I have a 1985 240 sedan that just stoped running at a stop light. After towing it back to my place, a freind and I discovered that it had no spark. Its not the coil because we checked to see if there was spark from the coil to the distributer cap, and there is. but there is no spark from the distributer to the spark plugs. The distributer cap and rotar are less than 6 months old and look good with no cracks. Does any body know what I should check next to figure out whats wrong with this car?
Thanks
Anthony
Denver, CO

do you know how to check spark at plugs?if you have spark coming out of coil,there is nothing to check anywhere inside the distributor or anywhere else. if anything was wrong inside of distributor you would not have spark anywhere. the last place spark goes is to the plug. if you pull a spark plug wire and put a screwdriver into it and hold near the block or a certain ground you can check for spark while someone cranks the engine. if you do not have it,then you back track. if you have spark there. then your problem is not spark. if you have no spark at the plug then backtracking, you check the rotor. the rotor has a resistor built in between the center contact and the outside contact. this could be your problem. but if you are certain that the spark is godd to the cap and not to the plug, it can be nothing else but the cap or the rotor. most likely the rotor. if you check it at the plug and you do have spark going to ground but it does not seem to be firing, then there is a very good possibility that it is flooded. fouled plugs will not fire.

if you have spark from coil to distributor cap,but not to plugs it can be only dist cap or rotor. most likely rotor. did you check to make certain that carbon button inside cap did not break off? was cap possible installed wrong? are they bosch parts? get a new rotor, if it does not fix get a cap also.

Just wondering if ou've resolved anything yet. The more you update the more it sounds like what I went through only to find that, like I said earlier, it was the 25 amp spade type fuse. 2 months ago I would not have been able to explain this but, what you have to remember is that the spark going from the distributer to the plugs is controlled by the ECU which, electricly speaking, comes in line after the coil, or something like that. So, if your getting spark from the dist. to the cap as I was when I was dealing with this, if your hall sensor isn't functing becuase the 25 amp fuse isn't allowing juice to get to the ECU which controls the hall sensor, then you will not have spark at the plugs.

In many ways I miss the HEI distributer I installed in my 63 Chevy Nova. No, AC, no PS, no computer. Things were much easier to diagnose on that thing when they went wrong.
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Portland, OR 1987 240 dl wagon 'rustbucket'

Another update. I replaced the distributer and I have spark but the car still woln't start. It seems like its flooded. When I was replaced the distributer I was very careful to line up everything exactly the same as the other distributer. The wires are good the rotor and cap are new. I checked the 25amp fuse next to the battery, and I searched for the crank position sensor, but I don think there is one on a 1985 240. mabey its a fuel problem or a wiring harness? I am going to go through the fuel system next. Otherwise I am stumped.
Anthony

there is no crank position sensor on the '85.

Last year on my late '88 245, when it was plagued with a no-start condition, I checked the 25-amp blade fuse with the continuity tester on my meter - it beeped fine. Days later, out of frustration, I put in a new fuse and it started right up! Turns out the fuse filament was intact but had high enough resistance to limit current flow! So check your fuse and fuse holder again, just to be sure.

Have you checked the fuel pump relay? That's a frequent no-start problem source.

Does it have a crank position sensor? if it does that could be the problem. thats what happened to mine it is on top of the bell housing right next to the firewall in mine.

I checked all the wires and all the conections with an ohm meter and a timing gun. the coil is definatly good all the wires are good and the battery is fine. There is definatly no spark reaching the plugs but the rotor and the cap are working fine. The rotor turns when I try to start the car, so its not the timing belt. It appears that there is something wrong inside my distributer it appears to be a hall effect switch of some kind. Do I have to remove the distributer to fix this? And if so how do I do that? If I need to do this would it be easier to replace the whole distributer with one found at a junk yard?
Anthony
1985 240

You said previously that you have a spark from the large coil wire to the distributor. I am assuming that you held the wire close to the block and cranked the engine, and saw a good blue secondary ignition spark. If the spark is not going out to the plugs, then the rotor is faulty. Here's how to check it. Remove the distributor cap. Remove the coil wire from the cap. Use a dry rag or insulated pliers and hold the wire above the rotor, about 1/4 inch away. Have someone crank the engine. If the wire sparks to the top of the rotor, then that indicates that the rotor is going to ground, which it shouldn't. Replace it. If it doesn't spark, the rotor is either good, or you have no spark to the block as well.

check the 25 amp fuse just behind the battery. Mine did exactly the same thing not too long ago. Teh fuse looked fine but upon closer inspection was kinda grimey on the spades. I replaced it and 5 days of guessing turned out to be a 25 cent part.
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Portland, OR 1987 240 dl wagon 'rustbucket'

I would go ahead and replace cap and rotor, unless they are close to brand new; they are not terribly expensive. Just recently a friend pulled his rotor while looking into a no-start and although it looked fine externally, internally it had arced and would not pass current. The cap, too, may have a problem with the little carbon button in the center.

The other place to look is the plug wires. Replace them if they're more than a couple of years old or have 50K on them.

And in case your parts are all close to brand new - is the coil wire fully seated in the cap and on the coil?

good luck, and let us know when you find the problem.

Maybe it's the plugs? If you try to start it too much, while you cant start, your plugs will become black.
My car started fine, untill one winter day, when it suddenly didnt start any more. I had just bought it, and I hoped and prayed that it was only the spark plugs, and it was so!

I guess I should have changed the spark wires also, since one of them fell apart while I pulled it of the spark plug, but hey! I'm going to swap to a more modern engine.. I dont want to use un-needed money on an old b19a engine.. die engine, die!! :p