Sputtering!

[TRSmith99]

My wife has a 1977 Spider. It sporadically will start sputtering and I'm at a loss (so far) as to what it may be. I'm hoping a few guru's here may have some suggestions.

Symptom: After the car has warmed up (typically after 15 min or more of driving), when accelerating, the engine will start sputtering/lurching. This seems to happen mostly in some combination of the following....
a) Gas is below half a tank
b) We're driving uphill or up an incline
c) Seems to happen the most in 3rd gear
d) Seems to happen the most when pushing the torque/acceleration a bit

What we've done so far...
1. Been using premium gas in the tank for ~ a year
2. Added some "seafoam" to get any water out (a couple times)
3. Replaced the fuel filters
4. Tune-up (timing, plugs, filters, etc.)

Most recently, we've moved from OR to CA. My wife just filled the tank and within a few miles, the problem started again. We've been focusing on a "gas issue", but I'm now starting to wonder if maybe its a clutch/transmission issue since it happens mostly in 3rd gear.

Thoughts? Suggestions? Ideas?

Your help is appreciated!


TR-

[wizard124]

I'd keep on the "gas" things. Test the fuel pump. Check/ clean the pick up in the tank. Check volume into the carb.

[So Cal Mark]

have you checked the point gap?

[TRSmith99]

I'd keep on the "gas" things. Test the fuel pump. Check/ clean the pick up in the tank. Check volume into the carb.

Will continue to do so. I am a bit perplexed though... If it is a "gas issue", then why only when uphill...? Mostly in 3rd gear...? Higher RPMs (lower gear) would make a "lack of gas" issue more prevalent - wouldn't it...?

Could it be vacuum or an air leak....?


T-

[TRSmith99]

have you checked the point gap?

Had everything checked at the last tune-up: points, plugs, timing, etc. No changes.


T-

[TStark]

Yes, does sound like fuel starvation.
If you have the electric fuel pump, I found mine clogged with sediment. There is a screen inside.
I bought a low pressure pump to replace it, but took the original apart afterward. Im certain now I could still be using the original pump after a clean.