Troubleshooting '84 Corvette stumbling on acceleration
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Joined: Apr 2002
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From: O'Fallon Illinois
Troubleshooting '84 Corvette stumbling on acceleration
Ok, looking for some opinions on this one:
I've got 180K mileage and all the injection and electronic components as well as throttle bodies are original. Basically enginewise everything is original minus alternator and starter not including wear items (plugs, cap & rotor, wires, O2 sensor, etc.). If I slowly accelerate I don't have any problems, but when under normal acceleration the engine stumbles to get up to speed. I know it's not a plug or wire problem and am starting to suspect it lies either in a throttle body or one of the electronic components. It used to only occur maybe 20% of the time but now is pretty much 80-100% of the time. Looking for suggestions rather then replacing each component and finding that it is the last one. :confused: I have an AutoXray scanner and can check out many of the operating variables, but don't know what the norm is for many of them and it's not triggering any trouble codes. Any info appreciated since I'm holding off for one more year before I do a rebuild on it. Thanks!
Hoose84
[Modified by Hoose84, 5:27 PM 4/8/2002]
I've got 180K mileage and all the injection and electronic components as well as throttle bodies are original. Basically enginewise everything is original minus alternator and starter not including wear items (plugs, cap & rotor, wires, O2 sensor, etc.). If I slowly accelerate I don't have any problems, but when under normal acceleration the engine stumbles to get up to speed. I know it's not a plug or wire problem and am starting to suspect it lies either in a throttle body or one of the electronic components. It used to only occur maybe 20% of the time but now is pretty much 80-100% of the time. Looking for suggestions rather then replacing each component and finding that it is the last one. :confused: I have an AutoXray scanner and can check out many of the operating variables, but don't know what the norm is for many of them and it's not triggering any trouble codes. Any info appreciated since I'm holding off for one more year before I do a rebuild on it. Thanks!
Hoose84
[Modified by Hoose84, 5:27 PM 4/8/2002]
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Re: Troubleshooting '84 Corvette stumbling on acceleration (Hoose84)
Check your Air/Fuel ratio..if with a heated O2, check for fuel pressure at rail *have some one check it with car in park and different rpm ranges* to check for faulty fuel pressure regulator. Look over plug wires for any damage. Dissconnect knock sensor to see if car runs better or worse..it does run the same, check into a ESC or EST. Have your ignition coil tested for proper resistance. Also try dissconnecting your MAF (with car warm), and check results. Good luck
Burning Brakes
Joined: Apr 2001
Posts: 904
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From: Langley, BC, Canada
Re: Troubleshooting '84 Corvette stumbling on acceleration (Oh My)
none of those tips will work on an 84, they dont have fuel rails, they dont have a maf, you cant check the a/f ratio
go here http://www.crossfire.webhop.net/cftest
[Modified by nsimmons, 2:38 PM 4/8/2002]
go here http://www.crossfire.webhop.net/cftest
[Modified by nsimmons, 2:38 PM 4/8/2002]
Safety Car
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From: Guam
Re: Troubleshooting '84 Corvette stumbling on acceleration (nsimmons)
You did not say if you have sufficient fuel. when did you last change your fuel filter? :eek:
I would also check to see if the fuel pump is giving sufficient pressure.
[Modified by Sharky Guam, 8:50 AM 4/9/2002]
I would also check to see if the fuel pump is giving sufficient pressure.
[Modified by Sharky Guam, 8:50 AM 4/9/2002]
Drifting
Joined: Nov 2001
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From: Bucks county Pa
Re: Troubleshooting '84 Corvette stumbling on acceleration (Sharky Guam)
You did not say if you have sufficient fuel. when did you last change your fuel filter? :eek:
I would also check to see if the fuel pump is giving sufficient pressure.
[Modified by Sharky Guam, 8:50 AM 4/9/2002]
I would also check to see if the fuel pump is giving sufficient pressure.
[Modified by Sharky Guam, 8:50 AM 4/9/2002]
Burning Brakes
Joined: Apr 2001
Posts: 904
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From: Langley, BC, Canada
Re: Troubleshooting '84 Corvette stumbling on acceleration (blk90rdstr)
if it does turn out to be the fuel pump, i suggest you upgrade to the 85, it has no problems maintaining pressure, it does take a little bit of wiring, just 2 leads though, took me 1/2 hour to swap it in.
