need fuel related assistance...

[rubberducky]

its a 91 n/a...

drove it two days ago fine, 200+ miles.  came home, shut her down - no issues all day.  ran fine (as far as i can tell)

yesterday, she had a hard time starting up, causing me to scratch my head.  started down the road, she sputtered and croaked.  had a peek in the fuel filter, sure enough, it was dry, so i refilled just to get her back (all of half mile), and she idled fine...  some bubbles in the transparent fuel line going into the injector pump, but nothing too concerning...

later on during the day, i drove out, ran about an mile, and the same thing.  after that she's been running irregularly, seems like she's not getting enough fuel.  and the fuel filter's dry, each and every time.  i just replaced the thing about a month ago, so i don't think its the filter.  but now there's a lot of bubbles going through...  i'm wondering if there's a blockage in the fuel line between the tank and the fuel filter.  i don't have my bentley on hand, but is there a check valve somewhere between the tank and fuel filter?  i'm wondering if that's gone bad?

i'm going to have another go at filling the fuel filter, and taking it from there.  as a last resort, i'm going to install some form of a fuel pump near the tank, just so it'll push fuel with additional pressure over to the fuel filter, so that's not going dry.

i guess if i wasn't being clear enough (i haven't had my coffee yet) - she runs fine when i fill the fuel filter, when that's running dry, she sputters.

any ideas, suggestions are greatly appreciated.  she's my daily driver, and i prefer her over my V8 pickup (sorry babe!).

Cheers,

rd

[rubberducky]

well,

she's up and running - i put in a temp pump between the fuel tank and fuel filter, and had it pumping until the filter was full...  don't know if for whatever reason the line got airlocked or something, but she's running ok...  a few bubbles here and there.  i may permamently install that pump, and connect it to a toggle switch on the dash - there were definitely less bubbles when that pump was running - and the next time for whatever reason the fuel filter decides to go dry, i can run that pump and fill it without undoing anything.

we'll see how long this'll last.

rd

[shwartzbewithyou]

Did you place this temp pump inline with the current fuel line?  So it's drawing from the same tank, filter, and lines that the old pump was?  Sounds like a sending unit.

[rubberducky]

not to sound like a complete idiot, but the sending unit does pump fuel to the fuel filter?

its been running fine all afternoon - but yes, i did put it inline, immediately 'before' (as in on the side of the fuel tank) of the fuel filter.

many thanks,

rd

[shwartzbewithyou]

The sending unit in most vehicel's is in the gas tank but on these diesels I'm not completely sure.  This is what one of my manuals said about VW's in general.

"Pre mid 1989

1. The main fuel pump is located in the
accumulator housing beneath the rear of the
vehicle. An additional lift pump is located in
the fuel tank, together with the fuel gauge
sender (see illustration).
2. With the engine stopped, have an assistant
switch on the ignition. It should be possible to
hear both pumps running for a short period. If
not, check fuse 5 for continuity and also
check all wiring connections.
3. With the ignition on, disconnect each wire
connector from the pumps and check that
there is a 12 volt supply by using a voltmeter.
4. Should there be no voltage at the pumps
with the ignition switched on, the fuel pump
relay (No 2 on fusebox) may be faulty. This is
best checked by substituting a new relay.

From mid 1989

From mid 1989, certain models fitted with
the Digifant system are fitted with a single fuel
pump in the fuel tank rather than the previous
arrangement described above. The pump can
be tested in the same manner as that
described for the previously fitted “in-tank”
dual pump."

-My guess is whatever pump (in tank or not) you have previous to your temporary pump is dying slowly and thus your line is being sucked dry by your injector pump.  Then when the line goes dry it starts drawing air.

[rubberducky]

shwartzbewithyou, thanks for the info.

i think i'm going to install this little pump closer to the tank to push the fuel along...  just a matter of when.  but before i do that, i'm going to have a buddy of mine help me  listen to the sender unit - and see if its the relay that's bad.  if its just a relay, its a lot easier to replace than installing a second pump - and if its the sender unit, that's not so bad as well, since my car's a 2 door, and i have access via the trunk.  i'm just not all that thrilled about trying to wire the 'other' pump to my ignition...  or perhaps i can just wire it into the sender unit wiring?  hmmm...

btw, anyone know where i might be able to get a sender unit?  the usual places that i go to doesn't seem to have 'em.

again, continued thanks for everyone for their help - additional suggestions / input appreciated.

rd

[rubberducky]

little late, but just to let you guys know...

i've installed the secondary pump - didn't fiddle with the sender unit, didn't think it was worth the extra effort, especially since i was going to install the pump anyhow.

the pump is definitely making a difference, no bubbles and i feel more power out of the engine - maybe i'm just imagining it, but on the whole, it does seem to run a lot smoother.

since its a 2-door, i mounted the pump on the wheel well on the passenger side, first with self-tapping screws - but they kept backing it self out, ultimately disconnecting the ground.  the car's currently on stands, since i'm replacing the struts/shocks, so while i have the wheel out, i've bolted it on instead.  i should have loc-tite it on, i'll probably do that today.

i've run the power thrugh the passenger compartment into the relay/fuse box.  using a spade terminal, found a slot that gets power when the key gets turned on the 'on' poisition, and plugged it in.

hopefully, i can get the suspension back into the car today, and have it on the road by tomorrow or at the latest, day after.

thanks everyone for your help.

rd