Mercruiser 140 stalling problem

[j4ivi35]

Hi, I have a 1975 tahiti whit a mercruiser 140 in it. The problem is that after about 5-10 min of running the engine above idle it will bog and stall. And engine vacuum drops every time this happens im not sure it that causes it to stall or happens because of the stall? When it dies it will start right back up if you spray some starting fluid in otherwise you have to let it sit for awhile. It has new plugs, wires, cap, rotor, points, condenser, new fuel line from tank, just rebuilt the carb, and new fuel filters. And the timing is set to 6* BTDC. Just to be sure the #1 cylinder is the one closest to the stern? I dont know what to try anymore?

 

[WillyBWright]

Re: Mercruiser 140 stalling problem

The cylinder closest to the stern in #4. #1 is in front. But I'll bet your timing will be the same when you flash off of #1. I'd retard that timing to 2 degrees instead. Today's gas can cause problems at old timing settings.

 

[Bondo]

Re: Mercruiser 140 stalling problem

Ayuh,.........
But,...... It sounds like you have a Fuel Delivery Issue........

 

[j4ivi35]

Re: Mercruiser 140 stalling problem

So should i replace the fuel pump? I've tried running it with the gas cap lose and off to make sure it was venting. Is there a way to convert to an electric fuel pump on that engine?

 

[JustJason]

Re: Mercruiser 140 stalling problem

make sure your timing is correct before you do anything... remember this... timing before fuel!!!!!!!!!!

 

[Haut Medoc]

Re: Mercruiser 140 stalling problem

So should i replace the fuel pump? I've tried running it with the gas cap lose and off to make sure it was venting. Is there a way to convert to an electric fuel pump on that engine?

There is no need to convert to an electric fuel pump on that engine.....
It will not help any more than a new mechanical fuel pump, if that is your problem.......
What happens when you restart it?.....
Will it do the same thing, & if so how long does it take the second time around?........
I'm thinking that I would be looking at the anti-siphon valve or the tank pick up screen.......
For your case, I would get a portable six gallon tank, connect it to the new fuel hose & with fresh gas see if you can recreate your symptom.....
If not, you will know where to look......

 

[j4ivi35]

Re: Mercruiser 140 stalling problem

If i try to reastart it after it dies it will not start without starting fluid and it needs a good amount as well. But once it gets running it lasts about the same. Let me clear it up it will run for 5-10 min in the no wake zone but trying to leave the no wake you usually get no more then a hundred yards till it dies, and if it doesnt die letting of to turn around almost always kills it.

 

[jimmytee]

Re: Mercruiser 140 stalling problem

try the portable tank. I was told to do that and didn't; I swore it was something else. It wasn't. The last thing I tried was the tank and that was it. Not sure exactly what part since I shotgunned it with new tubing, anti siphon valve and installed a water separating filter while I was at it. Either a combination of rust in the tank or the valve, but either case, fuel delivery.

 

[j4ivi35]

Re: Mercruiser 140 stalling problem

Thanks to everyone for the help it really helped. I never woulda thought to check the pick up tube in the tank and that was the problem it was all cloged and gummed up. All that work and it was a little $8 part. Thanks again!n