1973 L-82 Intermittant Engine 'Surge'

[Timothy K.]

1973 L-82 - Was driving the car today at 55 or so and all of a sudden there was a 'surge' or a 'jerk' the lasted for a second. About 5 miles later it happened again, no smoke, nothing.... and again only for a second. I then put a load on the car kicking in the 4BBL and it ran fine up the through the gears. It starts and idles normally.... Any thoughts would be appreciated and thanks - Tim

[Mark E.]

Re: 1973 L-82 Intermittant Engine 'Surge'

1973 L-82...my first Corvette! Great car.

This symptom can have many causes so we need to narrow down the possibilities.

Do you have a sense if it's fuel or ignition problem? "Binary" symptoms (car runs normal then surge/jerk then car runs normal... no variation in intensity/severity of problem from incident to incident) are more likely ignition or electical related. Furl related problems tend to vary more with intensity.

Did this happen after the car was serviced? Look at those things touched first. For example, if plugs were changed, check that all cable connections are secure. Checking that all primary and secondary ignition connections are clean and tight is easy to check and could cause this symptom.

Is the fuel old? Water in fuel can cause intermittent cutting out... but should affect idle and WOT too.

[Duke W.]

Re: 1973 L-82 Intermittant Engine 'Surge'

I suspect it's a momentary loss of continuity somewhere in the ignition circuit due to some corrosion in a connector. It's a common C2 problem with the two cowl connectors. Use the service manual wiring diagram to check all the ignition circuit connectors.

I had a similar problem with my Cosworth Vega about 20 years ago. The was an occasional "glitch" that felt like the ignition or fuel flow quit for a fraction of a second. I suspected the D-Jetronic type FI system since it has many small low voltage connectors. So I systematically removed all, carefully inspected them for corrosion or any other contamination, and then gave them a shot of electrical contact cleaner. It took me about 45 minutes to do the job. I didn't find anything obvious, and the problem never occurred again.

Electrical connector problems are pretty common on vintage cars.

Duke

[Edward J.]

Re: 1973 L-82 Intermittant Engine 'Surge'

Tim sometimes we do not drive our cars enough, start them on occasion and do fully warm them up or do not drive any great distances. This can cause spark plugs get loaded up, and sometimes just a quick drive to fully warm engine up to temp can clear everything out, and a hot bath like you did with running the RPMs will help to.