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Engine won't start/run? Beginners, read this.

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There are always so many questions about cars not starting or cars that won't stay running so I thought I would take a shot at covering it thoroughly even though I tend to think in a scatter-brained way.

 

From the beginning:

 

If you car doesn't do anything when you try to start it:

You might have a bad solenoid, starter, or ignition switch. A Voltmeter should be used at the starter solenoid to make sure you have 12V going to the main power prong and the switched 12V (small wire) when your ignition is in the "start" poistion. If not I don't envy you and you will need a wiring diagram, voltmeter and a few hours to trace which wire does what. Start at the ignition switch and move forward.

 

If your car clicks while you're trying to start it:

You probably have a dead battery which could be caused by a bad battery, a bad alternator or faulty wiring. Jump the car off and if the car will stay running your alternator is working and your battery is probably bad. If your car dies soon after disconnecting it from the other car your alternator isn't working properly AND your battery is dead (but the battery is only dead because the alternator isn't charging it). If you can make it to a place that tests batteries and alternators you should. Taking just the battery to get tested is not a bad idea. In the process of testing the battery some places will charge it for you also.

 

If your car loses all power as soon as you try to start it (lights go off and won't come back on, radio stays off etc.):

You probably have a bad connection at the battery or solenoid. Clean the terminals and tighten.

 

So the car will crank but not start, now what:

 

Engines must have fuel, spark and air to run:

Fuel:

One of the easiest ways to figure out if you're NOT getting fuel is to spray gas, starting fluid or carburetor cleaner into the carb/throttle body. If you are able to get the car to fire or even run for a short period of time then you're not getting enough fuel to the engine. Many things could cause this with the most prominent probably being the fuel pump. You can of course hear an electric fuel pump running and it will probably be near the gas tank if not in it. If you have a mechanical fuel pump you probably can not hear it and will need to use a fuel pressure gauge or prime the engine as said earlier. If you have a carburetor with sight plugs you could pull them to see if there is fuel in the floats. With fuel injection, if you are getting fuel pressure you should move on to things like checking to see if your injectors are getting 12V from the computer while cranking (use a voltmeter). A clogged fuel filter will almost NEVER cause an engine to not start. This could be possible in a car that has sat for a long time and then run close to empty or if you were experiencing an EXTREME lack of power before.

Spark:

(If the above didn't work) The easiest way to insure that your are getting spark is to take a spark plug out and ground it to the engine or body (not a painted or plastic/aluminum part). You can also do this with a timing light. If you do not get any spark you should check to make sure that your coil (this could be part of the distributor such as an HEI) is getting power (with a voltmeter) and that your ignition module is hooked up properly. If you still do not get any spark you should think about replacing your coil.

So you've got spark and fuel but your car still won't start. It is very likely that your timing (either ignition or valve) is wrong. Backfiring and popping through the intake is a good sign you have your ignition timing wrong. You should triple check your firing order. If you have moved the distributor or are working on a car that you do not know what the PO has done, you should set the car to top dead center. You can usually do this by setting the slit on the harmonic balancer to the "0" on the timing indicator. You must make sure you are on the compression stroke when you do this which can be done easily by holding your finger over the #1 spark plug hole while cranking or turning the engine (taking all of the spark plugs out will help because you won't be fighting the compression of the engine). When the pressure pushes your finger off of the hole and you are nearing "0" on the indicator you are on the compression stroke. Now you need to get it right on "0" (and you might have to try it a few times), remove the distributor cap and make sure the rotor is pointing to the #1 spark plug post. If it is on the complete other side ("180 degrees out"), you should unbolt the distributor and move the rotor to the #1 position. With an L28 this should be easy because it should only go in two ways and if you haven't messed with the oil pump rod rotating it 180 degrees around should be perfect. On a Chevy engine you might have to move the oil pump slot/rod with a long flat-head screwdriver and do your best to put the rotor around the #1 position.

So you're getting fuel, spark, you're at top dead center and your rotor is pointing at the #1 post and still the thing won't start. It is very possible that your ignition module is bad especially with a Z. You can take these off the distributor and have a parts store test them. Take what the machine tells you with a tiny grain of salt because I've had good modules test bad (one time it was new off of their shelf and another time it was off of a car that I had been running for about a year) and I've also had bad modules test good. Sometimes modules will work some times and not other times. If your Z will start only sometimes and even die on the road sometimes and start right back up you probably have a bad ignition module. You should check to make sure your spark plugs aren't fouled. You could be flooded at this point also in which case you should try to crank the engine with the throttle wide open (gas floored) and if that doesn't work you might think about calling it a day and trying tomorrow. I'm not going to cover valve timing because if you think you can play with a cam you should be able to install it correctly :lol:.

