Fuel Pump Relay question

[Chris Hall]

I've pretty much eliminated the hall sender as a problem because when
testing the car for another stalling problem, I noticed that
disconnecting the hall sender makes the tach drop straight to 0... no
backfire, and the tach needle doesn't follow the engine rpms after the
stall.

Fuel pump relay... I've had to repair it before, and I have gone over
it with a magnifying glass.. and I have a 2nd relay that I've swapped
in... So that seems fine (although when I was having the relay
problem, the symptoms were VERY much like this one... only difference
being the car would sometimes run and just run ROUGH as if the "spare
fuse" was missing)

I think the backfire problem could be the possibility of arching
between the spark plug wires... firing the wrong plugs off at the
wrong time, etc.  Seems logical, right?  I mean... I relpaced the cap
and rotor, and the car ran FINE all week finally.  Then last night,
the first humid conditions this year in Chicago, the stalling /
occasional backfire happens, and the only part of the chain that I
didn't replace (the wires) could possibly produce those symptoms.  The
cap and rotor definatly helped a LOT... so I think by trying these new
wires I'm still heading in the same direction that I was with the new
Cap and Rotor.

The only thing that doesn't seem to sit right with me is the fact that
the car just won't "catch" after the stalls.  I always mess around
under the hood, and 10 min later or so, it starts perfect like
nothing's wrong.  I've even switched ECUs in this time period, and no
change.  I have a new (non bosch) ignition control module in the car,
so I don't think that's a problem... although it could be acting up
and over-heating, then cooling off as I sit for 10 minutes.  The only
thing is, I had a bad coil that was burning those things up, and they
NEVER caused a backfire, and they ALWAYS caused the tach to drop
straight to 0... so I don't think that's the problem...

I might just try disconnecting the CSV if the problem continues to see
if maybe it's leaking fuel in.  Maybe I'll yank the old one out of my
83 or something...

Haven't been driving the car long enough to see what the fuel
situation is like.  With gas being $2.50 a gallon or whatever, every
car I drive seems to be getting crappy gas mile
age  lol .


I'll try that 15 sec cycle you spoke of.  I kinda tried it WITH the
relay in, thinking maybe if the fuel pump or system wasn't at proper
pressure, I could build up pressure by cyling the pump on with each
turn of the key to build pressure.

I miss my 83.  No electronic fuel pressure regulator.  No temp sensor
for the ECU... not nearly as many vacuum hoses....

I guess the more parts you have, the more can go wrong.  Maybe I'll
ditch the engine, go buy 42 car batteries and some electric motors and
turn it EV  lol.

I'll keep ya posted.

Thanks.

On 6/4/05, Jim Jordan <superba at comcast.net> wrote:
> Hi Chris,
> 
> Have you looked at the Hall Sensor?  I don't recall it being mentioned.
> They used to be rather fragile and easy to break making their function
> intermittent.
> 
> What is strange is that you were able to accumulate enough raw fuel in the
> muffler area to cause a backfire.  Have you tried unplugging the cold start
> valve?  (if there is one).
> 
> One more thought.  The next time your engine stalls, unplug the fuel pump
> relay entirely and turn over the engine for about a minute.  Do it ~15
> seconds on, ~15 seconds off to keep from overheating the starter motor.  See
> if that clears your engine, and if it does, it means that your fuel delivery
> is faulty, injectors, air flow, all cold start valves.
> 
> It might be dumb to ask, but have you noticed that you're using a lot more
> fuel than before the problem started?
> 
> Perhaps it's time to have someone else take a look;  a fresh eye often sees
> things that we've overlooked.
> 
> Cheers!
> 
> Jim Jordan
> 
> 
> >  -----Original Message-----
> >  From: Kent McLean [mailto:kentmclean at mindspring.com]
> >  Sent: Saturday, June 04, 2005 6:00 AM
> >  To: Chris Hall
> >  Cc: quattro at audifans.com
> >  Subject: Re: Fuel Pump Relay question
> >
> >  Chris Hall wrote:
> >   > ... I'm wondering if the plug wires are arching.  I'd
> >  LIKE to do the  > "spray bottle" test, but 85% of my plug
> >  wires are in that loom that  > mounts to the valve cover, so
> >  the problem could be hidden in there...
> >
> >  The weakness in the wires will more than likely be at the
> >  ends, by the spark plug and distributor terminals.
> >  So wait for a dark night and spray those areas, and don't
> >  worry about what is under the cover.
> >
> >  --
> >  Kent McLean
> >  '94 100 S Avant, "Moody"
> >  '89 200 TQ, "Bad Puppy" up in smoke
> >  '56 Austin-Healey 100 BN2, for sale
> >
> >
> >
> 
> 


-- 
Chris Hall
badcomrade at gmail.com
"making girls cry since 1974"