Author Topic: Rough idle and revs after repair, need help (Read 1749 times)

patracy · « **on:** January 17, 2009, 11:06:41 am »

I had an issue with the seal at the LDA portion of the pump. I removed the top of the pump and replaced that seal without much issue. I've tried putting everything back the way it came. But honestly I've lost track of the max fuel screw. Now I can get the engine to run. But idle is rough. And I can't get the idle and revs just right. I can tinker and get the idle ok, but the revs aren't right. Then I can get the revs right and the idle is wrong. Other times I can get things just about right playing with the fuel screw, but then it'll rev way to high.

I guess I need to understand how to get the idle smooth again and how to adjust the max fuel screw. I understand how to adjust the idle speed with the two threaded rods. But I don't think I'm at that place yet. Timing seemed to be fine before. I was just trying to fix the fuel leak.

patracy · « **Reply #1 on:** January 17, 2009, 02:54:36 pm »

I've played with it all day. Idle is rough no matter what. It'll rev ok now and idle back down. But there's no power. What do I do?

jtanguay · « **Reply #2 on:** January 17, 2009, 03:43:27 pm »

any air in the lines when you rev it? give it a good few revs and if you see lots of bubbles then that could be part of the issue.

messing with the fuel screw is a bit of an art... if you go too far it can throw things right out of whack, make the RPM's hang, make it idle like crap, have no bottom end power, etc. i think you might need to give it more fuel in very small increments by threading the fuel screw inward (1/4 turns or even 1/8 turns) and adjusting the idle as necessary. its a painstaking process, but it should give you the result you want. you'll need to rev the motor right up after each small increment (and check for black smoke), but before that give it a bit just to be sure that the rpm's aren't hanging. if the RPM's start hanging, you've gone too far. usually at that point though, the car will really start to smoke if you have a heavy foot...

but... before you do all that maybe you should make sure that the LDA is sealing properly... do you have a boost gauge tee'd into the boost line going to it? maybe when you say 'lacks power' you mean it just doesn't have boost enrichment??? i've driven like that before... and the car didn't have the same pickup, but wasn't horrible either. now when my boost line was disconnected, i felt a pretty big loss. nothing registered on the boost gauge though so it was easily diagnosed. maybe thats all that is wrong? don't forget that the boost line going to the LDA might be old. just cut a small portion of the end off and re-connect it. should work.

Smokey Eddy · « **Reply #3 on:** January 17, 2009, 04:40:59 pm »

ps. All of those small rubber lines perish after a few years and develop cracks. (ie. the ones that connect the injectors together are the same stuff, the fuel returns)

jtanguay · « **Reply #4 on:** January 17, 2009, 05:44:35 pm »

Quote from: "Smokey Eddy"

ps. All of those small rubber lines perish after a few years and develop cracks. (ie. the ones that connect the injectors together are the same stuff, the fuel returns)

especially when you use vacuum lines for fuel lines :lol:

patracy · « **Reply #5 on:** January 17, 2009, 06:02:14 pm »

Quote from: "jtanguay"

any air in the lines when you rev it? give it a good few revs and if you see lots of bubbles then that could be part of the issue.

messing with the fuel screw is a bit of an art... if you go too far it can throw things right out of whack, make the RPM's hang, make it idle like crap, have no bottom end power, etc. i think you might need to give it more fuel in very small increments by threading the fuel screw inward (1/4 turns or even 1/8 turns) and adjusting the idle as necessary. its a painstaking process, but it should give you the result you want. you'll need to rev the motor right up after each small increment (and check for black smoke), but before that give it a bit just to be sure that the rpm's aren't hanging. if the RPM's start hanging, you've gone too far. usually at that point though, the car will really start to smoke if you have a heavy foot...

but... before you do all that maybe you should make sure that the LDA is sealing properly... do you have a boost gauge tee'd into the boost line going to it? maybe when you say 'lacks power' you mean it just doesn't have boost enrichment??? i've driven like that before... and the car didn't have the same pickup, but wasn't horrible either. now when my boost line was disconnected, i felt a pretty big loss. nothing registered on the boost gauge though so it was easily diagnosed. maybe thats all that is wrong? don't forget that the boost line going to the LDA might be old. just cut a small portion of the end off and re-connect it. should work.

Air in the lines? I assume you mean the return lines?

I've been playing with it like that all day and only got it to rev decent now. It doesn't smoke like it did when it ran well. I can keep on, but honestly I don't feel I'm making any ground. The idle is still extremely rough. That's what is making it difficult. To get it smooth I have to set the arm so high, then it sticks on RPM's from the fuel screw. I guess I'll play with the throttle valve and get it dialed in for a decent idle. Then play with the fuel screw. Juggling them both is impossible as I've learned today.

LDA's hose is connected. But I'm wondering how well it's functioning. I think it should kick in for mid an high rpm power. But I'm not getting past the bottom end? Maybe that's related to the other problem.

patracy · « **Reply #6 on:** January 17, 2009, 06:03:12 pm »

Quote from: "Smokey Eddy"

ps. All of those small rubber lines perish after a few years and develop cracks. (ie. the ones that connect the injectors together are the same stuff, the fuel returns)

All new lines. New engine. And I was told rebuilt IP (looked like it too). Hopefully it's just a matter of someone not replacing that top seal.

patracy · « **Reply #7 on:** January 17, 2009, 06:45:35 pm »

Ok I did find one point where it'd idle nice again, but I had to move the throttle lever. Once I swaped the marks on the sides, the idle was fine (with the fuel screw) But I don't have any throttle then?

Is there a base setting for the throttle arm? I'm ready to pull the stupid pump off and just replace it. Makes me mad because the pump was fine except for the leak.

patracy · « **Reply #8 on:** January 18, 2009, 04:08:15 pm »

I think I've just about got the pump back in place. I took the fuel screw completely out of the pump and set it close (yet back out a few turns) to where it was stock. Then I placed everything exactly back like it was. It seemed to run close to what it did before and back to black smoke!

Now for the new problem. :cry:

The bolts for the accessory housing and water pump backed loose and I get to take everything apart. Time for brand new bolts and THREADLOCKER! Wish I'd have done that the first time. UGH!