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View Full Version : 79 Stars and Stripes runs good then shuts down


cll695
05-23-2012, 02:02 PM
I have a 79 Stars and Stripes only second season with boat and never owned one before. I have a 351 with velvet drive and starts right up with no problem but after 20 mins running starts running rough, stops and then shuts down. Temp doesn't get over 200 but can't start the boat afterwards. The few times I did get it started it ran pretty well in neutral but once in gear got rough and shut down. After I let the boat sit and cool it started up again but would only run about 20 -30 min. Could it be the trans cooler?

SkiDog
05-23-2012, 02:14 PM
I have a 79 Stars and Stripes only second season with boat and never owned one before. I have a 351 with velvet drive and starts right up with no problem but after 20 mins running starts running rough, stops and then shuts down. Temp doesn't get over 200 but can't start the boat afterwards. The few times I did get it started it ran pretty well in neutral but once in gear got rough and shut down. After I let the boat sit and cool it started up again but would only run about 20 -30 min. Could it be the trans cooler?

Change out the fuel line! Same exact thing happened with my boat. Ethanol fuel is eating away the insides of the fuel line., causing blockages.

thatsmrmastercraft
05-23-2012, 02:18 PM
I have a 79 Stars and Stripes only second season with boat and never owned one before. I have a 351 with velvet drive and starts right up with no problem but after 20 mins running starts running rough, stops and then shuts down. Temp doesn't get over 200 but can't start the boat afterwards. The few times I did get it started it ran pretty well in neutral but once in gear got rough and shut down. After I let the boat sit and cool it started up again but would only run about 20 -30 min. Could it be the trans cooler?

How hot is it running? Should run a lot closer to 160.

markismm
05-23-2012, 02:24 PM
Sounds like you have two probs. Sounds like you have a cooling problem and potentially a fuel delivery problem. Check impeller. Then work on fuel delivery. This usually entails a carburetor rebuild, potentially replacing fuel lines and definitely checking the fuel pick up tube inside the gas tank for blockages.

mzimme
05-23-2012, 02:29 PM
If temp is at 200, heat soak is probably playing a part in the no restart. The coil and starter will be affected by the hot temps.

The impeller is a good place to start as TMMC mentioned. It's a quick 30 minute (1 beer) job at most to replace one.

TRBenj
05-23-2012, 02:30 PM
Sounds like you have two probs. Sounds like you have a cooling problem and potentially a fuel delivery problem. Check impeller. Then work on fuel delivery. This usually entails a carburetor rebuild, potentially replacing fuel lines and definitely checking the fuel pick up tube inside the gas tank for blockages.
I agree... mostly.

Definitely agree on the cooling problem. You should never run over 160 deg. 200 is about where you should start to get nervous that you may cause damage.

I also agree that it is *probably* a fuel delivery problem. Nonetheless, troubleshooting an engine in an unknown state of tune is an exercise in futility. If the boat is new to you, then give it a full ignition tuneup (plugs, wires, cap, rotor, points, condensor, set the timing). I have seen an oddball ignition issue cause the exact symptoms you describe.

Once the ignition is in a known-good state, then move on to fuel. I would not start with a carb rebuild based on the symptoms you describe. Look for a blockage in the system, its easier and cheaper, and more likely to be the culprit. Check the pick up the tank, the antisiphon valve (if you have one), the filter (fuel/water separator), and the screen/filter at the carb bowl inlet. It only takes a little bit of junk or sediment to block proper flow and starve the engine of gas.

I have NEVER seen heat soak cause a poor hot restart condition on a carb'd boat. Ive heard its possible on some of the early Multiport engines... but Im willing to bet that 99% of people who think theyve experienced "heat soak" on a carb'd boat actually have another ignition or fuel related issue plaguing their engine.

cll695
05-23-2012, 03:25 PM
Thanks for all the input. I did replace the impeller last year but will check it out again to see if its bad. Also, I should have mentioned the previous owner put electronic ignition in it. I'm not sure about the full tune up because the boat runs strong with no hesitation for first 20 or so minutes then heats up and quits. Would the fuel pick up still be an issue if it runs strong until heats up?

