Trouble Starting Mercruiser 5.7L Carb

[DWard0618]

Hi All,

I have been having issues getting my 2001 Bayliner 2455 Ciera started. She has a Mercruiser 5.7L with Bravo III. This is very recent and I have never had issues starting her, before. When I go to start, it turns and turns and turns, will start for less than 1 second, and shut off. Sometimes, it just turns and turns and turns and doesn't start.

The boat had sat for about two weeks, in the slip, and we had a bunch of rain. My first thought was maybe the kill switch had gone bad. Pulled the old kill switch and connected the wires, same thing. I have almost 3/4 of a tank of fuel, that is less than a month old. I replaced my fuel filter this spring. I didn't pull the carburetor out, but it appears clean and not gunked up. Distributor cap was replaced this past spring. Also checked the plugs (replaced this spring) and the are fine.

I have been able to, a couple times since this happened, get her to start (randomly). Once she is running, there are no issues at all. Took her out for about an hour and a half and ran her at idle for a little while and at cruising speed.

Any ideas or suggestions would be greatly appreciated. This one has me a little stumped.

Thanks,

Dave

 

[Alumarine]

Welcome.
When it's cold, are you engaging the throttle only feature, then pumping the throttle a couple of times, and advancing the throttle slightly before attempting to start?

 

[DWard0618]

Hi Marc,

Yes. I am engaging the throttle only and pumping a few times, and advancing the throttle slightly. I am following the normal starting routine that I always have. That is what has me stumped.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... Which carb,..?? 2bbl, or 4bbl,..??

 

[DWard0618]

Bondo,

It is 2bbl.

 

[harleyman1975]

Could be it needs a good cleaning/rebuild. there are little check balls in hidden places that can get gunked up or corroded and allow the fuel in the bowl to drain into the engine. causing the hard start you are describing

 

[DWard0618]

Thanks Harleyman. Do you suggest pulling the carburetor off and inspecting or just using some carb cleaner, to start? Also, my apologies. I type 2bbl by mistake. It is a 4bbl.

 

[thumpar]

Once it is started does it run OK? Have you checked the choke? It could just in need of a carb rebuild.

 

[alldodge]

before. When I go to start, it turns and turns and turns, will start for less than 1 second, and shut off. Sometimes, it just turns and turns and turns and doesn't start.

The boat had sat for about two weeks, in the slip, and we had a bunch of rain.

Once she is running, there are no issues at all. Took her out for about an hour and a half and ran her at idle for a little while and at cruising speed..

Got me leaning toward an electrical issue. Need to start doing some testing before you start taking things apart.

When it doesn't start, check for 12V at the coil (+) terminal.

If you get 12V, check for spark by removing the coil wire and hold it away from the carb and close to the engine block, look for a white spark.

If you get spark, remove the flame arrestor and pump the throttle while someone is looking down the throat or the carb. Check to see if the chock plate is closed except for about 1/8 inch gap

 

[Bondo]

Do you suggest pulling the carburetor off and inspecting or just using some carb cleaner, to start? Also, my apologies. I type 2bbl by mistake. It is a 4bbl.

Ayuh,..... Then you've got the Merc/ Weber AFB clone carb,.....

They're known to leak off through welch plugs into the intake, floodin' motors when restartin' shortly after shut-down, 'n of course the bowls are dry after sittin' a day or more,....
Achris has spent abunch of energy chasin' the problem,...

Canned carb cleaner don't fix anything, the inner workin's are where the problems lie, long past the plastic straws capabilities,....

The carb needs to be torn down, soaked, 'n blown out with compressed air,....
A rebuild kit from Edlebrock for their 1409 is the kit for yer carb,... Much cheaper, 'n easier to find than OEM Merc kits,...
The leak can be epoxied while it's apart,...

Lookin' at the bottom of the carb, the spots needin' epoxy are pretty obvious,....
Scratch 'em clean, blow 'em out, 'n epoxy over 'em,....

Or,....
Put a jumper circuit to yer fuel pump, 'n run it for 30 or 45 seconds, before ya pump the throttle, 'n hit the key,.....
Mines been that way for over a decade, 'n 1/2,...... if I ever pull it, I'll rebuild it, 'n epoxy it,....

 

[DWard0618]

Got me leaning toward an electrical issue. Need to start doing some testing before you start taking things apart.

When it doesn't start, check for 12V at the coil (+) terminal.

If you get 12V, check for spark by removing the coil wire and hold it away from the carb and close to the engine block, look for a white spark.

If you get spark, remove the flame arrestor and pump the throttle while someone is looking down the throat or the carb. Check to see if the chock plate is closed except for about 1/8 inch gap

AllDodge,

Electrical was my first thought. I had a mechanic (not a marine mechanic) look and listen. He says, from everything he's looking at and hearing, he does not think it is a mechanical issue. I'll trace the steps you listed and see what that does.

I was hoping not to rip the carb apart. But if it needs to be done, I'll certainly try that too.

 

[DWard0618]

Once it is started does it run OK? Have you checked the choke? It could just in need of a carb rebuild.

Thumpar, when/if i can get it started, it runs fine. No issues, no hesitation, no sputtering. I can run at idle, cruise, or WOT and it is totally fine.

 

[harleyman1975]

I'm a good wrench. Own a bodyshop. I bring my carb to a pro for rebuilding...but that's just me. never had more than a .500 average when it comes to successfully rebuilding carbs. spend $250 and know it's done right...but again that's just me.

 

[DWard0618]

Update:

The batteries were 3 years old. I thought the batteries may have been on their last leg, so I got new ones. Same issue. I had a mechanic buddy come and look and listen and check the carb and said there was absolutely no issue with the carb getting fuel. I checked the coil and there is definitely spark. I pulled the fuel filter over the weekend, to see if there was any issues. The fuel in the filter and gas in it, looked good.

I'm now at a loss. Could it be the ignition switch or module?

 

[Bayou Dave]

I suggest trying the control module. You might be able to test the one you have, but not sure how.

 

[alldodge]

You have fuel and are getting spark, How was spark checked?

When your cranking the motor does it try to start and does not, or does it not hit a lick?

 

[DWard0618]

Thought I'd give everyone an update. After a long and stressful process, I ended up calling a marine mechanic. Problem was resolved within 5 minutes. Turns out that the wiring harness, on the block, was slightly loose and wasn't making all of the connections. Cleaned up the harness, plugged it back in, tightened the clamp and started right up. Let it run for about 15 minutes, no issues. Started her up about 5 more times and everything was fine...

So a breakdown for you;
$200 on new batteries.
$20 on new kill switch
$30 on new ignition switch
$35 on new oil pressured switch
$30 on new digital voltmeter
$30 on other miscellaneous stuff trying to track down the problem
$75 on a marine mechanic
Grand total of $420 spent, chasing a problem for a month, and was resolved in 5 minutes, by a $3 screwdriver!

I guess another valuable boat electronics lesson learned...

 

[Bayou Dave]

I guess a positive note is that you have a lot of new parts that you won't have to replace for many years!

 

[DWard0618]

I guess a positive note is that you have a lot of new parts that you won't have to replace for many years!

DRS4164... Right you are!