cranks with spark and fuel but wont start - I must be missing something

[Dodgecharger74]

Did you change the resistor ahead of the coil  may have no voltage while cranking  if no power their check for bad ignition switch

[b5blue]

I'm thinking jumped timing chain now, can you put a light on it and check? 

[oldrock]

is the restistor the little round cylinder that ties to the positive on the coil? If so, I didn't change that out and wasn't thinking that could have an impact on the coil but maybe I need to change that out too.

I didn't save the old rotor so can't swap that one out but the new rotor looks good ie no carbon build up, etc and looks to be making good contact.

I have charged the battery and checked it to make sure it is getting good voltage. Didn't try cranking with a charger hooked up but will try that to see if the extra juice might make a difference. The starter is spinning nice and fast so don't think that will be it but at this point, I'll try anything

[R2]

 

[elacruze]

what's the resistance across the coil? Verify that it's not shorted or open circuit.
put a phillips screwdriver in the distributor end of the coil wire and gap the shaft to a bare ground. The spark should be fearsome.

I'm still wondering about the fuel/water. The symptoms sound like water contamination (the running jets suck water before the idle jets) and it would still smell like gas. Drain the float bowl(s) into a jar and let it settle a minute to see if water separates out. dip a little onto a screwdriver tip and see if you can light it.

If it was a timing issue such as a jumped chain, it wouldn't have come on gradually so that's not likely. Weak spark could be the issue, but if it fires even with a yellow spark every time, it should at least try to run or run poorly.

[R2]

I think elacruze has some good suggestions.....

Oldrock, Where are you located,,,,,

[oldrock]

Although I think we changed out pretty much everything on the ignition, there is one little bit I didn't change. On the positive side of the coil, there was a second wire attached to the old coil. I leads to a small metal cylinder mounted to the coil bracket. I didn't see it in the manual and car was running with it on there so I left it attached when we put the new coil on. Here is a pic of the new coil and you can see what I am talking about under the coil. I assumed maybe it was just a noise suppressor for a radio or something like that but maybe not? Anyone know what it is and do I need to disconnect or replace it?



Oh and just to confirm I did change out the ballast resistor which is mounted to the firewall so if this happens to be some other type of generic ballast resistor, maybe I should disconnect the one mounted to the positive pole on the coil?

I did confirm the coil is making a strong spark by using the coil wire. I checked ohms reading on the coil too and it was right in spec.

Re water in gas, it is a possibility and although I have drained the carb, I didn't catch it in a jar to look for water in gas. I looked at the wet plugs and they def smell like gas but if water were mixed in, that is something I could miss. I guess I need to pull the fuel line off the carb again and see if there is water in there.

[mindless1]

I remember what my high-school was like and I would recommend trying to change out the fuel in the tank, or at least running a test from a known good batch of gas in a gas can feeding the carb.  Man a car like this is a beacon for sugar, water, coke, any number of other things that highschoolers will add to a non-locked gas cap....

[R2]

That wire going to the + side of the coil doesnt look so hot,,,, 

[oldrock]

dang, another thing I didn't think of. Josh doesn't have a locking gas cap and his car has gotten alot of attention at school. I suppose some bonehead could have dumped something in the tank just out of spite. After all the headaches I've gone thru, if that ends up being what it is I will be very happy and also very angry  

I am going to wait till Josh comes home from school to check the gas. It will be good experience for him anyway.

[oldrock]

That wire going to the + side of the coil doesnt look so hot,,,, 

I thought about that too and frankly all the wiring in the charger is looking tired but it is still making good connection. The spark off the coil is very strong. Josh is a broke high school student so we are trying to limit cost to must do stuff right now. Once he gets the original restoration cost paid off, he can start doing the other stuff. We just need to get it up and running now so he can use it for school and his part time job.

[b5blue]

I got sugared in high school,    for now check it out by feeding from a clean gas can with fresh gas to the supply side of the pump.

