Had similar problems on my 67 GTX. Turned out the fuel pump push rod had worn down a little shorter than it should have been.
Bill Huff
sounds like a serious fuel flow rate restriction drops pressure or starved at steady flow .At lower flows , volume in carb bowls keep--it going in average--
You can measure PSI with temporary tee rig driving — or let it idle on carb internal fuel with fuel feed line open through hose into pail etc . There is a spec on pump flow GOM and psi should stay at 3- 4 or better driving 60
But to cut right to it , most likely is corrosion in gas tank clogging the nylon sock , or sock was removed in past rust travels then ruins fuel pump check valves , bad fuel pump in general , clogged gas filter ( obvious?) .Some carbs have a mesh at inlet , although should never see dirt with in line filter
Slight chance ignition points not right but that presents as an rpm skip more than a uniform boggood luck ,J g
Sent from my iPhone
On Aug 5, 2023, at 1:04 PM, Keith Boonstra <kboonstra.zeegroup@xxxxxxxxx> wrote:
Brian,
It doesn't sound like it could be an accelerator pump symptom, but maybe fuel starvation.Do you know your fuel pump is good? Does it only stumble under load, or in neutral too?
And don't forget your ignition - points, condenser, plug wires. And consider the coil as well.
Keith Boonstra
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--On Sat, Aug 5, 2023 at 12:15 PM bwalk05 <bwalk05@xxxxxxxxxxx> wrote:
Hello Everyone,
Anyone have any suggestions for troubleshooting Carter adjustments (or otherwise) for a car that stumbles beyond 60 mph. It starts up fine, idles smooth, accelerates strong up to 60 mph and then stumbles...even at fully open throttle.
I suspect there is an accelerator pump issue or secondary is not opening under vacuum. Any thoughts/suggestions would be greatly appreciated!
Thanks,
Brian W.--
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