TOPIC: 1964 650 starts fine, runs fine... restarting bad

Have a 1964 650 - starts up fine. Runs fine. But when I'm stopped at a fishing hole for a while - when starting it back up an hour or so later - it doesn't want to run.

For now the workaround is to open the throttle all the way and start it up that way while in gear. It's that or I'm stuck on the water.

At times when starting back up when I do get it running after a spell on the lake - I have to slowly get it up to full throttle - otherwise it'll just stall out at higher RPM's.

After a few minutes of this - it's running fine. Happening with a fresh tank of fuel (no water or anything).

Any ideas?

sounds like the carbs leaking down and flooding a cylider or two

sticking float or leaky needle & seat in the carbs is where Id look first

when is the last time the fuel pump, carbs, distrib been serviced? Are the spark plugs fresh?
What do they look like?

additionally if you could get the motor to quit again try squirting fuel in the carbs to see if it will attempt to start and then also pull the plugs to see if they are wet......this will help to isolate the problem quicker

Starting with it in gear means you have bypassed the neutral saftey switch? You mentioned nothing about what you are doing for choking and bulb priming. Do you pump the bulb when first starting when it starts OK? Choke? High idle lever lifted? Do you still do this after sitting? I would use the primer bulb both times. If the check valve in the pumps or the bulb is not too good then gas can drain back leaving the lines empty but there will would be residual fule in the bowls.
Wide open throttle indicates flooding but I doubt the motor would run fine if floats where stuck so I would look at more of a fuel starvation issue.
Theory: at start-up excess cranking eventually pumps fuel up and then you get going again.
Good luck,
Randy

I forgot to ask if you tilt motor up while fishing becasue that will drain fuel out of the carbs too.
R

Wide open throttle indicates flooding but I doubt the motor would run fine if floats where stuck

I have a 6cyl that had the same probs it was a sticking float so it did run ok but when the float hit the spot it would stick till the starter vibration or whatever freed it
made me crazy nuts dude trying to figure the problem
looky see the plugs maybe there are a couple wet like mine was

edit: nice site by the way

Thanks everyone...

Yes - motor is in the down position when this is happening. If the neutral safety is bypassed - it must have been from a previous owner.

Haven't done anything with the carbs except changing the mixture screws as necessary.

Spark Plugs were new in 2007. Not too many hours on them.

I usually choke when starting... I prime the bulb til it's firm and the fuel filter is full. Start with the high idle lifted. Make sure the gas tank cap is vented, etc...

Any ideas? Bad fuel pump? Bad fuel line?

nessman wrote:

Any ideas? Bad fuel pump? Bad fuel line?

The fact that you are questioning them tells me they havent been replaced recently and very well could be an issue. Id start there...new fuel pump diaphragm(s), completely new fuel lines(from the tank to the carbs), replace any filters, etc...

Very well could be a float issue too...if you dont want to dive into the carbs, at a minimum, id pull the floats out and inspect them and make sure they are within tolerance. Also check to see if there are any fuel line deposits in the bottom of the bowls. If there is, might want to tear them down completely as those little bits of junk can and will clog your jets causing a whole slew of other problems.

Im finding, 9 times out of 10, when an old Merc is being cranky, its a fuel issue.

Not quite ready to pull the boat out of the water, but not wanting to risk little parts falling in the water, I dumped a can of Seafoam in with a tank of gas. Actually worked great. Ran it for an hour or so - even down the Erie Canal at 8 MPH or so with no variation in RPM... found a place to shut down and fish for an hour... started right back up... no problems... even at idle while in gear as I was approaching my dock.

Of course, I'm not a believer in a "mechanic in a can" products - and will give the carbs a closer look after I pull it out of the water in a few weeks. But hopefully this will keep things running smooth.

Think I found the problem. Winterized the motor this year... when pulling the plugs to fog the cylinders, the top 2 came off with no effort - not even hand tight. So basically had little to no compression on the top 2. The bottom 2 were snug but not tight.

Any ideas how they would get loose like that? At some point this season I did snug them up but somehow they worked themselves loose over the season. Threads aren't stripped or anything, but I think they've all been helicoiled at some point over the life of the motor.

I must note the engine was overhauled this season.

Clearly loose plugs will loose you compression but not a huge amount, I wouldn't think that is your problem in my opinion.

Alacrity is correct....thats not your problem, even if the threads were loose and sloppy

was most likely crap in the carbs , floats, needle & seat or???
and possibly the Seafoam has done its job and dissolved the material, continue to use the seafoam for a while in each new tank of fuel, also use it to setup for winter as directed on the can

OK... could be a carb problem.

But should I be concerned if the plugs are loosening up themselves? Should I be putting lock-tite on them or something?

Nessman, I sure wouldn't put locktite on your spark plugs. Are the heli-coils tight and in position? Did they stay in the head or come out with the plug(s)? If the heli-coils are properly installed and not pulling out of the head, and the plugs are properly torqued down, the plugs should not come loose. I myself have gotten in a hurry (or gotten distracted) and forgot to tighten a bolt or a spark plug before calling the job "finished", only to discover my error later. Is it at all possible?

Not sure about that particular motor, but some use a crush washer under the spark plug that is only designed to work one time. After that, the washer is not effective at sealing, and could work loose. Do you have a manual for your motor to check this out?

Short of the two possibilities mentioned above, it sounds to me like the coils (or threads) are pulling out of the head. I hope this isn't the case, might be worth trying a fresh set of new spark plugs next time to see if that helps.

Nah - the helicoils are seated fine... but the plugs have been in there for a few seasons. You could be right about the washer. Was planning on putting in new plugs next season anyway. Will keep that in mind.

nessman put in some fresh plugs

the crushable washers on the spark plugs maybe shot maybe from over torqueing....