Rough Idle, POOR performance!

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  #1  
Old 08-06-05, 02:40 PM
SimK68
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Exclamation Rough Idle, POOR performance!

I have a 81 olds Delta 88. 307 4 bbl carb. When you 1st start it, it runs SMOOTH and takes off smooth, but then after 2 minutes of driving, in a instant it idels ROUGH and hard and runs very sluggish and I get POOR fuel millage. But when you start it back up and or re-boot it, it goes away, and 2 or more minutes, starts back up.

Im hopping its NOT the 'MIXTURE CONTROLL SILINOID', because that means on THAT carb, I have to take the WHOLE carb off to replace it. BUT! When I disconnect it, and it runs smooth then the 2 minute timer kicks it, it IDLES SMOOTh...BUT... It performs like crap! Giving me again, very crappy milage.

Im fixing to move to another town and have to drive it 350 miles in about less than 2 weeks, dunno what to do.
 
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  #2  
Old 08-06-05, 03:53 PM
Comptech
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A very common problem with them was a bad purge valve,look for a round black thingy with 3 or 4 vacuum hose going to it two will be large diameter and it should be towards the front of the intake.Take it off and shake it if you get gas out of it it is bad.Whoa back to the history books!
 
  #3  
Old 08-06-05, 06:13 PM
SimK68
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Originally Posted by Comptech
A very common problem with them was a bad purge valve,look for a round black thingy with 3 or 4 vacuum hose going to it two will be large diameter and it should be towards the front of the intake.Take it off and shake it if you get gas out of it it is bad.Whoa back to the history books!
Ok, well ill just replace the darn thing. I do that 1st thing in the morning. And yea it also makes a loud exhaust RUMBELING sound from the hose that goes to the smog-pump which I just replaced, and made a diffrence.

Thanks in advance.
 
  #4  
Old 08-07-05, 01:18 PM
SimK68
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Ok Comptech... Just to make sure before I go buy a new one, is this the 'Purge Valve' youre refering to? (indicated by the bottom arrow) of course the air pump hose is in the way....



And where the top arrow is, is the M.C.S. which has a bad plug, but I think the wires themself are still good, would THAT have a effect?

Another thing, this also wouldnt have any effect... It has bad wires on it, and its located right by the oil sending unit as you can see on the left. Its broken on the bottom and the wires are all distored. What is this thingy?.....




Thanks again in advance.
 
  #5  
Old 08-07-05, 01:41 PM
jeffstevens
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Check your floats. I'm pretty sure thats the problem, I need more info. What do you mean running good, perfect? I've seen ign modules cause the running rough issue after they heat up. When its cold, works perfect.
 
  #6  
Old 08-07-05, 02:03 PM
SimK68
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Originally Posted by jeffstevens
Check your floats. I'm pretty sure thats the problem, I need more info. What do you mean running good, perfect? I've seen ign modules cause the running rough issue after they heat up. When its cold, works perfect.

This is after 2 minutes after you have running or driving. It instatanioulsy drops and runs sluggish as though somthing has become disconnected. It runs SMOOTH as silk before then.

But im going to start with that purge valve and see what happens, because like he mentioned, where ONE of the vacume lines goes to the carb FROM the purge valve, it has gas resadue all around it where it plugs into the carb., and is somtimes wet.
 
  #7  
Old 08-07-05, 02:20 PM
jeffstevens
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Its gas not oil?
Originally Posted by SimK68
This is after 2 minutes after you have running or driving. It instatanioulsy drops and runs sluggish as though somthing has become disconnected. It runs SMOOTH as silk before then.

But im going to start with that purge valve and see what happens, because like he mentioned, where ONE of the vacume lines goes to the carb FROM the purge valve, it has gas resadue all around it where it plugs into the carb., and is somtimes wet.
 
  #8  
Old 08-07-05, 02:27 PM
SimK68
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Originally Posted by jeffstevens
Its gas not oil?

Its gas, because somtimes you can smell it when you drive, then it goes away.
 
  #9  
Old 08-07-05, 02:37 PM
jeffstevens
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You can smell gas, rub your finger around where you see the leak. Smell to confirm.
The floats in the carb could me sticky, causing it to overflow.

post some more pic's
 
  #10  
Old 08-07-05, 11:31 PM
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the bottom pic is the coolant sensor it can be replaced with a newer version sensor and connector if ever needed and im sure that is the purge valve that comptech was reffering to.
does this car have a check engine light on, if it does have you checked codes?
 
  #11  
Old 08-08-05, 05:15 PM
Comptech
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Yep that's the one, just take the hoses off and smack it agaist your hand a few times, if you get gas out of it it is bad. One of the hoses is manifold vacuum and another goes to the vent on the carb. When the diaphram goes bad it sucks raw fuel through the vacuum line.
 
  #12  
Old 08-08-05, 07:59 PM
SimK68
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Originally Posted by Comptech
Yep that's the one, just take the hoses off and smack it agaist your hand a few times, if you get gas out of it it is bad. One of the hoses is manifold vacuum and another goes to the vent on the carb. When the diaphram goes bad it sucks raw fuel through the vacuum line.
Ok thanks, still havent had a chance to take it off. I went to the parts place didnt have a clue what I was talking about wheni explained to them, so im just going to drive it up there to show.

I still have a funny feeling this may NOT be it, because when I hooked the MCS back up last night, it ran even WORSE than ever before when all of this started (in that 2 minute 'after run')... It started poping out of the carb. I hope I dont have to replace that, because for one, i dont have the time to take that carb apart... 2 im not spending another $300 on another 'refurbished' carb.
 
  #13  
Old 08-09-05, 01:15 AM
SimK68
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Originally Posted by bejay
the bottom pic is the coolant sensor it can be replaced with a newer version sensor and connector if ever needed and im sure that is the purge valve that comptech was reffering to.
does this car have a check engine light on, if it does have you checked codes?
No, its not equiped...It has a check engine light lense, but no bulb was ever put in...there is not even a wire gram hooked to it nor the jumper dio. box on the bottom...Maybe because the car is a 81' and we think it was manufactured in Canada.

Like I said, im going to replace the purge valve for starters..and if the parts house does not have it..to the salvage yard for that AND the coolant sensor if they dont have that either. What also frustrates me, auto parts places like AutoZone are getting more difficult each year with stocking parts for my baby im tring to restore. I mean good GOD that place IS or should be for cars that are as OLD as mine! Ill let you know CompTech and bejay the end result.

Thanks again
 
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