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Dan, Technician
Category: Pontiac
Satisfied Customers: 23989
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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1990 Firebird: V6 auto..Injectors replaced about 2 years ago

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1990 Firebird 3.1 V6 auto trans
only 57k miles. Injectors replaced about 2 years ago. Have replaced EGR valve as it was leaking exhaust gas and car was not running properly. Was running, now won't start. Will turn over, but will not run. I don't believe it is fuel, it would run for a second and quit when I tried to start it.

Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks.


It sounds like a bad injector, you can try to feed engine with fuel to see if it stays running to prove its fuel related. Disconnect the fuel injector connector, near the upper intake plenum. Ohm test each fuel injector branch, from A to E and B to F. Each fuel injector branch should have just over 4 ohms at room temperature. If either branch is below 4 ohms, remove the upper plenum, check each fuel injector separately. Each fuel injector should have just over 12 ohms at room temperature.

Customer: replied 6 years ago.
The injectors were replaced only about 25 to 30K ago and about 2 years ago. The reason I replaced the electronic EGR is when the valve malfunctioned (it was leaking exhaust gas) the speedometer would not work and the transmission torque converter lockup would not work. It got really bad gas mileage when things weren't working right. Sometimes it would not idle at all and other times it would have a very high idle speed. When the car quit running on me (in the WalMart parking lot) I repeatedly tried to start it to no avail. A couple of times when I was trying to start it, it ran for a couple of seconds and quit again. I am getting the car home today (it is still at WalMart)and I will check the injectors as you suggested.

What you are calling the upper intake plenum, that is the manifold with the Mass Airflow Sensor in the front and the six runners going to the heads, right? Once I remove that, then I have access to the injectors according to your reply.

As far as feeding fuel to the engine, do I just squirt some gas down the intake? And checking the injectors,I use a multimeter and check the ohms (resistance) with the switch on?

Thanks for your reply, I just have trouble accepting that it is the injectors, but I will check everything you suggest. I don't have your experience, however I am good at fixing things.
Your are correct about the intake and to feed fuel you can pour fuel in engine or spray starting fluid in intake. TO check resistance switch should be off and injectors should be disconnected. The main reason I think its the injectos is because thats a very common cause of start/stall condition. Let me know what you find, thanks.
Customer: replied 6 years ago.
I just tried squirting fuel into the intake and it would not start.
I am going to check the plugs next and see if it is getting spark. I sincerely XXXXX XXXXX is something to do with the ignition; it won't event begin to run when I squirt the fuel in the intake. I will get back to you as soon as I can.
If it didnt fire with fuel then its definitly ignition or compression/timing related. Check to see if you have saprk and let me know what you find. Thanks.
Customer: replied 6 years ago.
OK, no spark when I pull a plug wire and hold it against metal to jump the gap.
Ok, it sounds like your ignition module may have failed. Verify that the ignition module has power and ground at the 2-wire connector while cranking. Disconnect the crank sensor from the module. Check for(NNN) NNN-NNNNohms resistance between terminals A and C. Check for at least 500 mV AC output between A and C at a good cranking speed. If all OK, replace the module.
Customer: replied 6 years ago.
I appreciate your help, however, I need a little guidance on the location of the ignition module.
Sorry about delays in response, website is going slow. The ignition module is located under distirbutor cap.
Customer: replied 6 years ago.
OK, I am running out of daylight to see,however, the distributor is at the back of the motor next to the firewall. Looks like I will have to remove the upper plenum of the manifold just to get to it. There are two little bolts holding the cap to the body of the dist.

Once I have got access to the distributor the plan is to check the connectors for power and resistance and providing all is well, replace the ignition module, correct? I can see the two wire connector and a four-wire connector on the side of the distributor where the cap meets the body of the dist.

I will have to wait till tomorrow to start this phase, but I will keep you posted as to what I discover. Many thanks for the advice in the meantime.
You shouldnt need to remove intake but that will make it easier. But yes, it sounds like your on the right track. Let me now how it turns out or if you have questions, thanks.
Customer: replied 6 years ago.
I got the ignition module out of the distributor. On the rotor shaft there are some projections and some finger-like projections that they come in contact with sort of like ignition points. These are all corroded with what appears to be rust. When I removed the cap it was not tightly secured with the two bolts. There is corrosion around the two screws holding the ignition module in. The car was running before like this and was not hesitating or misfiring.

When you are describing terminals A and C on the crankshaft position sensor connector are you talking about the two connectors on the plug?

If you can be a little less technical and just tell me what contacts to check that would really help.

Clean all the contacts you see that are dirty and could cause a possible problem. White/green wires on connector shoudl be tested for AC voltage while cranking engine....IF no voltage replace crank sensor/pickup coil. Here is a wire diagram, let me know if you have questions. Thanks.



Customer: replied 6 years ago.
Hi Dan,

I am going to replace the ignition module and the distributor cap because the cap is worn on the inside and corroded and the ignition module has corrosion around the mounting holes. I just want to ward off any future crap, even if the module was (is) good. I will plug everything back together and let you know if we have fire in the hole.
Ok, pink wire going to coil should also have voltage...something you could check right away too. I think replacing ignition module an cap will take care of issue..."Test pickup coil before replacing module"..If not we will need to start checking wiring between ignition module and coil and ignition module and ecm. Let me know how it goes. Thanks.

Edited by Dan on 12/23/2010 at 8:25 PM EST
Customer: replied 6 years ago.
OK, it will try to start but will not run, I smell fuel so that is definitely not the issue.

I will have to test the wire going to the coil as you suggested. When I test the pink wire going to the coil,is this with switch on and cranking or just switch on?

