Need help figuring out an issue
Thread Starter
Cruising
Joined: Aug 2017
Posts: 12
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Need help figuring out an issue
Hi I have a 79 corvette that has some issues and I was wondering if I could ask someone a few questions to try and figure out what the issue could be, the car runs and idles pretty good but as soon as I put it into anything other than park it just looses all power I can rev it to keep it going but it'll continue to bog out. I'm only 17 so I'm not so experienced with these things so any help would be appreciated.
Thank you
Thank you
Race Director
Joined: Mar 2016
Posts: 14,444
Likes: 8,239
From: Napa Valley California
Welcome to the Forum.
People will need to know details like, engine type, engine modifications, has this been an ongoing issue or something that just started and maybe any work to the car you have recently done.
People will need to know details like, engine type, engine modifications, has this been an ongoing issue or something that just started and maybe any work to the car you have recently done.
Thread Starter
Cruising
Joined: Aug 2017
Posts: 12
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Well it's has the l82 engine and the only thing I really know that was done to it is that it has an aftermarket air filter and big cooling fan and radiator which I'm not certain if it's stock or not, I was practically given the car yesterday so I'm just figuring everything out
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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You also need to let us know what RPM it is idling at and when the last tuneup was. When you Rev it, what is the lowest rpm it will stay running at?
It could be something as easy as the idle set to low, a vacuum leak because a vacuum line is disconnected, in need of a tuneup, the timing is way off.
talk to whoever gave it to you and see if they've got any maintenance records.
I would first, change the oil. Then go buy an old shop manual that has the specifications for your years tuneup. You'll need to get a timing light( I would get a digital one with a tach setting and adjustable advance) at a minimum depending on the distributor that your engine has. If it's an HEI then that's it, if it's a points distributor you'll need a dwell meter too. You also need a points/spark plug gapping tool and a good basic set of tools and a set of jack stands
It could be something as easy as the idle set to low, a vacuum leak because a vacuum line is disconnected, in need of a tuneup, the timing is way off.
talk to whoever gave it to you and see if they've got any maintenance records.
I would first, change the oil. Then go buy an old shop manual that has the specifications for your years tuneup. You'll need to get a timing light( I would get a digital one with a tach setting and adjustable advance) at a minimum depending on the distributor that your engine has. If it's an HEI then that's it, if it's a points distributor you'll need a dwell meter too. You also need a points/spark plug gapping tool and a good basic set of tools and a set of jack stands
Last edited by Rescue Rogers; Aug 2, 2017 at 12:00 PM.
Thread Starter
Cruising
Joined: Aug 2017
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Well that's my issue too only the speedo works so I can't tell the rpm but it seems to idle kinda low so I'll try and get it to a higher idle and see if that'll help.
where would I have to check for the vaccum lines cause I'd like to try the simple things I can do myself with the tools I have here before running out and getting things considering funds are pretty tight for me haha. Any information helps a lot
where would I have to check for the vaccum lines cause I'd like to try the simple things I can do myself with the tools I have here before running out and getting things considering funds are pretty tight for me haha. Any information helps a lot
Thread Starter
Cruising
Joined: Aug 2017
Posts: 12
Likes: 0
Well that's my issue too only the speedo works so I can't tell the rpm but it seems to idle kinda low so I'll try and get it to a higher idle and see if that'll help
where would my best bet be for looking for a vaccum leak I've tried and looked it up but I can't figures the scamatics out half the time. Another thing is that the headlights don't go up and I saw on some pictures that the vaccum lines seem to go to them also, could that be an issue
I'm trying to figure out if it's an issue I can fix today without going to get anything else funds are pretty tight
where would my best bet be for looking for a vaccum leak I've tried and looked it up but I can't figures the scamatics out half the time. Another thing is that the headlights don't go up and I saw on some pictures that the vaccum lines seem to go to them also, could that be an issue
I'm trying to figure out if it's an issue I can fix today without going to get anything else funds are pretty tight
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Drifting
Joined: Jan 2011
Posts: 1,853
Likes: 81
From: Hamilton Virginia
Should be HEI ignition for that year unless someone changed it. Was the car sitting for awhile ? Could have bad gas,clogged fuel filter, or carb. I would start with a tuneup including changing plugs,wires,cap and rotor,oil and filter. Also change the fuel filter. I have seen weak coils in the cap cause issues once under load. How much gas is in the tank ? Is it missing or stuttering when you are trying to go? or does it bog down as if your dragging a ship behind you ? If it's bogging like trying to drag a ship, you might have brakes dragging bad.
