Strange engine cut out after heating up.

[danzee]

So I hope someone can help me.... We just bought a 1980 Carver Mariner with twin crusaders, old school electric ignition. Starboard motor just starts to cut out after about 20-30 minutes of running. This only happens when we throttle up. We can sit all day long at 1000-1500 rpms and she runs smooth as can be. First 30 minutes or so we can run full throttle smooth and no issues.

On occasion, we have to restart the motor or run on one for about 15 minutes and then it cranks right up again, but cannot run over 1500rpms without sputtering sounds and erratic tach readings?

The motor heats to about 200 when running full throttle and cools to about 180 on low rpms.

We have added fresh gas to what was believed to be old gas and I have replace the filter/water separator and added a rebuilt water pump.

Any help is greatly appreciated!!!

 

[rdc54yty]

Re: Strange engine cut out after heating up.

I struggled with a similar problem on a Chris Craft 340 with twin Penta 350's. Replaced stuff that probably didn't need it, tested ignition, heat, venting probs, all to no avail. Even built the fuel pressure test rig that's described in the adults only section. Before I used it I (finally quit being lazy and) removed the tank pickup - a vinyl tube with a screen in the end. Couldn't even see light through the gunked up screen. It's a wonder it ran at idle. Sprayed it with carb cleaner and the problem went away.

http://forums.iboats.com/showthread.php?t=321445

I could have kicked myself. K.I.S.S. truly applies. A mechanic told me the engines should have backfired as the carb bowl was near empty. It may have but the motors are pretty loud so I could have missed that.

 

[danzee]

Re: Strange engine cut out after heating up.

I read your thread and it sounds just like our problem! Where is this fuel tank pickup? We have a clear tube coming off the base of the carb? Or is this on the tank itself? Strange thing is that we are running both tanks together so it must be a carb hose???

thanks for clarification...

 

[rdc54yty]

Re: Strange engine cut out after heating up.

Pickup fitting is probably on the top of your tank. Pickup tube extends down from the fitting almost to the bottom of the tank, where fuel enters the lines enroute to the carbs. The pickup tube on mine is attached to a threaded fitting that screws into the top of the fuel tank. I used a crescent wrench to remove the fitting and pull out the tube. Mine doesn't have a crossover so your problem could be elsewhere... Maybe switch the coils and the fuel pumps and see if the problem travels to the port engine.