View Full Version : stall

01-28-2006, 02:46 AM
Hell I have a 78 stars and stipes it stalls when it gets hot. If I let it set and cool off it will run fine till it gets hot agin don't know if it relly has anything to do with the heat. could it be vapor lock. thank for your help.

01-28-2006, 05:18 AM

01-28-2006, 09:47 AM
Did you recently do an electronic ignition conversion?? If so I would say you forgot to remove the ballast resistor.

01-28-2006, 02:02 PM
Thank you for your reply!
No do not have electronic ignition conversion. However I would lik to. Do you have any thoughts.

Hoosier Bob
01-28-2006, 02:09 PM
I had an older CC that would do it. Moisture in the distributer. After awhile engine temp would rise and steam would accumulate on the inside of the cap. Blew it out and after awhile no problems. How the moisture got in there was beyond me but it is a boat. Just a thought.

01-28-2006, 02:12 PM
thanks great point I did not think about that but it make sence

01-28-2006, 03:27 PM
78skier- what service work has been done to the motor in the last year? That will help in finding the problem.

01-29-2006, 04:39 PM
I gave it a compleat tune up plugs, timing, carb ajustment, fuel filter, oil cahange, so on.

01-29-2006, 11:38 PM
Anybody out there ever drill a small whole in the cap to allow moisture to evap? Just an idea...:banana:

88 PS190
01-29-2006, 11:40 PM
and all that moisture that is going to make its way back inside.

Check to make sure the seal is intact. and perhaps open it up and let it evap on a hot sunny day.

But then make sure its sealed up.

01-30-2006, 11:58 AM
Anybody out there ever drill a small whole in the cap to allow moisture to evap? Just an idea...:banana:

I think the cap is supposed to be sealed to prevent the ignition of bilge vapors. There are two screens on the bottom of the distributor.

01-30-2006, 12:25 PM

01-30-2006, 02:13 PM
When it's hot and won't fire you need to determine if it's a fuel problem or an electrical problem. I suggest you test for spark when it won't fire. You can do this by pulling a plug and then putting the boot back on and grounding the plug while cranking. It you see a good spark then it's probably not electrical. If you get no spark I would suspect the coil as they sometimes start to fail when they get hot if they are on their way out. If you have a good spark then it's got to be a fuel problem and if you have the old 4010 carb then I would suspect that's what it is. The 4160 seems to be a better choice.

Do that test and let us know whay you find. It's easier than shooting in the dark.



01-30-2006, 07:07 PM
Yes I did that I did have spark I think it is the 4010
I would like to put fuel injection on it anyway so I may just do that Any one have any thoughts on that However there is something about the sound of a carb but there is something to say about fuel infection

88 PS190
01-30-2006, 08:19 PM
Fuel injection has a few issues as far as retrofitting it sucessfully, it can be done but it can be trouble.

01-30-2006, 10:46 PM
There are aftermarket systems available that have been pretty well debugged. Edelbrock is one of the companies selling them. The fuel mapping is the main issue and it's really not that hard to adjust. The mechanical fuel pump will have to go, though.

01-30-2006, 11:01 PM
Ya I would like to have an electronic fuel pump any way so that would be cool with me
some say I might loose power I'm not so shur that is true. Maybe I to young to understand I know fuel injection.

01-30-2006, 11:48 PM
Why would they possibly say you would lose HP? Because the injectors don't just dump a buttload of gas down the intake when the throttle is opened? The fuel mapping can be set up so there will be no difference in top HP. Might even get more due to not running rich or lean at WOT. EFI isn't terribly complicated.

Remove the knock, MAP and Throttle Position sensors, get rid of the ECM and swap the intake/injectors with a carb. What do you get? A working motor, just less accurately controlled than before.

88 PS190
01-31-2006, 01:28 AM
What about the wet exaust issues? Don't most fuel injection systems want O2 sensors or have you found a marine that solves this.

That's the main issue i've been seeing, being unable to set up w/ O2 sensors past the manifolds.

lemme know.

01-31-2006, 02:07 AM
EFI doesn't need to be closed loop. None of the MC/Indmar motors have O2 sensors, as far as I know. It's a matter of the program running on the ECM.

01-31-2006, 02:37 AM
The TBI type of EFI is so basic it doesn't rely on input from sensors. They just have a basic program in the ECM for typical conditions. Take the boat to a high elevation & the boat doesn't have a clue & may run like crap till the ECM gets updated somehow.

02-02-2006, 12:50 AM
I would run a stand alone system then the ECM would not mater. It would not read what the sencers tell it. You can hook up a laptop and and tell it what you want it to do.


02-02-2006, 01:07 AM
Airjunky- The ECM takes a barometric reading every time the key is turned on, via the MAP sensor. At high elevation, the ECM definitely adjusts the fuel input. The motor won't develop the same HP as at sea level because, with less air, there isn't as much fuel required. The ECM absolutely relies on sensors. The Map gives it vacuum info, the ECT tells it the coolant temperature and the fuel mapping is partially determined by that, the TPS lets it know if it's at idle (<2% throttle) and when there's > 20% change in throttle position, it either enriches the fuel or leans it out. Also, if the motor is overheating, the ECM goes into RPM reduction and shuts off alternating injectors. The ECM also retards the timing when there's input from the knock sensor in 5 degree increments until it reaches base timing.

I don't know where you got the info about TBI not running off of sensors, but it's wrong.

02-02-2006, 01:11 AM
78 skier- As far as I know, there isn't a stand alone fuel injection system without electronic control. There were mechanical injection systems in the late 50's and early 60's, but they went away due to being finnicky and people don't generally want touchy cars. Some don't seem to mind, but they're in the minority.

88 PS190
02-02-2006, 02:22 AM
mechanical injectors are brilliant, like on the 300SL Gullwings. just have to be done properly, and its not like working on a carb.

02-02-2006, 07:08 PM
Thanks Jim for the input your right I did not mean the ECM would not mater for the hole motor I should have clarafied. I dont know as much about these american motors as I do Datsun Z motors import racing motors like the RB26dett and the L28et they make stand alone fuel management systems for the imports. Many things are the same on amirican motors however many thins are not. And I am no expert. :) And your right it is electronic control you must change much of the electronics to make it work.
Thanks again great point.

02-02-2006, 07:16 PM
I don't know where you got the info about TBI not running off of sensors, but it's wrong.
I stand corrected, Jim. This is info I was told by Indmar. Guess I'm wrong.

03-03-2006, 09:13 AM
To get back to the 'stall' problem, I had a similar problem last summer, it ended up being the fuel pump, but it just happened to correlate with it warming up and going to WOT.