New Batteries :: 250ProXS Lost RPM's and Top Speed.

[simplecircuit]

Per some recommendations on this board, I recently replaced all three of my batteries with DieHard Platinum 31's.
This added ~75lbs to the back of the boat. Around the same time, I also switched over to ethanol-free 89 fuel [from ethanol-free 87]. The past couple of times out, I've noticed that the boat is coming out of the hole a little slower. I've also lost about 5mph of top-end speed and my RPM's are topping out at ~5500-5600. Would the higher octane gas be causing this sluggishness? Or is it possible that something else is out of whack. Also, would the additional rear weight necessitate a change in motor height? Environmental factors include much colder air and much colder water.
Thanks. j.

2004 BassCat Cougar FTD - 2012 Mercury 250 ProXS

[Savage]

The switch to the 89 octane should cause no issues. Remove the two trolling motor batteries and lake test to see if your performance (RPM'S) returns. Doing this FIRST will help to guide you in the right direction to correct your problem.

[simplecircuit]

Thanks for the quick reply.
I was most curious about the 89 v. 87 gas - hence my post on this board. As heavy as those batteries are, I don't think I'll be pulling them out. I can live with a little slower boat that always starts [knock on wood]. I know this isn't the proper place for the question, but in theory, would going from a 26 to a 25 pitch prop possibly help the hole shot?
thanks. j.

[jbh3]

I'd try removing a PVS plug(s) on your existing prop to improve hole shot. Adding 75# to your battery load shouldn't cost you 5 MPH and several hundred RPM's, IMO. Suggest getting your engine in for service.

[Nova Kaw 650]

If the motor calls for 87, then go back to 87.

[simplecircuit]

Thanks for the suggestions.
Don gave a thumbs up to using the 89 previously since it is coming from a high-volume station instead of 87 from a low volume off brand retailer. As for getting the engine serviced... It was just in for a leaking lower unit seal at the prop [PSA :: please dispose of fishing line properly]. While it was in, they checked the codes and the compression and everything looks good. So, I'm thinking it is something with the weight distribution. I haven't been running with much gas in the tanks, no water in the livewells, almost no tackle up front... So, overall weight shouldn't be that different, but moved further back towards the motor. I'll move the discussion to another board. Thanks for the help.
j.

[echunts]

I have had the same issue. Don checked with mercury and running non ethanol gas would cause this. The motors was programmed to be run on ethanol gas. Don maybe you could add more info on this. l

[iron banks]

I have had the same issue. Don checked with mercury and running non ethanol gas would cause this. The motors was programmed to be run on ethanol gas. Don maybe you could add more info on this. l

Really, never heard this before.

[G Whiz]

How much E-10 was in the tank at the time E Free 89 was added?
Due to environmental conditions the -OH molecules could have separated and created H2O.

[Savage]

Mercury recommends that alcohol free gasoline be used where possible. The motors fuel system components can withstand up to a 10% alcohol content in the gasoline.

Alcohol free 89 is Better than 87 with alcohol....period!

[EuropeanAM]

Mercury recommends that alcohol free gasoline be used where possible. The motors fuel system components can withstand up to a 10% alcohol content in the gasoline.

Alcohol free 89 is Better than 87 with alcohol....period!

Agreed. However... we must also remember that all NTE Emissions engines (latest engine models with new calibrations) were CALIBRATED on E-10 fuel (and will, thus, run best on the fuel they were calibrated for).

I very much agree with your suggestion on the batteries. However- removing JUST ONE of those PM-1 batteries (for test run purposes) would put you back at virtually the exact same weight you were at previously (thus ruling out that as a potential cause of the performance change).

If performance does not return by removing the battery... your problem is elsewhere (start by checking the ENGINE for problems... beginning with the BASICS).

[OHBMQUINN2]

has any one checked the alt output esp when running bat went dead I know that with all of todays electronics 31 are better but I would b checking it out seen this problem before the weight might in theory hurt the hole shot bot not the top end so much ya already have the weight movin my 2 cents if it matters