'92 7.4 Carburetor Accelerator Pump Not Working

[San_Diego_SeaRay]

1992 Carb'd Bravo 7.4L (Weber/Carter AFB?)

I haven't run this boat for a couple years and now that I did, I noticed there isn't a jet of fuel when I manually apply quick throttle. But there isn't much of a hesitation, either. (Also there isn't a load; running it on muffs.)

Are accelerator pumps as important for boats as they are on cars?

You can see the primary jets providing gas but accelerator ports are not:

 

[bman440440]

yes they are

 

[04fxdwgi25]

That carb is overdue for a rebuild.

 

[Scott Danforth]

Are accelerator pumps as important for boats as they are on cars?

if you never do anything other than keep the motor running at idle, you do not need the accelerator pump (assuming you use ether to start it initially).

however if you ever want to open the throttle regardless of what the motor is in and pick up load (accelerate, etc) you need a working accelerator pump.

since the boat sat, the old fuel most likely has varnished in the check balls.

as stated above, time to go thru the carb.

 

[Lou C]

I did see some fuel squirted out not sure if that amount is normal for a Weber 4 bbl or not.

 

[Lou C]

1992 Carb'd Bravo 7.4L (Weber/Carter AFB?)

I haven't run this boat for a couple years and now that I did, I noticed there isn't a jet of fuel when I manually apply quick throttle. But there isn't much of a hesitation, either. (Also there isn't a load; running it on muffs.)

Are accelerator pumps as important for boats as they are on cars?

You can see the primary jets providing gas but accelerator ports are not:

I think you're confusing the primary throttle system with the secondary throttle system, the secondaries will not squirt out fuel till the load on the engine demands it (usually they are vacuum operated, when the vacuum drops the secondaries will open). They work like the secondaries on a Quadrajet, the lower throttle valves are mechanically linked to the primaries and will open when the throttle is about 75% open but the upper air doors are vacuum operated and won't open till the vacuum signal drops enough to allow it.
If your accel pump really wasn't working there would be a noticeable hesitation.

 

[Lou C]

https://www.edelbrock.com/pub/media/wysiwyg/documents/carb-owners-manual.pdf

this is the edelbrock version of the same carb you have, take a look at how it operates

 

[San_Diego_SeaRay]

I think you're confusing the primary throttle system with the secondary throttle system, the secondaries will not squirt out fuel till the load on the engine demands it (usually they are vacuum operated, when the vacuum drops the secondaries will open). They work like the secondaries on a Quadrajet, the lower throttle valves are mechanically linked to the primaries and will open when the throttle is about 75% open but the upper air doors are vacuum operated and won't open till the vacuum signal drops enough to allow it.
If your accel pump really wasn't working there would be a noticeable hesitation.

My observation first started when I went to fire up the engine after a long dormancy. I went to "pump" the carb a few times to get a few squirts of gas into it. Noticed there weren't any squirts. Completely dry. I got a small atomizer spray bottle and sprayed gas that way, and got the engine started. So the secondaries never came into play. I think Scott Danforth might have nailed it that the check balls have stuck. I'll need to go back to the boat and re-try to pump the carb before starting to observe if there has been an improvement. Just running an engine sometimes gets things going. Thanks for the link. More reading material in my man cave.

I know some people don't believe in "mechanic in a can", but if YOU do believe that some products work, what product would YOU run through a carb that has been idle for a long time? I used to know a very good boat mechanic who has long since retired and he swore by some fuel system cleaner. I wanna say it was Johnson outboard stuff but I can't remember. Like Scott Danforth indicated, maybe something that breaks down varnish?

 

[Lou C]

If the engine was not started for months the float bowl was likely empty (evaporation) and it takes some cranking over to fill the bowl enough for the accel pump to have anything to squirt.
The best way is to take it all apart, carefully clean all the passages and re-assemble with new gaskets. I do this approx every 4-6 seasons. When I can't adjust it for a good smooth idle