Bubble Bubble, Swirl Pot Trouble

[JohnD]

This thread on Piston Heads may be of interest.  The OP is moving his swirl pot and pump OUT of the underbonnet, because of heat problems.

http://www.pistonheads.com/gassing/topic.asp?h=0&f=66&t=1626853

 

JOhn

[oldtuckunder]

I always liked the system on my V12 XJS, which had a neat swirl pot with integral LP pump and the HP pump in the boot. I always said to my self that if I ever went EFI on anything else I'd just use the XJS bits. It also had a aircon/return from fuel rail heat exchanger to cool the return to the swirl pot. Mind you if you ever want to experience high under bonnet temperatures just pop the bonnet on an XJS on a summers day, they didn't call it the Valley of Death for nothing, if it doesn't go brittle or melt in there it will easily survive anywhere else!

 

Alan

[GT6MK3]

No way I'd be trusting a piece of clear hose anywhere on an EFI system, especially under the bonnet of a GT6.

 

I bought a genuine sard from efi hardware for the piece of mind.  $220  https://www.efihardware.com/products/c76/Regulators-and-Adapters

 

My $60 ebay sard is on my shelf of shame.

 

C.

[josh18]

Hey guys, this is an interesting read.

If it were me I would be moving all the pumps and filters into the boot for a couple of reasons.

1, to it all out of the heat of the engine bay- it just seems really dangerous in such proximity to the engine/ electrics and

2, I reckon the long run of pipe could be causing a pressure drop to the CAV filter and pump mouth. From what I have read and experienced, the bosch pumps can push heaps but 'suck' at sucking. I would be keeping the pipe run to the HP pump as short, large and smooth as possible, the bosch will have no trouble pumping the fuel at reliable pressure op to the front of the car. I don't know if you've changed it or not but I reckon even that brass elbow could be causing cavitation due to the turbulent flow around the corner.

I did try setting up a CAV filter like Andreas at one point and it seemed like a really good idea, but I cant remember if it still functions as a filter set up that way. At least any induced air can then go back to tank with the over flow.

Cheers

Josh

[dggt6]

Hi Josh,

glad you have found the article interesting. From where I sit it has been excruciatingly painful!!

The pump location started as a wishful thought that the original mechanical pump could supply the fuel to the high pressure pump, hence the location on the shocker tower. This position also solved the problem of where to put an "out of tank" pump in the boot space of my GT6 and saved a few dollars using normal pressure fuel hose from the tank to engine bay. With 20/20 hindsight this is probably where it all fell apart, at the beginning!!!!!

I agree that the engine bay heat may/can effect the pump but given that there are about 14 high pressure hose joins on the fuel rail and injectors sitting above the exhaust manifold, one more on the fuel pump doesn't really matter. The fuel pump position is also in a direct uninterrupted line from the grille opening for fresh air when moving.

I have been playing with all sorts of variations trying to eliminate the bubbles of just late and the most interesting is the the high pressure pump does seem to suck quite well in this position.

For the time being I have settled with a flex line from the tank into an online fuel filter then into the pump. I have given up on a one way valve, swirl pot and CAV filter.

I have spent the last 6 months putting an O/Drive box in (and an unexpected crank rebuild and clutch replacement) and I just wanna get out and try this new box!!!!!!!!!

 

Craig, don't worry about the clear pipe, when I am ready to forget about the bubbles it will be going!!!!!!

 

Cheers,

Doug

[josh18]

Best of luck tracking it down. I spent ages improving my PI fuel plumbing chasing a misfire up high in the revs which I believed was leaning out. It turns out I had a dying coil and it was not fuel related at all! So i felt pretty stupid but at least i have really good fuel flow to the pump now lol.