PURGE questions

[lhw1172]

Ok, after reading a lot I've decided to go with a dead head wvo with a purge line. With no open return will I need a fuel pump with a built in pressure regulator? Also what psi regulator should I use on the purge line? I'm not sure where but I do remember reading on guy that uses a ball valve and has it set at 25 psi to purge while idling (if memory serves me right). That's it for now but I'm sure ill have more questions later. Thanks for any advice.

[vegginpsd]

Originally Posted by lhw1172

Ok, after reading a lot I've decided to go with a dead head wvo with a purge line.
With no open return will I need a fuel pump with a built in pressure regulator?

Yes. Something needs to regulate pressure. Get a Fass HPFP with the adjustable regulator, or, get one with preset pressure. I ran a HPFP without an external regulator for 100K or more. The spring was a 75# spring. I dont think there is a significant price differance now between the adjustable and fixed pressure Fass pumps, so I highly recomend the adjustable pump. Pressures can be highly dependant on your truck and how much heat is in the oil at the pump.
Also what psi regulator should I use on the purge line? I'm not sure where but I do remember reading on guy that uses a ball valve and has it set at 25 psi to purge while idling (if memory serves me right). That is pretty sound advise if you are concerned about a pressure drop when the purge solenoid opens. A regulator may be overkill. A flow control valve (parker) or a small inline ball valve restricting the purged fuel flow will help your D2 pump maintain adequate operating fuel pressures while the purge valve is actuated at a fraction of the cost of a regulator on the purged fuel retun line.

That's it for now but I'm sure ill have more questions later. Thanks for any advice.

Replies in color above.
Post up other questions as needed. I will do my best to assist.

[tubular031]

Originally Posted by lhw1172

... Also what psi regulator should I use on the purge line? I'm not sure where but I do remember reading on guy that uses a ball valve and has it set at 25 psi to purge while idling (if memory serves me right). That's it for now but I'm sure ill have more questions later. Thanks for any advice.

Haha I think that was probably me that said that

When I designed my system I put a ball valve after my purge valve as a safety just incase the purge valve were to fail. When I purged and that valve was wide open I would see less than 5 psi on the rail and my injectors screamed with displeasure. So I closed that ball valve a little till I got to about 25 psi on the fuel rail and my injectors thank me daily for that! No need for a regulator on the purge side, just find a way to limit the flow. I highly suggest a ball valve. you can limit flow and also close it if the purge valve sticks open.

Also I HIGHLY HIGHLY HIGHLY suggest you also add this:
Don't care what kit you run, you NEED this!

It has saved my bacon 4 or 5 times now!!! With out it, I would have to have been towed home or left my truck where it was and go get parts to fix it before I could drive it!!

[lhw1172]

Thanks for the advice its appreciated. I was looking at ways to tie in to the stock fuel system after the filter would adding a tee on the head where d2 line is now and connecting wvo there work fine. It will be a separate system with its own pump and filter. Also in setting up purge line I noticed on the left side behind the alternater a plug in the end of the fuel rail. Is it plugged on both ends or just up front and if fuel enters the center of the rail and purges out one end wouldn't that leave wvo trapped in the other end and not totally purged out. Thanks again for the help

[vegginpsd]

You need check valves in the D2 line, to prevent VO flowing into the fuel bowl.

On the 7.3 PSD, the heads are identical. 1/8 NPT service ports in all 4 corners. Use the other two for VO, dont mess around with the stock D2 lines, except for gutting/drilling out the stock CV's and installing sone sort of CV between the heads and fuel filter.