MicroSquirt.com read only forum (Jan.15,2018)

jonfx4com wrote:I tried a facet gold top low pressure fuel pump to fill a surge tank before the HP fuel pump and it was a hopeless case. The flow rate of the HP pump was way higher than the LP pump and the surge tank was empty within seconds of the HP pump running up. Result was a dead HP pump.

Jon,

How was your return connected? If your return line from the regulator also goes back to the surge tank, then the low pressure pump only needs to provide the fuel consumed by the engine. Any fuel not consumed is returned for the efi pump to send through again.

Roger.

And before anyone tells me that in

http://www.sdsefi.com/techsurge.htm

the fuel bleeding out of the fuel pressure reg is going back into the swirl pot- forget it! After 5 mins in traffic the recirculating fuel gets so hot it starts vaporizing in the lines, its a bad solution which I fell for when I saw a similar drawing on another website. I suppose you could add a fuel cooler but then you're buying 2 fuel pumps a swirl pot and a fuel cooler to save you doing it right!

Jon

jonfx4com wrote:And before anyone tells me that...

Too late!

I've recently installed a fuel pressure transducer on the pressure line, and will be datalogging fuel pressure during my runs at higher boost levels. This will hopefully allow me to spot any fuel system inadequacies before damage is done.

I'll agree with you though, as I said earlier, converting the fuel tank to a modern efi-type setup would certainly be my preferred route if I were to start over again. I doubt it's any more work than fab'ing and installing a surge tank.

Hi Roger,

yes that was how I killed my first HP pump, they don't like pumpimg scalding hot fuel and vapour much, in fact they quickly refuse to do it anymore! I dont doubt that there are folks out there getting away with it but I could not recomend it to someone setting up a new system after already costing myself a small fortune trying the "shortcut methods".

Jon

I killed a couple of pumps as well trying to get the surge tank to work. Eventually I just cut a hole in the top of my fuel tank and used a Honda Civic in-tank pump with a custom top plate (I needed it to be rectangular).

Cheers,
Simon

I also have a surge tank in my 85 previously carbed RX-7 (seems to be a few 1st gen rotor heads in this thread ). When I first got the car running I didnt have one and the car would buck and surge like crazy 1st trip around the block. Only took a week before I decided to put one in and I used the same info off of sds website. Im running a large carter pump to fill the surge tank and have the return from the regulator going back to the surge tank. The carter pump is kinda loud for me though but its been going for 4 years and I drive the car every day so I havent touched it. Now im thinking about doing what a buddy of mine did and switch to a bosch volvo FI pump to fill the surge tank much quiter.

jonfx4com wrote:And before anyone tells me that in ...

There are inconsistencies in your setup to get multiple symptoms like you are describing. Surge and header tank systems were developed to solve problems like these - not create them. The troubles you describe indicate it was not set up following the sdsefi (or other proven system) diagram.

I am not promoting surge and header tanks over any other delivery system. There are many benefits to them, but they must be done correctly, such as when they are used in the racing and aviation fields. They are not a "shortcut" when properly applied.

David

Renns, what sensor did you use for the fuel pressure monitoring? - has some cheap honeywell sensors come back out?

To see how the professionals deal with surge tanks, here's the insides of a Subaru WRC surge tank. It has two bosch 044 motosport pumps and a couple of delco lift pumps

http://homepages.nildram.co.uk/~eliotmez/liftpump1.jpg
http://homepages.nildram.co.uk/~eliotmez/liftpump2.jpg
http://homepages.nildram.co.uk/~eliotmez/liftpump3.jpg

Speaking of surge tanks .

I've never been able to source the electrical isolated
connector to feed 12V to the pump inside .
I had to machine it myself .

Pat

Here's the connector:
http://www.deutsch.co.uk/corporate/defa ... er_ftc.asp

or go to root of site, product search, enter nothing, press search, scroll down to autosport range.