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Joe, ASE Certified Technician
Category: Pontiac
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine inboards and electronics, automotive drivability, all around repair tech,
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99 Grand AM: GT...My car cranks but wont start

Customer Question

99 Grand AM GT. My car cranks but won't start. I have done some troubleshooting and here is what I have found. 1) I do NOT have power to the fuel pump. However, I can power on the fuel pump directly with a battery. Also, my ground is good at the pump. 2) I DO have power at the fuse box and the fuel pump relay and the fp/inj fuse are both good and getting power. 3) When I supply direct battery power to the fuel pump, good fuel pressure gets to the injectors. However, if I try to start the vehicle, it will NOT start. If I pull a spark plug right after this, the spark plug is dry which leads me to believe the injectors are NOT firing. Also, I pulled off the intake and put a test light to the injector connector. I get power there, but it does not blink when I try to start it, as though the injector is not pulsing. 4) At the left dash junction box, I have power at the gry B10 wire at connector C2, but I do NOT have power at the gry B3 wire at connector C3. 5) Since this happened, my fuel guage powers, but reads below empty and the fuel light is on. There is a full tank of gas. 6) I DO have spark and if I spray starter fluid in the intake, the car will start for a second. 7) If you are going to tell me it is the PCM or a security issue (security light NOT on) right off the bat, please don't respond. I want someone to help me further troubleshoot this. I believe the problem lies with some ground or power wire that the sending unit, fuel pump, and injectors all have in common. PLEASE HELP!!!
Submitted: 5 years ago.
Category: Pontiac
Expert:  Joe replied 5 years ago.



My name is XXXXX XXXXX I will be happy to try and assist you.


When you crank the engine can you tell me if the tachometer bounces a little only while cranking?




Customer: replied 5 years ago.
Going back to the car...give me 10 mins.
Expert:  Joe replied 5 years ago.

No problem, once you return I have a feeling its going to be a bad crank sensor so will await your reply.


Can you also explain how you found that you do not have power to the fuel pump?


The pump should not matter what have a 3 sec prime when the key is turned on then no power....... Until you crank or delay with key off then key on 3 sec prime again, when are you showing no power at pump, key on engine off or key on engine cranking?





Customer: replied 5 years ago.
No the tach does nothing when I try to start it. Its just stays at bouncing. Having someone turn the key to on, immediately testing voltage at the fuel pump, there is none. There is also no voltage when they try and start it.
Customer: replied 5 years ago.
Any info?
Expert:  Joe replied 5 years ago.

It could be that either system is already under the prime and delay for reset has not been reset yet to allow new 3 sec prime, or could be that the event takes place so fast that the voltage is applied and removed so fast that the meter does not show it, at the same time it could actually be a problem with the system, the lack of tach signal is telling me that there is a problem usually resulting from the crank sensor being faulty, when complete functional system is working during cranking you should be able to see the tach slightly bounce indicating a tach signal, while this is not always conclusive so long as the tach is correctly working then it is usually a good indication of such.


The best thing to do in this situation to aid in the diganosis is connecting a full scan tool to it, not one that just does codes, you need to connect a full diagnostic scan tool to it, this way you can evaluate the peramiters and you can also check for crank signal which comes from the crank sensor.....


At such time evaluate the power to the fuel pump as well.....




Customer: replied 5 years ago.
I know that I am not getting power to the fuel pump because there is not fuel pressure to the injectors unless I manually run battery power to the fuel pump. If I leave it connected to the car and try to start it, there is no pressure. Also, I can verifiably say that it is NOT the cam or crank as I jùst put two new ones in as of a few minutes ago and still have the same symptoms. Please open this back up. The problem needs to be further troubleshot via circuit testing as I feel that it is wire related.
Expert:  Joe replied 5 years ago.

I explained that the car needs to be connected to a diagnositc scan tool to diagnose the problem, I also explained that there is a lack of crank signal since the tach does not move such as if the tach works, this could mean in that wiring circuit or ecu related as well this is the entire reason the car needs to be connected to a diagnostic tool.


There are lots of diagnostic tools to use and thus far I don't see any that have been used, you have explained that there is no fuel pressure yet you have not indicated if you used a fuel pressure tester or if you just opened a line, you havent told me if you have used a voltmeter at the pump either. Theres a very strong chance that you are not getting fuel due to other things...... A scan tool again needs to be connected to the vehicle, no matter how much people don't want to take their car to a shop it needs to be done for proper diagnosis otherwise people guess and just throw parts at something they don't need. Theres no reason to replace any crank sensor either until they where tested and evaluated with the tool. Electronic parts are non-returnable......






Customer: replied 5 years ago.
First, my ASE certs are in electrical electronics and engine performance.

2nd). Do you think people with the above knowledge that I have presented come on just answer to be told that my car needs to be hooked to a scan tool? Do you think that this is what I'm paying for?

3rd). Do you think that, with the knowledge I have presented to you, that I didn't use a volt meter on the fuel pump? Of course I did. I used a volt meter on everything. If you would have read my question thoroughly, you would know that this is how I tested my power and ground wires. I KNOW that it is not getting power.

4th) I told you it was wiring related to begin with. I can get parts for a very inexpensive price and I wanted to show you that it wasn't the crank or cam. You never said a word about wiring or ecm. You suggested Cranks Sensor. BTW...there are many vehicles that crank without the tach going up and down.

5th). If you don't have wiring diagrams (as I do) and electrical knowledge (as I do), you probably shouldn't have answered the question as I specifically said that I wanted a tech to help me troublehoot the car electrically. I ALREADY know where the problem lies.

Thank you anyway.