[Modified by nsimmons, 5:51 PM 4/8/2002]
[Modified by nsimmons, 5:51 PM 4/8/2002]
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From: O'Fallon Illinois
Re: Troubleshooting '84 Corvette stumbling on acceleration (nsimmons)
I'm going to check the fuel pressure, and I can't remember the last time I changed the filter either. So both are likely culprits that I totally overlooked, thanks for all the tips. Couple questions though, anyone have good recommendations on fuel pressure tester for this particular application and how much trouble is the pump to get access to it. I have shop manuals and all, but am in the middle of moving and they are packed up some where. Can you access the pump from under the fuel door area? I haven't really looked to see what I'm getting into, but if I do need to replace it, I will go with the 85 pump and replace the wire (Probably from front to rear since I am starting to have some wiring issues here and there with the car anyway). Thanks!
Hoose84
'84 Z51 Grand Sport Look-a-like
Hoose84
'84 Z51 Grand Sport Look-a-like
Melting Slicks
Joined: Mar 2001
Posts: 2,150
Likes: 304
From: Timra, Sweden
Re: Troubleshooting '84 Corvette stumbling on acceleration (Hoose84)
Fuel pump is a simple job.
I have some pictures from when I changed it here:
http://w1.601.telia.com/~u60113744/f...p/fuelpump.htm
The fuel filter is located on the frame behind the right front wheel:
This is a simple fuel pressure gauge I made. It is easy to put it on the fuel exit of the filter. ( just a hose clamp there )
You want to have it after the filter to detect if it is clogged.
[Modified by JoBy, 7:16 PM 4/9/2002]
I have some pictures from when I changed it here:
http://w1.601.telia.com/~u60113744/f...p/fuelpump.htm
The fuel filter is located on the frame behind the right front wheel:
This is a simple fuel pressure gauge I made. It is easy to put it on the fuel exit of the filter. ( just a hose clamp there )
You want to have it after the filter to detect if it is clogged.
[Modified by JoBy, 7:16 PM 4/9/2002]
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Thread Starter
Navigator
Joined: Apr 2002
Posts: 9
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From: O'Fallon Illinois
Re: Troubleshooting '84 Corvette stumbling on acceleration (Hoose84)
Ok, turns out that it was in fact NOT the fuel pump or filter. Although the car does seem to have alot more pep. But still have the same issue, looking for suggestions on the next culprit.
Hoose84
84 Z51 coupe (Grand Sport look-a-like)
Hoose84
84 Z51 coupe (Grand Sport look-a-like)
Burning Brakes
Joined: Apr 2001
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From: Langley, BC, Canada
Re: Troubleshooting '84 Corvette stumbling on acceleration (Hoose84)
i would pull the plugs check them out, also the wires and the ignition system. I had fouled plugs once which made the car act like it was starving for fuel
Melting Slicks
Joined: Nov 2000
Posts: 3,388
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From: X
Re: Troubleshooting '84 Corvette stumbling on acceleration (Hoose84)
Try testing your TPS see if you are getting 5.4 volts. As suggested above, pull the plugs and take a look see. Make sure the doors on the Thermac are opening as it warms. Check your timing. Make sure you are getting enough voltage out of your altenator 9 volts min 16 volts max. Check your EGR make sure its closed when ideling, and moves upwards when you give it gas. Disconnect your injector connections, crank it over, you should see NO fuel coming out. Make sure both sprays look the same when running. And make sure your CAT isn't clogged.
Thread Starter
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From: O'Fallon Illinois
Re: Troubleshooting '84 Corvette stumbling on acceleration (JonM)
I guess I should have given a little more information. :) I have switched out the plugs (All of them that I took out look fine BTW, not fouled or burnt or anything. Almost picture perfect.) My cat converter is about a year old (as well as the rest of the exhaust). Year old alternator, but I will double check voltage since you never know. Thanks for the other tips though, I will check them out. Mostly the problem seems to be in the mid RPM range and checking the TPS was my next guess. Possibly the wires as well, since the problem is intermitant. Thanks!
Hoose84
Hoose84
