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1998 Evinrude 115 hp Intruder V4, WOT RPM concerns

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Bransid

New member
E115GLECM. New to me boat. VRO needed to be replaced (seller had been running premix), so I had my mechanic do that with a brand new kit. First time taking the boat out to do a test run after mechanic installed the VRO, it started easily, had a slow hole shot, would not creep over 4300 RPMs on the tach at WOT, and topped out at around 36 mph on my gps. This was a relatively light load, just my wife and I, a full tank of gas, and no cooler, fishing gear, dogs, etc. I inspected the exhaust port on the engine, and it was caked with what looked to be carbon buildup which I thought to indicate the engine was overpropped and lugging. Propeller was a 14x19, so I swapped it for a 13 pitch at the recommendation of a local propeller guy.

Next time I ran the boat, 2 guys, loaded with a cooler, full tank of gas, fishing gear, its hole shot was GREATLY improved, however, other than an initial jump to 5500 on the first rev when laying the throttle down, it reduces back to 5100 RPMS at WOT. Top speed is roughly 31 mph with the 13 pitch. I still feel like I am leaving RPMs on the table. I boat in freshwater at about 3,000 feet over sea level. I also noticed that, while idle seems to be smooth, the engine seems quite rough at real low forward speeds.

Is this what I should expect?


  1. Boat is a 1998 Alumacraft Trophy Sport 175 ~ 1100 lbs
  2. Engine weighs 319 lbs
  3. Kicker weighs 108 lbs
  4. Fuel @ 23 gallons ~ 200 lbs
  5. Gear ~ 50 lbs
  6. Guys ~ 400 lbs
-----------------------------
~2,177 lbs

The engine has good compression, new spark plugs. Seller stated he had just had new carbs put in. I am going to replace the fuel filter. Fuel lines appear fine, but I'm not super knowledgeable with outboard or marine repair in general, and this is my first outboard. I am also considering removing and cleaning the carbs thoroughly, but hesitate considering they were apparently just replaced earlier this season.

Am I overthinking this? For an engine that is rated for WOT from 5k-6k, I am "just there", but I would have thought dropping from a 19 to a 13 pitch would have been more dramatic RPM-wise. The condition of the 19 pitch was pretty poor, and makes me wonder if it was the original prop that was outfitted on the boat in 1998 -- can anyone here speak to this? Alumacraft customer service has not been helpful. If that is the case, and this boat was designed to be pushed by a 19 pitch, I am not sure where I should begin to troubleshoot the engine's performance.

I have a factory service manual and a seloc manual.

Thoughts?
 
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Hi Bransid, I'm experiencing a similar situation but not quite as extreme. I recently purchased a Kenner 18.5 ft. center console with a 1998 Evinrude 115 SPL. Someone had installed a 13.5" x 16 pitch 4 blade stainless prop and the boat would only get 4400 rpm's and 32 mph.

I purchased a Solas aluminum 3 blade prop 13.25" x 17 pitch. ​
I made my test run yesterday and improved both low end and top speed - 5000 rpm and 36.5 mph with good power through out. I think a 15 pitch would increase the rpm more into the 5400 range and probably increase the top end.

I'm not sure of the difference between the 115 Intruder and the 115 SPL other than the SPL is designed for pre-mix (no VRO). I've done a lot of research on this engine and seems that 1998 was a kind of a transition year for Evinrude. They were beginning the Ficht technology but I don't think it was implemented until 1999 (I could be wrong).

You didn't mention if the prop you have is a 3 or 4 blade but I would run a 3 blade 13.25" 15 pitch prop. I always thought a 4 blade prop would provide better performance and was surprised that the 3 blade out performed it on this engine. Just my 2 cents.
 
Hi Bill, It's a 3 blade prop. It's interesting you recommend swapping to a 15 pitch - I was under the impression that as the pitch decreases your RPMs should increase. It is my understanding that going from a 13 to a 15 would only result in less RPMs (considering I'm running a 3 blade). I've done quite a bit of research on this particular motor as well. From all accounts, this 1998 V4 Intruder was an extremely reliable motor.
 
1998 was the last production year for the 115 HP special and crossflow motors..------Yes by changing props you can increase top RPM.-------But have the motor checked on a dynomometer or with a factory test propeller.-----This determines the condition of the motor.-----Or post compression numbers for these engines.-----Having to drop from 19" pitch to 13" pitch tells me there is something WRONG with the motor.
 
Compression numbers, I cannot remember exactly, but, what I do remember is that all 4 cylinders were no more than 5 psi apart. I believe the gauge read somewhere in the high 90s with one or two cylinders over 100, but the gauge was my buddy's from Harbor Freight and he told me it has always read low. Test was done while engine was cold, and I was more concerned with consistency.
 
