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J_Bar

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Reply with quote  #1 
I have a 2007 Etec 250hp on a Blackjack bay boat. I recently bought the motor/boat and immediately brought it to a certified Etec dealer for general engine upkeep...sparkplugs, water pump, filters, lower unit oil etc. I also wanted them to scan the motor. The results of which were fine. 

It's an older boat, and few if any of the gauges work. I installed a NMEA2000 network recently and now have engine info on my GPS. RPM at wot is 5100 with a 21 pitch prop. After consulting with many blackjack owners, I gathered that most boats with a 250 run a 21p prop but see 5700-5800 Rpm and 56-60mph. I'm on pace to 58mph. The engine feels plenty strong while accelerating from a stop and is basically 3k rpm at 30mph, 4k rpm at 40 mph and maxes out at 5,100rpm and 51mph. Its plenty fast, but I'd like the engine and/or prop to be running the way it should.

What's the issue? Is it a prop issue? or is a Plug / coil not firing? If the latter, would that info have shown up on the dealer's scan results report?

Any help would be great

thanks
PhilH12

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Reply with quote  #2 
Check motor height First!  If it's too low, you're dragging a "sea anchor" behind your boat.  AV plate above solid water when on plane and trimmed.  I see 5,500 - 5,600 as Optimum for your motor, so get the height right and then play with props for your particular hull and loading.

Some will and some won't on the EV Diag - Opens or Shorts usually show up, but not "everything".  A "drop test" may be in order if your height is OK.

Phil

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20' Weeres fishing pontoon
90 HP E-Tec E90DPLSUM  05184332
Lake Tawakoni, TX - Catfish Capital of Texas
J_Bar

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Reply with quote  #3 
[1WFNUzq] 

Thanks for the reply! You can see part of the motor height story in this picture by looking at the bolt setting. It appears on the higher side. I realize the pic doesn't show where the cavitation plate sits in relation to the transom bottom. I'll try to get a pic with the motor trimmed down. There is a small possibility that I'm not trimmed out when underway...but I feel like my rpm would still be low even if trimmed out.
seahorse

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Reply with quote  #4 
You may want the dealer tech to check the accuracy of your tach, especially if the speed is where it should be with the same prop as your friends'.

To check that the motor is putting out full power, the tech can also perform a cylinder balance test to check output on each cylinder. Of course, set up and engine height has to be correct.

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steelhead

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Reply with quote  #5 
We need the exact full model # off the motor transom plate.  Serial # will help also to ID lower unit gearcase and if it was changed on factory warranty replacement.  May also have been changed to L2 1.71 gear case by prior owner for extra speed on light boats.

Some of the early yrs large block V6 E-TECs had the Lightning L2 lower unit with the 1.71 gears.  Won't turn as large a pitch prop as all the later 1.85 gear cases.

Have your shop run boat fuel system restriction vacuum and air leak bubbles in fuel test with clear fuel line on motor.  Restricted or aired fuel will cut top speed HP.  Older boats suffer from boat fuel line interior breakdown, dirt buildup plugging of fuel pickup and lines.

What brand motors are you comparing with?  The Suzukis have another gear reduction below power head before gearcase reduction.  They will turn a hellacious pitch prop but it spins at a slower rpm.


tmd11111

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Reply with quote  #6 
Quote:
There is a small possibility that I'm not trimmed out when underway...but I feel like my rpm would still be low even if trimmed out.


Keep trimming out until your rpm's raise and your speed doesn't then bump it back down.  You'd be surprised how much more there may be.  
J_Bar

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Reply with quote  #7 
Thanks so much for the replies

I will work on getting you all the requested additional information. The boat is in storage across town so full model # is unavailable for the moment. The serial # is 05155321.

I hope the issue is not with the engine and/or fuel system, but rather engine/trim position/prop/bad rpm reading. 

If/when I bring the boat back to the dealer, I will have them execute the suggested tests.

Most of the Blackjack owners with whom I have spoken, run Yam 250 and 250 SHO or Merc 250 optimax. The SHO seems to run the fastest (lower 60's). Most everyone with a 250hp is hitting at least 60mph. Also, most all have jackplates. Unfortunately, I have not found any Blackjack owners with an Etec.  

Thanks again. I will keep you all posted
J_Bar

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Reply with quote  #8 
A member of the Blackjack FB page says he gets 63mph @ 5700rpm with a 22p raker with his G1 250 Etec.

Hope to get numbers close to that some day.



seahorse

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Reply with quote  #9 
Quote:
Originally Posted by J_Bar


A member of the Blackjack FB page says he gets 63mph @ 5700rpm with a 22p raker with his G1 250 Etec.

Hope to get numbers close to that some day.





Plugging that into a prop-slip calculator, that equates to just 2% slip. Normal slip is 8-10%

At a reasonable 9% slippage rate, the top speed would be 58 mph

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rickmcd53

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Reply with quote  #10 
A boat with the offset and extra height of a jack plate will run a different prop than a transom mounted engine. First verify your rpm at optimum trim, then try a 19p prop.
J_Bar

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Reply with quote  #11 
Quote:
Originally Posted by seahorse




Plugging that into a prop-slip calculator, that equates to just 2% slip. Normal slip is 8-10%

At a reasonable 9% slippage rate, the top speed would be 58 mph


I try to take a fisherman's word with a grain of salt when it comes to size of fish, speed of boat and draft! 

Rickmcd53, you've got the right idea. I'll work on trim and go from there. Admittedly, I have only owned a tiller poling skiff. It has TNT, but it's much much easier for me to feel when the boat has trimmed out. The new boat has revealed many learning curves!
J_Bar

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Reply with quote  #12 
quick update...

I ran her yesterday evening in the local ditch with the 21p prop that has been restored by a local prop shop. I put the throttle all the way down and when I reached max RPM, I began trimming until there was no more increase in speed/rpm. The RPM needle was still around 5100 with a speed of around 50mph.

I have a new theory which might be far fetched. When bumped out of neutral and into forward, the throttle lever takes a good 30-45 degrees of forward movement before the engine responds. Could it be that the throttle is unable to reach wide open due to improper set up? 

I'm having new controls put in for unrelated reasons, and if the dealer installs it correctly, then perhaps this issue will resolve. While at the dealer, I will have them conduct a cylinder balance test anyway. 

Again, thanks everyone for the 'hand holding' [biggrin]
seahorse

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Reply with quote  #13 
When the new controls are installed, ask your dealer to use the diagnostic software to see the TPS voltage when the throttle lever is at full. 
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steelhead

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Reply with quote  #14 

Also have the shop run a compression test on the cylinders when in for the other tests.  They should also run both ignition and fuel injector drop tests on the water, dynamic in Testing subsection of the Diagnostics SW. 

There are NO cylinder balance tests on E-TECs except for individual cylinder fuel injector enrichment and lean adjustment tests via the Diagnostics software.  Under Fuel Control tests.

rickmcd53

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Reply with quote  #15 
It may just be terminology or me being from back before equipment had automatic cylinder balance tests. Shutting off fuel or spark on each cylinder and noting rpm drop is a cylinder balance test.
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