QuestionQUESTION: i have a 97 elantra and it is moody sometimes it wont start and sometimes it will and i want to be clear it always turns over its just that sometimes it starts and sometimes it don't it had a bad alternator so i replaced it no difference checked wiring seems ok but its not like i have Xray vision i need a place to start looking and i thought i found the problem in a ground wire but it is still acting up i now there is still a problem i just need a place to start looking
ANSWER: Hi, Allan. You're going to need to start to see whether you have some basic ingredients necessary for the car to run. And you're going to need to do this while the car will not start. I'm presuming this vehicle has multiport fuel injection.
At that time:
1. Do you have spark at the spark plugs? You can test this by placing a spare plug in a wire and laying on the intake manifold. (Do not do this if there's fuel around, such as from the fuel pressure test).
2. What is your fuel pressure?
3. If you turn the ignition key to the on position, does the check engine lamp illuminate?
Also, has your check engine lamp been coming on? If so, did anyone read the trouble codes? If so, what were they?
---------- FOLLOW-UP ----------
QUESTION: answers to questions as follows.
1.no to the spark.
2.40 or 50 psi when it runs, when it doesn't run 0 psi.
3.Check engine light is on when i turn the key to the on position.yes to the code thing but when it don't start there is no more codes.
i didn't get a chance to right them down.
ANSWER: Does your 0 PSI indicate that this is the pressure during cranking? If not, what is the fuel pressure during engine cranking?
This will help me understand whether it's likely that the ECM isn't seeing sufficient information (crank sensor signal) to supply spark, or whether there's another issue preventing the ECM from functioning in general.
If your check engine lamp comes on again, make checking the codes a priority. This may greatly reduce the amount of time and aggravation you endure finding this problem.
---------- FOLLOW-UP ----------
QUESTION: 0 psi when it doesn't want to start. during cranking or not it doesn't matter, no fuel or spark when it doesn't want to start.
AnswerThis is odd. I see nothing that should cause both the fuel pump to not run and the ignition coil to not fire, that would also allow the check engine lamp to illuminate when the key is turned to the on position. Since the necessary ingredients for spark are difficult to test, it may be better to start your diagnosis with the lack of fuel pressure. At this point, I'm going to encourage you to (if you haven't done so already) register for a free account at www.hmaservice.com. That will enable you to look at the schematics, which will be a valuable tool for this diagnosis.
First, check to see if the fuel pump relay applies power to the fuel pump. There's a test connector under the hood that's easily accessible; you can view a drawing or picture of it in the component location area of the schematic index (under the heading "general"). If you have no power there, it's a safe bet that there's none at the fuel pump. On the other hand, if you do have power there, you cannot necessarily conclude that this power reaches the fuel pump. Additionally, if no power is present, you can apply power to the test connector and see if you have fuel pressure. If you do, you then know that the fuel pump and fuel pump ground are okay, and most likely, the wiring between the fuel pump relay and fuel pump is okay as well.
Based on your findings, consult the schematic and check how to proceed depending on what you've found.
