89 3.0 Merc Hard to start after warmed then sitting

toneybrown

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I'm back again with yet another issue! :mad:

Took my boat out today after doing a little tuneup work in it, started it up in the driveway before heading out just to make sure she was going to cooperate.

Get to the lake, put her in the water starts up like normal. We cruise for a while, even pull my son on the tube for the first time. Boat was running way better then a few weeks ago before the new plugs and things. Not a hitch in her getty up at all.

After sitting, I try to restart and the boat doesn't want to fire up. It seemed to be cranking slower then normal but started to crank faster and faster till the motor would finally fire up and rough idle for a few seconds then smooth out and run fine.

We went back to the dock and I could kill and restart the motor immediately and it would fire right up. No slow crank, nothing. Turn the key and boom she was running. I killed it and let it set for a couple minutes, and it was hard to restart again but would finally fire up. This boat has never done this, first time starting after setting for days or overnight would take a few turns of the engine before it got fuel, but once it had warmed up out on the water it typically would start right up on the first bump of the key.

I looked around the interweb and found some suggestions made by people with their own problems and did some testing in the driveway.

Here is what I found

#1 cranking from cold seemed to be normal after the boat had sat for several hours.
#2 after starting, I could still kill and restart immediately without issue.
#3 killing and letting it sit for a few minutes always resulted in many cranks before fire off
#4 couldn't recreate the slower then normal crank I perceived on the water
#5 I removed the flame suppressor and ran the boat for a bit, killed the motor and looking into the carb I can see gas dripping into the carb from the two tubes above the valves. I watched and they kept dripping for several minutes.

So, I am thinking that #5 is my problem. Gas is dripping into the carb and flooding it. It wasn't a lot of gas, and the drips weren't very fast, but they seemed like fairly big drops. From what little I have read, no gas should be moving once the engine stops.

So, what kind of issue am I looking at here? Is it simply a carb rebuild is needed. Could there be something else along the fuel system that could be causing these issues?
 

alldodge

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#5 I removed the flame suppressor and ran the boat for a bit, killed the motor and looking into the carb I can see gas dripping into the carb from the two tubes above the valves. I watched and they kept dripping for several minutes.

So, I am thinking that #5 is my problem. Gas is dripping into the carb and flooding it. It wasn't a lot of gas, and the drips weren't very fast, but they seemed like fairly big drops. From what little I have read, no gas should be moving once the engine stops.

Agree that's your problem

So, what kind of issue am I looking at here? Is it simply a carb rebuild is needed. Could there be something else along the fuel system that could be causing these issues?

The float level or needle valve is the issue and a carb rebuild should fix. Do look close at the float and try to determine it is not fuel soaked. If float gets fuel soaked it is heavier and needs replaced. If float is brass, then all good so long as no fuel is sloshing inside
 

toneybrown

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Agree that's your problem



The float level or needle valve is the issue and a carb rebuild should fix. Do look close at the float and try to determine it is not fuel soaked. If float gets fuel soaked it is heavier and needs replaced. If float is brass, then all good so long as no fuel is sloshing inside

Thanks for the input.

What would you say the difficulty level would be of rebuilding one of these carbs? Most likely will have a professional do it if I can find one to do it locally, but may give it a shot myself if the turn around time is too long.
 

SDSeville

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Where is the gas dripping from?

Similar thing happened to me with an 86 Sea Ray I had. It was a bad fuel pump. I guess there was an internal seal that had worn out and after shutoff (and low RPM) it would send fuel back up an overflow type hose and into the carb and flood it.
 

alldodge

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Thanks for the input.

What would you say the difficulty level would be of rebuilding one of these carbs? Most likely will have a professional do it if I can find one to do it locally, but may give it a shot myself if the turn around time is too long.

Crabs are easy enough to rebuild, the hardest part is cleaning them. They come with the info needed to adjust, and if you have any issues doing so we are here to help
 

toneybrown

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Crabs are easy enough to rebuild, the hardest part is cleaning them. They come with the info needed to adjust, and if you have any issues doing so we are here to help

Any recommendations on which kit I should buy?
 

alldodge

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Need to know which carb you have, should be a Merc or Rochester. Don't know your serial number is but think its in the0B450801 THRU 0C856558 range

Look on the carb and see what the number is, should be a tag or stamped in the body of it
 

nola mike

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Since I'm lazy, if it were me I'd just start by checking the float and needle/seat (or just replacing those) unless it looked nasty when you opened it. If it still runs bad, you're only out 30 minutes to install/remove again and do a full rebuild. The float and needle require minimal disassembly to get to
 

toneybrown

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Since I'm lazy, if it were me I'd just start by checking the float and needle/seat (or just replacing those) unless it looked nasty when you opened it. If it still runs bad, you're only out 30 minutes to install/remove again and do a full rebuild. The float and needle require minimal disassembly to get to

I think I might try that first. The boat was running really good out on the water, just the restarting issue had me very worried yesterday that I was gonna be dead in the water. Now that I know what is going on I'm not as worried about that, but would like it to start like it is suppose to.

I have softball practice, but I will check the carb for the serial later today and post my findings. Thanks again.
 

toneybrown

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Need to know which carb you have, should be a Merc or Rochester. Don't know your serial number is but think its in the0B450801 THRU 0C856558 range

Look on the carb and see what the number is, should be a tag or stamped in the body of it

Hmm, I didn't find a number on the carb that started with a 0, or had a letter in it......this is the only number I found

13899562
6603

This was on the side of the carb facing foward. I didn't see one anywhere else I could see, but I may not have been looking in the right spot.

Found a Youtube video of a guy showing a carb like mine, those are the correct numbers. So I guess I can search for a kit for that carb serial number?
 

toneybrown

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Thanks for the link, Just to be clear this is the needle and seat?
 

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alldodge

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Two different items there, the one on the right is the seat. If you go back to the amazon pic and look at the middle gasket in the bottom row, and the 2 items in it. The brass thing on top with the black tip is the needle valve
 

toneybrown

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Two different items there, the one on the right is the seat. If you go back to the amazon pic and look at the middle gasket in the bottom row, and the 2 items in it. The brass thing on top with the black tip is the needle valve

Thanks, I knew all the parts I need are there, just wanted to identify what to look for. I found a great Youtube video of a guy doing a complete rebuild of my exact carb. So going to watch the part were he is putting in the float and need/valve.
 

AShipShow

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If its the mercarb I have a video on my youtube channel on rebuilding it... actually 3 videos for teardown, rebuild, and adjustments...

The mikes carb parts channel is good but i thought the video was way too dark to see what was going on...

 

toneybrown

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If its the mercarb I have a video on my youtube channel on rebuilding it... actually 3 videos for teardown, rebuild, and adjustments...

The mikes carb parts channel is good but i thought the video was way too dark to see what was going on...


Thanks for the video link.

Question. Using the only terms I know. How do you remove the "throttle lever rods" to separate the top of the carb from the bottom?
 

AShipShow

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They have little e clips on them... usually the clip is on one side and the other side rotates until a little flat can fit thru the opening in the lever.
 

toneybrown

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They have little e clips on them... usually the clip is on one side and the other side rotates until a little flat can fit thru the opening in the lever.

Got it pulled apart, but when I was carrying it from the boat to my work bench apparently one of the e clips popped off..... So, where can a guy get some more small e clips? lol
 

alldodge

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Got it pulled apart, but when I was carrying it from the boat to my work bench apparently one of the e clips popped off..... So, where can a guy get some more small e clips? lol

NAPA, local auto store, amazon, but suggest local, so you can do a show and tell to get the right size
 
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