 

Air:

It would be pretty rare for a car not to start because it either can't get air or can't let the air it gets out of the exhaust. If the car has sat outside for a long time you could have a rat or bird nest in the exhaust or intake. If you have some punk friends they may have tried to plug your exhaust with a potato or sock. If your car has been sitting long enough for it to be clogged you should go through every aspect of the car (including the brakes) before you decide to start/run/drive it. Weed eaters/whacker/trimmers, mowers and small engines are pretty notorious for having their little muffler or a screen that goes over it to be clogged to the point where they won't start. Maybe someone will get their weed eater running from me writing all of this :icon51:

 

Anyone have anything to add?

 

- I am in no way responsible for the use or mis-use of these "opinions".

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Sometimes just clicking (no cranking) may due to bad contacts in the starter solenoid. If another person is available, turn on the headlights and have them watch while you try to start the car. If the headlights go out (or get very dim) you probably have a battery/ connection/ charging problem. (Another scenario for the voltage drop could be a locked or shorted starter motor... much less likely). If the lights stay nice and bright, there's a good chance the contacts aren't doing their job.

Dome lights may do for a solo tester, but don't provide much battery load.

 

Vehicles with a dropping resistor in the ignition circuit usually bypass it when starting. If this resistor goes bad (open) the engine will start, but die as soon as the starter is disengaged.

 

Looks like a good start on a 'sticky'.

I'd Add a caveat about the dangers of playing with gasoline, starter fluid etc. because someone, somewhere could do something stupid and find a lawyer.

 

(My paranoia/ faith in lawyers is showing).:puke:

 

 

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IN my case the voltage does not drop, instead it peaks out. I changed my MAF sensor for a twin turbo MAF ( I have and 1986 Turbo Z) and I don't know if that is one of the problems and I wish somebody could answer mew this. Another thing a friend of mine told me is one of the "Fusible links" gone bad...can this be it? Another thing is that I changed my stock regulator for one that looks from a Porsche and I don't seem to find where's the fuel entry, the fuel exit and the air vaccum. This fuel regulator is completely different because unlike the stock one it only has one fuel entrance ( the stock one has two). I'm breaking my head here because of thinking too much, can someone somewhere help me?!?!?!?!

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IN my case the voltage does not drop, instead it peaks out. I changed my MAF sensor for a twin turbo MAF ( I have and 1986 Turbo Z) and I don't know if that is one of the problems and I wish somebody could answer mew this. Another thing a friend of mine told me is one of the "Fusible links" gone bad...can this be it? Another thing is that I changed my stock regulator for one that looks from a Porsche and I don't seem to find where's the fuel entry, the fuel exit and the air vaccum. This fuel regulator is completely different because unlike the stock one it only has one fuel entrance ( the stock one has two). I'm breaking my head here because of thinking too much, can someone somewhere help me?!?!?!?!

 

 

If the engine isn't running, I don't see how the voltage can be going up... starter and other electrical loads will be draining the battery, eventually causing the voltage to go down.

 

You can check your fusible links with a voltmeter: If you find battery voltage across one, it is blown. I'd change any link with a significant (volt or so??) reading.

 

Sorry, I can't help with EFI stuff.

 

Sounds like you may have picked up a 'deadhead' fuel pressure regulator to replace a bypass type. Not a good idea. http://forums.hybridz.org/showthread.php?t=105947

I'd guess that you also need that vacuum/pressure connection on your regulator for boost enrichment, but that is strictly speculation.

 

Life is simpler if a person makes only one change at a time. :hs:

 

 

 

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well i have a question. my car doesnt run but it did just two weeks ago? maybe last week. its a 75 280z and the radio works and head lights all the good stuff.. but the engine i guess you can say it cranks the fan turns like 5 degrees and then it stops and the starter makes a clicking noise. any idea what i should do? thanks.

