Turns over, but wIll not start

RP
20

Asked by RP Apr 02, 2010 at 03:03 PM about the 1990 Pontiac Grand Prix

Question type: Maintenance & Repair

New computer. New Fuel pump. New dist. pack plus wires. It's getting spark.  New Cam pos. sensor. Ignition switch looks good.  Mechanic says it gives the code of now getting power to the ecm.  Still won't start. Any other suggestion?

9 Answers

Danny Wang
2,505

is the fuel pump relay good or is the fuel pump getting electrical power? is the crank sensor good?

3 out of 3 people think this is helpful.
RP
20

Have not checked the relay, but if pump is pumping, I assumed that relay was working as well. A new one is only about 7 bucks... or I could check for continuity if I which pins to contact. Is is possible to have placed the cam sensor in wrong... does it have to be at TDC or something?

1 out of 1 people think this is helpful.
Jay Sicht
165

If it's getting spark, I would think the ECM has power. You need to see if the injectors are firing (also controlled by the ECM) and that you have proper fuel pressure at the fuel rail. The injectors can be checked by unplugging the electrical connector at the top of each injector and plugging in what is called a "noid light", made by mfrs. such as Borg Warner, Standard Ignition Products, etc. It should pulse as the engine is cranked. Fuel pressure should be in the neighborhood of 35 PSI, but as long as you're getting ANY volume of fuel at the rail at all (when you depress the Schrader valve that looks like a tire valve, fuel should spray out.) I am not that familiar with the anti-theft systems on these cars, but wonder if a problem with that would allow spark but not for the injectors to fire?

3 out of 3 people think this is helpful.
RP
20

I will check for power at the injectors via the "noid light". Not sure about the anti-theft system, though. If FI's not getting power or opening, what does this mean? Pardon the ignorance on my part, but what is failing if this happens? (ECM?) Also, I haven't checked the other "basic" re: timing chain/belt. What's a quick and easy test for this without having to make a visual inspection of said chain/belt? I really do appreciate everyone's help.

1 out of 1 people think this is helpful.
Jay Sicht
165

Well, an engine needs several things to run: Fuel, air, and spark. It needs enough compression to run well. You can check that the timing chain has not broken by checking compression. A compression tester screws into the spark plug hole. If the timing chain is broken, compression will be low. I'd recommend subscribing to an online DIY "repair manual" information site such as www.alldatadiy.com. It is much more comprehensive than the typical Chilton or Haynes manual, and also has many diagnostic guides and technical bulletins. The ECM has "drivers" inside that tell the injectors when to fire. I am unsure, though, if this car has an antitheft system (PASS key with a resistor in the key), and if so if it disables only the injectors and not the ignition. The online repair information ("manual")l would lead you in the right direction. I've been in the automotive parts/service industry one way or another for the past 15 years and am a serious do-it-yourselfer (mostly with GM, and had an '88 Cutlass Supreme with a 2.8), but I am no expert on the subject. Regardless of whether you tackle it yourself or have a mechanic help, though, the more diagnostics you can do on your own, the better off you'll be. One thing I don't understand is the code "not (that's what I think it meant to read) getting power to the ECM." If it's not getting power, how is it operating to give a trouble code and is getting spark?

2 out of 2 people think this is helpful.
Jay Sicht
165

Here's a good short article about the GM antitheft system, even though it's on an F-body site: http://sethirdgen.org/vats.htm But again, I'd recommend alldatadiy or similar. There should be a troubleshooting flowchart to help you eliminate possible problems and help you come up with a solution. Good luck and let us know what you find out!

6 out of 6 people think this is helpful.
CrackMonkey
40

My 97 Grand Prix has this same issue. About a month ago, the car alarm started randomly going off also (I seen your other post). It's in the shop now, and they are having issues diagnosing. I will let you know what I find out.

2 out of 2 people think this is helpful.
CrackMonkey
40

I was having the same issue. The dealership said the battery is on it's last leg and needs to be charged or buy a new one.

CrackMonkey
40

When one of the cells on the battery starts going bad, it trips up the alarm system (hence the car alarm going off randomly). The battery had charge, just a compromised cell which tripped up the alarm system not allowing the car to start.

2 out of 2 people think this is helpful.

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