Car Turns Over But Doesn’t Start – Cranks No Start

9:24 am Consumer, How To Auto Repair

 

A

Car cranks over but doesn’t start.

OK, so you don’t have a Model T like in the picture but all your car does is crank over and does NOT start. I’ve been writing some articles geared more for the weekend mechanic and publishing them on a different site. Since this auto repair blog is mainly for professional technicians, I generally don’t post the more basic auto repair tips and tricks articles here. But I realize that not everyone that reads this blog is a professional tech, so I wanted to provide this link to one of my articles I originally posted at EzineArticles.com.

Many times in the past as an automotive technician, I would be given a car to diagnose that either had a problem that prevented the car’s engine from turning over or that prevented the car’s engine from starting. These are two completely different scenarios and these problems are approached differently. Sometimes when the service writer would create a work order, he wouldn’t convey the REAL problem that the customer was experiencing. If the customer or the service writer would make sure the correct explanation of the problem is written, some unnecessary trips out to the car with the wrong tools would be avoided. For instance if the car doesn’t crank over at all, I would need to take my jump box with me. And if the car cranked over but didn’t start, I would want my scan tool and some starting fluid.

A car that cranks over but doesn’t start, in many cases will be due to a bad fuel pump, a broken timing belt, an inoperative cam sensor or crank sensor. The first step in diagnosing a no start is to scan for codes with a code reader or scan tool. Approximately 40% of the cars towed in that I worked on in the last 25 years, either had a bad fuel pump or the fuel gage read incorrectly and the car was just out of fuel. Yes, some people actually have their cars towed in when all they need is some gas! If the fuel gage indicates that there is fuel in the tank, most people will assume naturally that the car does have fuel. But if the fuel sending unit or gage is off slightly, the car’s gas tank could actually be empty. One of the easiest ways to check for a fuel pump related problem is to spray a little starting fluid into the air intake while trying to start the car. If the car starts momentarily, then there’s a good chance the fuel pump is not working or the car is out of gas. You can also listen for the fuel pump’s humming sound when the key is first turned on. Also if a inoperative fuel pump is suspected, a good technician will always check to verify there is power and ground being supplied to the pump, to eliminate the possibility of a bad relay or electrical issue. Fuel pressure can be checked with a pressure gage and if there is pressure, pulse can be checked at the fuel injectors in several ways including the most common, with the use of noid lights. If the injectors don’t have pulse the engine won’t start.

Broken timing belts also caused about 40% of the tow ins in my experience. A broken timing belt can fail causing the car to seem as if it ran out of fuel while driving. When trying to start the car though, the engine typically spins over faster than normal due to the engine having low compression from the timing being off and the valves being open at the wrong time. If the timing belt breaks, there sometimes could be a code set in the vehicles ECU (Electronic Control Unit) for no signal from the cam sensor. If this code is present, you can sometimes check to see if the cam is moving by removing the oil cap while someone engages the starter. Also the upper timing cover can be removed to allow access to the timing belt for inspection. Most of the time when a timing belt breaks the teeth (or cogs) are stripped down at the crank pulley the bottom sprocket preventing the belt from turning the camshaft.

Lack of pulse from the fuel injectors as stated before can prevent a car from running. This brings me to the third most common cause of a car that cranks over but doesn’t start, approximately 20% of the tow ins that I worked on had the following problem. Many times the cause of lack of pulse is because of a bad cam or crank sensor. If the computer doesn’t see either the crank or the cam turning, the fuel injectors won’t be commanded to pulse. One quick indication that a cam or crank sensor may be bad is to check for RPM movement on the tachometer (if equipped) when trying to start the engine. If you have a scan tool not just a code reader, the cam and crank sensor data can be checked on many vehicles by accessing the appropriate screen. If no revolutions are shown when attempting to start the car, the respective sensor could be bad.

Obviously there are many vehicle makes, with different ignition and fuel delivery systems that may require a service manual to properly diagnose or to delve deeper. But with the above tips and tricks that I’ve used over the years you’ll be checking the most likely causes, that hopefully will point you in the right direction.

Automotive Scan Tools

2 Responses
  1. trev :

    Date: May 12, 2015 @ 12:58 am

    I have a 02 eclipse with a 2.4 I thought it jumped time as I was going down the road and just before I shifted it just died. I have learned the hard way in the past that if these type of cars just dies leave it alone. After i pulled over immediately and sat there trying to replay what happened I then turn it over for just two seconds and it acted like it was outta time but had no clanking. Had it towed to the house and had a buddy that knows these cars come over to help/teach me how to do the timing belt. I did some research before hand so I wasn’t totally blind and remember the book saying to turn the crank clockwise. He was headstrong and assured me it gets turned counter clock wise. Belts are on so I told him thanks I got it from here. What my I’m asking is what damage if any should I look for before I put it all back together and ruin my motor? I plan on taking it back apart since I’ve seen it done wrong and know the right way but I fear there’s another addition to the repair’s needed for it to be a sound car again. Love to learn but I like to learn the right way the first time.

  2. dennisb - Auto Tool Sales :

    Date: May 12, 2015 @ 11:38 am

    Going by the book, is definitely a good practice. However, I don’t think you would do any damage going counter clockwise, unless you forced it. That being said, sometimes the cams will spring action from valve springs, so if the valves interfere from being out of time it’s possible to bend a valve. It’s also possible to have bent valves anytime the belt strips or breaks also. You may not hear any clanking but there could be damage. You can do leak down testing or inspect with a good video inspection camera for marks on top of the piston, but most guys will just install the belt and hope for the best. This is because, by the time you do the extra steps to test and inspect you might possibly just have the car up and running if you proceed with the timing belt installation as normal. Good Luck.

Comment Below, Please Unlock Caps

Tell us your thoughts or ask a question. For best results please provide relevant details like your vehicle's year, make, model, engine size, the problem and when it occurs etc. - Comments need to be approved before they are seen by everyone. Notice we don't post Spam. Comment below (*SPAM, ALL CAPS & unrelated comments will be deleted). Click the following to view Dennis' "about page" for info on his background in automotive repair.

Please note: Your comment will not be posted until it's approved. We appreciate and read all on topic, relevant comments. Please don't ask for repair manual info like torque specs, wiring diagrams and specific repair procedures. If quick assistance is needed with purchasing a tool or part, please visit our tool website DenLorsTools.com or call to place an order at 800-524-9783. *Note we don't offer repair advice on the phone.