Your donations help keep this valuable resource free and growing. Thank you.
|
Fuel Bleed-down '79 Concord D/L |
Post Reply |
Author | |
Markindy
AMC Fan Joined: Sep/07/2020 Location: Indianapolis Status: Offline Points: 11 |
Post Options
Thanks(0)
Posted: May/23/2022 at 4:36pm |
I'm having problems keeping the fuel in the lines after sitting a few days. I have a '79 Concord with the Carter 2bbl 258 engine. It seems the fuel returns completely to the tank, requiring a lot of cranking to start the engine when it sits a few days. I did have to replace nearly every vapor-return line due to critters chewing on the hoses. I've checked, and double-checked, but can't find any leaks or broken hoses in the fuel system. The pump seems to work fine, once you get it going. Any ideas?
|
|
Hemirambler
AMC Apprentice Joined: Jan/18/2012 Location: Ohio Status: Offline Points: 197 |
Post Options
Thanks(0)
|
My first guess is heat soak boiling the fuel out of the carb. That was what was happening to me. Shut it off for a few minutes - no problem. shut it off for an hour = hard starting.
Cures are to insulate the carb from heat, wrap the lines, insulator spacer under carb - things along those lines. For me I had no room for a spacer ('64 American) so I had to hilbilly up a solution. I ran a secondary electric fuel pump plumbed into the line. Yes, it is a bandaid, but it does work. Best of Luck, Jacin
|
|
1964 American Convertible (stock)
1964 American Hardtop (Not Stock) |
|
Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3529 |
Post Options
Thanks(0)
|
Being a 79, does it still have the iron intake with the heat riser beneath the carb? Sticking or is it stuck closed?
|
|
Regamble1969
AMC Apprentice Joined: Dec/01/2021 Location: Boise Idaho Status: Offline Points: 204 |
Post Options
Thanks(0)
|
My son bought an 83 Dodge pickup from my step dad who had owned it for 15ish years. For that entire time it has had a major problem starting after a day or two sitting. I cleaned the carb, new mechanical fuel pump, phenoloc spacer... all of it. Finally I got fired up to check that the carb was full then shut it off so there was no heat soaking or boiling of the fuel. Went out the next day and it was dry. The carb, the fuel pump, the fuel lines... all bone dry. I put a check valve on the fuel pump inlet side and it has started perfectly since. Every day no matter how long it sits. Technically it shouldn't be able to siphon the carb dry but it is. The fuel pump should have a check valve to keep it from doing this but this is the 3rd pump since my step-dad bought it. So as much as I wanted to say it can't be, a $10 check valve fixed it and has been fixed for a few weeks now after 15 years.
|
|
Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3529 |
Post Options
Thanks(0)
|
Phsically impossible to syphon a carb.
|
|
Regamble1969
AMC Apprentice Joined: Dec/01/2021 Location: Boise Idaho Status: Offline Points: 204 |
Post Options
Thanks(0)
|
Trust me, you're preaching to the choir on this. Hence the carb rebuild, spacer, and fuel pumps to try and resolve it. I checked, rechecked, and checked it again. I can't explain it and certainly wouldn't believe it had I not done all the diag work myself. Called my buddy who has been a mechanic as long as I have, then we talked to his dad who has been a mechanic since the 60s and we all agreed that it doesn't make sense... yet here we are.
|
|
tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
Post Options
Thanks(0)
|
Crappy pump or air leak in one of the many hoses. It's possible if unlikely that a microscopic crack in hose of filter (3 legged type, isn't it?) That when wetcwith fuel doesn't leak (microscopic crack; lbs per sq in with vanishingly small area crack) that does allow air when depressurized; air is less viscous then even fuel).
You can check this: after running and filling the system, wait until you know it will take all that cranking, and pull a hose somewhere down low. If the system is dry then it leaked back. If it's wet, try up higher. Etc. If it's wet and still won't flow, definitely some weird bad pimp issue. Have you done the most basic pump test? Fill a jar in fixed time to measure pimp capacity? Pumps can have soft failures, not just go/no-go. |
|
1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
|
FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
Post Options
Thanks(0)
|
There isn't anything wrong with it. The Carter BBD has a tiny fuel bowl that evaporates dry in practically no time. Engine heat after shutdown or hot weather only make it happen faster. My BBD's evaporate dry within a few hours during this time of year if I shut the engine off hot and leave the hood own. Opening the hood lets the heat out so it's not as bad. Even in wintertime they will evaporate dry in a week.
You just have to operate the starter for a few seconds to pump more fuel into the carburetor before it'll start. Maybe five seconds or so. It's not anything our starters aren't designed to handle. There is supposed to be a check valve in the fuel return line from the fuel filter to the fuel tank that can help shorten the time it takes to restart, but ignorant mechanics often removed that check valve without knowing since it fits inside the rubber hose, completely undetected. You cannot see it from the outside. It's rare to find a car with the check valve still inside the fuel line.
|
|
1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
|
Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3529 |
Post Options
Thanks(0)
|
Which year had these factory bandaids(check valves) installed in the fuel line?
|
|
FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
Post Options
Thanks(0)
|
All BBD 258's had a check valve, which I think started in 1977.
|
|
1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
|
Post Reply | |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |