Question about 1990 Oldsmobile Ninety Eight
IT HAS BRAND NEW BATTERY. FUEL PUMP WAS CHECKED BY OPENING THE END OF CANNISTER CLOSEST TO ENG. THEN TURNED ON TO SEE & HEAR IT PUMP FUEL WITH GOOD PRESSURE. IGNITION SEEMS TO WORK FINE, LIGHTS IN DASH ARE FUNCTIONING PROPERLY. MAKES ME THINK EITHER FUEL SENDING UNIT SENSOR MODULE OR THE INJECTORS THEMSELVES. WHAT ELSE IS THERE IN THIS MODEL ENGINE?
You cant check fuel pressure that way. You have to connect a fuel pressure guage to the fuel rail at the schrader valve. It should have 30-40psi when ignition is turned on. Injectors not functioning properly will cause a misfire Sounds like a fuel pump or fuel going out.
Posted on Jan 01, 2014
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Posted on Jan 02, 2017
SOURCE: 99 olds alero 2.4
I'm sure you have installed a fuel pressure gauge and monitored the fuel pressure while the problem is occurring?Another diagnostic tool which is easy to do,is while the problem is occurring,unplug one sensor at a time beginning with the Mass Air Flow first,.if it uses one.Many times,not always,depending on the sensor,if the sensor is taken out of the picture as far as what the PCM is seeing,like unplugging the MAF,the PCM will substitute the missing sensor output with a generic value that will allow the engine to at least run,and if unplugging for example the MAF,the engine idle speed returns to normal,you know you're onto the problem.You didn't mention if the engine ran ok other than the idle problem.As far as checking for vacuum leaks,i use something like brake cleaner or WD 40,more of a liquid,and it does sound like a vacuum leak.Plastic intake manifolds do develop nearly invisible cracks that open up more with heat.Revsisit the possibility.And as for the PCM,it is possible,but more likely a mechanical problem.Lastly,remove an O2 sensor or two before the catalytic convertor,run the engine and see if anything changes.Cheap way to verify the catalytic convertor is flowing and not restricting engine airflow,as i have seen bad cats cause misfire codes and strange problems.Good luck.
Posted on Dec 04, 2008
Try disconnecting the electrical connector at the transmission and see if it stall when you put it in gear. You will get a service engine light, but not to worry, it will go back out once you reconnect.
By disconnecting the wire connector we can tell if it is transmission related.
Good luck, let me know.
Posted on Mar 08, 2009
could it be the A/C pump kicking in. might be boging down the motor or electrical circuit, not letting the injectors get enough power. This could happen if the bearings are going bad in th A/C pump or there is a short in it. Just an idea. sounds like you have done the main components.
Posted on Apr 16, 2009
check for a good spark first, if there is none look at ignition circuits its more likley this part,
it could also be the car alarm the immobiliser shutting of the ignition ""stops it getting nicked?"
try resetting the alarm if you take off pipe to carb and there is fule pumping out!!! fule filter is "ok" for starting up on!!! take care working with fule!
Posted on Oct 30, 2009
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