No fuel

Hi, need some help with a simple problem..so simple I can not see why!
I am running a Carter Heavy duty fuel pump thru a standard Summit (sum G3032) fuel pressure regulator feeding 4 twin choke 40mm De Orto downdraft carbs.
I can set the pressure at 3 to 4 psi and the car has run successfully until last weekend when it started normally at the end of the day and then appeared to run out of fuel (tank was more than half full). Always fun pushing it on the trailer!
At home I striped it down and could find no apparent fault with the fuel regulator so pulled a hose off the front carb and no fuel despite the gauge still showing 4psi. Blew all the lines back thru the reg and all clear, re assembled the regulator and with it removed from the fuel accumulator bowl, turned on the pump and had very good open pipe flow. Re attached accumulator bowl and turned on the pump.....bugger no flow to the carbs. There is nothing inside the accumulator bowl there for there is nothing to halt flow. I have stripped that damn reg down more time than I care and its so simple in design that it baffles me as to what may be the cause. I am determined to find the fault rather than just fitting my spare regulator on.
Any ideas please.
The second photo shows the fuel accumulator with the 4 fuel hoses out the bottom....
Cheers
 

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Randy V

Admin
Lifetime Supporter
Russell - That is a vane style pump and not a positive displacement pump such as a diaphragm or gearotor pump. From my experience - They will work for a while when placed above the level of the fuel, but start to score and heat up a bit, then they lose their prime and stop working. This is evident by the pumps innability to achieve or maintain pressure at first.
The proper location for pumps such as this is at or below the level of the fuel - so as to keep a constant supply of fuel to the inlet side of the pump.
Holley and others make a good gerotor pump. I think the model number is HP150 but may be wrong (memory thing)...
 
Looks like you have a 'dead head' system from pics, if so the pump will tend to overheat during low fuel requirement periods, convert to full loop bypass system to increase flow and cooling of pump.
 
Jac, I seem to remember that you have posted a drawing previously....could you please resend it thanks.
I am still puzzled as to why it pumps with an open outlet yet refuses to pass fuel thru the open carb hoses....and that it had worked before and suddenly just stopped flowing.
Regards
Russell
 
Page 9, post #176 of your 'visual' build thread...20 Aug 2015.
Is the pump hot to touch when engine quits? Does your pickup simply tap into lowest point in tank or do you have flop tube inside?
 
Jac
The car has not been driven more than 200 mtrs in the car park yet.
Max pump run time when it failed was about 30 secs and it had fired up and run earlier when unloading from trailer so es its a puzzle.
Thanks for your input.
Cheers
Russell
 

flatchat(Chris)

Supporter
Sounds like an air lock or a Vac lock ?
The accumulator --maybe the hoses should be at the top ?
Does the fuel tank breath ?
Eh ?
 
The hoses are at the bottom of the accumulator / surge tank to take any possible fuel surge, the pump has very strong flow out of the carb side of the regulator and yes the tank breaths.
The question really revolves around why it has worked before and why the regulator suddenly stopped passing fuel. It is set up as a deadhead arrangement and the regulator is designed for this set up. There are also overflow drains to the tank from each carb and each carb feed pipe is clear back to the surge tank.
Russell
 

flatchat(Chris)

Supporter
I suspect a vapour lock in the accumulator--- when that can gets hot the fuel vapours expand creating back pressure --locking out incoming fuel
While everything is cool and flowing --probably OK --a bit of heat soak and you're in trouble again
By pass the accumulator or put a pressure relief in it back to the tank
-- better still all surging and accumulation done before the pump

That's my Trumps worth :)
 
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