Author Topic: Marine Hot Restart  (Read 409 times)

Offline rudie20

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Marine Hot Restart
« on: July 24, 2017, 09:27:28 PM »
Had my marine quadrajet rebuilt by Cliff (part number 17085013). Runs great in all aspects except one minor issue. When good and hot, the boat needs extra throttle to restart. I cannot simply turn the key at idle and have it fire up. It has a new distributor, coil, and Mercruiser OEM fuel pump. Any ideas on how I can tune this?

Offline Cliff Ruggles

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Re: Marine Hot Restart
« Reply #1 on: July 25, 2017, 03:51:18 AM »
Did you fine tune the idle mixture screws for best idle quality?

Offline rudie20

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Re: Marine Hot Restart
« Reply #2 on: July 25, 2017, 04:09:05 PM »
I thought so but must not be doing it correctly. I turned the idle screws to 2 turns out each. I then turned one in looking for a noticeable change in engine idle. There was a slight increase in rpm but no clear change even with the idle screw all the way seated!  Is this process correct? Idle is set between 600 -700 rpm.
« Last Edit: July 25, 2017, 04:13:23 PM by rudie20 »

Offline Cliff Ruggles

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Re: Marine Hot Restart
« Reply #3 on: July 26, 2017, 04:58:02 AM »
Marine carburetors do not use idle bypass air so the throttle angle is high and they have a lot of transfer slot exposed.  Not uncommon at all to seat the screws and not kill out the engine.

They are also very sensitive at the mixture screws for fuel delivery so a little goes a long ways.  The mixture screws typically don't need backed out very much on them to get plenty of idle fuel to the engine. 

I would set them for highest vacuum and best idle quality.....Cliff