Fuel Pump Relay question
syfer at mindspring.com
Sat Jun 4 22:30:16 EDT 2005
Chris Hall wrote:
>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
>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.
>On 6/4/05, Jim Jordan <superba at comcast.net> wrote:
>>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
>>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.
>>> -----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
You know i had almost that (except it did not backfire) same problem one
time on my 200... When i had A STALL it would do the same start for a
second then die you toch the gas forget it for about 10 - 15 minits
then would start .
Turned out to be a heat sensor problem the connector was very coroded
put new connector on and starts ok .
I also had a stall problem on my 86 5000 turns out i had a bad fuel pump
filter / screen was some kinda recall were screen at bottom of fuel pump
had to be removed.
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