engine losing power

[cmcpherson]

I have a 1998 Monterey 236BR with a 5.7 carb engine with a Bravo 3 drive. Yesterday while out on the lake, the boat started hesitating, while moving at any speed I would suddenly lose RPM's, momentarily. The engine sounds like it is running fine. To me it feels like a fuel problem, my fuel gauge was jumping around quiet a bit, nothing really unusual though and the tank is about 3/4 full (not relying on the fuel gauge). Last night took it out again on the river to go to dinner and and it was doing this even more often. After leaving from dinner, the boat sat for about 1 1/2 hours while we were eating, no problems at all. The only difference that I noticed was that the gas gauge was not jumping around at all. Like I said feels like a fuel problem to me, I don't think it is a fuel filter problem because I think that would be more consistent. Almost reminds me of the old vapor lock days with cars in the heat. Any thoughts?

 

[Coors]

Re: engine losing power

Water in the fuel, and a bad connection to the sending unit?

 

[cmcpherson]

Re: engine losing power

Any other thoughts?

 

[Don S]

Re: engine losing power

Start it up and do a wiggle test on every connection on the engine. Also check any harness connections under the helm, along with checking fuses for corrosion etc.

 

[cmcpherson]

Re: engine losing power

Well, I put water evaporator in the gas did the wiggle test and looked at all the fusesm, the problem seems to have stopped for the time being. We shall see...

 

[cmcpherson]

Re: engine losing power

Took the boat out tonight, ran fine for about 10 minutes it sputtered and died. Took me about 5 minutes to get it restarted, ran fine for a couple of minutes died and I could not get it restarted, did not want to turn over. Got a tow back to port, any other thoughts?

 

[Dakota47]

Re: engine losing power

Clean the carb & put in a new Fuel filter..

 

[ziggy]

Re: engine losing power

since it didn't want to turn over. ya might try pulling the sparkplugs and see if it turns over. or if any water comes out of the sparkplug holes........or maybe dons' trouble shooting your engines starting system.....http://forums.iboats.com/showthread.php?t=167035

if yer thinking water in the fuel. ya might try a remote fuel tank with some nice fresh, for sure, non water contaminated fuel.......but since it didn't want to turn over, i wouldn't think fuel is the issure..........

 

[cmcpherson]

Re: engine losing power

Ok, my mechanic is telling me their is water in the cylinders and he wants to pull the engine to check the heads to see if there is a cracked head. Need help quick!!!!

 

[cmcpherson]

Re: engine losing power

any thoughts?

 

[cmcpherson]

Re: engine losing power

Does this sound reasonable?

 

[cmcpherson]

Re: engine losing power

any help????????????

 

[Haut Medoc]

Re: engine losing power

No.....
If you have water in your cylinders, I would be inclined to think that you have a bad riser or exhaust manifold or the joint between them.....
Is there water in your oil?.....​

 

[cmcpherson]

Re: engine losing power

doesn't seem to be water in the oil.

 

[Haut Medoc]

Re: engine losing power

If you only have wate rin the cylinders on one side, I would pull the riser & look for a badgasket/joint where the ex manifold & the riser meet.....
If you had a cracked head, you would have water in your oil.....
If your manifolds/risers are the original ones, they are due for replacement, esp. if you boat in salt water....
Check your manifolds/risers....​

 

[cmcpherson]

Re: engine losing power

no salt water, but you are right about the manifolds and risers. what about the varying compression?

 

[cmcpherson]

Re: engine losing power

sorry for the bump, but would a manifold or riser problem cause compression to be off???

 

[Haut Medoc]

Re: engine losing power

No, they would have no effect. on compression #'s.....
I did not see where you posted about bad/low compression?....​

 

[cmcpherson]

Re: engine losing power

sorry about that, you are correct, I thought I had mentioned in one of my posts that he said the compression was kind of all over the board on both sides everyone being over 150 though.

 

[cmcpherson]

Re: engine losing power

seems to have multiple problems, turns out the water in the cylinders was due to a bad exhaust flapper. My mechanic had the loss of power narrowed down to either a bad/dirty carb or the ignition control module.