Throttle cable question.

[Bilgamesh]

I recently bought a '98 Regal with a 3.0L Mercruiser. I rebuilt the carburetor, and set the idle and mixture by the book. It runs and idles fine. Unfortunately when I give it throttle and then try to return to idle, it won't idle back down. I have to open the engine bay and push down on the barrel on the throttle arm to get it to idle back down. I guess it seems like it is not stiff enough to push the throttle back to idle position. I am wondering if this indicates it needs to be replaced, or should I look elsewhere for spring action that should accomplish this? Thanks for any replies.

 

[mkast]

Re: Throttle cable question.

Have you tried adjusting the cable?

 

[atomb]

Re: Throttle cable question.

I have the same exact situation with my 3.0 mercruiser - i took the cable out and took it to my guy he said it was fine so i tightened up the screw on the throtle cable that attaches to the engine - I also cant get it to knock the idle arm fully back- I have to push it back myself as well -Im curious to what the folks here think.

 

[Bondo]

Re: Throttle cable question.

Ayuh,... Adjust the cable so it's Pushing the throttle to idle...

 

[Bilgamesh]

Re: Throttle cable question.

That seems the obvious answer, but I did not want to start screwing without asking for guidance. It looks like the rod is slightly skew in the barrel already, possibly from over-adjustment. - Thanks

 

[Bilgamesh]

Re: Throttle cable question.

I only have about 1/4" of adjustment left on this thing at the barrel/rod. Does this indicate the assembly might be worn and needs replacing, or should I make some adjustment elsewhere to take up more slack? - Thanks for the assist!

 

[JustJason]

Re: Throttle cable question.

take the throttle cable off the carb. open the carb throttle plate by hand and let it go, it should snap shut. if yours does not snap shut or if it takes any kind of effort at all to close the throttle plates you need a new carb.

 

[Bilgamesh]

Re: Throttle cable question.

"open the carb throttle plate by hand and let it go, it should snap shut. if yours does not snap shut or if it takes any kind of effort at all to close the throttle plates you need a new carb."

Thanks for the reply, but maybe you could clarify, as this sounds inconsistent with what Bond-o posted, i.e

Adjust the cable so it's Pushing the throttle to idle...

His post suggests the cable push the throttle back to position, while yours suggests there is a native spring action to the throttle mechanism. I will surely do what you have suggested, but it would be nice to understand how it is all supposed to work. - Thanks

 

[JustJason]

Re: Throttle cable question.

the cable does "push" the throttle closed, but really the return springs pull the throttle shut. What i mean by that is you want the carb to come to its own stop and you don't want the cable to put any postive pressure on the carb linkage once it's reached it's stop.

sowrry about the typeing... my finger is all buggered up.

 

[Bilgamesh]

Re: Throttle cable question.

Thanks for taking your time to respond in spite of your buggeredness!

Sorry to belabor the point, but as you might imagine, I want to measure twice and cut once when it comes to spending several hundred dollars for a new carb. If the carb is not settling back down to idle after revving, it would seem the return spring action is not adequate to push the throttle plates closed, or the cable length is a bit short and applying just enough force against the throttle to keep it open a bit. Assuming the spring action functions as you suggest it should, ie. it springs closed, and the cable is adjusted such that it does not prevent this action, is there anything else I can look at to make sure all the bases are covered before I buy a carb?

Is the return spring you mention the "Accelerator pump return spring" or another?

Thanks

 

[rbh]

Re: Throttle cable question.

I am going to take a stab in the dark with this one.
when you had the carb rebuilt did the butterfly return spring get put on properly?
as well is the cable/cable bracket seated were it is supposed to be?
rob

 

[Bilgamesh]

Re: Throttle cable question.

I am going to take a stab in the dark with this one.
when you had the carb rebuilt did the butterfly return spring get put on properly?
as well is the cable/cable bracket seated were it is supposed to be?
rob

Thanks for the reply.

In the exploded view of the carb, I don't see a "butterfly return spring" There is an accelerator pump return spring, and I did put that one in. If there is supposed to be another spring, I cannot see it or tell where it would go. At this point my main confusion is understanding where the spring action should come from to close the throttle plates. I cannot see a spring that does that on this carb.

The cable bracket was not removed from the engine, only at the carb for removal.

 

[rbh]

Re: Throttle cable question.

was there never a return spring on the side of the carb?
rob

 

[Bilgamesh]

Re: Throttle cable question.

I have only owned it 3 weeks, but in that time, no.

 

[rbh]

Re: Throttle cable question.

if you have a car or truck with a carb still, have a look.
rob

 

[Bilgamesh]

Re: Throttle cable question.

I understand, as I have had plenty of cars I have had to work on. There is normally one or more springs on there. This is where I am puzzled. It sounds like either somebody left it off before I bought it, or the design is such that the throttle cable is supposed to push it back.

Here is another thread that suggests the cable does it:
http://forums.iboats.com/showthread.php?t=57163

If such a spring does exist by design, I would appreciate it if somebody would post a picture of where it should go on this carb/engine? - Thanks

 

[JustJason]

Re: Throttle cable question.

You need to post a pic or to of what YOU have, then we go from there. try to get a good shot of where the throttle cable attaches.

 

[JustJason]

Re: Throttle cable question.

post your engines serial ## to.

 

[Bilgamesh]

Re: Throttle cable question.

I am sitting at my desk at the office right now, and not in a position to photograph at the moment, but my setup is identical to the one in manual #26. I cannot see any external springs on the carb, on mine, or in the manual.

Furthermore, JustJason said,

...if yours does not snap shut or if it takes any kind of effort at all to close the throttle plates you need a new carb.

How can this be true, and why would I replace the carb if it was as simple as putting on a spring?

On page 2A-15, the manual instructs placing a pre-load on the throttle by adjusting the barrel. This seems to suggest the cable is doing the work. While my own experience with such springs on car carburetors is similar to those expressed here, the evidence suggests no such spring is called for in this instance.

I appreciate all information in support, or to the contrary, and your kind attention to my problem in general. - Thanks

 

[badger42]

Re: Throttle cable question.

I had the same issue with my engine when i bought it, sometimes not returning to idle...I added a 99 cent spring from the hardware store and it worked great to back it down that final bit. I eventually got some engine work done at the dealer and they correctly adjusted it so now it no longer needs that spring.