I have a few post running a few pages back on a rough idle I have been chasing. I searched the archives for many hours and tried most everything, and of course all the no brainer stuff first like plugs, cap, rotor, idle ICM, clean throttle body, etc, etc. Then,
I ran the test for the prepump and the main pump, and found the pre-pump was dead in the water. I replaced it today (my God, what a nightmare job without the IPD bung hole nut toll, I will NEVER do this job again without it.) and my idle is smooth as silk, and the main pump noise/hissing has stopped.

Yeah, I thought I ain't paying 24.00 for that stinkin tool, now I think otherwise.

If you are having an idle issue, jumper power from the left of fuse # 5,6,7,or8 to the right of fuse#4 (with fuse removed of course) and lister at the gas filler, or remove the access plate in the trunk and lister to see if you hear it running. If all is quiet, your pre-pump is DOA.

Thanks to everyone for all of the help with my idle.

A new pre-pump does wonders doesn't it? My old '89 was a slug until it got a new little "aquarium pump." Now I cruise down the interstate with the Bimmers. Boy they look surprised when I pass them.
Charles

Ya I learned that lesson the first time changing out the pump. It wasn't until I realized its the two little tabs sticking up that the screw driver needs to be hitting that I then got any results. But never again since I've got the tool.

Not having ever tried the "brass drift" method or any of its hammer-based cousins, I imagine the tough part is not removing the ring, but getting it started back on, with a fresh fat O-ring to compress.

Though my kludge with the two-arm puller fits the slots well, it would be easier to apply pressure at the same time as rotation with the tools described in the 7/9 FAQ, or the one IPD sells.




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Art Benstein near Baltimore

Time may be a great healer, but it's a lousy beautician.

OK, apparentlyit isn't 100% better. It idles and runs better overall. But, I noticed that it still idles a little rough when in gear at stop signs/lights. But, in neutral, or park it idles fine. It is definitely way better than before the pre-pump swap, but still a rough idle at a stop? What would cause that?



Thanks

Hi Jeff,

I don't know if you tried this, but on your 91 you can remove fuse #6 for a second to reset the computer's adapting to the low fuel pressure condition it saw before your repairs. Then give it about 10 miles of driving to work itself in.

Don't forget to grab the codes before you reset it.
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Art Benstein near Baltimore

Always keep your words soft and sweet, just in case you have to eat them.

Art,
Thank you so much for all of your help during this fiasco. I did pull fuse#6 at some point during my trouble shooting, so it has already been out of the holder.

I am getting ready to order a bentley manual, but so far I am not sure how to check codes on the 240's. What should I do at this point? Remove the fuse again? It was removed before I replaced the pump. It is barely noticeable, but it is a little rough in drive, at a stop (it has an auto trans.)

Thanks everyone for all of your help!! Next, strut inserts and urethane CA bushings. Then, I will have it pretty much done for now.

Jeff, you might offer some help to J.R. who has rough idle with lean-looking plugs. I pointed him to your thread here.

If you've already reset the computer, it will need about 10 miles of real driving, not idling, to re-adapt. To grab the codes look for the test box shown here, and refer to the 7/9 FAQ paragraph on using the diagnostics until you get your Bentley.




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Art Benstein near Baltimore

Mothers of teens now know why some animals eat their young.

Art,
Please excuse my ignorance, but I am not sure how to reset the computer, pull the negative battery cable? So,I check current code, pull fuse#6, reset computer in that order?

I will help JR anyway I can, but I haven't pulled my plugs to check their color since I put in new ones at the very beginning of this. But, I will pull the plugs soon and report back.


Thanks,
Jeff

I'm not saying you need to pull your plugs. I was just giving you a clue the symptoms are similar since JR took that reading.

Anyway, pulling fuse 6 is resetting the computer. You could do the same thing by disconnecting the battery, but that is annoying if your radio presets go with it.

Just a good idea to check the current codes to know whether things improve afterward.


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Art Benstein near Baltimore

When everything's coming your way, you're in the wrong lane.