I will do that and get back to you ASAP.
With key in on position pink wire should have voltage....make sure to test white and green wires frmo pickup coil going to module for AC voltage while cranking engine. Let me know what you find out, thanks.
Customer: replied 6 years ago.
The pink wire has voltage, the white and green wires must be under the cap. I don't have any daylight left to pull the cap again so I have to try it tomorrow.

I suppose I can try replacing the crankshaft sensor to see if that will work. I am into it 160 bucks for EGR valve, 55 bucks for cap and ignition module. The sensor is 17 bucks
Yes the white and green wire are under cap....Dont just replace crank sensor or it will get expensive....But if it doesnt put out AC votlage while cranking then replace. Did you get it all put together with new ignition module and check for spark?
Customer: replied 6 years ago.
As I crank it, the motor cranks like the timing is off, it will try to fire, maybe it is the crankshaft position sensor.
If it Tries to fire then you have spark....we need to figure out if you have spark or not because if you do we are wasting our time.....If you have saprk and fuel then the problem is either low compression possibly due to flooding or timing.....If oil is flooeded you may need to do oil change and put a teaspoon of oil into each cylinder to restore lost compression....Let me know if you have questions, thanks.
Customer: replied 6 years ago.
The motor only has 57k on it, I don't think it is compression. It doesn't have spark or at least the ignition isn't in sync. I have put a new ignition module in, but I haven't checked for spark. I will do that in the morning because it is getting dark out and I can't see what I am doing.

I will keep trying, I know I can fix it with your guidance. Thanks for being so patient with me.
I've seen vehicles with 20k not start becauase of low compression due to flooding....I was suprised the first time also.....Also if the spark plugs look wet dry them with a torch....If you have a compression tester I'd check compression just to eliminate it as a possible cause....If low "below 100" change oil and put a teaspoon in each cylidner. Let me know how it goes tomorrow. Thanks.
Customer: replied 6 years ago.
As I turn it over it will hit but not run.
I checked the coil wire and on the side from the coil the spark is strong with a blue white spark, on the other end it looks weaker and reddish. Could it be the coil wire?
Check pink and white wires between coil and ignition module, if both wirs are good then replace coil.
Customer: replied 6 years ago.
Pink wire has 13.99 volts DC with switch on, white wire no voltage.
There are two pink wires, your checking the wrong one.....this isnt something you can check for voltage you need to just verify wiring is in good condition.....Have you checked spark at plugs?
Customer: replied 6 years ago.
From the terminal on the coil I get a spark. From the end of the coil wire to the terminal on the distributor cap I get a sort of weak spark. At the plugs I get no spark at all. I have held the plug wire near the top of the plug to try to see a spark jump the gap and near a bolt on the motor (ground) to get a spark. No evidence of a spark.
Ok, it sounds like a weak coil if I'm understanding right.
Customer: replied 6 years ago.
I think so, too. I am going to replace the coil and get back to you.
Ok, let me know. thanks.
Customer: replied 6 years ago.
I plugged in a new coil and no change. I turn the engine over and the motor will seem to hit but will not run. It is getting gas ( I can smell it)

Could it be the coil wire itself? How do I check continuity to see?
Customer: replied 6 years ago.
I am going to replace the rotor in the distributor and see if that helps. I called a tech that I know and he suggested that
If the distributer cap is corroded I'd also replace that. If the coil is putting out spark then it is a problem between coil and distributor. Let me know if the rotor helps. To do a continuity test you will need to use a voltmeter and put it in the OHMS option. Then put one voltmeter lead on each side of the wire. Let me know what you find, thanks.
Dan and 3 other Pontiac Specialists are ready to help you
Customer: replied 6 years ago.
Hi Dan,

I replaced the rotor and it started right up. I had already replaced the cap when I replaced the ignition module. I drove it around and it developed a glitch: The speedo quit working and it seemed to lag a little taking off from the stoplight. However, I am happy that it is running. If you have any ideas why the speedo quit working, let me know.
It did that when the electronic EGR valve was bad. I replaced the EGR valve so I don't think that is it.

At any rate, Happy New Year. I am clicking Accept so you can be paid for all your help. Let me know if you have any ideas about the speedo problem. Thanks again for all your patience with me.

I meant to send this as a info-request, no need to accept as its a follow-up question. Thanks for accept though. Thats great to hear the rotor fixed it. At the cluster make sure the black wire has good ground and check the brown for ground pulsations....If good replace cluster. If no plusations check vehicle speed sensor operation. If the vehicle speed sensor isnt putting out AC voltage it needs to be replaced. IF it is you need to check wiring between cluster and ecm and speed sensor and ecm....If all is good replace ecm. Here are wire diagrams, let me know if you need anything. Thanks.






Edited by Dan on 1/1/2011 at 12:50 AM EST
Customer: replied 6 years ago.
The speedometer works intermittently. When the speedometer is working, the car runs better and the transmission will go into overdrive. When the speedo is not working, the car runs poorly, gets about 10 mpg and the transmission will not go to O/D

You suggested last time to check the cluster and speed sensor. I don't think that is the problem. I think the problem is the ECM. Or could it be the O2 sensor? The reason I say that is the car has a different exhaust note when the speedo isn't working and then runs quietly and smoothly when the speedo works.

Further, sometimes the engine won't idle, sometimes it idles at 1500 rpm and when the speedo works it idles about 750rpm as it should. I need to figure out the problem because I drive the car about 50 miles a day or more and the poor gas mileage is costing me out the A** at 3.75 a gallon!
Check engine light on? have you checked codes?
Customer: replied 6 years ago.
No, the CL light is NOT on. It will illuminate and then go out quickly. I have NOT checked codes. The CL light will sometimes illuminate and stay on but it will go out again. Should I try to check codes anyway?
Ya, check codes and let me know what they are.