'08 Etec 150 WOT Temporary Loss of RPM

[Draht]

Alright, My 2008 Etec 150 HO (E150DHLSCR) has been running like a top all spring. I took her out today, and all normal for most of the day. First crank start, smooth idle, smooth acceleration, smooth run at top-end spot to spot with some fishing time at each. Always started and ran smooth each time.

Later in the day, was making a run for several miles to get to a bay I wanted to fish, and had a hiccup with throttle wide open. RPMs were running at 5000, then dipped to 4900 for a moment, then back to normal. Ran normal the rest of the few miles, and didn't think much of it.

Fished for a while and decided to make the long run back towards the launch (about 20 miles). In that 20 miles, the hiccups of temporary loss of RPMs down from 5000 to 4900 or 4800 happened more frequently.. Probably a total of 12 times in that 20 miles. Each time bogged down for a few seconds, but came back to normal. When I got closer to the ramp, I worked it through all ranges from idle to WOT. Idle still nice and smooth. Smooth and normal acceleration to plane, and smooth transition to top-end RPMs. But still had a couple more hiccups before the ramp while opened up.

History on the motor.. I'm second owner and purchased 4.5 years ago with about 25 hours on it. The first owner did not use it much, obviously, and it spent a lot of storage time in his garage before I bought it. Only major issue I've had is an injector went out shortly after purchasing when I had the motor up around 40 hours. I attributed that to extended storage gumming that injector and made the painful decision to replace all 6 injectors at that time expecting the others were probably in the same condition. Since then, the engine has been great to me, and I use it a lot in the summers, keep it maintained, garage kept, winterized in winter, and have only run ethanol-free premium fuel for the 4.5 years I've owned it. The motor currently has 78 hours on it.

This model has the inline disposable fuel filter that I'm going to replace first in hopes it might be dirty enough to have restricted fuel flow at the top end on those long runs, but I'm guessing that might not be the issue... as much as I hope it is... I can see some particulates caught in the folds of the filter, so maybe I'll be that lucky...

I'm reaching out to see if folks have dealt with this, and would love to hear advise on some likely culprits.

Thanks in advance!

[bighare]

Basics first. Spark plugs, engine fuel filter.
An external inline fuel filter is not typical. The on-engine canister filter is standard. A boat mounted canister filter is usually added to supplement fuel filtration. You should add and engine history report so experts here can see if anything unusual sticks out.

[Draht]

Basics first. Spark plugs, engine fuel filter.
An external inline fuel filter is not typical. The on-engine canister filter is standard. A boat mounted canister filter is usually added to supplement fuel filtration. You should add and engine history report so experts here can see if anything unusual sticks out.

Waiting on new plugs and filter to do those replacements in the next day or two. I did pull each plug, and all looked good with no soot buildup or anything weird in appearance, but will still replace them all.

I didn't realize the need for the canister filters as this model does not have a motor-mounted one from the factory... I'm going to install an on-board filter/separator this week though... Do you have any recommendations for a good filter system to add between fuel tank and motor? Thanks!

[bighare]

Racor is the most common brand besides the OEM equivelent.

[Draht]

Racor is the most common brand besides the OEM equivelent.

I have been looking at the Racor, but not exactly sure which size I need based on Flow rate and fitting size...

Also a little confused if it is supposed to go between tank and primer bulb, or between bulb an motor... have seen it both ways, but not sure which would be better..

[bighare]

Follow the selection instruction from racor. Plenty on line.
Install on the suction side of the bulb.

[Draht]

Update on this post.

-I changed spark plugs, making sure of proper gapping, torque, and index.

-changed the inline disposable filter on motor

-Added an onboard racor fuel filter/water separator

First trip after the above, the boat ran fantastic, and seemed problem was fixed. Wasn’t able to get it back out for about a week and a half, and took it out again a couple days ago. This time, it was back to the occasional 100-200 rpm fluctuations at WOT.... only thing that would have changed in that time was a top-off of 91 oct. ethanol free fuel.

