Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Before you can align the distributor up correctly, the timing chain must be aligned correctly. The camshaft and crankshaft must be in sync with each other. Here is a picture of the timing marks.
ok well that's where i put the marks what about the ignition modules why does it keep on going through these the mechanic working on it said here already put two in I put a third one in and got spark but still no run just backfires ?
If you are going through ignition modules, then it can be one of three things.
THe module itself does not have good enough power or ground.
The ignition coil or any of the secondary ignition components have excessive resistance causing the ignition module to work harder than normal.
Or the ignition modules that were put on are simply bad or defective.
Trust me... I work in a shop and have been working in a shop now for years. I have seen brand spanking new parts right out of the box... bad! And yes... it is possible to get a batch of bad new parts. They very well could have been made wrong at the factory. I see this quite a bit!
Yes.. it is possible that it is a bad ignition switch. THis supplies power to the ignition module. If voltage is too low, then this can burn up modules.
A back fire is simple a cylinder firing at the wrong time or at the right time but a valve is hung open for some reason and it will sound like a back fire. If its out of the exhaust, the exhaust valve in one of the cylinders was open at the time of the combustion. If it was out of the intake manifold, then it was an intake valve that was stuck open causing the noise to come from what sounded like the intake.
So to answer your question... there are lots of things that can cause a "back fire". The fuel pressure needs to be checked, the ignition timing needs to be checked. The engine mechanically needs to be checked... lifters, guides, timing chain camshaft etc.
Sorry for the delay!
To check engine engine mechanically, just hook up a vacuum gauge to the intake manifold or some sort or engine vacuum source....like any vacuum line when the engine is at idle. You want to see about 21 inches of steady vacuum. Make sure the needle on the vacuum gauge does not move around or fluctuate at all.
Next, is fuel pressure. Fuel injected vehicles are very fuel pressure sensitive and pressure must be within specifications. IF the fuel pressure is low, the fuel filter, kinked fuel pressure lines and low voltage to the fuel pump needs to be ruled out.
Here is the tests we need ot run to diagnose this problem.
I will try to get you a picture of number one cylinder on the distributor.
We will have to pinpoint what the engine is missing.
All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the car to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should! Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.
I have all of these along with compression but the engine won't run it just pops through the carb. (TBI ) now when i walked into this job the mechanic before me said he couldn't get the timing marks to line up he would line the crank up and then the cam and turn the engine over but only get compression on #1 cly. when the dot on the cam is 180 degrees out in other words getting compression when the crank dot is at 12:00 and the cam dot is @ 12:00 and when he pulled this thing apart he tells he the timing marks were@ 12:00 on the crank & 6:00 on the cam @ #1 compression stroke?? Thanks
SO if this is true, it sounds like the valve timing is off.
If you want to double check it with the timing cover on, just pull out number one spark plug and turn the engine over by hand until the piston is at tdc. Pull off the distributor can and see where the rotor is pointing.
Or, what you could do it pull off the valve cover on the head that number one cylinder is on and watch the valves as the number one cylinder is at tdc. You are going to want to be sure that both valves are closed when the piston is at TDC. Or... when valve overlap occurs.