out any dirt from the fuel line/needle valve and reassemble.
Another cause of flooding, often mistaken for an over high fuel pump pressure, is caused by air trapped in the float chamber. When fuel is fed into the float chamber it rises and the float shuts off the needle valve. If, however, the chamber air vent is blocked, the fuel rising compresses the air in the chamber and fuel is forced out of the jet at pump pressure."

Does anyone know where the chamber air vent is located, so I can check if that is blocked ? (although the petrol is being forced out of the overflow pipes, not the jets).

I need to get the car sorted ready for the Festival Of The Unexpected next Saturday, but I'm at a loss here - does anyone else have any ideas ?
2003 Renault Grand Espace 3.5
2001 Cadillac Seville STS 4.6
2002 Lexus IS200
1977 Princess 2200HL
1980 Austin Maxi 1750
1979 Triumph TR7V8 DHC
1994 Rover Metro 1.4Li
2009 Graber La Bala 4.6
1986 Lincoln Excalibur 5.0 limo
1931 Jowett Kingfisher

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Gasman
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Gasman » Sat Jul 13, 2019 6:26 pm

I had a similar problem some time ago. I also changed floats, needle valves and seats and it still flooded. I didn't check the fuel pump pressure (I'd also fitted new fuel pump) but sorted it by putting a (variably) pressure reducing valve in the fuel line. I have since removed that without a re-occurrence of the problem! So I don't know what caused it.

The flooding the Burlen site is talking about is flooding the engine caused by the overflow vents being blocked & pressurising the main jets, which yours obviously aren't.

Do you have a fuel filter (it wasn't standard)? If not, you should fit one to ensure no dirt can clog the needle valve.

I'm sure this won't be the cause but it is possible to fit the floats in upside down which would cause this problem!
Martin
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Owner of:
Oldest known surviving wedge, hand-built 15th Pre-Production Wolseley in June 1974
Last Ambassador down the line in November 1983, Austin Ambassador VDP

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Peter Laursen
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Peter Laursen » Sun Jul 14, 2019 9:55 am

I suppose, you are sure, the floats are not punctured? I think the Burlen comments are for HS6 carburettors, as the mention a lid on the float chamber, and there is an air vent in the lid.
If you are sure, the needle valves close, I can only think of too high fuel pressure.
Although it may not be of any use to you now, I got fed up with having til remove the whole HIF carburettor assembly every time there was a problem, so I installed the HS6 carburettors as used for the Landcrab 2200.
Peter
Princess 2200 HLS 1975
Morris 1800 MK1
Wolseley 18/85 MK1
MGB Roadster MK1

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Dave289
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Dave289 » Sun Jul 14, 2019 11:43 am

Gasman wrote:
Sat Jul 13, 2019 6:26 pm
I had a similar problem some time ago. I also changed floats, needle valves and seats and it still flooded. I didn't check the fuel pump pressure (I'd also fitted new fuel pump) but sorted it by putting a (variably) pressure reducing valve in the fuel line. I have since removed that without a re-occurrence of the problem! So I don't know what caused it.

The flooding the Burlen site is talking about is flooding the engine caused by the overflow vents being blocked & pressurising the main jets, which yours obviously aren't.

Do you have a fuel filter (it wasn't standard)? If not, you should fit one to ensure no dirt can clog the needle valve.

I'm sure this won't be the cause but it is possible to fit the floats in upside down which would cause this problem!
Many thanks for your ideas.

The fuel pump died at the end of last year, so I fitted a new one (mechanical, £15 on eBay) and a clear plastic in-line fuel filter then. We have done about 200 trouble-free miles since, and the flooding suddenly started last weekend when we got the car out of the garage to clean it for Gaydon.

I'm certain that I didn't fit the new floats in upside down (they are the same way up that the old ones were, but maybe they were fitted wrongly ?), so am off to check that now, and buy a pressure reducing valve on eBay.
2003 Renault Grand Espace 3.5
2001 Cadillac Seville STS 4.6
2002 Lexus IS200
1977 Princess 2200HL
1980 Austin Maxi 1750
1979 Triumph TR7V8 DHC
1994 Rover Metro 1.4Li
2009 Graber La Bala 4.6
1986 Lincoln Excalibur 5.0 limo
1931 Jowett Kingfisher

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Dave289
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Location: Colden Common, Winchester
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Dave289 » Sun Jul 14, 2019 11:57 am

Peter Laursen wrote:
Sun Jul 14, 2019 9:55 am
I suppose, you are sure, the floats are not punctured? I think the Burlen comments are for HS6 carburettors, as the mention a lid on the float chamber, and there is an air vent in the lid.
If you are sure, the needle valves close, I can only think of too high fuel pressure.
Although it may not be of any use to you now, I got fed up with having til remove the whole HIF carburettor assembly every time there was a problem, so I installed the HS6 carburettors as used for the Landcrab 2200.
Peter
My old floats didn't seem to be punctured, but were strongly discoloured, hence I replaced both of them (plus the needle valves and seats) with new ones from Burlen SU, so these must be OK.

I couldn't find any mention of a chamber air vent for the HIF6 in the Haynes book-of-lies, nor see one anywhere. I dismantled and cleaned the HS6 carb. on my Maxi (which also had loads of crud inthe bottom of the chamber) yesterday, but I haven't fitted new float or needle valve here yet, fearing a repeat of the Princess :-(

Many thanks, it sounds like another vote for a fuel pressure regulator ;-)
2003 Renault Grand Espace 3.5
2001 Cadillac Seville STS 4.6
2002 Lexus IS200
1977 Princess 2200HL
1980 Austin Maxi 1750
1979 Triumph TR7V8 DHC
1994 Rover Metro 1.4Li
2009 Graber La Bala 4.6
1986 Lincoln Excalibur 5.0 limo
1931 Jowett Kingfisher

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Gasman
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Gasman » Sun Jul 14, 2019 12:45 pm

The float chamber vent on the HIF6 carbs is the overflow outlet. Yours are obviously not blocked!
Martin
Club Treasurer


Owner of:
Oldest known surviving wedge, hand-built 15th Pre-Production Wolseley in June 1974
Last Ambassador down the line in November 1983, Austin Ambassador VDP

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Dave289
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Re: HIF6 carbs. petrol overflowing on Princess 2200

Post by Dave289 » Mon Aug 26, 2019 6:36 pm

Quick update - fuel pressure regulator bought off eBay (£16) and fitted between new petrol pump and filter, engine now running sweetly with no petrol flooding out of either carburettor :D
2003 Renault Grand Espace 3.5
2001 Cadillac Seville STS 4.6
2002 Lexus IS200
1977 Princess 2200HL
1980 Austin Maxi 1750
1979 Triumph TR7V8 DHC
1994 Rover Metro 1.4Li
2009 Graber La Bala 4.6
1986 Lincoln Excalibur 5.0 limo
1931 Jowett Kingfisher

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