3.9 EFI fuel pressure and flow for fuel pump

What is the pressure and flow rating for the fuel pump on a 3.9efi engine? Just starting to plot my swap over...

I would like to use an external facet fuel pump so that i can find/make a custom fuel tank (or just run it out of a jerry can!).

One like these:

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Am trying to work out which model i need and what sort of connectors/pipe.

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The 101 Forward Control Club and Register

Reply to
Tom Woods
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if you can find a scrapped Jaguar XJS (shouldn't be too difficult!), either

3.6 or 5.3, get the efi pump, pipework and filter from the boot of it. It's an external pump and works just fine. Apparently, vauxhall cavalier pumps do ok as well...... Badger.
Reply to
Badger

I think the pressure is about 36 psi BICBW

Martin

Reply to
Oily

of the 2 local car scrappies here, one doesnt know what he has in and the other only know if its new and, so by the time ive spent the afternoon driving to and walking round them its usually easier to have bought the stuff new :( I actually have pipe left from when i did my car (k jet so it'll take

10 bar or something similar!) so should just need some connectors for it..

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Tom Woods

So 2.5bar ish..

I assume there is a fuel pressure regulator before the injectors too? (still not actually got a 3.9 to look at!) Im new to all this injection car stuff :)

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Reply to
Tom Woods

That's the regulated pressure, not what the pump's capable of outputing. The pump must be capable of maintaining about 45psi at maximum flow rate. Don't ask me what the maximum flow rate is though..... When it comes to sourcing things like this, ebay is your friend...... Badger.

Reply to
Badger

What is the mpg at full throttle on a v8?

In the 101, foot to the floor is about 60mph. This gives around 10mpg.

1 hour is therefore 60 miles which would give 6 gallons/hour which is about 30 litres/hour. This is probably not the correct way of working it out but it gives some numbers! ;)

I assume the 3.9 could be a bit higher?

I can find proper pumps on ebay but they are all in-tank ones - Could i mount one of these on the outside of the tank? or would that kill it?

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Reply to
Tom Woods

Terrible! (Sorry, couldn't resist!)

Most efi pumps will deliver over 100 ltrs per hour at a given pressure.

My 110 weighs 2.6tons, has a 4.7 V8 (heavily modified 4.6) and ZF4 autobox, running a hybrid Thor inlet and hotwire efi setup. Foot to the floor it'll easily break 100mph without too much trouble, but it isn't safe at anything over 80mph due to the aerodynamics having a detrimental effect on handling and I wouldn't want to brake too hard at high speed either as the back tries to overtake the front, even at that weight! In a nutshell, I can't give any meaningful mpg figures, but I reckon on about 8mpg at an average journey speed of 80mph, 12mpg at an average of 60mph. I use an early efi rangerover (3.5) in-tank pump with no issues.

No, the in-tank pumps are designed to operate in fuel. They can't realistically be used in air. If you intend to make a swirl-pot/collector tank as I suggested on a previous thread though, there's nothing to stop you fitting a top-mounted type of 3.5 or 3.9 rangie efi fuel pump if you make the swirl pot the correct height and drill and tap the correct number of holes for the screws that hold the pump in. Badger.

Reply to
Badger

Just read that post again! :)

Fitting just an external pump would be a lot less work.. and if it will do the job i'm inclined to go with it. I only want petrol in it as a backup fuel anyhow for now!

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