Ran fine one day, the next it won't hold an idle and surges on the road. Lotta gunk from the tailpipes. Some gas around the carb on both sides of the intake. Where to start?

Just checked the fuel filter and inlet filter. No problems there.

JamesC

 

I would be thinking cracked baseplate.

 

Removed the carb. Took the bowls off and thoroughly shot everything with carb cleaner, including the primary needle and seat. No crack in the base that jumped out at me. Same issue as above.

JamesC

 

Surging tends to be from a lean condition. This is why I was thinking cracked baseplate (vaccuum leak = extra air). Since that is out, verify the fuel pressure, make sure the manofold gaskets and bolts are good. The gas around the carb is hard to explain (other than an obvious leak).

 

If the weather cooperates this afternoon, I may start the car and spray the carb base with some WD-40. See what happens. Perhaps the carb base is warped.

JamesC

 

The accelerator pump diaphragm is notorious for leaking....sounds like fuel pressure loss through that possibly?

 

I removed the carb again today, disassembled it, cleaned the parts, and shot everything out with compressed air, yada yada.

After reinstalling the carb, I tried to fire it up which took a while and when it did fire very briefly, a bloody awful noise accompanied it, a noise that couldn't be carb related. Frankly, it scared the hell out of this old fart.

I did a visual. The garage floor was wet/damp in the area of the mechanical fuel pump. The swab I took smelled of gas.

Anything there that might be an issue?

JamesC

 

Metal on metal noise? Pop the mechanical pump off and inspect the suel pump push rod and the arm on the pump.

 

Yes. Any tips on how to reinstall the push rod (I'm starting to guess that the fuel pump or some part of it are faulty)?

JamesC

 

There is a bolt in the front of the engine. The hole for that bolt goes to the pump rod bore. Remove the bolt, find one the same size/thread that is a little longer (1" of thread should do it, if memory serves). Push the rod up against the cam and hold it there, install the longer bolt so that it lightly contacts the rod. Install the pump. Remove the long bolt, reinstall the original short bolt.

 

Thanks, five7. I should have mentioned that a large serpentine bracket covers that hole so that it's not accessible.

I've also tried the heavy grease method to 'stick' the push rod in place. Didn't work well.

JamesC