The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 78 Suburban surging then dies on long grade

geezer#99 · 07-25-2020, 01:34 PM

Unless you’re an expert leave the secondary adjustment alone. Real easy to make that spring become useless. Then you’ll have fun fixing it.
Instead just wire the air door shut so it won’t work at all.
That will eliminate secondary problems.
Had to do that on the father-in-law’s truck. Gave similar symptoms to yours. Eventually found out that some mechanic had hogged out all the secondary stuff (jets etc) to run natural gas.
Only difference on a carb from higher elevation might be it’s jetted leaner.

What’s your carb number?

07-25-2020, 01:34 PM	#38
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,528	Re: 78 Suburban surging then dies on long grade Unless you’re an expert leave the secondary adjustment alone. Real easy to make that spring become useless. Then you’ll have fun fixing it. Instead just wire the air door shut so it won’t work at all. That will eliminate secondary problems. Had to do that on the father-in-law’s truck. Gave similar symptoms to yours. Eventually found out that some mechanic had hogged out all the secondary stuff (jets etc) to run natural gas. Only difference on a carb from higher elevation might be it’s jetted leaner. What’s your carb number?