Why a Car Would Turn Over But Not Start
Lay answer: in addition to the battery voltage to "turn the engine over"...ignition requires spark and gas. I'm having the same problem with our 86 Volvo. The mechanic says the spark plugs are providing the spark...but fuel isn't getting to the cyliders. It's probably a blown fuse to the fuel pump or a bad fuel pump...or more remotely a poor connection between the fuse and the fuse clips...or a leak in the fuel line. Our car has two fuel pumps and since our problem has been intermittant, like yours, and we've checked fuses and connections, we're betting it's one of the fuel pumps pooped out.
Here are more opinions and answers from other FAQ Farmers:
- If I remember right I think compression is the 3rd element to an engine running. timing belt or timing chain? You need to eliminate each one(fuel,spark or compression)first and then continue narrowing down from there. I have seen dampness cause ignition wires to fail among a multitude of others. Have a real tech troubleshoot it, other wise your gonna replace good parts guessing.
- It is one of three things. It isn't getting proper spark, proper fuel, or proper compression. Use the process of deduction and find out. If the engine turns over the starter isn't bad.
- Well it depends on the car but it could be that you don't have spark, you could have a big vacuum leak, timing might be off. But don't flood your motor if your in a hurry!
- There are several possibilities: lack of fuel, sprk or compression, these are possible Maintenence items among many other possiblities: spark plugs (worn), ignition wire (Worn), distributor cap (worn), distributor rotor (worn), fuel filter (too dirty), air filter (no air getting in) and timing belt (timing is off).
- It is worthwile to check for spark from the coil before considering the distributor, spark plug wires or sparkplugs. Assuming that lack of spark is the problem.
- Another thing it could be is that your car is flooded , requiring possibly 3 hours for plugs to dry.
- I had a problem on a 1994 ranger that turned out to be a motion switch that had been tripped when the car was bumped. It caused the electric fuel pump not to turn on.
- If the car is a Chrysler product and just cranks but won't fire, it could be the fusible link. On Ford and GM cars the car will not even crank if it is bad but on Chryslers it will just crank. I don't know about imports.
- Other possible sources of fuel related problems are a collapsed fuel line(depending on how old the car is) or plugged filter. Before you drive yourself nuts trying to locate the fuel shut off that the fellow described on the ranger.....it's been my experience that is only on ford models(you don't say anything about your make or yr)in the trunk in cars. Good luck
- Correction: It's primarily fuel, spark, and timing. Timing problem of course can lead to lack of compression. Clarification: The comment on the '94 Ranger is correct. Many Fords have what is called an "inertia switch" which will cut off the fuel pump. This is designed to benefit the occupants in the case of a severe accident. I don't believe any other domestic maker uses this, but some imports do such as Jaguar.
- A GASOLINE internal combustion engine needs 3 things to function properly: 1) fuel, preferrably delivered at the right mixture, but generally if it's there and the other two components are met, the engine will at least run. 2) ignition, often referred to as a spark or fire, ignition timing must be within a couple degrees of factory settings otherwise the engine may not run at all. Ignition spark strength must also be high enough to be adequate for the air/fuel mixture to ignite, but generally it is an all or nothing situation in the newer, electronic ignition systems. 3) compression, if the compression is up, the cylinders, valves and camshaft are functioning adequately and the timing chain/belt/gear is timed properly. If all three of the above conditions are met, the engine will start when it is cranked. To find out why it won't start, you have to find out which of the above conditions isn't being met. Rather than approach the problem in a "shotgun" manner, it's best to be methodical in your approach. First, spray some starting fluid into the air intake while a friend tries to start the engine. If the engine runs briefly while you are spraying starting fluid, you have good reason to believe that the engine is not getting fuel... item 1 on the requirements. If the starting fluid didn't give you any clues, pull a sparkplug wire from the plug (any one will do) and connect it to a spare sparkplug. Set the sparkplug on a solid metal part of the engine and have your friend crank the engine again while you watch the sparkplug. You should see a bright