Just read your post about the choke fuse missing. remove the air cleaner and check and make sure your butterfly on the carb is not closed or almost closed. with the engine warmed up, that butterfly needs to be straight up open.
Just read your post about the choke fuse missing. remove the air cleaner and check and make sure your butterfly on the carb is not closed or almost closed. with the engine warmed up, that butterfly needs to be straight up open.
Last edited by scrappy76; Aug 2, 2017 at 01:28 PM. Reason: add
Race Director
Joined: Mar 2016
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From: Napa Valley California
Please do us a favor. open the hood, remove the air filter and take several photographs of the engine compartment from the front and both sides, then down from the top so we can see what is under the hood. I'm guessing you have very limited knowledge about vehicles or how to repair them. At least with the visuals it could take much of the guess work out of it for those why are willing to help.
Thread Starter
Cruising
Joined: Aug 2017
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Hey everyone thank you all so much for the assistance with this I'm new to most things but really interested in learning, I've been very busy today and haven't been able to repsond how I'd like to but I'll take the pictures and such soon and read all the responses. I'm so shocked by the amount of help this all has been I though no one would answer me haha
still figuring out the forum ha
still figuring out the forum ha
Thread Starter
Cruising
Joined: Aug 2017
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Oh and In respsose about how it is after it warms up it pretty much idles the same and it still doesn't wanna be sitting still while in say reverse it'll instantly start bogging out
Last edited by Robert Walsh; Aug 2, 2017 at 06:53 PM.
Thread Starter
Cruising
Joined: Aug 2017
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There's also two wires that I'm curious about cause ones not conected which the guy told me is for the headlight system but he didn't really tell me much and the other is literealy just a cut wire and he doesn't know what it's for I'll point them out with pictures later today or tomorrow morning if the rain doesn't stop tonight
Team Owner
Joined: Jan 2006
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From: Crossville TN
Robert...
The most likely items to check out would be:
1. Does the car still have its original catalytic converter? If so, it may be plugged up and unable to pass exhaust gasses. That will bog an engine down big time!
2. The fuel filter (inside the carb inlet housing, if it still have the Quadra-Jet carb, could be plugged up and preventing adequate fuel from entering the carb. Be sure to use TWO adjustable wrenches to loosen that outer nut. You MUST hold the carb nut hex with one wrench and use a "line wrench" (six-sided box wrench with a slot to fit over the fuel line) to loosen the fuel line nut. Otherwise, you could fracture the carb housing.
3. Less likely...but possible...is that the torque converter on the transmission is damaged and will not transfer power from the engine well.
The most likely items to check out would be:
1. Does the car still have its original catalytic converter? If so, it may be plugged up and unable to pass exhaust gasses. That will bog an engine down big time!
2. The fuel filter (inside the carb inlet housing, if it still have the Quadra-Jet carb, could be plugged up and preventing adequate fuel from entering the carb. Be sure to use TWO adjustable wrenches to loosen that outer nut. You MUST hold the carb nut hex with one wrench and use a "line wrench" (six-sided box wrench with a slot to fit over the fuel line) to loosen the fuel line nut. Otherwise, you could fracture the carb housing.
3. Less likely...but possible...is that the torque converter on the transmission is damaged and will not transfer power from the engine well.
Last edited by 7T1vette; Aug 2, 2017 at 09:17 PM.
Thread Starter
Cruising
Joined: Aug 2017
Posts: 12
Likes: 0
Robert...
