BC Clark
09-04-2005, 19:09
My daughter's '88 Jimmy started blowing quite a bit of black smoke under full throttle. Not sure for how long since I haven't driven it in a while. I decided to check the IP timing and found it running about 2 BTDC at idle and 1 to 1.5 ADTC at 1300 rpm. I noticed the pump was already advanced pretty well. Went to max adjustment and could only pick up about .5. So I spent this weekend replacing the timing set. It was very loose. I set the pump back at the mark with the new timing set, much to my surprise (and dismay), I was showing 2 ATDC at idle and 5 to 6 ADTC at 1300. With the pump at full advance I'm still only getting about 4.5 BTDC at idle and 1.5 to 2 BTDC at 1300.
Some things to note: while the pump does not appear to be a rebuilt (only a Stanadyne label on it) neither it nor the front cover have anything but a scribe mark (no dynamic timing circle as the Service Manual indicates).
Used an MT1480 Lumy/Mag on number 3 with an offset of 99.5. The glowplug had some resistance in coming out (AC 60g's replaced about a year and a half ago). Seemed to be a build up that I polished off with some steel wool.
Yes the marks are lined up on both the chain and gears. I can at least assume the valves are not retarded anymore. I'm told a pump gear tooth is more like 20 dergees anyway off.
It didn't do this when I bought the truck two years ago.
It has an old 5 digit odometer, so I don't know if it's 60,000 (unlikely but the rest of the truck is very clean), 160,000 (more likely) or 260,000 (don't think so because the rest of the drive train is in good shape).
It runs great, starts fast, smooth idle, but I know it's blowing wasted fuel out the pipe.
I can't think of anything but a new pump at this point.
Some things to note: while the pump does not appear to be a rebuilt (only a Stanadyne label on it) neither it nor the front cover have anything but a scribe mark (no dynamic timing circle as the Service Manual indicates).
Used an MT1480 Lumy/Mag on number 3 with an offset of 99.5. The glowplug had some resistance in coming out (AC 60g's replaced about a year and a half ago). Seemed to be a build up that I polished off with some steel wool.
Yes the marks are lined up on both the chain and gears. I can at least assume the valves are not retarded anymore. I'm told a pump gear tooth is more like 20 dergees anyway off.
It didn't do this when I bought the truck two years ago.
It has an old 5 digit odometer, so I don't know if it's 60,000 (unlikely but the rest of the truck is very clean), 160,000 (more likely) or 260,000 (don't think so because the rest of the drive train is in good shape).
It runs great, starts fast, smooth idle, but I know it's blowing wasted fuel out the pipe.
I can't think of anything but a new pump at this point.