Engine dying on throttle up.

I started discussing this in another post but want give it its own one.

When throttling up from idle with the choke plate fully open the engine dies. Unless I "gun it". Then it sees to run, mostly at least. Could this be a fuel filter problem? I would assume the air/fuel mixture screws are not a concern as they are for the idle. Not sure what else can be adjusted. The carb was rebuilt last year and fogged before winterizing. It stays running if I close up the choke plate manually. Fuel pump is also new last year. Fuel was stabilized as well.

This is an original Autolite carb on a 302 H/M.

Thanks.

I'll check the Accel pump 79, it was replaced last year so I would think it's still good. Maybe something got in it.

I replaced the choke with an electric one and can't really change how fast it opens, not that I am aware of at least.

Either way, if I have let it idle for 5 minutes or so, shouldn't it be well beyond the choke point? At least on an 80 degree day?

thanks!

accel pump needs adjusting, not neccessarily replaced unless bad. the choke does has some adjustment to it that's why you can rotate it but after 5 min no it's done.

So a carb issue most likely.

gotta feed both banks, yes

I agree with the other guys, if you hit the throttle and only one venturi discharges then you will have to check the accel pump. The diaphragm may have been damaged when you had it rebuilt. If you can get the engine to accelerate does it run correctly up to high idle? If you can get the motor to run past the stumble when accelerating, and it will go to high idle then it is deffinetly the accel pump. The whole rebuild kit is only about $50.

newoldboat wrote: I agree with the other guys, if you hit the throttle and only one venturi discharges then you will have to check the accel pump. The diaphragm may have been damaged when you had it rebuilt. If you can get the engine to accelerate does it run correctly up to high idle? If you can get the motor to run past the stumble when accelerating, and it will go to high idle then it is deffinetly the accel pump. The whole rebuild kit is only about $50.

if your carb has a high idle cam then you have the wrong carb because it's automotive, marine applications do not have a fast idle cam or high idle setting on the carb.

Well I thought I had it fixed. Ran her today and pretty much the same result. Slowly accelerating kills her. And I had her plenty warmed up. Thermostat open.

Looking down the carb, as soon as I touch the throttle, the jets inject fuel. It kind of hard to tell but it seems like it's not a constant stream. Unless I accel faster.

Also, my idle seems a little rough. If rough is the word. It's going along nicely then the RPMs drop a bit the bounce back up. It will do this off idle as well.

My Autolite has a fast idle cam, slow idle cam, all that stuff I don't know if it does anything.

The accel pump deffinatly needs checking. Open the choke plate and manually pump it once or twice. You should see two STREAMS of fuel shooting into the center of the throat. My 74 did the same thing. The holes could be clogged, or maybe you have the wrong cam in or possibly its in backwards. Its a fuel problem because when you close the choke, it gets better meaning not enough fuel.

I guess I'll pull apart the pump and check it out. There are two steams when I manually pump. Although they sometimes seem to be broken streams.

74 what cam are you referring to? Something to do with the accel pump or are you talking about the fast idle cam?

Gary it's a great offer for sure. Not sure how much good it would do me. I cleaned mine pretty good last year and rebuilt. I'm hoping I'm just missing some small with this problem. The Holley is on the list right after the stringers.

And I keep asking this question and I think 79 answered the last time but not sure I understood correctly. In this pic, should this tube be capped off? I swear I feel a vacuum on it.



And on the choke. Should I remove this cap on the hot air intake now that I have an electric choke? Would that cool the choke coil making it open slower? Mine opens in like 30 seconds, seems fast. But I could be wrong.

74SkiNautique wrote:     I am not familiar with your carb, but on my holley, there is a rubber cam that rotates on the throttle body, which moves the lever on the accelerator pump. .

then your Holley would not be orginal equipement either as that is not typical of the 4160 carb's PCM sent out the door.

Pulled the carb, going to soak it. I just sprayed with carb cleaner last time. Should have soaked overnight. It looks like it could be cleaner. Hopefully she'll be working better afterwards.

Gary, yours is capped in the pic.



Apparently the tube is a distributor vacuum tube for the auto side.

that sure does look like an automotive carb can you take a shot of the top so we can see if it has J-tubes?

These definitely were auto carbs. No J tubes.