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1973 Stalling After Running

Posted: Mon Jun 15, 2015 3:04 pm
by Nicksdad
Hi, I am new to the forum. I have a 1973 F30 w/Mercruiser 305's. The STBD engine stalls only after going out for any amount of time,
then on the return in the no wake zone at 1000 RPMs, it stalls....Every time. Normally It will start right back up, and return with
no issues. The engine will idle forever at the dock and runs great! I changed the plugs. It needed a raw water pump, so I switched
the old one to a CS driven one. One neighbor says to change out the points for Pertronix, another neighbor say No. Looking for any ideas to help.
I have a disabled son who loves my boat, but I need to fix this to take him out.
Thanks!!
Dave

Re: 1973 Stalling After Running

Posted: Mon Jun 15, 2015 6:07 pm
by P-Dogg
Welcome to the forum. How many hours on your engines? Fresh water cooled? Raw water? Recent risers?

Sounds not unlike the symptoms of my 30 year old raw-water cooled engine as the block was dissolving. Are the plugs rusty? Did you pull them and crank the suspect engine over? Loosely place paper towels over the plug ports to catch what is coming out, if it is anything besides air. Is the oil milky? Have you changed the fuel filters? All of them, including the tiny one at the carb (if so equipped)? Switched fuel supply from one engine to the other, so you know if it is fuel feed related? Does it run in gear but not in neutral? Neutral but not in gear?

The above items are either practically free, or worth doing anyway. And more data will result in more accurate armchair troubleshooting....

Did a search of "boat engine runs wide open stalls at idle"

found http://www.thehulltruth.com/boating-for ... -help.html

Re: 1973 Stalling After Running

Posted: Mon Jun 15, 2015 8:17 pm
by bjanakos
Had a similar issue with my Slickcraft using the same motors....

The boat would start and run and haul ass. But the port motor would sometimes stall for no apparent reason while trolling, and I could almost count on it to stall upon return and at a critical point during the docking procedure.

Ended up being a points/dwell issue.

Re: 1973 Stalling After Running

Posted: Mon Jun 15, 2015 8:36 pm
by prowlersfish
Are you coming off plan suddenly ? Try slowing down off plane slowly . When you come of fast , you have a hot engine and you suddenly reduce the water flow by reducing rpm . And it heats up monetarily

Re: 1973 Stalling After Running

Posted: Mon Jun 15, 2015 9:17 pm
by CaptG
I switched my points distributors to Pertronix and have been real happy with results. I do have different engines, but don't see that it would be any different.

Re: 1973 Stalling After Running

Posted: Mon Jun 15, 2015 11:24 pm
by captainmaniac
To Prowler's questions... how quickly are you dropping throttle? Yanking it back can be a case of simple fuel starvation, timing, or accelerator pump. If you throttle back slowly, wondering if you have a choke issue that it juts closes and shuts you down.. but restarting resets it? I have had issues with lack of timing advance in the past but they typically were related more to lack of acceleration or being able to get RPMs to proper cruising range. Shutdown on deceleration is more likely loss of fuel or oxygen to the carb.

Re: 1973 Stalling After Running

Posted: Tue Jun 16, 2015 9:32 pm
by Big D
Above are all valid points. Also check your advance weights/mechanism and make sure they are springing back easily. If not, they can be sticking in advanced position at higher rpm and not returning for a while when you throttle back.

Re: 1973 Stalling After Running

Posted: Fri Jun 19, 2015 8:04 am
by Nicksdad
Thank you all for your assistance. I will try to answer each question. The plugs were replaced last May. I have not checked them this year. I changed all the fuel filters last month.
I've only owned the boat since 2012 so I don't know the hours on engines. They seemed well maintained when I bought it. I don't put a lot of hours on them relatively. When returning from the bay, I throttle down from 2800 to 1400 I guess fast. It stalls after about 3-5 mins at 1400-1000 rpm in the pre no wake zone. The boat is at my shore house so I only get it work on it/test it on weekends. I'm going to try all of your suggestions tomorrow and see how it goes. I may install the Pertronix at some point too. I don't think it can hurt, even though my neighbor says points are much more reliable and repairable. I will also try to throttle down much slower and see what happens as well.

Re: 1973 Stalling After Running

Posted: Mon Jun 22, 2015 3:18 pm
by lawyerdave71
Been there done that - I had similar issues and I say its the carburetor. Had both of mine rebuilt and professionally dialed in and no more stalling issues.

A bad carb can mess up a new set of plugs rather quickly,

Re: 1973 Stalling After Running

Posted: Mon Jun 22, 2015 9:40 pm
by wetbuoy
I just wrote for help and accidentally erased the message and found yours, similar to mine. My F28 stbd would idle fine then run well for some time, then stall usually as I was trying to back in my slip. Excellent. Think we traced it to the coil overheating due to poor cooling (bad impeller), and some assorted ignition issues. I have put in new Flamethrower Distributors with electronic ign. modules and no more stalling. Also carb rebuild kit is around 35$. Had to match the coils and wires and distributors for correct resistances but great now.
Good luck,
Wetbuoy

Re: 1973 Stalling After Running

Posted: Mon Jul 06, 2015 8:48 am
by Nicksdad
Hi All, the problem continues with a twist. I changed the fuel water sep. filter and inline fuel filters again, and the dist. condenser too this past week. Added a good amount of StarTron fuel treatment, and I cleaned the points. She ran great as usual out on the bay, I came off plane very slowly and ran at 1200 rpm longer than normal all the way thru the no wake zone. Both engines stalled at the usual spot (about 15 mins at that speed)! The port side started right up and ran for about 5 mins alone, the STBD side, started right up in my lagoon and I brought it back to the dock. Unreal. I think I may do the Electronic ignition conversion on the STBD engine. I'm at a loss. Both engines ran beautifully. I have dual points with all ACCEL parts. So frustrating with a short season in NJ. I would try a mechanic but no one can recommend one in my local area.

Re: 1973 Stalling After Running

Posted: Tue Jul 07, 2015 6:36 am
by Big D
Do they start running poorly right before they stall or do they run fine then suddenly quit?

Re: 1973 Stalling After Running

Posted: Tue Jul 07, 2015 8:03 am
by Nicksdad
They just die. This is the first time ever the port side stalled. The Stbd side has done it all season. And it makes no sense to me that you can
restart them, and they run fine (better than the alternative of just not restarting), but its driving me crazy. Also, the fact that it dies in almost the
exact spot every time is really frustrating.

Re: 1973 Stalling After Running

Posted: Tue Jul 07, 2015 1:25 pm
by Nicksdad
Just a thought. Is it worth it to change out the thermostat? I've only owned the boat 4 years, so I don't know the age. Could the engine be heating up in the creek/no wake zone after running?
I'm so desperate that I will change anything out if it's relatively inexpensive.

Re: 1973 Stalling After Running

Posted: Tue Jul 07, 2015 3:47 pm
by trojanwars
Hello,
This might sound crazy but it just might be two things that can be hard to figure out, First, it could be the ballast resisters that regulate the voltage going to the coils but it could be a thing called an anti-perculator valve on the carbs, when engines are hot and idling or low throttle the fuel can boil in the bowls and will make the motors stall, they will start right back up.