An air bubble in the filter is fine, just as long as it's mostly full. You need consistant fuel pressure though, that's high enough. Could be that some trash got into the carb and is blocking the fuel inside. You need to see what your fuel pressure is though, and if it's steady

 

Just curious, but if I install a gauge in the fuel line, and it is running poorly from something other than the fuel pump, won't the gauge go high and low because of the engine speed changing since its a mechanical pump??

 

No, it shouldn't, pump flow vs fuel demand, higher rpm needs more fuel, pump moves more fuel, engine consumes it, pressure stays consistant(relatively speaking). At idle it may be lower, and at higher rpm it may be higher, but it shouldn't jump up and down, if it changes it should be a steady even increase with rpm, and even then not much. It's gonna depend on the fuel pump. But if when it's surging it has 2psi of pressure, you found your problem. It should be somewhere between 6-9psi. and have you checked for a vacuum leak? Spray some Brakleen first, if you have no vacuum leak then move on to fuel pressure

 

Sounds like a vacuum leak to me, just went through this on an old Blazer. Definitely do the Brakleen first, spray all around the carb base and the manifold runners.

 

I ordered a new cap and rotor for the MSD ignition because there were all sorts of small metal flecks inside the cap. Reminded me of the old caps that would get carbon tracking causing a crossfire. So after I install it, if no change, I will install an inline gas pressure gauge and see what happens.

Thanks,

 

i would start at the distributor, then if that doesnt fix it i would check the vaccuum lines and the fuel pump. I have the same problem, but i know mine is the in tank fuel pump. All in All my bet is on the vaccum lines are dry rotted/ cut/ cracked.

 

I will check the vac lines, but the only one's on there are the large one to the brake booster, the one to the trans, and one to the pcv valve.

 

Maybe that's the problem, you should have one to your distributor as well.

 

+1
Worst case scenario is you have to pull your tank and put a new fuel pump in.

 

The MSD ignition doesn't have any vac lines to it at all, and the fuel pump is on the front of the motor, but I do have brakeclean and will try that also.