No warmup - Maxum Boat Owners Club

mjimbouno1 · 07-23-2019, 09:04 PM

I have a 1999 Maxum 2100 SC up until last year no problems, this year the spring loaded button for advanced throttle control stopped working, not sure if this serviceable or if the whole shifter control box will have to be replaced. Forward,reverse and neutral all still function, but without advanced throttle I am unable to warm up the boat quickly when launched. The removal of this component looks involved.

Phillbo · 07-23-2019, 09:16 PM

The engine should warm up at idle just fine. I never advance my throttle to warm up.

I'm not sure what is required to fix the button so will leave that up to someone else.

mmwjr · 07-24-2019, 01:23 AM

Did the button fall off or just letting you disengage the shift mechanism? May just be time to replace if after 20 years of service.

You should still be able to pump it a few times to prime the engine and set the choke then start in neutral.

rwc · 07-30-2019, 01:09 AM

What does it mean if you can't warm up in neutral? I have never been able to - I have to open the throttle and run at about 1500 rpm for a few minutes to warm up before I can shift into neutral without stalling - always suspected this was not right, but not sure what the problem is.

I rebuilt my carburetor over the weekend and watched the choke plate open as it warmed - the plate was fully open after about 30 seconds, but from previous experience this has not nearly enough been enough time to warm up for the engine to keep running.

I haven't been able to try it post rebuild, as I just did the tuning last night, but will do so next time. What should I watch for if it doesn't work?

mmwjr · 07-30-2019, 02:46 AM

Is the choke plate closing most of the way? Should be about an 1/8” gap when closed. Did you adjust the idle screws using a vacuum gauge?

rwc · 07-30-2019, 03:22 AM

Choke plate is closing.

Did not use a vacuum gauge to set idle mixture. I leaned out until it stuttered, made it rich until it stuttered, then split the difference. I’ve never used a vacuum gauge and don’t own one. Will it be substantially better than my method? (Sorry, I recognize that is likely a dumb question)

mmwjr · 07-30-2019, 12:18 PM

Quote:

Originally Posted by rwc

Choke plate is closing.

Did not use a vacuum gauge to set idle mixture. I leaned out until it stuttered, made it rich until it stuttered, then split the difference. I’ve never used a vacuum gauge and don’t own one. Will it be substantially better than my method? (Sorry, I recognize that is likely a dumb question)

Yes it's a better method. Doing it your way I would lean it out till it stutters then back off till it smoothens out then 1/2 turn.

rwc · 07-30-2019, 08:18 PM

Thanks Mike.

I think I've found a vacuum gauge I can borrow, so next dumb question... where do I stick it??

mmwjr · 07-31-2019, 02:06 AM

Quote:

Originally Posted by rwc

Thanks Mike.

I think I've found a vacuum gauge I can borrow, so next dumb question... where do I stick it??

See if there is a vacuum port at the base of the carb. Do you know what carb you have?

rwc · 07-31-2019, 03:31 AM

2 barrel mercarb

I don’t remember seeing a port but to be honest I wasn’t looking for one.

Dad’s answer was “Just jam the tube down the barrel!”

mmwjr · 07-31-2019, 12:36 PM

Not sure I have a good answer as many marine carbs plug the vacuum ports since they are not needed. What your dad suggested will not work as you want to sample vacuum under the base of the carb at idle (throttle plates closed) so the hose cannot get to the right area. I looked in Mercruiser manual #24 section 5B for the 2bbl and it tells you how to set initial mixture then refers you to section 4B which is timing to set final mixture. But all it says in step 8 is to set the mixture, big help. This is where you adjust the mixture to achieve max vacuum.

shrew · 08-08-2019, 02:21 PM

I wouldn't warm up a cold engine by throwing RPM's at it. There would be no point in Warming Up, if that were the case.

How long do you sit in your driveway with your foot on the gas to warm the car up before you drive somewhere?

jrsick · 08-08-2019, 04:45 PM

I have always assumed that the vacuum port is the plug located on top of the intake manifold just behind the carb. My plug has a fitting for a 3/8 ratchet to remove it. Vacuum gauge should screw in there.

mmwjr · 08-08-2019, 05:15 PM

Quote:

Originally Posted by jrsick

I have always assumed that the vacuum port is the plug located on top of the intake manifold just behind the carb. My plug has a fitting for a 3/8 ratchet to remove it. Vacuum gauge should screw in there.

That would work as it's under the base of the carb.