Difficulty "cold" starting - Third Generation F-Body Message Boards


Carburetors Carb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.

Difficulty "cold" starting

Reply
 
Thread Tools Search this Thread
Old 06-14-2018, 01:51 PM   #1  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Difficulty "cold" starting

When I first go to start my car, it tends to take a bit of coaxing to get it to turn over. I'd say probably a good 3-5 seconds and a bit of pumping the gas pedal before I can get it to turn over. Even then, it idles really low and will cut out if I don't keep giving it a little bit of gas and lightly rev it. Once it's been running for a bit, it will idle without needing me to give it any gas, and I can even shut it off and it will fire right up the next time I start it, but probably the first few minutes or so it's a bit finicky.

I say it has difficulty with "cold" starts because it did the exact same thing yesterday afternoon in 81 degree weather on a sunny day. The engine should have been plenty warm between the ambient temperature and the added warmth under the hood from the direct sunlight, but I still had to coax it a little, and it nearly cut out on me when I took my foot off the gas.

I'm wondering if this is maybe a sign of the choke not working properly? Maybe the carb needs a tune-up or rebuild? Those seem to be the most likely possibilities in my mind, but there may be something else I might not have considered. Does anyone have any ideas on what the cause could be, and how to best fix it?
Venom_1138 is offline   Reply With Quote
Old 06-14-2018, 03:48 PM   #2  
Supreme Member
iTrader: (1)
 
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere


Re: Difficulty "cold" starting

If it's a Q-jet, it's leaking primary metering well plugs.

When the car sits for awhile, all the fuel leaks out of the bowl; then when you go to restart it, it's empty. The fuel pump has to refill it before it will start.

Those cause other problems too. You'll be AMAZED at the difference in how the car runs, and especially the gas mileage, when you fix them.



#3-6; not 1 & 2.
sofakingdom is offline   Reply With Quote
Old 06-15-2018, 12:34 AM   #3  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Re: Difficulty "cold" starting

Thanks for the reply, that makes sense based on the behavior of the car since it is running a quadrajet. I guess since I'd be replacing those, I might as well go ahead and do a full rebuild while I'm at it. Aside from the starting issues, it runs pretty strong, so the potential for added performance is certainly exciting as well. 😉
Venom_1138 is offline   Reply With Quote
Old 06-15-2018, 07:57 AM   #4  
Supreme Member
iTrader: (1)
 
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere


Re: Difficulty "cold" starting

You can't really "replace" them. All you can do is repair them.

The plugs are aluminum, but the carb body is chinesium. What happens over time is, the 2 dissimilar metals in contact make a little battery, which erodes one of them; specifically, the chinesium. Eventually it turns to a white powder, and where the plug used to fit tight to metal, it doesn't any more. Then since those are at the bottom of the fuel bowl, and exposed to vacuum, the engine constantly sucks extra fuel past them while it's running, especially at high vacuum conditions (idle and cruise), which drastically degrades the gas mileage; and of course, drains the fuel bowl over a period of hours, leading to the starting problem.

Disassemble the carb carefully, making careful notes as you go of how many turns the rich stop, lean stop, and idle air bleed are from bottoming, by gently and carefully screwing each of them all the way to the bottom FIRST before removing them. Clean the whole carb up, except for the electronic parts, in lacquer thinner or similar NON-RESIDUE solvent such as MEK or acetone. NOT brake cleaner, paint thinner, mineral spirits, turpentine. Sand or wire-brush the plugs down to bright metal and clean them again. Cover them with a nice thick void-free layer of epoxy such as JB Weld with the steel filler, making sure that the outer circumference of each plug is particularly well-coated. Put it in your oven on "warm" and let it bake for acoupla hours. Reassemble the carb, with all-new paper & rubber of course, paying careful attention to put the adjustable parts back in at the same # of turns out from bottoming that you counted before you took it apart, and otherwise following the instructions that will come in the kit. Might be wise to replace the float and the TPS as well so that you don't have to worry about those again for a good while.
sofakingdom is offline   Reply With Quote
Old 06-15-2018, 10:10 AM   #5  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Re: Difficulty "cold" starting

Ah, okay. I thought since it was a 'troublesome' part, a new one would be part of a rebuild kit.

Thanks for the very detailed rundown, I've only rebuilt a carb on a lawnmower before, and well... Let's just say that as of this year, that rebuilt carburetor is now technically old enough to vote, lol. I'm fairly mechanically inclined (I managed to rebuild the timing system on the infamous 5.4L Triton on my F-150... Great way to kill an entire Memorial Day weekend, lemme tell ya), but the rundown you posted will undoubtedly save me a boatload of time and trouble, to say the least, plus gave me a few things to do that I probably wouldn't have thought of.

Thanks again for all your help! Hopefully I can get a rebuild kit locally and knock that whole thing out this weekend.

Last edited by Venom_1138; 06-15-2018 at 10:13 AM.
Venom_1138 is offline   Reply With Quote
Old 06-15-2018, 10:54 AM   #6  
Supreme Member
iTrader: (1)
 
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere


Re: Difficulty "cold" starting

No unfortunately, not part of a kit; they're considered part of the casting for that purpose.

