Automotive Repair Problems
Engine or Motor
Which is it. Well it's a engine, a motor is run by electricity. A engine is a air pump, yea really. Let me explain, it sucks in air and pushes air out, of course it's got some kind of fluid mixed in with it. Be it gas or diesel or steam or anything you can make a engine run on. But to make a engine run you need a few things to go with the fuel. You will need fire, compression, timing, air. A engine most have at the least 90 pounds of compression to run, the more compression the stronger the engine. Most engines run with about 130 pounds or more compression. There's a lot of moving parts inside a engine. There are pistons going up and down, rods going up and down, crankshaft going round and round, camshaft going round and round, valves going up and down. All those parts moving together have to be timed to move at a certain time with each other. That's where timing comes into making a engine run. The fire has to go off at the right time, are you have a problem. So lets see if I can explain how all those things together make a engine run. Ok, there's a starter that starts the motion of going round and round started. It moves the pistons were it sucks in air and fuel together, into the piston cylinder thru the intake valve which opens at the same time the piston is going down. Then the piston starts going up and building compression with the fuel and air on top of it. Now when the piston gets to the top of the cylinder the spark plug fires and pushes the piston down, this is the power stroke. Now the piston rounds the bottom and is headed back up, were it pushes the burned fuel up out of the engine, thru the exhaust valve and the piston starts down again starting the cycle over again.
There are so many things that can go wrong within a engine, from a no start to running bad to a number of problems. I will try to address a few of those problems here. I will start with a no start and work around that.
So Your Car Won't Start
Lets start with does it spin over. Lets assume thru all of these no start problems that the battery and starter are working like they are suppose to be doing.
We start by checking to see if you have fire, pull a spark plug wire, are pulling a coil pack off, make sure that you plug the coil pack to the wiring harness if you had to disconnect it. Now stick a screw driver into the plug wire and hold the metal part of the screw driver about 1/4" off a metal part of the engine. Do not hold the metal part of screw driver with your hand, unless you want to get a shock!!!!I like to use a test light to do the job, but not everyone has a test light. So with your plug wire in position, spin engine over and see if you have a spark, if yes lets look at fuel. This is were you are going to need a can of starting fluid or a coke bottle of gas. Find the inlet to the engine, where the air filter hooks to engine, pull the hose off the engine and spray some starting fluid into the opening while trying to start engine. If yes it started, you have a fuel problem.
Do you have a fuel pressure problem or a fuel injector problem.
Lets start with a fuel pressure problem. You are going to need a fuel pressure tester, with these cars today you can't guess at this. If you got a fuel pressure tester, find the valve located on the fuel rail, hook the tester to it, turn key on and read gauge. If you don't know what the fuel pressure reading should be, call your local parts house and tell them what your working on and ask them to look and see what the pressure should be on your car. If you have no pressure or it's low, you have a fuel pump going bad. If you are on the side of the road, and your not by yourself. Have the person your with try to start the car while you beat on the fuel tank with a hammer are something else. Sometimes this will start the car, and you know that you are having a fuel pump problem.
So you have no fuel pump pressure
If you have low fuel pressure, you know your getting voltage to fuel pump, so you have a bad fuel pump.
If you have no fuel pressure, you need to make sure you are getting voltage to fuel pump. First lets see if it has maybe blown a fuse, turn key on and find fuse panel, find fuel pump fuse. Take a test light and probe both sides of the top of fuse and make sure both sides light up with test light. Look at the picture of the fuse above, and probe with test light where the arrows are pointing. If not, you have a bad fuse, replace and see if car starts. If fuse is good, find fuel pump relay, should be in same panel as fuse. Pull relay and probe each slot in panel, there should be 4 slots to probe with test light. Two slots should light up when probed, that is one lights up from battery, and the other with key on. If both light up your ok with getting voltage. Now hook your test light to the positive cable on the battery and probe the other two slots.With test light in one slot, turn key on and light should come on for 2 to 5 seconds, this is the computer grounding the relay to turn fuel pump on, If it lights up everything in panel working and you have a bad fuel pump. Now don't get me wrong, you could have a bad wire between relay and pump, but that don't happen to often. To make sure the wire going to fuel pump is good, pull plugin off fuel pump and probe each slot, while turning key on and checking for a test light to come on. Remember fuel pump relay will only come on for 2 to 5 seconds when key is turned on. So you will have to turn key on, off, on every time you probe a different slot. So you ask why didn't we do that from the start. Well when you work on a bunch of different makes and models of cars like I do, you'll find out that the fuel pump is sometimes the hardest thing to get to. If it's easy to get to, then by all means do that first, but if you don't get any voltage by the fuel pump, you will have to find out why your not getting voltage there. And then you have to look at fuse and relay. If fuse and relay are good and your not getting voltage to fuel pump then you have a bad wire between pump and relay.
So you got fuel pressure, now what
Find the easiest fuel injector to get too. Pull the plugin off and get you a test light. With the key on, probe both slots on harness, one side should light up with battery voltage. If it lights up, voltage ok. Now with a paper clip in the clip end of your test light, put both ends of test light into harness and spin engine to see if test light bleaks off and on. If it does not, you have a computer problem or something is telling computer to not pluse injector. Could be a few things causing a no injector pulse, could be a control module inside distributor, could be a TPS (throttle position sensor).This is where you are going to need a scanner, that looks into the computer and shows what the sensors are telling the computer.
So you got no spark
Lets start with a engine that uses a distributor. You got no spark at the spark plug, look for a coil on the engine, found it, now what. Pull coil wire and spin engine, take a test light and hold it about 1/4" from the end where coil wire came out. Spin engine and check for spark, got spark, you have a bad distributer rotor and cap. No spark coming out of coil,unplug wiring harness at coil, probe both slots with test light and key on, one slot should light up. If it does voltage to coil ok. Plug harness back into coil, remember which slot lit up with key on, and stick test light into other wire of harness, now spin engine and watch test light, it should bleak on and off brightly while spinning engine.
If it bleaks, you have a bad coil. If it doesn't bleak you have a problem with crankshaft sensor or control module. This is were a scanner comes in handy, you can see if crankshaft sensor is sending a signal to control module and computer.