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check the battery. Mine did the same thing and turned out to be a dead battery. I say it's the battery. Try with another one. If it don't start after you changed batteries then check fuses and all that sort of stuff with a tester. I back up the battery theory. Once you've taken the battery out clean the battery terminal with sand paper or a the metallic hair brush that comes for cleaning the terminals. Might as well do the same for all the cables that are connected to the battery and one of them comes out of the starter that might as well be false contact between battery terminal and starter solenoid.

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Guest nathan11

Ok I have had a problem with my 1975 280Z. I would be driving normally and all off a sudden the engine dies. My radio and the accessories would still be on but my engine just turns off. I know this because the RPM would drop to 0. Now I changed spark plugs (wires aswell), ignition coil, distributor cap and rotor. Problem is still present so I went and replaced the fuel pump, fuel injectors, injector plugs, fuel pressure regulator, fuel filter (twice), Hoses, and new air filter. Problem is still there. Now I figured it may just be the ignition switch so i replaced that but no results. I had the battery and altenator testing and are fine. I also had the cd player and alarm system taking out due to me thinking maybe it was interfering with the ignition.

 

I sent the car to a Nissan Service Center and they cant figure it out. It is still there at the moment.

 

Now here is the weird part. I found a technique that if I hold the key half way from ON position and Start position it will stay as long as im holding it there. As soon as i let go the car will either shut off at the moment or stay on for a bit and shut off again.

 

What nissan has done is got another ignition switch because they swore 99.9% that the the problem but nothing. Then they said it may be the ballast resistor. Still nothing. And they havent called me back with any update yet. Nissan states it is something to do with my ignition/electrical system.

 

Any input would be great

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i just go an 1988 300zx turbo. when i got it it wasnt running too well because it had be sitting for a while. it started up real easy but ran real rough an jerky under acceleration problely from old gas, fouled plug and a dirty fuel system. i drove it about 20 miles back home. i change the oil, spark plugs, wires, cap, rotor, coil, fuel filter, belts, air filter, and flished the radiator and changed the thermistat. after i had it all back it geather. it runs much smother but now is hard to get started when the engine is cold. when i try to start it in the morning it just cranks up then dies. after the 3rd or 4th try it will start but it won't idle good untill it gets up to operating tempiter. after i get it runing for the day it start up super easy for the rest of the day. i don't think its the fuel system because it gets plenty when i'm gunning it around the neiborhood. i had to unskrew F.I.C.D. soleniod valve to get to the 4th sperk plug. i skrewed it back up and pluged it in like it was but i don't know if i could have messed something up. the only other thing i could think of is the air regulator could be falty but i don't know how it could of broken because i didn't touch. ANYONE GOT ANY IDEAS?

l_e0d222cd28cc4df2f74e338d0dafe9b3.jpg

my engine

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NATHAN 11!!!!!!!!

ur problem is in ur ignition barrel itself, behind it r 5 wires! there is obviesly 1 loose or very weak, try checkn that mate get back to me,

 

 

people i alo got a problem myself,,,, my L20et is gettn fuel,, its getting spark, valve and ignition timing is fine, yetwont start, it wont even try start, it jus turns over by the power of te starter motor n thats it,,,,, nufn else, wont even try to ignight itself,,, yet its gettn all it needs, any ideas??????

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Looks like I may have a similar problem to Nathan11 - see here:

 

http://forums.hybridz.org/showthread.php?p=855170#post855170

 

Nathan11 - did you fox your issue yet?

 

Anyone else on this thread have an idea what happened to my Z? Sounds like possible bad grounds on my engine/dash connections (and/or alternator and battery issues).

 

Phil

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One thing to add to the inital post - In addition to spark, fuel and air, you need compression for an engine to run. Bent valves, broken valvetrains, broken camshafts or a timing belt or chain slip can cause you to have 0 dynamic compression. I have fixed a couple twin cam engines where the owner simply didn't set the cam to cam mechanical timing correctly and the motor would not run.

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Ok guys i have a problem as well my car starts runs for a few seconds then dies i can re start it and it will do the same thing i can repeat this about 5 times then it wont start at all. the guy i bought it off of said it sat for 6 years and then he started it and let it run for a while (before i came to buy it) and it died and did the same thing its doing now. any ideas ?

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Palmer765s:

 

Always include the make and model of the car you are discussing. Also, include type  of  fuel and ignition system.

 

The car sat for six years. What is the most likely cause of the symptoms you are seeing?  Go back to the very first post in this thread. The answer is there. You just have to think about it logically.

Edited by Miles

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