1969cutlazz

My carburetor was flooding. I pulled the rear pbowl and found the check valve stuck in the open position dumping fuel. I unstuck it. Cleaned up the Carb and put it back on the car. Started and idled nice n smooth. Took it for a test drive and it puked again. Its not flooding anymore. Just runs really really rough. Plugs are good. Fuel is fresh. Fuel filter new. Tested power valve and it is good. I don't know much about carbs. Maybe the accelerator pump is bad?? I'm lost. Its a Holly single feed model 1903 600cfm on my 69 Oldsmobile 350. NEW outta the box about 5 years ago. Any guesses welcome. THANKS

TripDeuces

Off the top of my head it sounds like something stuck in the needle and seat. Do you have a filter between the fuel pump and the carb?

bdub217

maybe it's now semi fixed and is slow flooding ..... i'm interested in finding the culprit on this one.

TripDeuces

If the car backfired at all then for sure your power valve is shot. Don't even think about it just change it, they are cheap.

Here's another thought. Is the engine stock? If you installed a bigger cam your vacuum may be low enough to trigger the power valve to open. That carb should have a 8.5 or 10.5 power valve in it. That would be a fairly radical cam to trigger that. In other words less than 8.5 inches of vacuum at idle.

bdub217

i edited out the part about spitback into the carb from power valve in my last post =( but good to know im thinkin in the right direction =P

HonestDave

"New out of the box five years ago" doesn't sound good for a Holley. For years I ran Holley double pumpers on my 70 GTO. Every winter I'd put the car away, and every spring I'd have it re-built or a new power valve put in. They just don't sit well. I can take a Rochester that's been sitting for a decade, bolt it on my car and have no issues. I just did it, actally, with my Trans Am. The carb I put on was filthy and covered with cob webs, but the car ran perfectly. I've got a Holley double pumper in my carb drawer that came new about four years ago. The lad tried it once and it's been sitting. I'm afraid to try it. It will be just like yours.

Reader's Digest version- I agree with TripDueces. Sounds like he's paid his dues and knows his stuff.

1969cutlazz

1969cutlazz

I saw a video that said if u turn the mixture screws in all the way while the car is idleing and the engine dies that the power valve is not blown. I tried that and the engine died. I've been running this Carb for five years and this is the first problem its ever given me.

1969cutlazz

1969cutlazz

Yes there's a new inline filter. I cleaned the bowls and everything inside it with Carb cleaner when I had it apart. Is there anything specific I should clean. ?

bdub217

if you can grab a factory carb and throw it on to see if that makes a difference, i know this doesnt fix the current carb problem but worth a shot to see if it is indeed a carb only problem. =/

HonestDave

My carb guy would say "Put a Rochester on it and throw the Holley in the garbage". I know it's hard to do, but I had him take at least three Holleys off my cars over the years and go back to stock. I always lamented the loss of power, but appreciated the smoothness, and the fact that thay sit well. Holleys just don't seem to sit well for me. Even if I get them running perfect, after winter storage they're all screwed up again. Follow bdub217's advice. Put a stock carb on it and see what happens.

Just one man's opinion, again.