[oldrock]

I am not sure how I will go about feeding gas from a can to the carb. I guess I could try to attach a rubber hose to the gas can and tie that into the outlet side of the fuel filter which is right before the mechanical fuel pump. The spout on our gas cans is much larger than needed so I have to figure out a way to step it down. If the carb didn't have a hard line running from the fuel pump to the inlet of the carb, it would be much easier as I could bypass the fuel pump and just gravity feed into the carb directly.

[b5blue]

Just run a line of stock size hose into the can and to the pump.  I've done this and a good stock pump will pull the fuel up the hose.

[mindless1]

Yeup - what he said!  My motor has no prob pulling fuel with ancient mechanical pump its got.   It may also be worth pulling the plugs and cranking a few times with throttle wide open before you give the gas can a try just to be sure you have a clean start. 

[oldrock]

great idea guys... that is simple enough so we will grab some hose and try it soon as Josh gets home. Might not be the issue here but certainly worth a try.

[mikepmcs]

I didn't see in there where you put a new set of plugs in prior to this new round of troubleshooting.  Do you have a brand new set of plugs in the car?

Anyone in the Dallas Fort Worth area to lend a hand with some parts or whatever???

[oldrock]

bought new set of bosch super plugs yesterday and put them in with all gaps set to spec.

[R2]

 

[b5blue]

Compression test? What motor is this? 

[oldrock]

didn't get to try the gas tank thing yet. Son had an interview for a job so will have to wait till tomorrow after school. I do have compression tester but didn't check that yet. I guess at this point it is time to check and see if maybe we have something going on there although from the way it sound when cranking, I doubt it. Motor is the original 318 v8. Does have long tube headers and dual exhaust.

[69charger440]

Are you getting spark at the Plug!!! Pull and plug and crank the motor to see!!! Also check to see if you have spark coming out of the distributor wires. just trace the spark until you can find it!! Also, you said it will start will cranking but dies when in RUN position? If so check you ignition switch.  Maybe that will help, if not then I am in the same boat as you....   LOST!!!!

[b5blue]

Compression will tell if timing chain jumped, they used plastic tipped gears on many cars back then for quite operation, they get brittle and I've pulled some that the gears were worn to points that allow them to slip 1 tooth. Look for odd/low readings. Chain is a pain but good schooling for Jr. and only take a day and a few bucks. The stumble stated early in the post is a possible indicator, they get loose, stumble trying to hold on and later just jump when you hit the key.

[oldrock]

hopefully I can get the timing gun tomorrow and check the timing. I would not look forward to changing out a timing gear/chain setup but if we gotta do it, I guess it would be a good chance to show my son what is inside that beast of his. At same time, we could clean out a bunch of the carbon deposits and sludge that is bound to be in an original 72 motor.

re spark, I did confirm spark was getting to all cylinders yesterday. The spark looked more orange than blue but it was a nice wide spark so thinking it should still run.

I am now thinking it is going to be one of three things.
Contamination in gas tank (sugar or water)
jumped timing
weak spark not hot enough to run engine (maybe that plus bad gas)

[Corellian Corvette]

Dude. Are you sure your son didn't put Diesel in his gas tank by mistake? Or that some kids at school didn't dump diesel down there?

You said "smells like gas but slightly oily?" That's what Diesel is.

I'm DEFINATLY going with the 'run a hose from a gas can and see if it starts' school right now.

My dad told me a story about some guys that he suspected "stole" some gas from my Grandfather. Then their car wouldn't start. They rebuilt the engine, and car wouldn't start. Paid to have the engine torn down again. Put it back in - car wouldn't start. After it cost them a bunch of money, and wasted a bunch of their time, he decided to tell them that maybe they next time they come by his house they should pay attention to all the Diesel-engined equipment around their shop. My dad loves that story.

One more thing you can do if you have the time (to confirm timing). Pull the #1 plug and turn the crank with a socket until the engine is #1 on compression (you'll know b/c it will try to push your finger out of the plug hole). Look at your timing mark - it should be right on (or really, really close) to TDC. Then look at your rotor. The rotor should be right on (or really, really close) to pointing to the #1 spark plug.

If everything lines up you're probably good. If not, then as others said you may have jumped the chain. But that's a fast way to check. BTW - A timing light may not help identifty this problem because it will just make your timing look off.

Keep us posted!