The Ford Barn

coolcoupe · 05-27-2017, 10:44 PM

Just wondering where a guy would do with a 1947 car (stock) when the car idles really nice but giving it the gas it bucks like its running out of gas, once its doing over 20 mph and you let off the gas it starts to backfire? Any ideas?

petehoovie · 05-27-2017, 11:33 PM

I'm thinking a bad condenser....

FlatheadTed · 05-28-2017, 12:43 AM

Dirt in carby ,Could be low on voltage check if the spark is yellow on revving it up ,Ted

rotorwrench · 05-28-2017, 09:01 AM

It could be a bad condenser since most available now are not made well. The points are generally burned if the condenser is failing.

Sounds like the idle circuit in the carb is working OK. The main metering circuit may have some blockage. The accelerator pump might not be working as it should. There also could be a power valve problem. The float valve could have a problem with blockage or adjustment of float is off.

The fuel pump out put might be off or maybe a partial blockage or a crack in the fuel supply line circuit allowing air bubbles in.

All are possibilities that will have to be eliminated, easiest one first till it's fixed.

Ken Bull · 05-28-2017, 12:41 PM

I had a simular thing and it turned out the vacuum hose to the wiper moter went bad .

Tinker · 05-28-2017, 01:56 PM

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Same thing happened to me. Hesitation,backfires, and misses at low rpms.

A New NEW condenser. second new one.

MMO down the carb for a bit at idle. Then fresh gas and MMO in the tank.

Drove it 10 plus miles and it leveled out. No issues now.

coolcoupe · 05-28-2017, 06:14 PM

Thanks guys, I will start at one thing at a time until I get it !!

05-27-2017, 10:44 PM	#1
coolcoupe Senior Member Join Date: May 2010 Location: ontario,Canada Posts: 450	bucking and backfiring Just wondering where a guy would do with a 1947 car (stock) when the car idles really nice but giving it the gas it bucks like its running out of gas, once its doing over 20 mph and you let off the gas it starts to backfire? Any ideas?

05-27-2017, 11:33 PM	#2
petehoovie Senior Member Join Date: May 2015 Posts: 8,076	Re: bucking and backfiring I'm thinking a bad condenser.... __________________ The only thing nice about being imperfect is the joy it brings to others.... *"Silver rings, your butt! Them's washers!"* "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0

05-28-2017, 12:43 AM	#3
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,700	Re: bucking and backfiring Dirt in carby ,Could be low on voltage check if the spark is yellow on revving it up ,Ted __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

05-28-2017, 09:01 AM	#4
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,423	Re: bucking and backfiring It could be a bad condenser since most available now are not made well. The points are generally burned if the condenser is failing. Sounds like the idle circuit in the carb is working OK. The main metering circuit may have some blockage. The accelerator pump might not be working as it should. There also could be a power valve problem. The float valve could have a problem with blockage or adjustment of float is off. The fuel pump out put might be off or maybe a partial blockage or a crack in the fuel supply line circuit allowing air bubbles in. All are possibilities that will have to be eliminated, easiest one first till it's fixed.

05-28-2017, 12:41 PM	#5
Ken Bull Senior Member Join Date: Dec 2010 Location: Port St Lucie Florida Posts: 398	Re: bucking and backfiring I had a simular thing and it turned out the vacuum hose to the wiper moter went bad .

05-28-2017, 01:56 PM	#6
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: bucking and backfiring Sponsored Links (Register now to hide all advertisements) Same thing happened to me. Hesitation,backfires, and misses at low rpms. A New NEW condenser. second new one. MMO down the carb for a bit at idle. Then fresh gas and MMO in the tank. Drove it 10 plus miles and it leveled out. No issues now.

05-28-2017, 06:14 PM	#7
coolcoupe Senior Member Join Date: May 2010 Location: ontario,Canada Posts: 450	Re: bucking and backfiring Thanks guys, I will start at one thing at a time until I get it !!