my engine looses power then gains power again

Tuck

New Member
Jul 12, 2011
1
Missouri
Boat Info
1998, 29 Bowrider
Engines
Mercruiser 4.7L Bravo II
I have a Searay 260 Bowrider with a Mercruiser 4.7L engine. From time to time, when the boat is moving, I will lose power and then get power back. The engine does not need to be restarted and the stall last only a short time.) This can happen at low or high RPMs/MPHs. It seems that the boat will go for a period of time and when this problem starts it will repeat for a while (it will continue to shut down/get going) for a while. Then I may go hours or days without a problem. I have spent a lot of time checking wiring and have found no issues. Do you have any ideas? I'm thinking oil filter. Thanks,
 
Water in fuel or fuel restriction?? I do not see how the oil filter would have anything to do with the erratic power.
 
Water in fuel or fuel restriction?? I do not see how the oil filter would have anything to do with the erratic power.

+1 My outboard did this after I had moisture build up in my fuel tank. I wouldn't add any treatment though as this stuff can cause other porblems. Either run your tank dry (close to empty) and then fill up with good fuel or if you have a fuel filter/water seperator remove the water and run the motor for a short time. Check the water seperator again and see if you have any additional water. If no water look at the fule filter or even possibly the fule pump.
 
I'm thinking oil filter. Thanks,

You could be on to something there. If it's not the oil filter, you might check the air in the trailer tires or it could be the voltage to the horn.:thumbsup:

Is it carbed or EFI? Sounds like a fuel problem to me. Try changing the FUEL filter.
 
What HP oil filter do you have? I put a 4bl oil filter on a 2bl engine once and didn't feel any differance...:huh:

What the........ You spelt differance wrongly! That's not good England!
 
sounds like you are dropping a cylinder possible fould spark plug or bad plug wire
had the same problem this past weekend and found a shorted plug wire.
this will cause most problems under load due to higher ignition voltage required in a load condition
 
Start with a general tune-up. Plugs, wires, cap, rotor. I had that problem for quite a while and the mechanics working on it under warranty (bought it used) couldn't figure it out. I finally tried new plugs and wires after they vehemently denied that it would help and it fixed the problem.
 
Spark or fuel. Plug wires? Plug fouled? EFI issue? Carb issue if you have one? Fuel filter fouled? Water separator filling with water? Check the simple stuff first.
 
I had the same problem with my 60 outboard on a 160 bowrider. The mercury dealer told me that I lost compression on 2 out of the 3 cylinders. Had the power heads rebuilt. Runs fine now but I think I was taken for a ride. They also said the stator was bad. $3400.00 later wish I tried some of the advise on the forum first.
 
Haven't heard of a 4.7 - Sea Ray archives show the 260BR as having a 7.4 MPI engine. Do your gauges do anything strange during the loss of power? A loss of electrical power due to a bad connection can cause strange issues - fuel pump goes out for a second, coil loses spark, etc. I would check and clean power and ground connections in addition to the suggestions above.

98 260 spec sheet - http://www.searay.com/boat_graphics/electronic_brochure/company1729/1C1_27_74DERNWKV946.pdf
 
Just helped a fellow boater with a similar issue. It ended up being a combination of three things...

1. Cracked distributor cap
2. One spark plug boot on the distibutor cap allowed an arc to the nearby coil, grounding that wire
3. Two plugs were badly fouled probably since the gap was too large

At first we thought it was a fuel issue, but after inspecting all the filters/check valve that theory was eliminated.
 

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