backfire

[CHRIS UNGER]

Can anyone tell me the sympoms of a coil getting hot and breaking down. Do you ever have any problems with points and condenser. My truck will act up y backfiring when you coast to running on five and eventually backfiring o bad you lose all power and stop. You can let it sit for ten minutes and it will barely get you home. thanks for any input. My m37 never gave me trouble like this and it has same distributor.

[Barrman]

While coils are a comon M715 ailment, they are normally an on or off kind of thing. Check your fuel filter, in tank fuel sock and the float needle. My stock engine would go down the road great, I let off the throttle and it would pop and back fire along with no idle at all. I learned this was the needle getting dirt in it. I carried spare fuel filters with me to swap them out, clean out the carb bowl and be back on my way in about 15 minutes. It would run great for a few months and do it again. I finally got the tank cleaned out and problem solved.

A coil intermitently not working can cause pooled up non burned fuel to fire off in a back fire or POW. So to can too much fuel from the carb or a sudden too lean condition on a hot engine.

Besides the procedures listed in the -20 manual for checking the coil, turn on the ignition switch for about 5 minutes and then feel the coil. If it is basically red hot, that is normally bad for so short a time with a cold off engine. This super hot coil might work just fine, but it is dying.

[randygar]

Sounds like you might want to check the ignition basics - condition of points and condensor, dwell angle, and timing... worn or misadjusted points can cause all sorts of annoying problems.

--Randy