Engine Rotates But Won't Start

I have a 1991 240sx SE fastback. Just replaced the cylinder head. But now the engine rotates (very well) but won't start. At times there is spark and at others there is none. HELP! What is it that we should be looking at as the culprit here?

start with simple shit like the ditributer. electrical problems are a bitch to diagnos with out a diagnotic tool. do you have any kinda volt meter?

Lokking at the distributor right now, but getting little of anywhere. Timing has been checked, so we know that isn't it, checked to make sure we'e getting fuel (we are), one thing peculiar, we have spark on 3,4 &5, but none on the #1 plug. Checked all fuses, traced all electrical wiring. Everything 'seems' to be in order, and the car still rotates very strongly, but refuses to start. Poor thing sounds like a wheezing asthmatic trying to start.

We do have volt meter. Sorry about crappy type-o's above.

sounds like a fuel problem....... make sure you have pressure on your fuel rail, make sure tank pump is working etc..

Thanks, checked that. We are getting fuel. And plenty of it. Still have spark on plugs 2,3 & 4 , still no spark on #1 and we think may be a bad wire, we know that spark is getting to and through the distributor, there is fuel in the heads, all fuses checked out good, all electrical checked out. Thus the confused, dumb-founded looks on our faces. It still seems, and I say that lightly, that everything we can think of has checked out. The engine still rotates very well, and still just won't start. (background) had cracked head - spitting coolant and water out exhaust- replaced head with new, checked that timing was alligned to Chilton manual specs, put it all back together, and this is where we are at.

I sit just me or does he sound like a multiple personality here?

Are you sure that the cam and crank are timed right?

If you just replaced the head, that could be another place to look.

welp if your getting spark, your getting fuel, and its cranking over lol, double check your timing.......

If Plug One Isn't Firing Check Cap, Rotor, Plug, And Plug Wire. Still No Go? Try The Distributor. Still No Go? Check Coilpack. Still No Go? Check Cam Timing. Still No Go? Any Suggestions?

Just Remember That It Is More Than Likely The Easiest Fix And Your Expecting The Worst So You Over Looked It.

as it has been said before, check the timing marks on the cap sprockets and crank sprocket.
if they are all lined up, try taking out your distributor and rotating it 180 degrees and then put it back in. when i put mine back it, i had the timing lines matched up, but i was 180 degrees off.

You might (like the last post said) be 180 degrees off. Your spark might be firering on the exaust stroke. Replace the #1 wire and plug to be sure. If no spark then replace the dis. cap. Then the disributer. Lastly the Coil. If no fire after that then I have no idea. As far as it being a fuel problem check the presure comeing from the pump and make sure its high enough. Mabey your injectors are cloged. Check and see if any of the fuel lines all the way from the tank to the rail are bent. As a cheap way to start prossess of elemination replace the fuel filter. Check idle screw to see if your running super rich/lean for idle. Thats all I can think of. Good luck

Every plug IS firing now. Timing is lined up, rotated distributor 180, fuel injectors are not clogged, has new fuel filter,idle screw set right. As far as we can tell, everything is set right where it should be. What's got us so confused is this... if you took all the plugs out and tried to start your car it would only rotate, right, well that's what this one is doing with all the plugs in and sparking. We checked to make sure we weren't firing on the exhaust stroke, we're not . We've checked everthing electrical, fuses, got new plugs, the plug wires are fine, timing marks are lined up. For all intents and purposes it should be starting. The damn thing just sits there and rotates, rotates, rotates but just won't start. Will try rotating distrubutor again. Anyone gets a brainstorm, please yell it out.

Any one want to buy this damn thing!? Just might consider selling at this point.

Did you check your compression? pull al lthe plugs and the ghetto way to check compression is just to put your thumb over the hole and have someone turn over the motor. Make sure you have compression in all 4 cylinders, it should blast your thumb right off the motor.

I know this sounds dumb, but make sure that your fuel lines are on correctly, I had the feed hooked up to the return and it would not start, took me about 5 days to figure it out also.

The only other thing I would suggest is that you have somthing unplugged???

Hope you figure it out soon though.

Good luck!

What if it don't just blow your thumb off? What then?

Whichever cylinder you arent getting compression on is your problem, is one of you valve bent or broken, is the headgasket bad, are the piston rings bad...You gotta find out why you arent getting compression. You said that you changed your head, why? did it over heat? You might have damaged alot more than you thought.

I would pull the head again and make sure that the valves all close.

Good luck.

even if one clyinder isn't getting compression, it still would run, just very poorly.

take out cyl. 1 spark plug wire and hold it close to the valve cover. when you turn the engine, you should see a spark jump from the wire to the valve cover. try this with all of the wires seperatly.

are you sure your timing marks on the cam and crank sprockets are lined up? the chain should be tight on both sides. when you take off the valve cover and you have piston #1 at TDC on the power stroke, the intake cam lobe for piston #1 should be pointing outwards, up and toward the passenger's side.


are you sure you're getting fuel?