Engine has trouble idling down
07-31-2015 | 09:49 PM
#11
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Joined: Nov 2004
Posts: 14,100
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From: On A Dirt Floor
I can take you out in a ride in a few boats tomorrow with same carburetor he has that does this too. I can also put in a higher tension vac secary spring that will stop this from happening. Issue, is that it will cut engine power down a decent amt too.
One restart will typically make it go back down to normal idle. Once in a while, 2 restarts.
As far as post #7 - you are correct. Most people don't realize the solid Morse cable combined with a throttle lever doesn't work the same in reagrds to idle speed the same way a gas pedal and carb with a return spring does.
example:
" take your foot off your cars gas pedal and the throttle returns to idle position.
take your hand of the boats throttle lever and it stays where you left it. So, when you put lever in neutral (idle) it leaves carb idle position where the cable dictates.
One restart will typically make it go back down to normal idle. Once in a while, 2 restarts.
As far as post #7 - you are correct. Most people don't realize the solid Morse cable combined with a throttle lever doesn't work the same in reagrds to idle speed the same way a gas pedal and carb with a return spring does.
example:
" take your foot off your cars gas pedal and the throttle returns to idle position.
take your hand of the boats throttle lever and it stays where you left it. So, when you put lever in neutral (idle) it leaves carb idle position where the cable dictates.
Last edited by SB; 07-31-2015 at 09:53 PM.
07-31-2015 | 10:07 PM
#13
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Joined: Jul 2011
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From: Ft. Worth TX
SB can I take you out in mercruiser TKS carb app and we will see how high that idle is at start up - talk about high and very load noise - really a poor carb by mercruiser - freakin 110 degrees down here and the carb takes 5 mins to warm up and return idle to normal.
Rut row he says mech secondaries
Rut row he says mech secondaries
07-31-2015 | 10:19 PM
#17
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From: On A Dirt Floor
Actually, it is basically the same I'm talking about. The wound spring on the throttle shaft does not have enough tension to fully seat the secondary throttle shaft. With vac secondries, the vac spring helps (a little) push it back also.
Before trying to add tesnsion, make sure your sec throttle blades are centered (loosen blad screws and open/slam shut throttle a few times to center them) and make sure t blades don't have rough edges that are slightly catching throttle bores.
Before trying to add tesnsion, make sure your sec throttle blades are centered (loosen blad screws and open/slam shut throttle a few times to center them) and make sure t blades don't have rough edges that are slightly catching throttle bores.
Last edited by SB; 07-31-2015 at 10:22 PM.
07-31-2015 | 10:29 PM
#20
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Joined: Jul 2011
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From: Ft. Worth TX
I will add that Demon Carbs Barry Grant had their share of problems in the marine world - he had even some lawsuits and federal marine recalls for his carbs. So did Holley with Volvo. here is a look at the Volvo service bulletin as we use to have problems with their carbs. read it
http://www.marinemechanic.com/volvo/...2010/23-1-22_A[1].pdf
http://www.marinemechanic.com/volvo/...2010/23-1-22_A[1].pdf