Again, the motor is not running rough at all, even when the RPMs fluctuate. Haven’t had bulb suck flat, or anything like that.

Also ran in the yard in water tank, and never had EMM fault lights come on for injectors, etc.

A couple things that I question are

1. bad fuel (but it seems fairly unlikely to me to get multiple tanks of poor ‘premium’ ethanol-free fuel)

2. Either Lifter or VST pump issue that isn’t keeping up with Max load.

Honestly at a loss right now. No dealers close to take a look for me, and only option seems to be 6 hours away and a month out before they could even touch it...

[bighare]

Please provide a picture of the “in-line filter” as you replaced. Are you sure you do not have 3 filters - racor, in-line and on engine spin on canister?
More experts will chime in but I suspect you will need to perform fuel pressure tests and fuel vacuum tests to point the issue.
A lift pump cannot keep up with fuel demand if there is an issue at the fuel tank fitting.

[ChampioNman]

A bad anti-siphon valve on the fuel tank has drove many a person crazy.

[Draht]

3ABA1540-D039-4DC7-BAD3-85810B102F25.jpeg
Here’s the inline fuel filter. This model does not have a canister filter on engine.

[Draht]

A bad anti-siphon valve on the fuel tank has drove many a person crazy.

I think I’ll just replace the fuel pickup and anti-siphon for kicks to rule that out at least.

[ChampioNman]

3ABA1540-D039-4DC7-BAD3-85810B102F25.jpeg
Here’s the inline fuel filter. This model does not have a canister filter on engine.

I knew that.

[Draht]

This issue continues to have me perplexed... is there any chance this could be an issue in the throttle control mechanics or position sensor? The easiest way to describe how the issue feels, it’s like hitting the governor in a vehicle at high rpms, but only about 200 rpm drop and the rpms do pick back up, at least for a while. No roughness in how it runs at all, just that loss of power.

It really does not seem to be a fuel delivery issue between tank and motor as no suction of the bulb has occurred. Still possible that it could be one of the fuel pumps as I do not quite understand how to properly test the fuel pressures... plugged into Etec software and no codes being thrown.

[DaleH]

Just noticed ... you say "ran at full throttle, 5000 RPMs" ... but I believe that OB should turn screws for 5,850 RPMs. Not sure how the lugging translates to any RPM loss, but if indeedy a 5800+ RPM motor ... yeah, I'd say you're lugging it pretty good!

Also confirm the proper tach setting. And what RPMs does your software tell you?

[Draht]

Circling back on this to let you all know what I’ve done so far. Unfortunately, the issue isn’t fixed as of yet… once trimmed and cruising, my boat likes 5700 rpms, and will run great for a while at that, but will run into the loss of 100-300 RPM for a bit, and back up. Once it starts, it will typically continue to fluctuate like that. The issue only happens at max load/rpms. Does not seem to happen below 5000 rpms, such as max throttle and motor trimmed down. Sorry, I had misquoted rpm range in my earlier post.

Replaced all fuel lines, bulb, and Anti-siphon valve between tank and motor.

replaced and indexed spark plugs

Replaced fuel lines on motor from supply to VST

New lift pump and pulse lines.

Added racor filter/separator, new inline fuel filter, and new fuel return screen filter in VST. No water has been observed in separator.

Still only running ethanol free premium fuel, and adding the evinrude fuel treatment every fillup.

Im not sure what to do next. Thinking about replacing the VST/high pressure pump, but not sure on that.. i tried to conduct a pressure test, but the fitting on the gauge I have is too bulky to fit on the pump valve…

[MAKO19]

I am having the same issue as the author of this thread. I sent him an e-mail through this site but I don't think he posts here anymore. Does anyone know this user or a way I can reach out to him? Thanks!

[CCGambler206]

Have your injectors serviced

[ChampioNman]

I am having the same issue as the author of this thread. I sent him an e-mail through this site but I don't think he posts here anymore. Does anyone know this user or a way I can reach out to him? Thanks!

His last post was 10-2021