The most likely items to check out would be:
1. Does the car still have its original catalytic converter? If so, it may be plugged up and unable to pass exhaust gasses. That will bog an engine down big time!
2. The fuel filter (inside the carb inlet housing, if it still have the Quadra-Jet carb, could be plugged up and preventing adequate fuel from entering the carb. Be sure to use TWO adjustable wrenches to loosen that outer nut. You MUST hold the carb nut hex with one wrench and use a "line wrench" (six-sided box wrench with a slot to fit over the fuel line) to loosen the fuel line nut. Otherwise, you could fracture the carb housing.
3. Less likely...but possible...is that the torque converter on the transmission is damaged and will not transfer power from the engine well.
The most likely items to check out would be:
1. Does the car still have its original catalytic converter? If so, it may be plugged up and unable to pass exhaust gasses. That will bog an engine down big time!
2. The fuel filter (inside the carb inlet housing, if it still have the Quadra-Jet carb, could be plugged up and preventing adequate fuel from entering the carb. Be sure to use TWO adjustable wrenches to loosen that outer nut. You MUST hold the carb nut hex with one wrench and use a "line wrench" (six-sided box wrench with a slot to fit over the fuel line) to loosen the fuel line nut. Otherwise, you could fracture the carb housing.
3. Less likely...but possible...is that the torque converter on the transmission is damaged and will not transfer power from the engine well.
i really hope it's not the torque converter cause that would suck for me haha oh and I'm pretty sure it is the stock catalytic converter
Last edited by Robert Walsh; Aug 2, 2017 at 09:57 PM.
Drifting
Joined: Apr 2004
Posts: 1,433
Likes: 127
From: Mequon WI
While your at it might as well re.love the fuel line to gain access to the fuel filter and change it.
Next look at that choke. Read up here about electric and hot air chokes. My 78 has a hot air choke. Not sure about 79. Sounds like you have an electric choke. Lots of guys made that simple conversion. If you have wires to your choke it is electric. If a wire is broken it is Not working. A closed choke will make your engine run like you describe. Lots of info on the forum about this
So far your biggest Cost is for those FLARE wrenches.
Next check for vacuum leaks. That is so much fun it calls for its own thread.
Thread Starter
Cruising
Joined: Aug 2017
Posts: 12
Likes: 0
Hey at least it starts and runs little. My first thought is a fuel problem. Run it for a few minutes. Let it sit for a few more. Loosen the nut on the fuel line at the carb. If fuel sprays out you can assume the pump and fuel lines are good. Oh by all means only use FLARE wrenches. Cost a few dollars but you don't want to mess up those nuts. If ready rusty get a can of penetrating oil and soak those nuts for a day first.
While your at it might as well re.love the fuel line to gain access to the fuel filter and change it.
Next look at that choke. Read up here about electric and hot air chokes. My 78 has a hot air choke. Not sure about 79. Sounds like you have an electric choke. Lots of guys made that simple conversion. If you have wires to your choke it is electric. If a wire is broken it is Not working. A closed choke will make your engine run like you describe. Lots of info on the forum about this
So far your biggest Cost is for those FLARE wrenches.
Next check for vacuum leaks. That is so much fun it calls for its own thread.
While your at it might as well re.love the fuel line to gain access to the fuel filter and change it.
Next look at that choke. Read up here about electric and hot air chokes. My 78 has a hot air choke. Not sure about 79. Sounds like you have an electric choke. Lots of guys made that simple conversion. If you have wires to your choke it is electric. If a wire is broken it is Not working. A closed choke will make your engine run like you describe. Lots of info on the forum about this
So far your biggest Cost is for those FLARE wrenches.
Next check for vacuum leaks. That is so much fun it calls for its own thread.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,259
Likes: 9,397
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
A vacuum leak would sound like a high pitched suckling noise, you should have some rubber hoses on the front of the carburetor that go to the distributor and a valve or 2. Just look for small diameter hoses or thin nipped on the front of the carb and the intake behind it. If you have starting fluid you could do some very short squirt around the carb and behind it. If the engine jumps up in rpm it has a vacuum leak in that area