Author Topic: Fuel pressure aka Vapor lock. (Read 389 times)

MANILA THRILLA · « **on:** 24 April 2013, 12:43:55 pm »

Hi all,

What is the correct fuel pressure (Petrol) with the standard fuel pump ? ( the one with the glass bowl )

Would it be advisable to use the diesel engine fuel pump.? Fuel pressure is higher right ?

How about using a electric fuel pump ?

Having problems with vapor lock I think. Series starts in the morning, runs well. When shutting down and starting right after no problem. After more than 30 minutes shut down it starts, runs for a minute and stops. No chance to restart, after engine has cooled down no problem. Carburetor is a Weber. Rotten hot here in the Philippines .

Thanks.

Helmuth

Series III-88 SW petrol

MANILA THRILLA · « **Reply #1 on:** 25 April 2013, 08:15:26 am »

Would anybody care to comment ??

gilbo · « **Reply #2 on:** 25 April 2013, 09:07:42 am »

Oh go on then

I suffered vapourlock no matter what carb I had/have fitted. I have had the Zenith, single choke Weber and now run a twin choke (and manifolds from a 89+1).
I think part of the problem is that I do not run the mechanical fan (I have an electric one which hardly ever needs using over here!). The heat from the exhaust manifold comes straight up under the carb when the engine is stopped and the boiling point of petrol is pretty low (I think?) so the fuel in the float tends to evapourate.
So - what did I do - well in the end I have fitted an electric pump (Facet) in line with the existing mech pump so I can press a button to energise the pump and re-prime the system before I try to fire up. Works for me!
By the way when you get this problem have you tried manually priming the pump?
There is a guy in Mexico who used to frequent the Series2 Club who had similar problems due to the heat - think heis name was Rainer?
HTH
Dave

Jagger · « **Reply #3 on:** 25 April 2013, 09:10:24 am »

Hi Helmuth.

It sounds very much like mine did when the electric fuel pump failed so I think you're on the right lines.Worth trying another fuel pump.

Mine has a V8 conversion with electric pump so I can't comment on the diesel pump idea.

Huffo-James · « **Reply #4 on:** 25 April 2013, 01:07:05 pm »

If the one-way valves in the fuel pump stop working properly, the engine will run but may stuggle at high revs and/or show symptoms of vapour lock in hot weather.

Not experienced this myself, but read about it in old copies of the various Land-Rover magazines.

I think somebody posted some instructions on the old forum for renewing the one way valves.

Cheers
James

MANILA THRILLA · « **Reply #5 on:** 25 April 2013, 04:04:11 pm »

Quote from: gilbo on 25 April 2013, 09:07:42 am

Oh go on then
I suffered vapourlock no matter what carb I had/have fitted. I have had the Zenith, single choke Weber and now run a twin choke (and manifolds from a 89+1).
I think part of the problem is that I do not run the mechanical fan (I have an electric one which hardly ever needs using over here!). The heat from the exhaust manifold comes straight up under the carb when the engine is stopped and the boiling point of petrol is pretty low (I think?) so the fuel in the float tends to evapourate.
So - what did I do - well in the end I have fitted an electric pump (Facet) in line with the existing mech pump so I can press a button to energise the pump and re-prime the system before I try to fire up. Works for me!
By the way when you get this problem have you tried manually priming the pump?
There is a guy in Mexico who used to frequent the Series2 Club who had similar problems due to the heat - think heis name was Rainer?
HTH
Dave

Thank you gilbo,
I also had a Zenith before I changed to the Weber. Same Banana really in terms of Vapor lock. Weber is better in fuel mileage by far. I do around 250km on a full tank (45L)
Will install a electric facet pump as you suggested.
The heat from the manifold goes straight up to the carburetor, I measured 85-93 degrees C !! Boiling point of mogas is around that number....
I tried manually priming the pump, engine starts and runs for about 3 minutes. Just enough to get out of a parking lot and die in the middle of a driveway

I do not know Rainer.

Today we had bloody 40 degrees C !!!

Thanks again for your very helpful input.

Cheers
Helmuth

MANILA THRILLA · « **Reply #6 on:** 25 April 2013, 04:06:04 pm »

Thank you Jagger and James.

Cheers
Helmuth

gilbo · « **Reply #7 on:** 25 April 2013, 04:38:24 pm »

No problem helmuth.
Just so you know I bought a low pressure Facet (about £30 here off ebay) and fitted it into the feed from the tank to the nornaml mech lift pump. I did wonder if it would restrict the flow but it doesn;t apear to and the lift pump still works happily too. I also put an inline filter so it goes....Tank, filter,facet pump, lift pump,carb. I only use the electric pump to prime the carb - after that I fire up and the lift pump does the business. Did consider using the electric pump ony but then thought about 'shock' switches to kill it in the event of a bump!! ALso the reliability - lift pump simple!!
Anyway ggod luck!
Dave

MANILA THRILLA · « **Reply #8 on:** 26 April 2013, 05:10:15 am »

Hi Dave,

thanks again.

That is exactly what I will do also.

Cheers
Helmuth

Old Leafsprung Land Rovers

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Author Topic: Fuel pressure aka Vapor lock. (Read 389 times)

MANILA THRILLA

Fuel pressure aka Vapor lock.

MANILA THRILLA

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gilbo

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Jagger

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Huffo-James

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MANILA THRILLA

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MANILA THRILLA

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gilbo

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MANILA THRILLA

Re: Fuel pressure aka Vapor lock.