Starting Troubles

[R733]

I have a 1994 Mariah with a 5.0 liter Mercruiser that has trouble starting after its been driven for any length of time. Cold statrts are not a problem. If the boats sits for any length of time in non calm waters after being driven it just won't start. If the boat is on the lift - ignition is not a problem. Numerous attempts eventially runs battery down. It's as if it won't fire. Could there be a fuel flooding problem or something else. I've heard that it might be the thunderbolt ignition. I have some blow back also occuring. Any thoughts!

 

[Reel Poor]

Re: Starting Troubles

When the engine won't start you need to check for fuel and spark. Remove the flame arrestor and look down in the carb and see if it's getting gas. If it is reinstall flame arrestor. Then remove the coil wire from the coil and check for spark comming out of the coil (not the coil wire). If you have spark there reinstall the coil wire and check for spark at he plugs. You have to determine what you don't have.

 

[kimchee]

Re: Starting Troubles

I have a 1994 Mariah with a 5.0 liter Mercruiser that has trouble starting after its been driven for any length of time. Cold statrts are not a problem. If the boats sits for any length of time in non calm waters after being driven it just won't start. If the boat is on the lift - ignition is not a problem. Numerous attempts eventially runs battery down. It's as if it won't fire. Could there be a fuel flooding problem or something else. I've heard that it might be the thunderbolt ignition. I have some blow back also occuring. Any thoughts!

WOW, R733, I am so glad you posted this problem... You pretty much summed up my ulcer in 3 sentences... I have a 96' MAXUM 2300SC (5.7L 8cyl carb thunderbolt engine) and have owned the thing for 3 years now... This issue which you describe has been plagueing me since I've owned it... It has caused me to troubleshoot it so often, that I have become familiar with everything else except the main problem (which is what you describe). My marina has been unable to duplicate the problem at the docks, the fact that you mention "non-calming waters" have always made me wonder if that could've been the problem.

Let's see, some other things I have noticed is, when I pull my plugs, they are almost always black with soot... Which I know, means I am running rich, I only mention this, as I suspect R733 has the same problem. When I try to start after the boat has run a while at the docks, it starts up just fine, in fact, very easily... But when I am in the ocean, I have a hell of a time... Sometimes, I need to pull off the flame arrestor, and prime the carb with carb cleaner really well, and then, I get it to turn over... I eventually get it to turn over, but I know something is happening which is causing this to occur... I just don't know what it is... Don't bother having the carb rebuilt, I did that, no help...

Bond-O and some others have suggested that I have a problem with my electric choke... and I plan on really paying attention to my choke the next few times I go out... As I understand it... It needs to be set while the engine is cold... Essentially, set it where it is closed, but just about to open. Which would mean, once the engine is warm, the choke flap should be completely opened... I notice my choke flap is not actually fully open, but hmm.... 75% open.. Which I think is normal...

Arhh... The point is, this is frustrating... I will be following this thread.. R733, please post back if you or your mechanic solves your problem... I would pay big money to solve this problem... But the problem is, nobody know what the problem is...

Oh... the reason why I need to prime the carb, is because it was probably flooded with the multiple attempts to start up... Keep in mind, this is happening out in the ocean, while it is rocking back and forth...

 

[kimchee]

Re: Starting Troubles

When the engine won't start you need to check for fuel and spark. Remove the flame arrestor and look down in the carb and see if it's getting gas. If it is reinstall flame arrestor. Then remove the coil wire from the coil and check for spark comming out of the coil (not the coil wire). If you have spark there reinstall the coil wire and check for spark at he plugs. You have to determine what you don't have.

Reel Poor, thanks for responding to R733, but I have removed the arrestors, and had the boss lady pump the throttle, and I can see the fuel mist fine (in addition to the fact that I get sudden exhaust blows after initial starts-ups when out in the ocean, and black plugs, which suggest too much fuel), so I think fuel is not the issue...

Now for the next part of your ruling out suggestion... This may seem stupid, but what do you mean by "remove coil wires from coil..." I am not sure, but I think you mean to pull the spark plug wires one-by-one out of the rotor...? and then to check the other end of the spark plug wires against the plugs? But if the engine is not running, how do you check this? Funny, as I rationalize your suggestion, I am almost sure this is not what you were suggesting....

But nevertheless, I am pretty sure R733 is getting spark, it is just having a hard time turning over... I have narrowed it down to:
-Vapor Lock - which I am pretty sure is not my problem... but it seems to be so common, I can't completely rule it out....
-Choke Problem - Will get back to you...

Thanks

 

[kimchee]

Re: Starting Troubles

Holy cow, I was just reading, and I read that the choke gets itc current from the alternator, which, it turns out, my marina mechanic had told me that my alternator is about to go, if not is crap already.. He said he was only getting 10-10.5 volts... So he went ahead and replaced it.... WOW, I hope the replacement of the alternator corrects my choke issue, which will ultimately fix my hard start on the water...
It just seems too easy... I know it is too good to be true...

 

[180shabah]

Re: Starting Troubles

Doubt a new alternator will do much for hardstarting

 

[wewefirex2x]

Re: Starting Troubles

Wow, I guess alot of people have this problem. I was out yesterday, took a 25 minute run to a cove to go swimming and when I got back in boat about 2.5 hours later the damn boat wouldn't start. 5.0 merc 2 barrel carb. I know I am getting fuel because I can smell it. Plugs, wires,rotor, and cap replaced. The "non calming waters" is what I was in yesterday with the tide coming in. I just hope someone can help us out because not only is it embarrassing, it's frustrating. Thanks guys great post

 

[Bondo]

Re: Starting Troubles

When the engine won't start you need to check for fuel and spark. Remove the flame arrestor and look down in the carb and see if it's getting gas. If it is reinstall flame arrestor. Then remove the coil wire from the coil and check for spark comming out of the coil (not the coil wire). If you have spark there reinstall the coil wire and check for spark at he plugs.
You have to determine what you don't have.

Ayuh,...........

When You Don't Have it............

 

[whathveIdone]

Re: Starting Troubles

Wow, I guess alot of people have this problem. I was out yesterday, took a 25 minute run to a cove to go swimming and when I got back in boat about 2.5 hours later the damn boat wouldn't start. 5.0 merc 2 barrel carb. I know I am getting fuel because I can smell it. Plugs, wires,rotor, and cap replaced. The "non calming waters" is what I was in yesterday with the tide coming in. I just hope someone can help us out because not only is it embarrassing, it's frustrating. Thanks guys great post

Same thoughts/issues as well with 4.3 L.

 

[180shabah]

Re: Starting Troubles

WhathveIdone - Although your symptoms may be the same as R733 your engine/drive package is different. Thus, many of the troubleshooting step may be different.

You need to start a new thread and include as much detail as possible about your engine (manufacturer, model, SN), the problem you are having, and what troubleshooting you have already done.