Metro turbo fuel pressures

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Metro turbo fuel pressures

Post  MattEll on 5th February 2013, 13:13

Guys,
Any idea where my problem is?
With engine off but ign. on, the carby is seeing about 11psi, and the reg is seeing about 12psi from the standard Metro Turbo Bosch pump.
No amount of adjustment of the reg alters the carby fuel pressure.
Needless to say, the HIF44 doesn't like 11psi!
Out of interest, I hooked up a pressure gauge to the return line and got 11psi there too.
One assumes there will always be some backpressure in the return line with such high flow rates, but how much is to be expected, and should this match the pump pressure to the reg?
Probably worth noting that the car has standard diameter fuel lines - but this is for supply and return, so if the fuel can get there in a std. line, it must be able to return, unless there is a blockage/kink etc.
Any adivce appreeciated!






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Re: Metro turbo fuel pressures

Post  benjamin on 6th February 2013, 07:29

have you got the regulator plumbed correctly?

so the side with two pipes> top is air pressure from plenum
> under is feed to carby

>the opposite side is feed from pump

>then bottom is return.

Secondly that pressure from pump is too low and pressure to carby is too high. You want to adjust the top so you have 3-4psi while engine is at idle. I cant remeber if the dome head nut is just a cover for the adjustment?.

Also its a good idea to run a 8mm or 5/16 feed and return line , but should work with the tiny 1/4'' 6.35 standard lines

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Re: Metro turbo fuel pressures

Post  MattEll on 6th February 2013, 10:41

Thanks Ben.
All connections to the reg. are correct, as I've been driving the car as set up, and has even had a trip to the dyno.
I've now installed an 8mm return line, and pressure in the feed and return line is something close to zero, but I don't see that as a problem - plenty of fuel draining back to tank, and if I block off the return line, pressure goes past 60psi (gauge stops at 60!).
So in this case it looks like the return line was a problem (or perhaps some of the in line fittings etc. restricting flow).
The dome nut is for aesthetics only; underneath is the locknut and adj. screw.
I'll have to see how it all goes once the reg. is readjusted - but will have to wait another day or so - my 15psi guage also saw the 60psi spike today, and is no longer returning to zero - new one required!
Cheers.

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Re: Metro turbo fuel pressures

Post  benjamin on 6th February 2013, 13:05

So I guess you removed the resistor pack ? , or new pump? Anyway 60+ psi your right for some decent boost now Smile and hopefully you can get the regulator adjusted correctly now. Im also interested to see if it was the return line causing all the drama.
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Re: Metro turbo fuel pressures

Post  MattEll on 6th February 2013, 13:15

Yes, resistor pack now gone. Apparently the Metro did have a resistor in the setup, but mine was too "big" - my mate the sparkie reckons our resistor setup took it back to about 6v, whereas the Metro was 9v (or so I understand from the TurboMini UK forum).

In any case, it looks like I'll stick with the full 12v now.

I can't be sure that it was the small return line diameter that was the problem, but if it wasn't that, then certainly the small bore fittings.

But as you say Ben, closer to being able to run high power than before.

Surely I wouldn't need to upsize the feed line would I? I mean, the tank and carby only have a 5/16" fittings!



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