Jacob Wilkie
Newbie
I'm new to the forum and have already found a ton of great info, still figuring out the forum though. Haven't found any threads on my particular problem but if there is one already, I apologize in advance. I've got a 1990 1500 with the 4.3 tbi with 235k on her. Single cab, long bed, 4wd, automatic. I personally know the older man that had it before for 14+ years and I know he took good care of it, never drove hard. Had a tune up done on it a year or so ago. The trouble I'm having is when it's under acceleration, I'd say about 1/2+ throttle, more so under WOT. If I'm stopped and put it to the floor, it'll sometimes backfire through the intake/throttle body 1-3 times while accelerating until it reaches a higher rpm (don't know what rpm as I do not have a tachometer). Will not do it every time and I can't make it do it, very intermittent. Also, it sometimes has a skip/miss when accelerating at about any throttle. This is also very intermittent and I cannot make the truck do it. Idles perfectly. Seems to run rougher and backfire more in 4wd (will backfire and run rough at lower rpm's in 4wd than 2wd). It's solely a hunting truck so it doesn't get driven much but does get driven at least twice a week, more during deer season. Have tried running 93 octane, gas and fuel additive and injector cleaner. Cruises down the road without missing a beat. I'm somewhat mechanically inclined, not a mechanic by no means but enjoy doing what I can. This is my first 4.3 tbi so it's platform is new to me. I'm going to start with doing another full tune up here soon (plugs, wires, cap, rotor button, air filter, fuel filter). I've been reading where it could possibly be low fuel pressure, timing could be off, or the fuel regulator? Also, could a leaking/stopped-up injector cause this issue? Or what do you guys think? I'm open to any suggestions and help. Thanks
