This is for a 2 tank setup with independant filters for each tank.

I have reconfigured the fuel lines so that fuel is sucked through either filter from the lift pump and then pushed directly into the IP. So it goes tank->filter->lift pump->IP

My problem is that I am not getting any fuel coming out of the return line on top of the fuel filter. When I push the hand prime pump, no fluid moves and it seems like its not being able to be let past the IP and pressure is just being built up

Can anyone tell what mistake I am making?

__________________
-Dan
1983 240D AT, 163K running on VO, "The Patience Tester"

So my problem may have lied with the stock banjo bolt. I plugged it with JB Weld, have to let it dry now and then going to try again, hopefully that does it.

__________________
-Dan
1983 240D AT, 163K running on VO, "The Patience Tester"

Its only a lift pump, it does not have the power to suck fuel though the filter. Its only made to pull fuel against gravity and push it through the filter.

Doesn't the lift pump suck the fuel through the primary filter?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

And yet lots of people are having success using the stock lift pump to draw fuel through the filter. I guess the concession is you feel the effects of a clogged filter sooner. I had my boost gauge monitoring the fuel line just before the lift pump to see if the filter was getting clogged, and there wasn't much vacuum, so it wasn't having to work very hard.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

The primary filter is a large particle strainer, not a 10 micron fine filter. Two totally different types.

Its like a spaghetti strainer compared to an air filter.

Fuel will flow through the pre-filter (a clean one) by gravity at a good speed, its just a metal mesh.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I understand the issue with efficiency here and understand the ideal situation would be to push the fluid, however, that isn't what I am doing because it would require 3 switching valves instead of 2 and the efficiency aspect of this setup is not in question right now. It is not a question whether this setup is successful or not either as hundreds have used the same.

What my question is is why isn't any fluid moving through the IP and out to the return??

I plugged the banjo bolt and that didn't make any difference

If I take off the connection to the IP inlet from the lift pump and then pump the hand primer pump, fuel draws from the tank then the stock filter then the primer pump and then spurts out the open hose. But once I connect that open hose to the IP, there is no further flow from the tank and no return flow (not even any dribble).

__________________
-Dan
1983 240D AT, 163K running on VO, "The Patience Tester"

you could bypass the stock lift pump entirely and have an electric one installed.

__________________
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

Put the system back like the German engineers had it when it was sold new and you wont have this problem.

I seem to remember having the same problem, so I put a mityvac on the fuel return line coming from the banjo fitting and managed to suck fuel through the whole system with that.
Have you tried cranking it?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

I had the return and send lines mixed for a while. The return is actually the upper metal line . Check you have the return and send from the tanks correct to start with.

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1983 240D Silver/Blue "Sadie", unknown miles. 100k miles on WVO single tank, converted to 2 tank about 10k miles ago, FPHE, Injector Heaters, Aux Fuel pump. Alcohol/Water injection. Frantz oil bypass filter
1992 300D 2.5 Turbo Green/Tan "Jade" 267K miles Stock.
1992 300D 2.5 tan/tan "Rocky" on 2 tank WVO. Pressure actuated Turbo "rat's nest" surgery completed. 197k miles

My feed and return are not mixed up

I have now bypassed all valves and bypassed the main filter. It is now going diesel tank->pump->IP->diesel tank and it still isn't working!!!!!

I tried sucking fuel through the return but little to nothing came out and it created huge vacuum pressure. Something is not letting fuel go by

__________________
-Dan
1983 240D AT, 163K running on VO, "The Patience Tester"

Un plug the banjo bolt. Also have you tested the fuel valves you installed? One could be stuck in closed position.

Put the system back how it was designed and test it, then begin adding in the other peices to the puzzle.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

The primer will make fuel squirt out of the line leading to the IP, right? But not from the IP back to the filter? Disconnect that hose (IP to filter) and crank it once or twice and see if the IP shoots diesel out of that line.

__________________
1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now