Fuel filter issue

[other dog]

the story so far-

I bypassed the secondary fuel filter because the canister was leaking. Bought a new base to install a spin on fuel filter. I was going to just run the one filter and leave the other on bypassed, but the new base didn't have double inlet/outlet fittings like the old one did, and they were backward from what I needed.

The lines are too short to just criss-cross so I decided to keep that filter as a primary, and mount the new base on the passenger side. I took the old canister and bracket off and drilled some holes to mount the new base on it.

Now, the problem is I can't remember what lines went where when I bypassed it. This line goes right there, but that line comes out of there and goes back into there...huh?

If Itake that line loose from the pump that comes from the primary filter and connect it to the "in" port on the new filter, does the out line go back into the same place?

Why did I run that line from the lower rear of the pump back into the front of the pump?

I'm gonna need another fuel line somewhere don't I?

I don't remember having an extra line when I bypassed it, I did have to go get some fittings though.

Well, I hope everybody else is as confused as I am now.

[Rob]

If I remember correctly the suction line from the tank goes to the transfer pump in your photo. The discharge of the transfer pump would go to the inlet of the primary filter, the discharge of the primary filter is to the inlet of the secondary filter, the outlet of the secondary filter is the inlet for the fuel gallery of the injection pump which is the forward port in your photo.

Rob

[other dog]

the line from my tank goes right into the primary filter inlet. the outlet line from the primary is the the one shown on the bottom there. so, what should I do next?

I can take that line off at the bottom, run it into the inlet, then run an outlet line into the front port. then what do I do with the transfer pump where the line goes now?

[other dog]

why didn't I pay more attention, or at least take a picture, when I bypassed the filter in the first place?

[other dog]

the line from my tank goes right into the primary filter inlet. the outlet line from the primary is the the one shown on the bottom there. so, what should I do next?

I can take that line off at the bottom, run it into the inlet, then run an outlet line into the front port. then what do I do with the transfer pump where the line goes now?

how's this? I think i've got it.

[leversole]

Looks like you have an APE type pump (like mine). A line from the tank to the primary filter, then to the manual pump, from the manual pump to the secondary filter then back to the inlet of the injector.

So in your drawing, the secondary filter should be between where you say your line loops. Out from the manual pump, return to the injector inlet. The primary filter keeps larger trash out of the pump, the secondary filter is finer and keeps all crap out of the injector...Hope this helps.

[rhasler]

the piping should proceed like this:

Suction from tank to inlet on primary filter

primary filter outlet to transfer pump inlet

transfer pump outlet to secondary filter inlet

secondary outlet to fuel pump

overflow fitting on pump back to fuel tank

This way the fuel is:

A. receiving filtration prior to entering the fuel transfer pump which prevents the transfer pump from being damaged by debris picked up out of the tank

B. receiving filtration after exiting the transfer pump which prevents any wear inside the transfer pump from being passed onto the fuel pump

[other dog]

the piping should proceed like this:

Suction from tank to inlet on primary filter

primary filter outlet to transfer pump inlet

transfer pump outlet to secondary filter inlet

secondary outlet to fuel pump

overflow fitting on pump back to fuel tank

This way the fuel is:

A. receiving filtration prior to entering the fuel transfer pump which prevents the transfer pump from being damaged by debris picked up out of the tank

B. receiving filtration after exiting the transfer pump which prevents any wear inside the transfer pump from being passed onto the fuel pump

so my last picture would be correct, correct?

[rhasler]

It kinda looks right but I'm not sure all those word bubbles and red lines belong there.

Truthfully it's hard for me to tell by looking at the picture what line is what. I think it should be a # 8 (7/8" wrench) on the line from the tank to the primary inlet and a #8 line from the primary outlet to the transfer pump. The transfer pump outlet to the secondary inlet and the secondary outlet to the fuel pump inlet should be #6 (3/4" wrench) as is the return line to the tank. Basically larger lines are suction and primary filtration and smaller lines are pressure, secondary filtration, and fuel return to the tank.

When I pull all of the lines loose, like if I were pulling an engine, I have matched sets of plugs and caps in the common sizes that I have number stamped that I use to keep all of the lines from getting mixed up.

[Rob]

My trucks, (B models) that only have a single filter are plumbed as I said from the tank to the transfer pump, then through the filter, then to the fuel pump gallery. My R models all have two filters and are as rhasler states. Think I was confusing with my original reply. The most rearward port on the pump itself is the overflow that returns to tank.

Rob

[macksmoke]

It may be too late now but back when I worked at the Mack dealer one of the oldtimers gave me a great tip. Find some phone or data cable (with multiple small wires within), about one foot. Pull a piece out and cut it in half (about six inch) and wrap one half on each end of whatever your removing. Works great because there is 12 or more wires in a cable, and they are all differnt colors. Steve.

[other dog]

My trucks, (B models) that only have a single filter are plumbed as I said from the tank to the transfer pump, then through the filter, then to the fuel pump gallery. My R models all have two filters and are as rhasler states. Think I was confusing with my original reply. The most rearward port on the pump itself is the overflow that returns to tank.

Rob

it was confusing with no pictures, word bubbles, and lines but I think if I go with the second picture it'll be right.

You're talking about this most rearward port right, not the other most rearward port.

[Rob]

it was confusing with no pictures, word bubbles, and lines but I think if I go with the second picture it'll be right.

You're talking about this most rearward port right, not the other most rearward port.

Yessir. That fitting is a pressure regulator/check in the return line to tank. It maintains fuel gallery pressure within the pump.

Rob