hey guys last weekend I went and bought a 1990 f250 7.3 idi with a 5 speed manual. Since I have had it I replaced the injection pump valve cover gaskets all belts and new alternator and fuel filter and return line kit. I had it timed yesterday but they had moved the throttle up on it so it would idle but now I can't get the high idle to touch any suggestions? What's the truck suppose to idle at? Mines at 700 to 800 warm.
High idle question
- Thread starter Fordfan90
- Start date
If I recall correctly, 650rpm is factory idle. 900-1000 is proper for high idle.
plywood
Recovered N/A
You can loosen the high idle bracket and put it where you want and also I think you can turn the plunger and it will adjust somewhat.
Macrobb
Full Access Member
Retarded timing, most likely.
You've probably got one injector that isn't perfectly balanced(it's slightly higher injector pop pressure than the others, it's in 'better' condition, perhaps only by 100 psi), and combined with the very little fuel being injected at idle, you get a miss due to late injection.
So, you replaced the injection pump: Where did you get it? Was it used(timing curve will be way off generally), or a auto parts crummy rebuild(could also be off)?
You had it timed. How did they time it? By ear? By a luminosity probe? By a clamp pulse-meter?
You've probably got one injector that isn't perfectly balanced(it's slightly higher injector pop pressure than the others, it's in 'better' condition, perhaps only by 100 psi), and combined with the very little fuel being injected at idle, you get a miss due to late injection.
So, you replaced the injection pump: Where did you get it? Was it used(timing curve will be way off generally), or a auto parts crummy rebuild(could also be off)?
You had it timed. How did they time it? By ear? By a luminosity probe? By a clamp pulse-meter?
Macrobb
Full Access Member
I'll bet you that it's several degrees retarded. Plain and simple.
Loosen the pump lines, rotate it to the mark being perhaps a dime's width on the passenger's side of the mark, and see if that fixes your miss issue. Make a mark where it is now, so you can go back. My view on timing is that you keep it where it runs best(has most power, no white/gray smoke), and that'll end up giving you good fuel economy.
Also, another way of checking being retarded or not - start the engine, and while it's still cold, disconnect the cold advance wire(back/top of the IP). The engine should become quieter, with less diesel rattle. Reconnect it and you should hear some rattle. If it doesn't change, or starts running really badly when disconnected... you're quite a bit retarded.
I just started it and was un plugging the wire on the top of the pump and I didn't notice any change in the motor or the sound. I'm confused with this pickup.
shawn deere
So many wrenches, so little time...
Sounds like you need to advance the timing. Disconnecting the timing advance should make it sound different
Loosen 3 nuts and rotate the ip twards passenger fender. A dime width is a big jump fyi
Loosen 3 nuts and rotate the ip twards passenger fender. A dime width is a big jump fyi
I started it again without moving the pump yet and it smoking white and my hand gets covered in soot
shawn deere
So many wrenches, so little time...
Dont move the pump while its running!
Also white/blue smoke point tward retarded timing
Also white/blue smoke point tward retarded timing
plywood
Recovered N/A
Cold advance will only make a difference if the engine is cold.