spark if the ignition is working properly. And finally, if the above two tests didn't give you any information, run a compression test. Since all valves and all cylinders don't generally fail at the same time, you'll only be testing the timing of the camshaft, but that's pretty important. Mark the location of each sparkplug wire. I generally use a piece of masking tape with the cylinder number, then wrap the tape around the sparkplug wire, making a little flag or tab. This part is important, since you don't want to finish the job and wonder where the wires go. Next, pull the sparkplugs and carefully observe the condition of each plug. Look for oil fouling, wet plugs, WHITE plug insulators, worn plugs and damaged plugs. If the center insulator (the part that goes INSIDE the cylinder) is too white, it's an indication that the engine is running too lean and you could be causing damage to valves or pistons. If the plug is black and oily, it indicates that the cylinder is worn and oil is leaking past the rings or valve stem seals. If the sparkplug is wet with fuel, it's an indicator that the cylinder is FLOODED, meaning that somehow there is too much fuel being delivered, and a wet sparkplug cannot properly ignite the fuel in the cylinder. If the plugs all check out ok, use a compression gauge while your friend again tries to start the engine. Since there are no plugs in the cylinders, the engine won't start, but you're measuring the pressure that is built up in the cylinders. Generally, it should be around 90 PSI, but that number may be different for different engines. Generally, the number should be withing 5 to 10 PSI for each cylinder. A variance of more than 15 PSI indicates burned valves or worn rings. If ALL cylinders are low, (below 70 PSI) it's a good indication that the camshaft is no longer timed properly. That is caused by a slipped timing belt or timing chain.
- THE 'KEY' COULD BE THE ANSWER. Well... some recent cars/vans have a immobilizer embedded. Such a car/van can only be started with an original key i.e. a key which comes with the cars and which has a electronic chip. So if you have recently cut a key from any roadside key-cutter and your car turns using this key but the engine fails to fire it could be the immobilising safety device in your car that's preventing it from starting. This is a good safety feature!
Another ting to try is removing the spark plugs (make sure you re- cord which wires go where) and pro vidind that the engine isn't flooded
spray some starting fluid(avalible at auto parts stores) in the hol where the spark plug was and put the spark plugs back in and try to start it if it begins to start but then shuts off
your problem is proboly fuel delivery, but if the engine is flooded take out the plugs and let it sitt for a while to dry out.
There is a little sprocket in your strarter looks like a cog with teeth on in, but the teeth can chip or break if the metal is cheap which in most cars now days it is. So the starter is turning but the missing teeth are not connecting to make a spark keep turning it samething happened to my Buick but i didnt gte is fixed rite away because if you keep cranking evetually the teeth will catch and ignite
a motor needs fuel/ spark / air / compression all at the correct time check sources of all from major parts to minor (id start with anything electrical) you should find the problem
- One other thing that could possibly have gone bad is the main relay, its a $50 part that gives the fuel pump power when the key is on, so bad relay, no power to pump, no gas, no start.
-you need, spark, compression and a proper fuel mixture for your car to start. Generally, the compression gives way over time, so it is the last thing you should suspect if this problem appeared overnight. First thing you should try is to turn the key to the "on" position (not the crank start position). You should hear an electronic hum coming from the fuel tank. If you don't hear the hum, check the fuel pump relay or fuse. If those are fine, the fuel pump is suspect. If you do hear the hum, your fuel pump is working fine. Check for fuel pressure in the fuel line. It should look like a valve like the one you might find on a bicycle tire. If fuel sprays out, your fuel pressure is fine, which means you can suspect the spark. The battery is not the culprit (it turned the starter remember). Check for spark as noted above. If you don't get spark, check spark from the coil. Depending on the model and technology of your car, you can then suspect the ignition control module (esp. if it was a hot day) , as well as the distributor and all its components like the rotor and distributor cap.
By the way, most, if not all new cars have an inertia trip switch. Mine is under the dash. .