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Car cranks but wont start intermittently.

23K views 20 replies 7 participants last post by  Samaran 
#1 · (Edited)
My Elantra 4 cyl with 93k miles has finally started giving me problems. I think it may be the starter (I honestly just pulling this out of my ass) but it cranks and wont start. I had my battery tested at autozone and they said it was fine. I'm not hearing any clicking noises from the alternator, but could it be that a bad alternator is draining my battery? If this was the case, then my stereo and dash lights would be dead, correct?


How easy/hard is it to get the alternator and starter replaced and what kind of costs would I be lookingn at for labor (i'll probably order the parts separately.
My last thought would be something with the o2 sensor, which has been the reason for my check engine light in the past few months. Could this be in all the issues I've been running into?

I've also havent cleaned my massive airflow sensor in a while, could this be a reason? Spark plugs were changed about 3 years ago. That also should be a problem, correct?

How would I check fuel and compression?
 
#2 ·
Hello, and welcome to the forum 00000732

How easy/hard is it to get the alternator and starter replaced and what kind of costs would I be lookingn at for labor
Save your money for something that might fix the fault. If the engine is cranking (at the normal speed) then the fault can't be the starter, battery or alternator.

When the engine fails to start, you want to check to see if there is spark at the plug wires. If you find there is no spark, next you want to check to see if the fuel pump is being powered. If there's no spark and no fuel then my guess is you have a crank sensor problem which is quite a common fault with intermittent non starts. I wouldn't worry about testing compression at this point and a fuel pressure test would be a waste of time if the pump isn't being powered.

Regards.

Scottie.
 
#3 · (Edited)
Thank you and I wish I was more adept at diagnosing cars. It's definitely cranking at normal speed since it sounds the same as it has sounded since I first bought it.

It's time to look how to test spark plugs and the fuel pump.

Btw, I saw this guys video (can't post links but he suggest to clean the mass air flow ). It almost accurately describes what I've been facing. I just need my obdii meter to verify it. It couldn't be that could it?
 
#5 ·
It's time to look how to test spark plugs and the fuel pump.
The easiest way to check for spark is to disconnect one of the spark plug wires from the spark plug on the engine and plug a spare spark plug into it. Now jam the spare plug in against the engine so that the threaded part is grounded to the engine. Just make sure the threads are touching something metal. Some engine have plastic rocker covers which obviously wont ground the plug. With the spare plug properly grounded, crank the engine over and see if a spark jumps across the plug's electrode. The spark wont be super bright so if it's a sunny day have someone else crank while you watch the plug gap.

The first test to do for the fuel pump is listen as you turn the ignition on before you crank it over. You should hear the pump running for a couple of seconds to prime the fuel rail. You can usually hear the relay click on and off too. Have you never noticed that in the past? Perhaps it's not that obvious on your car. Usually the pump is under the rear seat, so stick your ear down there and have someone else turn the key on.

Anyway, the next test to do for the fuel pump is to use a voltmeter to see if the relay is switching on during crank. The easiest place to test is at the idle control valve on the engine. Your engine doesn't have a separate fuel pump relay, so all the engine actuators (including the pump) are supplied by the main engine control relay. The idle valve is a metal cylinder at the back of the inlet manifold, between the engine and the bulkhead. It has a 3 terminal connector at one end and a hose at the opposite end. Unplug the 3 terminal connector, connect the voltmeter black lead to battery neg and the red lead to the center terminal of the connector. Be careful not to jam the meter probe into the terminal and damage it. Just touch it on lightly. Now crank the engine over and make sure you get about 9~10 volts on the meter.

If you have no spark at the spare spark plug and an incorrect voltage on the meter then I'd say the crank position sensor is faulty.

Your engine crank speed sounds good in the video you posted. Another thing I noticed in the video is that the rev counter on the instrument cluster didn't budge during crank. That is often another sign of a crank sensor failure since it's the crank sensor that measures engine RPM. But it's best to confirm by doing the tests above.

edgarh1992 said:
Btw, I saw this guys video (can't post links but he suggest to clean the mass air flow ). It almost accurately describes what I've been facing. I just need my obdii meter to verify it. It couldn't be that could it?
No, I wouldn't have thought so.

Scottie.
 
#9 ·
I be more interested in what the plug wire ends llok like, are they discolored. maybe freaky lightning strike looking with odd carbon or cracked plastic.. MAF wont make for rough idle sometimes..

Busted intake gasket make for rough idle, can of carb be your friend to see if intake gasket crack-leaking
 
#12 ·
New update. Looks like the engine only really rough idles when below 1k RPM. Everything about that is smooth. Additionally, the car will shut off when rough idling for more than 20 minutes. Gonna do the MAF sensor change tonight and hoping it's nothing more than that.
 
#13 ·
Can of carb for leak test is $3 at Wal-Mart..... How much is that MAF you want to drop $$$ as a test and find out it did nothing ??
 
#15 ·



With engine at idle, spritz (not flooding spray) along the seam where intake mates to cylinder head.. you'll know if you have leak when vacuum through busted gasket sucks the spray in...

Sometimes you can hear it, especially if you use water from a spray bottle.. is make loud gurgle/hiss sound when water jets through the crack under vacuum
 
#19 · (Edited)
i have a problem similar to this, i have a 99 elantra gls, i had my tranny rebuilt about 4 or 5 months ago, and now it will crank but won't start unless if i spray carb cleaner on my intake filter and after it depleted (full tank of gas) the car dies, i've replaced the spark plugs, wire set, crankshaft position sensor. the fuses are good (checked them several of times in the car and under the hood) got two sets of wires and connected it directly to the battery and the fuel pump worked fine then i took out the horn relay and replaced it with the fuel pumps relay and the cars horn still blowed so that was good so now i don't know what to do, any suggestions well be greatly appreciated
 
#20 ·
now it will crank but won't start unless if i spray carb cleaner on my intake filter
Clearly you have a fuel delivery problem. The first thing I'd suggest is you make sure the pump is being powered up during crank. I've given some advise about how to check that earlier in this thread (post #5 ). You also want to make sure there is a good 12V supply to the injectors during crank (red wires on the injector connectors).

Scottie.

PS...what engine is in your car? It's unusual for the fuel pump and the horn to use the same type of relay.
 
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