90 100q stalls out

[Mark R]

Not really enough data to answer the key question.  Classic symptoms of a
fuel delivery problem (which was also your guess with the relay).  Symptoms
of a clogged filter, water in the fuel, a fuel leak, or unmetered air.  A
fuel pressure and volume test would be a good place to start after checking
codes.  Leaving the exhaust nuts loose probably wasn't the best choice.
Where is the oxygen sensor in relation to that leak?  Downstream?

Have you tracked your fuel economy lately?  If the O2 sensor is getting
false air, then the computer would compensate by over fueling (rich
mixture).  Short trips would exacerbate this issue, causing more plug
fouling and carbon buildup.

Good luck,
Mark Rosenkrantz

On Dec 26, 2007 12:21 PM, <syljay at optonline.net> wrote:

> My 1990 100q, manual, non turbo stalled out at the mall.Pre-existingcondition:Car has an exhaust leak. I'm pretty sure its at the downpipe/cat
> flange. The leak noise goes away after the car warms up. Last time I was
> under the car, about 6 months ago, I left the flange bolts/nuts a bit on the
> loose side cause the downpipe flange was rusty, thin, and bending. I suspect
> with a bit of bouncing of the exhaust system, the flange worked its way a
> little loose. When the exhaust pipes are cold and contracted, an opening
> appears. After a warm-up, the pipes heat up, expand and seal off the gap.I've
> had this exhaust problem for about a month now . .. with no stalling
> issues.Sequence of events:Went to the mall on Christmas Eve in the 90
> 100q.Drove to the first store with no problems.Came back after about 45
> minutes and drove car to next store about 1 mile away. No problems.Cameout of the store about 30 minutes later - started the car - and proceeded to
> drive out of parking lot.I felt something wrong, the engine would
> buck/miss if given too much gas. I looked for an empty parking spot and
> creeped towards it. Engine was missing badly and finally stalled out. Engine
> would not start, cranking was fine. We got some good samaritans to help push
> the car into the parking space.I called wife who picked me up in the 88
> 5kq.Two hours later, I went back to get some things forgotten in the 90
> 100Q.I swapped out the Fuel pump relay with the one from my 88 5kq. Car
> started right up. I put back the original relay, car started right up.Iwent home, got a spare fuel pump relay, and drove back to the car with wife
> in tow.Put in the spare relay, started the car - no problem.Let the car
> warm up, and drove around the parking lot a bit.I felt a hesitation a
> couple of times when starting off and giving gas. I let it warm up some more
> and tried again. I was easy on the gas and the car seemed to work ok.Idecided to try getting the car
> home.All worked ok, until I got to a stop light just before the entrance
> to RT 80. As I was starting off, the car bucked and I thought it stalled
> out. Being in traffic, I didn't watch the RPM gauge and tried starting the
> engine . . got a grinding noise . .the engine was not stalled.I drove off,
> being gentle on the gas. By now I was suspecting that giving too much gas
> too quickly resulted in the bucking/cutting out. Maybe the engine torque and
> engine rotation was moving something.I drove all the way home (about 10
> miles) on the highway with no problems - - being gentle with the gas.Andnow, for the $64,000 question - Whats the problem?SJ in NJ
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