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Bransid said:
Hi Bill, It's a 3 blade prop. It's interesting you recommend swapping to a 15 pitch - I was under the impression that as the pitch decreases your RPMs should increase. It is my understanding that going from a 13 to a 15 would only result in less RPMs (considering I'm running a 3 blade). I've done quite a bit of research on this particular motor as well. From all accounts, this 1998 V4 Intruder was an extremely reliable motor.
Click to expand...

I'm just telling you my experience with a 1998 Evinrude 115. You are correct that a lower pitch prop should raise the rpm (typically 200 rpm per 1 inch pitch).
What is the diameter of the 13 pitch prop? aluminum or stainless?
 
Bransid said:
Aluminum. 13.75 I believe.
Click to expand...

It sounds like the right prop for the range of the motor. It's interesting that I get 5000 rpm from a 17 pitch and you get 5100 rpm from a 13 pitch with pretty much the same motor and very similar boat weight. However, it's expected that you would sacrifice top end speed for low end torque with the lower pitch prop form a 19 to 13.
The only other thing I can think of, other than the motor itself is:
1) The hub itself is slipping. Check if the prop hub (rubber part) is worn and if it is a pressed in hub or a replaceable hub.
2) Is the prop a brand name? Not all props are created equal.

Good luck.
 
Prop is not your problem. Did this motor run correctly before the VRO was reinstalled? Re-do your compression check. Checking with a known bad gauge is a waste of time. These 2 motors are not similar at all! The OPs motor is a 60 deg V4 looper with the ois ignition. Barnacle bills is the last yr of the crossflow motor a 90 deg v4.
 
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No, motor did not run properly. I bought the boat for a super deal because the previous owner was fed-up with trying to get the thing to work. I took a bit of a risk on it, but the price was right. Multiple signs pointed to a mechanic who did not know what he was doing just throwing parts at the motor before I bought it. Seller stated he thought the motor sounded like it was starving for fuel, brought it to a mechanic, and the mechanic started "throwing parts at it" (his words) unsuccessfully.

For example, he installed a toggle switch that cycled an automotive fuel pump on and off after attempting to bypass the VRO system. This one baffled me. Mechanic also could not figure out why the trim would not work. It was because he cut the trim wire. He had also installed an incorrect solenoid two separate times, which would stick open and cause the engine to constantly turn over. Only way to mitigate this was to disconnect the battery. When I picked up the boat I replaced the solenoid properly, and it has been fine since.

I plan on re-doing a compression check.
 
flyingscott said:
If the compression test comes back good start looking at the ignition system.
Click to expand...


Just completed a compression test.

Cylinder 1: 120
Cylinder 2: 120
Cylinder 3: 114
Cylinder 4: 115

While these plugs are new (5 hours of good running time on them with lots of WOT), I did note that cylinder 4's plug looked very clean compared to the other three. Here is an image of #4's plug vs this plug which represents how the rest of the cylinder's plugs looked. I also took note that #4's boot came off far easier than the others. What puzzles me about this, is, before I changed the plugs (assuming the plugs I changed had been in their typical cylinders before I changed them), the plug that was most fouled was from cylinder 4. Here is an image of that. With how clean it is could some water be getting in that cylinder, or perhaps the cylinder is intermittently firing, which is why the #4 plug was so fouled that I changed out? Odd that it was comparatively so fouled before I changed it.

Apologies for the links, I was not able to upload pictures.

Interestingly, the factory manual states that port/starboard cylinder banks may exhibit variation in compression, but the variation here is between top and bottom.

I also inspected the exhaust, and, even after swapping down to the 13 pitch propeller, the exhaust is once again coated in carbon after minimal run time.
 
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Compression is good. Now do a spark test and make sure spark can jump a 7/16" air gap. Were the carbs cleaned and serviced properly? you may need to find out if you can. Also try pumping the primer ball and see if that changes anything. May also want to take a look at the OIS sensor.
 
I have no faith that the carbs were rebuilt properly. I was planning to do that over the winter. I pumped primer while running last weekend and that did not change anything that I could notice. I was planning to do spark test next. Thanks for your advice. I will report back.
 
New carburetors are not available.------A clean sparkplug is a concern.-------May mean no crankcase compression , no spark or too much fuel.----Compression in cylinders seems ok.
 
flyingscott said:
Compression is good. Now do a spark test and make sure spark can jump a 7/16" air gap. Were the carbs cleaned and serviced properly? you may need to find out if you can. Also try pumping the primer ball and see if that changes anything. May also want to take a look at the OIS sensor.
Click to expand...

Spark test was good. All 4 jumped the 7/16” gap readily, and with audible snaps.
 
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