5.7 TBI barely idles, stalls in gear, runs and starts ok at part/full throttle - Chevy Impala SS Forum
Impala SS Forum
Go Back   Chevy Impala SS Forum > 91-96 Impala/B-body > Engine Problems/Maintenance
New User? Register - Forgot Password

Reply
 
Thread Tools Display Modes
  #1  
Old 03-13-2011, 01:52 AM
SaveOldSchoolMuscle's Avatar
SaveOldSchoolMuscle SaveOldSchoolMuscle is offline
Junior Member
 
Join Date: Nov 2009
Location: Clarendon Hills, IL
Posts: 6
SaveOldSchoolMuscle is on a distinguished road
Question 5.7 TBI barely idles, stalls in gear, runs and starts ok at part/full throttle

Hi everyone.

I'm helping a friend get his 92 Buick Roadmaster wagon ready to sell. It has a 5.7 Tbi with 190k on the clock. We were cleaning out the car as his daughter was not very tidy and the interior was a complete mess. We were also fixing some minor odd and ends, fixing the hood release, re-gluing some carpet, ect. I couldn't believe how big the back is with the seats folded down! Well Friday it started up with no problem, idled at about 1000 rpm when it first started then evened out about 800 rpm. So Friday the engine is good and sounds real nice.

Well I came over today to take some pictures and it ran like crap. It wouldn't start at all unless you held down the gas then the second you let off it stalled. I thought maybe it was low on gas (1/8 of a tank) so I add some gas from a gas can. It didn't help. I managed to get the engine idling if came of the gas very slowly but it idled unsteadily at about 400-600 rpm. The exhaust smelled very rich. When I put it into gear it dies. If I let off the gas quickly it dies. The odd thing is if I give it just a little gas maybe a little as 5% the "idle" stabilizes and if give it part/full throttle the engine runs fine. I checked under the hood no vacuum lines or plugs were disconnected but the snorkel to air box is missing. I didn't hear a hiss of a disconnected vacuum line at idle. I checked the air filter and ran it briefly w/o the air filter no change. There is no check engine light.

I'm guessing a vacuum leak but I'm not sure. The only other variable I can think of is it was about 10 degrees cooler today 39F. So what do you guys think? How should I start pinpointing the problem. Also keep in mind the budget for repairs will be limited.
__________________
1996 Impala SS
1966 Ford Mustang Coupe - Project Car WIP
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 03-13-2011, 04:02 AM
elbringit's Avatar
elbringit elbringit is offline
Senior Member
 
Join Date: Oct 2009
Location: Corpus Christi, TX
Posts: 365
elbringit is on a distinguished road
Default

Quote:
Originally Posted by SaveOldSchoolMuscle View Post
Hi everyone.

I'm helping a friend get his 92 Buick Roadmaster wagon ready to sell. It has a 5.7 Tbi with 190k on the clock. We were cleaning out the car as his daughter was not very tidy and the interior was a complete mess. We were also fixing some minor odd and ends, fixing the hood release, re-gluing some carpet, ect. I couldn't believe how big the back is with the seats folded down! Well Friday it started up with no problem, idled at about 1000 rpm when it first started then evened out about 800 rpm. So Friday the engine is good and sounds real nice.

Well I came over today to take some pictures and it ran like crap. It wouldn't start at all unless you held down the gas then the second you let off it stalled. I thought maybe it was low on gas (1/8 of a tank) so I add some gas from a gas can. It didn't help. I managed to get the engine idling if came of the gas very slowly but it idled unsteadily at about 400-600 rpm. The exhaust smelled very rich. When I put it into gear it dies. If I let off the gas quickly it dies. The odd thing is if I give it just a little gas maybe a little as 5% the "idle" stabilizes and if give it part/full throttle the engine runs fine. I checked under the hood no vacuum lines or plugs were disconnected but the snorkel to air box is missing. I didn't hear a hiss of a disconnected vacuum line at idle. I checked the air filter and ran it briefly w/o the air filter no change. There is no check engine light.

