I just bought a 1974 2.0 and am having a fuel delivery issue.

I am not getting any output from my fuel pump. There is fuel supply to the pump (into the S port) from the tank and through the filter. I removed the output line ("D" port -- the middle one) and attached a test line feeding the test line into a bottle. When the pump runs, I am not getting any fuel out of my test line from the D port. I can hear it going "pssst, pssst, pssst," but no fuel ever comes out.

In addition, although it isn't sending fuel out of the D port, it seems to be pumping fuel into the return line. The reason I can tell this is that when I removed all the lines from the pump, fuel drained out of the return line where the return line attaches to the R port. After I did my test, I removed the all the lines again (to switch pumps) and quite a bit of fuel again came out of the R line again.

I have a spare pump that I got from the previous owner, and both appear to be doing exactly the same thing.

It seems like both pumps are pumping fuel into the R line instead of the D line. What is going on and how to I fix it or test it?

Maybe your supply line and return line are switched at the tank. The supply line fitting at the tank picks up at the very bottom of the tank, the return line has an extension the makes it taller in the tank. If they were switched and the tank is low you would suck air from the tank and when the lines at the pump are disconnected you get fuel flowing from the return line.

Does any fuel flow from the supply line when disconnected at the pump?
Can you blow thru the supply line into the tank?

Jim

I don't think they are switched. Each appears to be the correct size (supply larger than return). When unplugged, the return line spills for a while, but then stops, but the supply line keeps pouring until I either clamp it off or the tank is empty.

I don't know anything about internal operation of the pump; however, I doubt a problem would cause the R or S ports to pump fuel. To double check you might immerse the pump in diesel and with a hose attached to "D," energize it with an appropriate source (battery).

A single in -- single out pump with the correct pressure and volume will work just as well, You can "T" the two return lines into the return hose. There are some recent posts about an inexpensive pump that can be found at NAPA. Use the search feature to find out more.
Good luck.

So the pump runs fine? I frequently have to disassemble pumps to free components that have become stuck with old fuel varnish. There is a pressure relief piston that should keep fuel from flowing out of the R line, unless pressure inside the pump increases beyond the spring strength. If fuel is coming out of your R line then either that piston is stuck, or the D line is blocked somewhere.

Is the fuel pressure regulator hooked up correctly? Fuel should run out of the D port, to the pass fuel rail, to the driver fuel rail, then to the FPR, then back to the pump return Y.

Also, test the pumps out of the car with a plastic fuel tank.

Oh, and check the wiring to confirm + goes to +.

Thanks for the ideas. I have not taken the pump apart. I was thinking that there could be some blockage to the D port, but then it seems like I wouldn't hear it trying to pump (the pssst, pssst, pssst). I will check the wiring first, then maybe open up the pump next. I was also thinking I will attach a test hose to the R line to see if it is really pumping out of that line.

I have checked the lines to the engine, and everything is where it is supposed to be.

Fun experiment:

Put pump in diesel bath, reverse polarity, watch dirt fly out.

"pssst, pssst, pssst" sounds doesn't "sound" right to me. "Whirr?"

It makes a very distinct Whirr sound.

If you are not getting a Whirl sound, it is probably clogged. Pull the pump and run it straight off the battery. You can try cleaning it with either diesel as mentioned or spray some brake cleaner in the pump. Try running it forward and then reverse the polarity and run it backwards. If it is clogged, then find out why, it you have trash in your tank, you may find yourself on the side of the road at some point, I can tell you from experience.

On the chance you're looking for a non-stock, but inexpensive, replacement pump here's a link to a discussion of a proven alternative:
Pump

Also, I see now some documentation for your concern about re-routed pump flow. Anders writes: Brad Anders invaluable d-jet diagnostic page

Hope you will post whatever you find out.

Thanks everyone. I now have some things to try, and I will report back.

Clarification on my noises. The pump itself makes the usual fuel pump "whirrr" noise. The pssst, pssst, pssst noise that I referred to is at regular intervals (maybe once per second) and comes out of the end of the 5' test hose that I attached to the D line to see if anything was being pumped out of that port.

I took apart the pump and cleaned it and it started working. The car started and ran for about 15 minutes and then the fuse blew. After some help from others in another thread, I traced the fuse problem to the AAR, which was unplugged. I plugged in the AAR and the car ran again without blowing the fuse. But then after about 5 minutes it's died again. I checked the line from the tank to the pump and fuel is getting to the pump (after passing through the filter). I unplugged the "D" line from the pump and put a test line on it and now I am not getting any fuel pumped out of the pump again.

Therefore, I am now back to wherei started. Fuel pump is getting fuel and is running (I can hear it whirring), but is not pumping any fuel out.

I will take the pump off again, take it apart and clean it again, but I am worried I am just going to end up with the same problem. Before I buy a new pump ($$$$$) or switch to an alternate pump, any ideas of what I should do/check?

Make sure you have a filter before the pump. You might have crap in your tank.

The easiest way to find out if the pump is bad is to install a known working pump.

Those cheap Bosch pumps from NAPA were still less than $50 last time I checked. Good pump. There are several threads on that topic.

And if there is enough rust/sour gas/gunk in the tank, even a filter won't keep dirt out of the fuel system.