BigChief

Before I get into the problem, let me tell you guys about my boat. It's a 1997 Donzi 28zx with a 509ci custom motor (carbed) with a bravo I drive. The first 20 minutes that the boat is on the water it runs 100%. After the 20 mins I notice a slight problem which increases as time goes on. The boat will be cruising at around 4000 rpm, I would hit a small wake ( not even bringing the prop out of the water) and the RPM's would kick back 500-1000, then instantly come back to where it originally was. ( note- the boat did this by itself..I did NOT touch the throttle) I had the same problem with my old engine,that was originally in the boat so I know it has to be with the drive.(same drive different motor) What could it possibly be?? I had the fuel pump replaced.. J.I.C, and the floaters checked.. and pretty much anything else that could cause this problem with the engine. The engine is brand new, only 4 hours on it so far. ( Could the drive be responsible for this problem???( is there somekind of shut off switch that could be cutting the fuel?) Could there be a problem with the fuel lines? PLEASE HELP.. I am desperate!
Thanks
JP

Turbojack

could be a fuel problem or electrical problem with the boat. I do not think it is the drive

Pwrbt33

iTrader: (2)

I had a simular problem with a Cigarette. Evrytime I went over a wake the one motor would loose rp, and come back. After checking everything out, it seems as thought the 10 gauge wire that feeds the back of the key switch was loose and moving around.

Just my 2cents worth.

Pwrbt33
Offshore Performance
1-877-GOFAST1
410-827-0200

MACDAD260

It sounds electrical to me. Loose wire somewhere. Check all the wires under the dash that go to the gauges and switches. I don't know how a drive could cause that unless it is locking up. You would know about that real fast because it you would not get very far. Good luck.

Daytona30mike

Watch the tach closely and see if it drops or jerks quickly. ...that would indicate
a short in the wiring. Check your other gauges that are electical for the same.

Then check fuel floats again...going over a wake would rock the boat enough
that if the floats were a little high, you would get a flooded condition for a
very short time and then it would clean out.

It kinda has to to be one or the other.

Mike

BigChief

The tach Jerks back, then comes back right away. Where should I look for a short or lose wire? Behind the tach itself, or a wire somewhere closer to the engine?
Thanks guys..

JP

JaayTeee

Does your volt, temp, or oil gauges
fluctuate or flutter when this "cut out" occurs ?

If so, your having a problem in the
ignition switch ( which also usually includes
the kill switch, also) circuit.


keep us posted.

jt

Daytona30mike

BigChief: For sure sounds like electrical now that we know the tach jerks. Just
check wires behind dash and on your coil, ignition, and even ground wires. It has to be in there somewhere. Let us know what you find.

Mike

Hey jt29olhp500s: Good one on Vandelay...always one of my favorites!!! Only George!!!!

SmallPP

My Formula was doing this and it was the wiring on the ignition switch. The only thing which can drop the tach is ignition power or ignition signal source.

sonic28

if you have a rev eliminator it could be defective. but go with the other threads first.