I'm guessing a vacuum leak but I'm not sure. The only other variable I can think of is it was about 10 degrees cooler today 39F. So what do you guys think? How should I start pinpointing the problem. Also keep in mind the budget for repairs will be limited.
Maybe TPS or fuel pump going out. JUst off the top of my head.
__________________
1995 B4U-running motor delete
Reply With Quote Quick reply to this message
  #3  
Old 03-13-2011, 09:45 AM
jayoldschool's Avatar
jayoldschool jayoldschool is offline
Senior Member
 
Join Date: Jan 2001
Location: the Great White North
Posts: 5,364
jayoldschool is on a distinguished road
Default

Fuel pump.
__________________
Old cars, just like classic rock... 60s, 70s, 80s, and 90s!
Reply With Quote Quick reply to this message
  #4  
Old 03-13-2011, 10:57 PM
SaveOldSchoolMuscle's Avatar
SaveOldSchoolMuscle SaveOldSchoolMuscle is offline
Junior Member
 
Join Date: Nov 2009
Location: Clarendon Hills, IL
Posts: 6
SaveOldSchoolMuscle is on a distinguished road
Default

If the fuel pump has gone bad how come the engine runs ok at part/full throttle but not at idle. In a low fuel pressure condition wouldn't the idle be ok and the engine stall and lack power at part/full throttle?

So I need to test fuel pressure to confirm the fuel pump providing the correct fuel pressure and that fuel filter is not clogged. I'm told I need to be about 11-14 psi correct? I have inline fuel filter with a 15 PSI pressure gauge attached I was planning to test with. So could I hook that up with some rubber fuel line and hose clamps at stock fuel filter location? From what I can tell from pictures of replacement fuel filters it looks like it uses some sort of special quick connect. I also need to know the location of and what fuse to pull to disable the fuel pump and so I can relieve line pressure.
__________________
1996 Impala SS
1966 Ford Mustang Coupe - Project Car WIP
Reply With Quote Quick reply to this message
  #5  
Old 03-15-2011, 02:13 AM
SaveOldSchoolMuscle's Avatar
SaveOldSchoolMuscle SaveOldSchoolMuscle is offline
Junior Member
 
Join Date: Nov 2009
Location: Clarendon Hills, IL
Posts: 6
SaveOldSchoolMuscle is on a distinguished road
Default

Well the engine is running again at idle. Good news is I don't have to replace the fuel pump. The problem was the idle control valve. It was stuck fully closed and the engine wasn't getting enough air at idle. On a hunch removed ICV and cleaned the tip of the valve and its mounting location in the throttle body with carb cleaner. I then cleaned the electrical connecters, replaced the gasket, and reinstalled the ICV. I still don't get why the computer didn't throw a code. Anyway cool no-cost fix.

So one last thing to get this wagon road worthy and sellable, brakes. I know it's not the right area in the forum but thought I would share. I hate deferred maintenance. See for yourselves:



This was the better of the 2 driver side pads!





Luckily somebody replaced the passenger side rotor not so long ago so can get away with pads on that side. I honestly don't know how anybody with a sense of self preservation could let the brakes get this bad and then continue driving the car.
__________________
1996 Impala SS
1966 Ford Mustang Coupe - Project Car WIP

Last edited by SaveOldSchoolMuscle; 03-15-2011 at 02:20 AM.
Reply With Quote Quick reply to this message
  #6  
Old 03-15-2011, 10:47 AM
kpeters59 kpeters59 is offline
Senior Member
 
Join Date: Jun 2008
Location: Bellaire, Texas (Houston)
Posts: 337
kpeters59 is on a distinguished road
Default

Aren't you being a bit harsh?

If you look closely at both the left and right sides of that rotor, there's still plenty of wear area left...

Take a close look...

-KP

Last edited by kpeters59; 03-15-2011 at 02:55 PM.
Reply With Quote Quick reply to this message
  #7  
Old 03-15-2011, 02:36 PM
Moparman Moparman is offline
Senior Member
 
Join Date: Jul 2007
Location: Manitoba
Posts: 495
Moparman
Default

"Lady driven."

Run away. Run far and run fast.
__________________
'93 Roadmaster wagon, 3.23 and posi. All stock except for Monroe SS shocks, WS6 front sway bar and Crown Vic bolt-on rear bar. AC Delco O2 sensor and spark plugs - MANDATORY! And now new GM rear LCAs and steering shaft. Air Lift 1000s installed. Also new center link and idler arm for MUCH less wander. Tie rods. Steering box adjusted for bearing preload and sector shaft interference.

** For sale in exchange, power vent windows and motors for wagon.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Chevy Impala SS Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:40 AM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.
(c) 2007-2014 Impala SS Forum