Shouldn't be any problem sourcing a kit and the other parts. Might not be in stock at yer corner parts store but they should be able to get everything within a day or so.

I'd recommend against the Tomco kit; not a big fan of their needle & seat. Standard Ignition, Borg-Warner, or of course AC/Delco (Delphi) would be better.

Don't be too surprised to see the electrolysis at other points in the carb as well... that, plus wear at the throttle shafts, is what turns them to carburetor-shaped scrap "metal". (I use the word loosely since it's just chinesium) Pay particular attention to screw hole threads in the castings: when those erode, the threads obviously are what goes away, and then of course you can't really reassemble the carb. A Heli-Coil fixes em right back up. Can't recall the sizes for sure; it's been awhile since I had to deal with em. I think the air horn ones are 10-32 and the TB are 12-24 but don't quote me on that.
sofakingdom is offline   Reply With Quote
Old 06-15-2018, 03:10 PM   #7  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Re: Difficulty "cold" starting

Turns out my local Autozone has a kit in stock and is holding it for me to pick up this evening. Just a couple of quick questions:

Is this the JB Weld epoxy you were talking about? https://m.autozone.com/sealants-glues-adhesives-and-tape/epoxy-compound/j-b-weld-original-cold-weld-epoxy/522961_0_0?aqs=

When you say to cover the plug with a thick coating, do you mean the entire plug, threads and all, or just a specific area of the plug? I'm just not sure how well putting epoxy over the threads would work out, given that it will make it harder to put back in place, plus the threads on the carb will probably remove all the epoxy as the pieces are threaded together. Just want to make sure I do things right the first time, the only thing I hate more than redoing a bad job is redoing a good one.
Venom_1138 is offline   Reply With Quote
Old 06-15-2018, 05:51 PM   #8  
Supreme Member
iTrader: (1)
 
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere


Re: Difficulty "cold" starting

There are no threads. There's no "remove" or "put back in place". It's just a blob of aluminum, maybe a short piece of rod, spun into the chinesium casting; supposedly permanently.

So yeah; just slather the epoxy all over all 4 plugs real good, making sure there's no bubbles in it. Pretty low-tech I'm ashamed to admit.

Yes that looks like the right stuff to use.

Did the store have the other parts as well? (TPS & float) If not, get them on order so you'll have them on hand by the time you're ready to put it back together.
sofakingdom is offline   Reply With Quote
Old 06-16-2018, 12:09 AM   #9  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Re: Difficulty "cold" starting

Ah, okay. I saw your comment about corrosion on threads and thought that was what you were referring to.

They did not have the TPS on hand, but my local NAPA apparently does according to their website. I'll have to call them tomorrow to confirm, but otherwise I should be all set. The weather this weekend is supposed to be pretty bad, so I have the perfect excuse to stay in and work on it.

Thanks again for all your advice, this car has seen some neglect and everything you've shared will definitely go a long way toward getting it back to its former glory. Greatly appreciated!
Venom_1138 is offline   Reply With Quote
Old 06-16-2018, 07:41 AM   #10  
Supreme Member
iTrader: (1)
 
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere


Re: Difficulty "cold" starting

Right: when I said "threads", I was referring to the ones that hold the carb together. Kinda hard to do without those. Can't just epoxy those up.

If you see ANY white powder looking stuff (no, not THAT KIND of white powder) on the screws or anything else when you take it apart, I'd recommend having the Heli-Coil kit for that size on hand before trying to reassemble it.
sofakingdom is offline   Reply With Quote
Old 06-16-2018, 11:54 AM   #11  
Junior Member
Thread Starter
 
Join Date: Feb 2002
Location: Stevensville MT
Posts: 40
Car: 1985 Trans Am
Engine: 5.0 305 High Output V8
Transmission: T5 Manual


Re: Difficulty "cold" starting

Quote:
Originally Posted by sofakingdom View Post
If you see ANY white powder looking stuff (no, not THAT KIND of white powder)
Well this car is from the 80's, so I don't know if I can rule that possibility out 100%

I'll put any parts that have any signs of corrosion under close scrutiny, for sure. I've got 2 hardware stores and a NAPA all within 5-10 minutes of me, so I should hopefully be able to get what I need from one of them if I encounter any corroded threads.

Last edited by Venom_1138; 06-16-2018 at 12:08 PM.
Venom_1138 is offline   Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Difficulty Starting strc09 Tech / General Engine 16 09-14-2009 08:52 AM
Difficulty starting Bane Tech / General Engine 2 03-04-2008 06:37 PM
Starting difficulty Tonyrodz Electronics 7 07-12-2004 08:50 PM
Occasional difficulty starting....does this sound like the starter? Yellow Camaro Tech / General Engine 1 06-02-2003 01:32 PM
Difficulty in rebuilding Hatch motor........ 1fastformula Electronics 2 03-22-2001 01:10 AM


Go Back   Third Generation F-Body Message Boards >

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Advertising
Featured Sponsors
Vendor Directory

1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 03:27 PM.


All content copyright 1997 - 2018 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.
We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: