350 MAG Tach Jumping and loss of power

DS24

Hello all,

I have a Rinker 232 Cuddy with a 350 MAG MPI.  Recently, while using the boat the Tach began jumping all over and the boat would randomly lose power when under power.  If I brought the throttle back quick enough the boat would stay running.  If I didn't it would die but start right back up.  It was fairly consistent every few minutes or so.  I just purchased the boat and this was the third time I have had it out.  Problem did not exist in first two outings.  Any ideas?  I wondering if it could be related to a failing ignition coil.

Thanks in advance!

aero3113

Could be the coil, also you can possible have water in your fuel. Try changing out the fuel filter first,cheap and easy.

DS24

I just changed both filters right before I went out.

Dream_Inn

First off, welcome to the forum & congrats on the new boat!

It could even be a bad ground.  My instincts tell me it's something electrical.  Even a bad connection at main wiring harness connector on engine.

Lake_Bum

My last boat had started doing that, it turned out to be the anti-siphon valve had gone bad in the fuel lines. If it did die, it really made it seem like a vapor lock situation, but it was EFI... 

MarkB

Was the tach the problem, or where the rpms really jumping all over the place ... ie. how did the engine pitch sound ... if it was really happening, you'd hear it.

DS24

Lake_Bum said:

My last boat had started doing that, it turned out to be the anti-siphon valve had gone bad in the fuel lines. If it did die, it really made it seem like a vapor lock situation, but it was EFI... 

Lake_Bum...when you had the problem would the boat start right back up?  

DS24

MarkB said:

Was the tach the problem, or where the rpms really jumping all over the place ... ie. how did the engine pitch sound ... if it was really happening, you'd hear it.

MarkB...the RPM's did not jump, it was a strictly a gauge indication problem.

Robs_232

I agree it sounds electrical. I would pull the 10 pin electrical connection for the engine like DI mentioned. It is at the back of the engine; big wire loom that has a boot cover with a hose clamp on it. Pull apart and check for corrosion or moisture in both female and male ends, take a very small flat screwdriver and slightly spread the male prongs as they have a slit in them. Clean any corrosion with electrical contact cleaner spray but be careful with it and read directions, let dry and apply di-electric grease to prongs and where cover boot seals. Moisture in any of the electrical connections can cause things to ground or short out.

Robs_232

BTW welcome to the forum. You should also do a search at top of the page just below where it says Rinker Owner's Club Forum.  Enter intermittent engine shut down or something like that. It think we have discussed this in the past and actually I think I may have had similar issues with my 2004 232 with 350 MAG MPI.

mattie

Lighten the mood a bit. When our kids were little on our 07 246 we had stuck a few TB burritos on the intake manifold to warm up for lunch. The foil made the tach go wild while underway.