1970 Pontiac Lemans 350

Asked by GuruCH84N Feb 22, 2019 at 09:06 AM about the 1970 Pontiac Le Mans

Question type: Maintenance & Repair

Sometimes during acceleration the car bucks.  Taking my foot off the gas stops the bucking.  This happens very intermittently but seems to be getting worse.  I have changed the plugs and wires and will be changing the  cap and router in the next couple days.  A previous owner installed an MSD part number 2601 ignition.  Last year I replaced the box because there was no spark.  Any ideas as to what could cause this bucking issue?

4 Answers

1,175

misfire from distributor?

350

Bucking sounds more like fuel related. Check the fuel filter. These older cars tend to develop a lot of rust in the fuel tank. 1970 should have a tiny filter in the carburetor at the inlet. Thats why most people add an additional fuel filter with a higher capacity to keep all the junk clogging up the smaller filter too quickly. Could be a tired fuel pump also.

Hi Everyone First let me thank you all for your replies. I finally found what was causing this issue and thought I should post it in case in the future someone else has a similar problem. It turns out that the positive battery cable going to the starter was routed too close to the header. The insulation melted off and while the car was moving the bare wire would intermittently short out on the header causing a temporary lose of all power. The cable has been replaced and rerouted away from all heat sources. The car now runs great.

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