Motor cuts out briefly after about 20 minutes

mrkstr

Hi.  I have a 1999 Rinker 330 Fiesta Vee.  My issue is that when I'm running on plane, after 20 minutes or so the starboard engine cuts out briefly and then kicks back in.  At first, you wouldn't even know its happening if you're not looking at the synchronizer.  After a few minutes, you can see it in the tach.  After that, you can hear and feel it.  The boat will pull to the starboard side for a split second.  Finally, the engine cuts out entirely.  When I stop, it will almost always fire back up after a minute.  I can run as long as I want at 2000 RPM, but if I take it up on plane, or try to, it will cut out again.  It never fails at 2000 RPM or below. There are no alarms associated with this failure. 

Here's what I've tried so far.  I have replaced plugs, wires, rotor and cap.  I replaced the ignition coil.  I have also replaced the ignition sensor under the rotor and cap.  None of this fixed the problem.  The engine doesn't appear to be overheating.  I don't know if I trust the guage, so I hit it with a heat gun, and its fine.  I also tested the fuel pressure.  I'm getting around 50 psi and its not dropping during failure. 

I've gone through more than a full tank of gas with this problem, so its not old gas. 

I'm at my wits end.  Nothing I've tried touches the problem.  Any help would be appreciated.  I'm not an expert mechanic, so I don't mind some detailed suggestions or ideas on testing.  (or if you think I missed something obvioius.)  Thanks in advance.

YYZRC

Sounds like spark if you have fuel pressure. 

mrkstr

Yeah, that's what I thought, but I don't know what else to do.  I have power.  The batteries and alternators are working.  I replaced the ignition coil, plugs and wires.  What else cuts off spark?

YYZRC

Are you certain about the fuel pressure? Sounds like a bad anti siphon valve could be cutting off fuel flow. 

aero3113

Maybe your vent is clogged.Try running with the fuel cap off and see what happens. Also replace your fuel filter.

Aqua_Aura

Look over all your wire connectors and physically try and touch then to make sure they are well connected and not corroded. 

mrkstr

I'm certain about the fuel pressure.  We had a gauge hooked up and were able to duplicate the problem under 50 lbs of pressure.  I have the valve open between the two tanks, so I thought that would alleviate a clogged vent, if that was the problem.  But I'll clean it out anyway.  The fuel filters were almost the first thing I tried.  I will go over the connections though.  I feel like I'm looking for a needle in a haystack.

LaRea

If it's a spark issue, it would have to be something that affects all cylinders at once.  Have you tried using an automotive timing light to check spark?  Clip it on the coil wire and see if it stops flashing when the engine stutters.