Dave J
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| posted on 17/3/04 at 12:02 PM |
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fuel pressure switch
Hi all,
Does anyone have any thoughts on the need to fit a fuel pressure switch?
Apparently it has been known for engines to be damaged because the pump was still running with the engine stalled and the ignition on.
I've never heard of this, is it peculiar to carb or injection systems?
Thanks.
Dave
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JAG
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| posted on 17/3/04 at 01:42 PM |
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The fuel pump running without the engine running should cause no problems. That applies to carb' or injection.
In most cases the fuel system is designed that way 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Dave J
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| posted on 17/3/04 at 01:53 PM |
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Thanks Jag,
Come to think of it, I did have a problem many eons ago with a Ford Capri. The float in the carb got stuck, the result being fuel pouring over my hot
exhaust manifold (lots of hissing and panic) thankfully by following fords instructions to hit the float chamber with a hammer (seriously!! ) My
pride and joy didn't become a raging inferno.
Cheers
Dave
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britishtrident
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| posted on 17/3/04 at 04:21 PM |
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On a lot of modern cars fitted with electric pumps the fuel pump relay is either wired through the oil pressure switch or controled by the ECU. The
idea being to prevent a fire in the aftermath of an accident. Togther with an impact "G" switch this quite a good idea.
Some Rover 80s/90s models had an oil pressure switch that worked the opposite way from normal ( ie it was NO not NC ) to trigger the relay.
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Dave J
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| posted on 18/3/04 at 03:51 PM |
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Thanks for your thoughts guys, I must admit the jury's out on this one at the moment.
Cheers
Dave.
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stephen_gusterson
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| posted on 18/3/04 at 04:27 PM |
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I dont understand your problem.....
on a carb car, they are often pumped mechanically. once the valve closes on the carb, the pump doesnt pump.
On an efi car, its a recirculating system. The excess fuel is CONSTANTLY pumped back to the tank, its normal and happens 100% of the time.
The EFI on my car runs the pump for 2 secs at start up to pressurise the system, then stops. The pump then runs after the engine fires up. Once
started, an EFI pump runs all the time
atb
steve
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Dave J
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| posted on 19/3/04 at 04:06 PM |
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Its not really a problem, the electric fuel pump I'm using suggests using a fuel pressure switch to avoid damage to the engine in case of stall,
as the fuel pump would still be running.
I was just wondering what possible damage they are alluding to.
Incidentally I'm using a webber 500 carb on Rover V8
Cheers.
Dave.
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