Mechanics

ENGINE CRANKS BUT WON'T START

2000 Plymouth Neon

Engine Mechanical problem
2000 Plymouth Neon 4 cyl Front Wheel Drive Automatic 90,000 miles

this is what i've done so far, replaced plugs and wires, checked coils I got good spark, replaced cmp sensor, checked battery that's good(12.5), checked fuel system, seems to be functioning properly, all I can think of that is left is the cpu but I can't replace without knowing the VECI which is missing, SOMEBODY HELP this car is making me crazy!
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Dsfunction69
July 7, 2010.




Hi dsfunction69. Have you checked for spark from both coils? Also, have you checked for fuel pressure. The fuel pump will run for one second after you turn on the ignition switch. Have you listened for its hum? It must also run during engine cranking. If you don't hear the pump run for that first second, bang on the bottom of the fuel tank while a helper cranks the engine. If it starts up and the engine runs, the pump will rarely quit while it's running.

If you're missing spark from just one coil, the Check Engine light should be on. If so, have you checked for diagnostic fault codes? If you get a code related to cam and crank sync, first check for a jumped timing belt. At one tooth off, the Check Engine light will turn on. At two teeth off, the computer will shut the engine down but you will often have spark from one coil. At three teeth off, the pistons will hit the valves.

If you do have a cam and crank sync fault code but the timing belt is in correct time, suspect a broken dowel pin between the camshaft and sprocket. That only applies to the single cam engine.

Caradiodoc

Caradiodoc
Jul 7, 2010.
Thanks for the quick reply, I finally got a chance to take a look, the coils are both good, the fuel pump works fine, now when I checked the timing I noticed after putting the first piston at TDC that the cam sprocket is not moving when I turn the crankshaft the timing marks are off by about 2 teeth. Any input will be greatly appreciated. THANK YOU
DSFUNCTION69

Tiny
Dsfunction69
Jul 21, 2010.
What do you mean by " the cam sprocket is not moving"? If there is a delay between turning the crankshaft before the camshaft starts to turn, look closely at the tensioner to see if the belt is loose. That will also allow the belt to jump teeth. When the cam sprocket is off by two teeth, the Engine Computer shuts the engine down before any valves can be damaged. If you leave the crank at top dead center, then loosen or remove the belt to reset it, the valves should not be damaged.

Caradiodoc

Caradiodoc
Jul 22, 2010.
Had a hell of a time getting the cranckshaft pulley off, still can't get the timing cover off, my book says remove the lower and upper timing cover bolts but all I find are the lower?Anyway it was enough to peek inside and what I found is the timing belt is shredded in pieces and little pieces of what looks like ball bearings cut in half, a lot of debris fell out when I pulled the bottom of the cover open.I'm starting to think the valves are destroyed and maybe even the pistons, should I just junk this engine and get a new one or maybe get what I can for the whole car. What do you think? Thank you
DSFUNCTION69

Tiny
Dsfunction69
Jul 22, 2010.
Not sure how much damage to the valves was done. The computer will shut the engine down when the timing belt jumps two teeth. It suggest installing the new timing belt first, then perform a compression test or cylinder leakage test to see what shape the valves are in.

Caradiodoc
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Caradiodoc
Jul 22, 2010.

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