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Topic: 69 350 sputtering under load

in Forum: C3 Fuel, Emission Control, and Exhaust Systems

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69 350 sputtering under load (1/4)
9/15/13 7:06pm

bjahn
Former Member
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Joined: 11/15/2003
Posts: 22

Lately I'm having problems with my small block sputtering and stumbling under load, as when on freeway on ramp under acceleration. Runs and idles fine otherwise. I'm thinking it may be a fuel problem as I don't drive it enough. Fuel filter? Fuel pump? Any suggestions out there?

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Re: 69 350 sputtering under load (2/4)
9/15/13 9:42pm

Adams' Apple

Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20128

Could certainly be a fuel problem. Pump, lines, hoses, carb. It could also be a problem with the points, or any other ignition component.

Start by changing the fuel filter in the carb. While you're doing that, take a look at the rubber fuel line(s) from the frame to the fuel pump, and make sure there are no kinks. Do the same at the rear of the car...check the rubber lines coming out of the fuel tank, and the hoses on the passenger side framerail, where the fuel line goes forward.

Check the points in the distributor. If you don't know when the last time they were replaced was, or IF they have been replaced, now would be a good time to do it. Thumbs Up

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Re: 69 350 sputtering under load (3/4)
9/29/13 7:22pm

BigShoes16
Former Member
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Worcester, MA - USA

Vette(s):
75 L-82 Coupe 4-spd

Joined: 2/25/2013
Posts: 52

Recently, I was getting a real hard bog when I pushed the pedal beyond half way. It would recover but wouldn't have much punch. I changed my plugs, wires, cap and rotor (1975) but it didn't seem to help. I just took my Q-jet carb off and opened it up for a rebuild to find both secondary feeder pipes and 1 primary feeder pipe had fallen out of the air horn and were laying in the body. This is a common problem if you're running a rochester, and they're not very difficult to re-build.

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Re: 69 350 sputtering under load (4/4)
11/11/13 12:15am

kevmcrae
Former Member
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Kalispell, MT - USA

Vette(s):
1969 427 sport coupe, Monza Red, matching numbers, all original.

Joined: 2/28/2013
Posts: 10

I've got a 427 but this sounds like the same issue I had. I replaced the fuel pump and it ran like a champ. Just wasn't enough pressure to feed enough fuel I assume.

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