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Jun 14, 2014 18:19:19 GMT
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On my throttle body conversion I've got a rear mounted Facet type pump as a lift pump to the swirl pot then a sytec high pressure pump to feed the injection. The main pump is mounted so it gravity primes and draws from the bottom of the swirl pot and pumps to the fuel rail via a filter. Return from the fuel line is through a pressure regulator set to 3 bar and then return to the swirl pot.
The pump always had the odd screech on start-up - recently it started doing it continuously. This is not the usual fuel pump whine but a really loud screech noise.
I assumed I'd got some crud in the pump and knackered it so I bought a replacement. Guess what? Same noise though now intermittent again.
I've checked the filter and it's free flowing. I've also checked the lift pump and it's keeping the swirl pot topped up.
Any bright ideas?
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Check the voltage at the pump whilst running mate make sure its a good strong 12v
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penguin45
Part of things
Still welding......
Posts: 70
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Pump cavitating (sucking air, failing to clear trapped air) can cause some weird noises.
P45.
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Exactly that. It IS cavitation. This could be sucking air (not true cavitation) or, more likely IMO, it could be a suction restriction causing excessive pressure drop at the pump suction causing the fuel to vapourise at that point, before collapsing back to liquid as it goes through the pump. This causes reduced flow (which may not be obvious), nasty noises and damage to the pump if left. Is this filter in the suction side of the pump? If so I'm inclined to suspect it. Although you say it is free flowing it may not be free flowing enough. I usually fit a strainer on the suction side as they create less pressure drop. Genuine Bosch pumps have strainer built in (you can see it through the inlet pipe) so you don't actually need anything extra but after marker ones don't.
Warm weather/warm fuel makes the problem worse as it'll then vapourise at higher pressures.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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On further inspection (and although I would have sworn the noise was coming from the pump) it turns out it's the fuel pressure regulator resonating.
I'm not sure why it would do that (all braided hose and no air in the fuel) or whether it can be repaired so I'll ask FSE / Glencoe for their advice before spending another £100.
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welshpug
Posted a lot
Posts: 4,332
Member is Online
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I guess you have it solid mounted?
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Jun 15, 2014 15:05:49 GMT
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Yes
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Jun 16, 2014 11:57:58 GMT
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I had this on a)my Porsche b)my Astra mk3 c)my other Astra mk3.
It was caused by low fuel. The Porsche was worst as when it sucked air, it made it difficult to start for about 1/2 an hour. Doesn't fuel keep the pump lubricated maybe or dampen the mechanism? It might be worth putting more fuel in as a test.
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