My PSD is looped and I'm very happy with it.

Wondering if anyone here has converted an old ford IDI? I'm redoing some WVO fuel lines on my venerable IDI and I'm reading elsewhere that the Standyne injection pumps on IDI's like their return lines to be atmospheric pressure in order to operate properly. I've run it for thousands of miles unlooped but would really like the extra heat looping can provide.

A looped return after the lift pump would supply back pressure and a looped return before the lift pump would supply vacuum. I don't care to destroy the IP via backpressure or vacuum...

I'm wondering if I should just do a return to tank and forget about looping?

Anyone?

quote:

Originally posted by mankypro:
a looped return before the lift pump would supply vacuum.

If you loop to before any filter in the line coming from the tank, there is no vacuum there unless you have a pickup screen thats clogged. Put the filter after the lift pump is best, and you can loop before the lift pump where there is no vacuum.

second to sunwizard. if you gonna loop, loop to the inlet before any "restriction" then it will be pretty close to atmospheric

My pump and filter are on the frame rail behind the cab, under the bed of the truck. Getting my loop to go all the way back there would make said loop about 8 feet long

Thinking of looping into the supply line in the engine bay with a T (after the loop valve). Or maybe just putting a Veg Therm Mega into the 8 foot long loop might be OK

quote:

Originally posted by mankypro:
My pump and filter are on the frame rail behind the cab, under the bed of the truck. Getting my loop to go all the way back there would make said loop about 8 feet long

Thats still shorter and better than a return to tank since the loop gets more heat.

quote:

Thinking of looping into the supply line in the engine bay with a T (after the loop valve).

Sounds bad since that would put the return under pressure?

quote:

Or maybe just putting a Veg Therm Mega into the 8 foot long loop might be OK

Shouldn't be needed, simply insulate the whole bundle of heated lines together.

What about air bubles ?, i've read somewhere on the site that if you have a looped return air will accumulate until engine doesnt... ? or there is something else that i didnt understood ?

quote:

Originally posted by Dark_flame221:
What about air bubles ?, i've read somewhere on the site that if you have a looped return air will accumulate until engine doesnt... ? or there is something else that i didnt understood ?

Air bubbles would work themselves out in a filter.

quote:

Originally posted by mankypro: Air bubbles would work themselves out in a filter.

hmmmmmmmmmmmmm? then what is the purpose of fancy air filtration units like air dogs or fass?

i have seen what i think are fuel driers on VWs and Intertrashionals they looked as if they sported a cintered bronze filling, minimal fuel volume therefore very suitable, but how effective are they
does any one know?

i have a 6.9 as well as a 7.3 IDI, both will be looped, the 6.9 is in a much more efficient vehicle
and therefore i am planning on doing slightly different setups. do you have a scematic if not could you scribble one up? also do you know of any other ones. i am wanting to weigh out all options...

what percentage of WMO are you running on your PSD?

quote:

Originally posted by mankypro:

quote:

Originally posted by SunWizard:

quote:

Originally posted by mankypro:
a looped return before the lift pump would supply vacuum.

Put the filter after the lift pump is best, and you can loop before the lift pump where there is no vacuum.

You mean that in a tank > pump > filter configuration to T the return between the pump and the filter?

No I said "loop before the lift pump where there is no vacuum."

quote:

Originally posted by 1.6D MKI GTI:

quote:

Originally posted by mankypro: Air bubbles would work themselves out in a filter.

hmmmmmmmmmmmmm? then what is the purpose of fancy air filtration units like air dogs or fass?

My filters are 9.7" long trust me there is no air issue...

quote:

what percentage of WMO are you running on your PSD?

None, the IDI was on 100% WMO for a long time, until I secured enough sources of veggie to abandon it. I still have 110 gallons of ATF/WMO filtered in drums which I will be burning this winter after I finish reconverting the IDI...I will be running 100%

quote:

Originally posted by SunWizard:

No I said "loop before the lift pump where there is no vacuum."

I appreciate the advice, but "before" is relative - and so I asked specifically what you meant - and now I know - thanks! I push through my filter with the Walbro, which is not that common for WVO setups from what I understand. Any advice on that front?

to eliminate air, go a partial loop or ahave a valve to make youre return go to the tank to push the air out after a filter change, i am a fan of a partial loop myself, push the air out, keep some heat in

quote:

Originally posted by extremeyoshi:
to eliminate air, go a partial loop or ahave a valve to make youre return go to the tank to push the air out after a filter change, i am a fan of a partial loop myself, push the air out, keep some heat in

I'm using a third 3 way valve for a controlled loop so simply switching to purge - which will run route diesel through the WVO return to tank line. This will not eliminate air from the loop, but will eliminate any air in the IP and injectors.

but how do people that have looped retrun systems manage to get the air out of their line ?, if it's not the filter ? !

quote:

Originally posted by Dark_flame221:
but how do people that have looped retrun systems manage to get the air out of their line ?, if it's not the filter ? !

I've never had any air issues on either my IDI or my PSD...

so it would be the filter taht is doing the job on your sytem? what kind of filter do you have ?! thx

On my 87 6.9 I have looped my return to before the stock lift pump, on the advice of Craig Reece at www.plantdrive.com. I haven't had any air or IP issues for the last 40,000 miles on svo.
I don't know how many miles are on the IP except it had been replaced at the time I bought it with 150,000 miles. They often only last 100,000 miles even on diesel alone.
Mike

on the IH 6.9L and 7.3L IDIs, does anyone know what percentage of the fuel going into the injectors is burned and how much is shed to the return lines?

The initial startup with all new lines can be a beeyatch - battling air and such, but after a few runs things stabilize themselves nicely. I'm seeing 180F pre-IP temps in very short periods.

I ended up looping to the pump inlet and put the vegtherm in the loop. Helps on cold mornings to get the WVO pump going.