F36 440's running weird

alexander38 · Post by **alexander38** » Mon Jul 19, 2010 1:42 pm

My money is on gas. Bad gas or corn gas. You said that you had old gas in that tank right? have you take another fuel filter off and checked it ? I know I beat this gas stuff to death but corn gas and worst yet old corn gas has cost me upwards of $2500.00 bucks in 18 months

and most of it was from one bad tank of gas. What kind of filters are you using ? ECU I doubt it most of the older ones shut down when they get hot, and then cool off and work again until they get hot so on and so on....

stevocom · Post by **stevocom** » Mon Jul 19, 2010 3:11 pm

I have changed the fuel filter twice,drained it several times. No water ever. Little bebris. I have also ran the star motor of the port tank and same issue's. Remember the port motor runs fine with no issues. ECU, you say it will "shut down when hot" Will it surge from 1500-3000 rpm when hot? Or just shut down? I guess i can swap the ECU units and possibly eliminate that from the list. I am installin a new fuel pump this eve as well.

alexander38 · Post by **alexander38** » Mon Jul 19, 2010 7:22 pm

What kind of carb do u have ? Do they have inlet filters? And good ideal on ecu

stevocom · Post by **stevocom** » Wed Jul 21, 2010 9:57 am

Carter Carbs with no inlet filters. Well I changed out the fuel pump, did a shake down last night and all seems well, at least for now.

alexander38 · Post by **alexander38** » Thu Jul 22, 2010 7:33 pm

take the pump apart if you can, no real reason but the rubber is most likely ate up. Do you have Two engines right? I'd change the other one too, I did it the hard way changed one put the other off and when I was 80 miles from homeport on a Friday afternoon it bit me in the a$$..

stevocom · Post by **stevocom** » Sun Jun 19, 2011 9:52 pm

And so it begins again. Well another new exciting season in the great lake of Erie and my real first time on the lake this year after I thought my weird running issues were a thing of the past after the new fuel pump and 60 some hours of great running motors, its back. Starboard motor is doing the
exact same thing again. Runs fine at a high idle and stalls out under power. Arrrrrrrr, please help.

Big D · Post by **Big D** » Sun Jun 19, 2011 11:00 pm

Start over from the begining; you must isolate the engine from the vessel to determine if it is a problem with the vessel's fuel supply hardware. Shut your fuel valves off, remove the fuel feed hose at the fuel pump, hook up a portable fuel tank with fresh fuel to the pump. Use caution here; tank should be above deck and ventilate ventilate! Run the engine and see if it gets to WOT. You have two engines, if starboard starts dying, let it. When it quits, quickly check to see if you're getting spark. This will at least tell you that the vessel's fuel delivery hardware is OK and whether ignition is cutting out on you. Let us know what you find.

prowlersfish · Post by **prowlersfish** » Mon Jun 20, 2011 8:20 am

Sounds like a fuel issue again , start with the filter and look for water in it. I agree with big D but would do the filter first as it should be change yearly anyway and with todays fuels

stevocom · Post by **stevocom** » Mon Jun 20, 2011 10:08 pm

Big D will try the portable tank this week. I had also noticed the starboard runs super rich, almost seams as if it floods out the motor, so how can I starve a rich motor of fuel? Also noticed when I juice the port it stalls the starboard, hmmmm. I run all fuel cocks to there open position.

Big D · Post by **Big D** » Mon Jun 20, 2011 10:18 pm

Shut the "crossover" fuel valve off so that each engine can only feed off it's respective tank. Sounds like you may have carb issues. Have you set idle mix properly? If so, could be a carb issue, choke, fuel pump over-pressure, stuck float, engine running cold etc etc.

TJWells · Post by **TJWells** » Wed Jun 29, 2011 2:15 pm

You really need to determine if this is fuel or spark related.
1. When the engine acts up, let it shut off or shut it off when it's at it's worst. Go to the carb on that engine take off the flame arrestor, and hold the choke open. Have someone pump the throttle on that engine. See if the accelerator pump is squirting a clean straight(no air bubbles) stream of fuel into the venturis. the acc. pump is on the front section of the bowl.
If you have fuel starvation issues your fuel bowl will be dry and the pump will be spitting a mist of fuel and air.
2. Check for spark. you will see a bright blue spark. I wonder if your coil is dying. ign. coils will run fine under light load and miss badly when under heavy load. So when your running and the coil is marginal, the engine will seem to run very rich and no power. Easy enough to check, move it to the other engine see if the problem follows. Ign. control modules on these are usually fly or die. When they quit they quit. Again you can switch it to the other engine, but only try one part at a time.
I've just gone through something like this on my boat 79 f30 318's.
Good Luck! Message me if you need help with this.

TADTOOMUCH · Post by **TADTOOMUCH** » Thu Jun 30, 2011 4:31 pm

I had a similar problem to you with my F-32. I had fixed a dirty tank and eliminated that problem and then I had a bad ballast resisitor on my Chrysler M360 250 hp engines. When the engine got hot the ballast resistor would short out and I would lose spark. The part is only about 11 to 15 bucks and is worth a try. You could also switch with the one on the other engine and see if the problem moves to the other engine before buying a ballast resistor. What engines do you have. Chryslers are well known for the ballast resistor problem. It is a rectangular white ceramic block located at the rear of the engine under the ignition box cover. It only takes about 15 minutes to change out.

stevocom · Post by **stevocom** » Sat Jul 02, 2011 10:41 pm

Hei. No ballast. Arrrrrgh, this is really getting to me now. Spark is great. Idle's great, tacs up great with No load, under load, loads up and stalls, will only run to 1300 rpm. Carbs? Can this entire starboard issue be in the port? Can The port starve the starboard to stall? By the way I I have full power and I mean runs super strong up to 3k, then 2 min later craps out.

Big D · Post by **Big D** » Sat Jul 02, 2011 10:58 pm

If you shut the crossover fuel valve off as suggested, the other engine should not be causing the problem. Did you try the portable fuel tank? If it dies, you need to pull a plug wire right away and see if you have spark. Just doing these two things will tell you a lot.

PS; ventilate, be carefull with an open spark and portable tank. Really should use an inboard marine rated spark tester for this reason.

prowlersfish · Post by **prowlersfish** » Sun Jul 03, 2011 8:35 am

Do you have a engine synchronizer ? If so disconnect it , its about the only thing that will cause one engine to effect the other , I have seen it happen more then once . As far as the one engine running rich (flooding ? ) make sure the choke opens if it is then it sounds like you need carb work and if its really flooding it needs to be fixed before using the boat could be a safety issue

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