I was driving my truck and it died at 40 mph. No spark, thought it may be pick up coil so I replaced it and still no spark. After replacing module I did get it running but after 5 seconds of chugging the engine it would back fire through the carburetor. I recently put new wires on so I checked my firing order the only thing I found odd (which has been like this since purchasing the truck) is according to the book the wire for the #1 cylinder is at 2:00 and on my distributor it is at 5:00 but it does have the correct firing order from that point. Since rotor spins counterclockwise I loosened up the bolt for the distributor and turned it clockwise as the engine idled and it started to run better. I do not think it would run if I slipped a tooth on the timing gear so I am assuming that is not the problem. The truck had set for approx. a month before I was able to get it started so I am wondering if it is a timing and carburetor problem? Will try to pick up timing light today. Cannot figure out why in the middle of running and dying it would have thrown it out of time so much to cause this problem as it was running fine right before it died. Any advice would be appreciated.

 

Welcome to the site..

So,, before the pick up coil and module change NO SPARK,, since it started and backfires we can assume it still has spark. If not or intermittent couple things to check...

Technically #1 can be or start anywhere in the rotation circle as long as the firing order is correct and the base timing is spot on. That said, I'd wire it up correct. Just lends to the confusion if not, for you or the other guy.

With no/intermittent spark, you'd also want to make sure the roll pin that holds the distributor gear/shaft in place on the lower housing end hasn't sheared. As well as check that the timing gears haven't jumped time. Both will affect spec timing. But unless they stopped moving generally there will still be spark, just not at the correct time.. if it was running fine prior, and advancing the timing significantly helps, checking the timing should be done to rule it out as a potential cause,, If jumped or a shear, chances are that it would just pop'n fart maybe a flame or two...

You mention idle, and that you "were able" to get it started, but does the engine come up in RPM smoothly once off idle? Or is it poor performance overall?

Also, fuel.
Correct fuel?, any chance at all it was polluted? Diesel, water etc.

 

thanks for the info, started the truck this morning and let it idle then put on a timing light, adjusted the timing at idle and watched the mark, there was no fluctuation with the timing mark, I was told if it jumped a tooth that the timing mark on the balancer would move back and forth across the timing point on the engine. it seems to sound good at idle but when you throttle it up you can hear it run rough. was told it could be a dirty carb so am going to take off carb and clean. the engine doesn't spin as easy at starting as it had, cant figure that out and still wondering why the timing got thrown off so much. hopefully the carb will fix it if not may have to look at the timing chain. on the distributor and the firing order it I change the order on the cap wont I have to pull the distributor and turn it for the rotor to hit the number one wire when the number one cylinder fires? thanks Mark

 

Yes on the distributor needing a re installed if you go #1 correct positioning. Good chance some of the plug wires may have to be relocated in order to make for sufficient 'reach' for a redirect postion.

Vacuum advance was unplugged and hose plugged off for the timing check?

If the timing had jumped, it would most likely run poor at idle, more so if anything close to spec timing on the balancer. You mentioned you 'advanced' the timing and it ran better. If the timing is now spec setting, idle quality good, doubt there's any base engine issues. Balancers can spin as well showing or registering timing mistakes or discrepancies. Not that often, but something to consider. Putting a vacuum gauge on the intake manifold tap (or non ported carb source) can show cam/valve/timing issues. Cam timing slip or excess variations can/will affect idle quality and tend to show up in vacuum values-gauge readings.
If the timing is good, manifold vacuum good, then doubt there's failures.

Also, when chain issues are suspect, debris in the oil may tell a story with a sample taken,, and another check prior to pulling the front cover is,,
You can remove the right/passenger valve cover and roll the engine over backwards until the #1 intake and exhaust valves "overlap" meaning,,, with a breaker bar etc on the crank/balancer bolt, roll the engine back'n forth over the balancer/pointer marks (TDC) a few degrees or so, at the VERY SAME time look at the #1 intake and exhaust valves, they should both 'just' start to open/close the valves (overlap) as the pointer/indicator heads back'n forth over 0-TDC mark ( not BTDC) If not, and valves don't follow the balancer moves,, or are significantly north/south of TDC it would indicate cam timing has changed.

Vacuum leaks/gaskets, EGR, and brake booster as well as any other potential bleeds can affect idle quality. Power valve leaks were common usually causing hard start after some sit time, or run rich at idle, unstable idle etc.

Fuel quality and correct fuel should be considered, more so if fueled with fuel cans, or other drivers or evil doers ��

 

finally got back to working on truck, took off carb and cleaned real good. started backup checked timing again , still ok. idles not to bad but when you throttle up very rough has to be babyed up for higher rpms. I remember many years ago my little datsun 4 banger ran like this one morning , i was able to drive it to a service station . the guy started pulling the plug wires one at a time bingo! it was afouled plug. put in a new one ran great. any thoughts?

 

Do the simplest and basic things first it is a lot cheaper that way.
The seat where the spark plug seals in the head needs to be clean enough to eat off. It is the electric ground for the plug. Pulling the wires and looking for a dead plug is a good test method.
Eric

 

got a new set of plugs and new cap, run much much better but not 100% more like 90% but much better rough when you throttle up. am going to check air and gas valves on carb today.