1991 Mighty max

[vaprobe87]

My truck is doing the same thing. It backfired one time through the intake the other day and started running worse and worse and finnaly got to where it would start up and idle for a few seconds then die. I thought it had maybe jumped time or something so I took it all apart and it looked like it was out of time. I ended up replacing the balance shaft belt because it was all dry rotted and then put everything back together and it fired up and did the same thing.

It would idle for a 4-5 seconds then die again. It did this two or three times and then now it will start up and then die right away. It don't even try to idle.

[Lon Moer]

My truck is doing the same thing. It backfired one time through the intake the other day and started running worse and worse and finnaly got to where it would start up and idle for a few seconds then die. I thought it had maybe jumped time or something so I took it all apart and it looked like it was out of time. I ended up replacing the balance shaft belt because it was all dry rotted and then put everything back together and it fired up and did the same thing.

It would idle for a 4-5 seconds then die again. It did this two or three times and then now it will start up and then die right away. It don't even try to idle.

your cat is probably clogged or melted.
When mine backfired it blew a melted hole through the cat, I figured it out when I was chasing down a rattle in my exhaust that turned out to be melted porcelain 'marbles' that had made it all the way to the muffler.