65 Riv - Accelerator pump working as it should?....

Recommended Posts

Hi all


Want to learn a bit more about the workings of the accelerator pump...


Running a 65 riv with original carter 4 bl AFB.


Engine warm, but turned off - work throttle by hand and I see two nice jets of gas squirted into carb so Acc pump seems good.


WhenI try same thing with engine running and in park there are no jets of gas - though engine revs/sounds good.


Am I right in saying this is normal and somehow when engine is in D and actually driven,  the jets ‘do their thing’ upon initial acceleration? Maybe the vacuum facilitates this?


The reason I’m  investigating is that I have a ‘bog’ spot when pulling away, but only when pulling away - my money at the moment is on the vacuum advance but that’s another story - at this point just want to learn a bit more about the pump and to confirm my conclusion that it’s working OK based on above tests .


Thanks in advance



Share this post

Link to post
Share on other sites

It isn't normal, and (no offense meant) do not see how it can occur.


Is it possible the pump squirt is there, but the vacuum present when the engine is running pulls the squirt through such that you do not see it? Again, possibly repeat this test with a couple of observers with younger eyes than mine watching.


Lots of possibilities causing bog. Top ones:


(1) electronic distributor conversion

(2) vacuum advance defective

(3) timing out of adjustment

(4) idle adjustment TOO RICH

(5) accelerator pump not functioning


One other which is very remote, but can occur: missing or incorrect pump discharge valve.



Share this post

Link to post
Share on other sites

Aha...see what you mean, maybe because if vacuum it’s more subtle...


will double check ....






Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now