Have spark but will not start

[PaFarmer]

I am having trouble with my 404. It has the civilian ignition. It had been running fine. Now I am getting good spark, but the motor does not try to start, either by pumping the accelerator or ether. The motor is turning over good. I checked the plugs, wires, cap and rotor, all seem to be in order. I got new plugs to install as the old ones has some carbon on them. It was running fine last month, now I have a no start condition.

 

[Sephirothq]

Do you have compression? Is it possible something happened to the timing?

 

[glcaines]

I would check out the timing chain to see if it has broken or jumped some teeth. If you have good spark and nothing happens with ether, there has got to be something wrong with the timing chain or valve train.

 

[Wildchild467]

"Got gas in it?" ~from the movie Slingblade

"Thats what I like about you boy, you think of the simple things!" ~ also from the movie Slingblade after he put gas in it and it started up

 

[PaFarmer]

Yes Tom it has gas in it. I do like that movie. It has good compression and pulls a good vacuum at the carb. The distributor hold down is tight, so it does not seem like the distributor moved. Motor work will be a bitch as the cab sits on the motor and everything is pretty tight to work on. The distributor rotates properly. A agree it appears to be a timing issue, spark and fuel are two of the three sides of the triangle of fire and I am sure both are being delivered, maybe not at the right time. Odd that it was running like a top when I shut it down last time.

 

[Sephirothq]

So you have spark and you have fuel and you have compression? Then it should run.

Are those distributors point and condensor type? Could the coil have gone bad, or what about the wires?

 

[saddamsnightmare]

February 25th, 2013.

PA Farmer:

You have verified it is getting gas in the carburettor jets? Are you using gasoline with Ethanol in it? If so, very probably your mechanical fuel pump either gave up the ghost or is about to. There is one thing I will tell you about the civillian distributor cap. There is a metal spacer plate made up to rest on the military distrubtor bottom and hold the cap in place with set screws and ears... Some of them were made up as incorrect copies of the original master cap set up, and when you put them on a stock S404.114, the distributors is too far advanced or too far retarded to fire correctly. I had to redrill my spacer to get it to the correct position for the truck to fire. Also be VERY careful of the little tiny "O" ring that seals the bosch cap to the distrubtor base, sometimes it does not seat properly and you will get water in the distributor and a ground out due to the hood joint being just above the cap. Some distributors are more sensitive to mositure then others.

Good luck,

 

[mudman]

Is it backfiring or coughing through the carb? If you have spark, and it's not coughing or backfiring, and you have fuel, it should be running. This is a long shot, but I had a wire fall off the back of the switch, and everytime you let go of the switch so it could return to run it would stall the engine, in other words you needed to hold the switch in the start position to keep it running, drove me batty, but then again I was only 18 yrs old too. Have you looked at the Spark, is it a nice bright blue color or just yellow. The Coil could be weak or going out also.

 

[PaFarmer]

It is not even sputtering or trying to start. It turns over fine. It is still The 24 volt setup. It has a solid state Pertronix ignitition, no points. I got the mog over the summer and it had the full civilian ignition set up when I got it. I did not mess with it. It ran fine for months, then one day it just would not start. It is possible it jumped time, but odd that it would happen between running fine and the next time. I had been running it every week because of the ethanol in the fuel.

Does anyone know where to download the manuals for a 404 cheaply. The factory owners manual was water damaged by rain at some point.

The cap and rotor looked fine. The distributor appears to be bolted down tight and the rotor turns properly. It has good spark. I actually found a bare spot on the handle of my pliers after holding the plug boot with the pliers to hold the plug near the block, checking for spark. My in-line spark plug tester does not work with the stud on the top of the spark plugs.

There was a loose ground wire, near the distributor. The wore is very light gauge and appears to have been fastened to the distributor at some point, but I can't see where it would have been mounted with the Pertronix ignition. The mounting screws were all tight, with no sign that a wire was previously retained.

 

[clinto]

When you say you have good spark, do you mean you have measured the output of the spark, or just the presence?

Reason I say this is one time, Dad's Chevelle wouldn't run. I went though EVERYTHING-compression test, fuel pressure, you name it. Finally, I put it on a scope and realized that although it had spark, it wasn't nearly enough because the (reasonably new) condenser had failed.

 

[shenkmen]

This video covers distributor wire connections and what is described as the #1 no spark cause which is an unseated magnetic ring under the rotor.

http://m.youtube.com/#/watch?v=wivi6tux690&desktop_uri=/watch?v=wivi6tux690

 

[PaFarmer]

I did not measure the output of the spark, just the presence of a spark. It felt like about 40,000 volts through the pliers.

The pickup and magnet seem to be mounted properly. I assume that Canister coils are pretty standard. I have a spare coil from a 6 cylinder jeep and plug wires that I can swap out to see if the spark is stronger. Today with a lot of ether it coughed but would not fire. It may have a fuel delivery issue. I will need to use a scope or mirror to see if fuel is being ejected from the jets.

 

[shenkmen]

Did you get the wire figured out?

 

[PaFarmer]

No I did not, that is what I have you for. The wire would not reach far. I do not know why it would have been connected to the distributor as the distributor is bolted to the block, it is already well grounded. Maybe there is something off in the advance. Maybe the spark is not strong enough, but it felt pretty strong.

 

[shenkmen]

No I did not, that is what I have you for.

Great... more work for me.

I'll be helping out with this issue in person this coming weekend. Any more suggestions from SS before we get started?

 

[197thhhc]

This is a long shot, but I had an issue recently where I had fuel and spark, timing was ok, air filter clean. It would sputter when you sprayed it. The issue turned out to be a damaged exhaust. It had resricted the airflow. Just something to check. I have also seen clogged cat convertors do this but I dont think yours would have one.

 

[saddamsnightmare]

March 1st, 2013.

Don't think its a catalytic converter on a early sixties S404.114. You may want to check the ground wire between the distributor body and the engine(let me check mine tomorrow, as I do remember a braided ground wire, but it may be between the block and some other part (its too dark to see right now outside)... You will find Unimogs that are nearly fifty years old can find all sorts of reasons to drive their owners nuts, but it's usually a very simple issue. Check your ignition system from end to end, and then consider the Pertronix unit may have gone if you have one, then even check the generator output to be sure its working as it should. Once you find the issue, its usually straightforward to correct.
And when in doubt, check the operator and shop manuals for troubleshooting tips.....

Good luck....

 

[PaFarmer]

Danmest thing, I swapped the plugs and it fired right up. I could understand fouled plugs preventing it from up running well, but not at all. Shenkman came over just in time to go for a ride.

Thanks for the input.

 

[mudman]

Sure glad you got it running....This thread was getting really old fast..!!!