1970 Coupe keeps cutting out when accelerating
Thread Starter
Intermediate
Joined: Sep 2018
Posts: 43
Likes: 4
From: Albany, NY
1970 Coupe keeps cutting out when accelerating
Hello. I recently purchased a 1970 base model with a matching # rebuilt engine (300hp) and new gas tank. Quadrajet, fuel pump, fuel filter, distributor, coil and most other parts have been replaced. It ran fine the first couple of times I drove it. Now, it will idle, but cuts out when I am driving it. When I step on the gas, it will stall and I have to start it back up. It seems like it isn't getting fuel?? This happened on a 90 degree day and a 65 degree day. I haven't had the car that long and have only put 1 tank of gas in it.
Any thoughts? I want to get it over to my mechanic to take a look without flat bedding it.
John
Any thoughts? I want to get it over to my mechanic to take a look without flat bedding it.
John
Last edited by John Parodi; Sep 12, 2018 at 09:26 AM. Reason: needed to correct some information
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
You might need a new accelerator pump.
Remove the air cleaner and while the car is at idle blip the throttle linkage and look for two streams of fuel being shot into the carb.
NAPA has a good pump, #2-4055
Remove the air cleaner and while the car is at idle blip the throttle linkage and look for two streams of fuel being shot into the carb.
NAPA has a good pump, #2-4055
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
My guess is a kinked rubber section of fuel line ("S" line from steel line to fuel pump?), a cracked rubber fuel line (at tank or before pump) which is sucking air, or a clogged up carb fuel filter.
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Thread Starter
Intermediate
Joined: Sep 2018
Posts: 43
Likes: 4
From: Albany, NY
Thank you to everyone for your feedback!! I replaced the fuel filter in the carburetor today. It was quite dark in color. It had a check valve in it. The new replacement filter did not have a check valve. Is that a problem? I took the car out and drove it for a half hour and it ran fine. I’m thinking the fuel filter was the problem. I’ll take it out for another drIve tomorrow. Looking forward to it.
Last edited by John Parodi; Sep 27, 2018 at 09:25 PM. Reason: needed to correct some information
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Is it a problem that the new filter does not have a check valve? Only if you have difficulty starting the car after the change. The tank is "gravity feed" to the fuel pump; then the fuel is 'pumped' up to the carb and into the fuel bowl. When the engine (and fuel pump) are turned off, the elevated fuel in the carb might back-flow to the pump by siphon action, leaving the fuel bowl empty. This would require you to crank the engine (and pump) long enough to refill the carb before the engine would fire. Again, I say that might happen. If it does, you should find a replacement fuel filter WITH the check valve and install it with the check valve on the outboard end of the filter (rather than placed down inside the inlet).
I believe that you have found the root cause of your hesitation problem. But the 'solution' could cause a secondary issue. But you know how to fix that, as well. Good luck.
I believe that you have found the root cause of your hesitation problem. But the 'solution' could cause a secondary issue. But you know how to fix that, as well. Good luck.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
Thank you to everyone for your feedback!! I replaced the fuel filter in the carburetor today. It was quite dark in color. It had a check valve in it. The new replacement filter did not have a check valve. Is that a problem? I took the car out and drove it for a half hour and it ran fine. I’m thinking the fuel filter was the problem. I’ll take it out for another drIve tomorrow. Looking forward to it.
Also, as 7T1 says above, make sure the filter is installed with the opening or inlet hole facing out of the carb towards the fuel line as that will make it even worse if reversed.
Last edited by CanadaGrant; Sep 28, 2018 at 12:46 AM.