Temp was 195 at hottest point but that was after it was shut down and sitting. While running temp was around 160.

SilviaMan
05-23-2012, 04:19 PM
My boat will heat soak too while sitting after running. I have never noted the temp it reaches while sitting TBH. Never worried about how warm it got just sitting while off after running for a bit. But I digress.
We need a bit more info.
Does it have spark when it won't start?
Does it have fuel spitting out of the carb when you hit the throttle when it won't start?

mzimme
05-23-2012, 04:25 PM
160 is a good temp for the boat to run at with a 160* tstat in it. It shouldnt go much higher than that at all unless you're in water with temps that rival a bath tub.

cll695
05-23-2012, 04:27 PM
My boat will heat soak too while sitting after running. I have never noted the temp it reaches while sitting TBH. Never worried about how warm it got just sitting while off after running for a bit. But I digress.
We need a bit more info.
Does it have spark when it won't start?
Does it have fuel spitting out of the carb when you hit the throttle when it won't start?

No fuel spitting out and not sure on spark. I definitely know it won't start when warmed up. After it sits and cools for several hours it will start right up and run great. Ran great last year had it winterized and only changed the oil this year so not sure what caused the issue.

SilviaMan
05-23-2012, 05:26 PM
If no fuel when you pump the throttle I would start looking at the fuel system. Could add a supplemental fuel to ensure it is a fuel issue. (open the throttle plates and splash a little fuel in the intake, close them and install flame arrestor and try to start) If it starts you have nailed down a fuel problem I would say.

SilviaMan
05-23-2012, 05:28 PM
160 is a good temp for the boat to run at with a 160* tstat in it. It shouldnt go much higher than that at all unless you're in water with temps that rival a bath tub.

agreed, I think he was talking about the temp after it sat not running a bit. the temp on mine goes up a bit too. Immediately cools off after start up.

TRBenj
05-23-2012, 05:51 PM
I'm not sure about the full tune up because the boat runs strong with no hesitation for first 20 or so minutes then heats up and quits. Would the fuel pick up still be an issue if it runs strong until heats up?
What are you not sure of about the full tune up? The last time it was done? Because I would recommend one if you dont. Or if its been at least a few years.

Because Ive seen a boat behave very similarly to the way youre describing... ran awesome for 20 minutes, then started to run a little rough and then all of a sudden would not take any load at all- would stall if pushed above idle. If it died, it *might* restart, but no guarantee.

My gut said fuel issue (blockage, carb rebuild, etc). A new cap and rotor fixed it- and the old ones didnt look bad.

So like I said, trying to troubleshoot an engine in an unknown state of tune can be an exercise in futility! Rule out the basics first (theyre cheap and good maintenance anyways) and then move onto some basic troubleshooting.

I have seen overheated coils act like you describe, as well as fuel blockages- sometimes it takes 10-20min to run the bowl down to a level to start cutting the motor off.

cll695
05-24-2012, 10:15 AM
Thanks, I 'll start with the full tune up and go from there. Just tried the 5 gallon bucket deal today and it sucked water up pretty quickly at idle so looks like impeller is working fine. I did notice, however while inspecting the engine a little oil on back lower side where the flywheel cover bolts on. After looking closely I noticed the lower bolt was missing and the cover was pulled away by about 1/2 inch. I am not losing oil though because the dipstick still reads full but I am sure when the engine is running it's throwing some out. Could this cause my problem or something totally different? I am glad the thing quit though because at least it caused me to look at things and I found that big problem. Seems like I'll have to pull the whole back end off and clean up and put a new gasket on and re seal. Thoughts?

cll695
05-24-2012, 11:15 AM
http://www.mastercraft.com/teamtalk/attachment.php?attachmentid=79298&stc=1&d=1337868648http://www.mastercraft.com/teamtalk/attachment.php?attachmentid=79297&stc=1&d=1337868648

Here are a couple pictures of what I am talking about