1990 Oldsmobile Ciera Car won't start---

JOHN_DOUGH

MEMBER
1990 OLDSMOBILE CIERA
4 CYL
2WD
AUTOMATIC
85,000 MILES

We've had this car for a few years and it hasn't had any major issues up until now. Out of nowhere, though, it stopped starting occasionally. Once in a great while we would go out in the morning and it wouldn't start, but two hours later it would start up just fine and drive away. This became more and more frequent until, now, it won't start at all. We had the vehicle towed to a mechanic and did multiple diagnostic tests, only to have him deciding that it was a computer issue, which he replaced. Fuel issues were ruled out due to testing which leads us to believe it is an electrical problem. All fuses, of course, were tested, as were the grounds. We are, frankly, at a loss and haven't the slightest clue where to go next. I'm starting to think a box of shotgun shells may be the best solution.

1 Reply

WRENCHTECH

MECHANIC
20,761 POSTS

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.