Suzuki 150EFI losing power...

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Easyvictor.14

New member
Here's the scenario....
2008 Suzuki EFI 4stroke
<100 hrs
Run regularly
Starts and runs perfectly for about 9 mins at cruise of 3600-4200RPM
Then, RPM drops and engine stumbles down to about 2200 RPM.
Runs fine 2200RPM or less.

If I shut engine off for a minute or two, it'll run fine again for a few minutes.

I have eliminated the following causes: new fuel lines with no kinks from tanks, selector valve, separator, bulb all the way to the fuel filter on back of the engine.

New filter on engine, new water separator.
Run from a seperate aux fuel tank.
It's running 42-47 PSI fuel pressure until it starts losing power, then it drops as RPM drops.

It acts like it's using all the fuel in the VST/VCT tank, and then just running off the fuel from the low pressure lift pump?


It's been doing this for 2-3 days.
Driving me crazy!
Any insight?
 
Also, when the engine is shut down, I can hear what sounds like a small electric fuel pump running in or on the fuel tanks.
I can't find any reference to this pump.
If I shut off the battery switch, it stops. It doesn't come back on when I turn battery back on.

What is it????
 
Journey On is a C-dory 25, not a Venture 23. That said, here are a couple of comments.

First, A C-dory 25 has hydraulic trim tabs. When the engine is shut down, the trim tab pump runs for 10-15 sec to bring the tabs up, even if they're up already. In my experience, there are no electric fuel pumps external to the outboard.

Do you get a overheat indication? Are there error codes on a suzuki outboard, similar to a car?

If you think its fuel, check all the filters. There are 2 internal filters on a Honda (which is not a Suzuki,) in addition to the external one. Several years ago, the internal filters got clogged and would not allow the engine to run above ~3500 rpm.

Just a few suggestions. I understand your configuration is different.

Boris
 
Thanks Journeyon,
It's not the trim pump, I'm familiar with that loud whine after shutdown.

It's a faint, continuous click,click,click.....just like an electric fuel pump in a Chevy fuel tank.

The only filter I haven't changed is in the VCT tank, I'd rather not crack that nut open if I don't have to.

As an update... I put 5 gallons in each tank today, it did the same thing for the first 20 mins. I shut the engine down, restarted it and ran it at 3800 RPM.......for 25 min on each tank...problem has just gone away.

Was there some crappy weak gas in the bottom of the tanks? No crud in separator or filter.

The worst kind of problem is an intermittent one!!!!!!
 
Glad it seems gone, one comment though if you have less than 100 hours in 7 years it wants to run more! Likely old gas, don't fill tanks if you won't use the fuel
Use Stabil to keep fuel fresh and buy "mission" fuel ie just want you figure you'll burn as it goes bad quickly, we try to run 100+ hours annually and failed this year with only 60 as we were happily anchored many nice spots. Oh well. I do think your Suzi wants out more, go get 'em!
George
 
George,
I bought the boat with 66 hrs on it in 7 years this past May. I'm doing my best given our flooded lakes here in North Texas. Up to 118 hrs since May!

I'll be resuming the Great Loop in Jacksonville in April or May.
 
Hello Vic,

I had a 2007 Cape Cruiser 23 witha similar problem (HOnda 135). It turned out to be the fuel pick up was suctioning to the bottom of the tanks. The fix is cumbersome but still a DIY...unmount tanks from the deck, swing them out to allow removal of pick up. Trim 1/4-1/2 off (I bevelled mine although the stock config was a simple 90 degree cut which promoted sticking to bottom of tank).

I bought that boat second hand; as best as I can recall this incident occurred at around 150 hours on the engine clock.

Second suggestion is check ALL points of possible air entrainment into the fuel system. I mean ALL and there is a LOT of places. Basically every joint or connection within the fuel system becomes a possible point for air to be sucked into the fuel system especially at higher demand times (like over 4000 rpm). The more you get into the fuel system to figure out the issue the more places become 'suspect' for leaking.

let us know what you find,

dave
 
Could be getting a code from one of the sensors putting the motor in safe mode, limiting the RPM. Check owners manual for possible causes.
 
Thanks for all the input guys!

Dave,
I'm leaning toward your point about the pickups in the tank, because I've eliminated all the others.
Hoses, kinks, bulb, vents, ( boat doesn't have anti siphon valves), fuel pump, bad gas, water separator, changed filter on engine because I've heard they can crack and suck air,

It's still a transient problem. Boat ran perfect for 2.5hrs yesterday at all power settings.
 
thanks for the update

It must be some part of the fuel system that is not being checked by computer.

I had a paddle wheel type fuel flow meter flow failed and found by bypassing it.

Long story
This was after we replaced under cowling and external Racor fuel filters, replaced fuel lines from tank to Racor head to OB, checked for leaks and loose fittings, vent hose was not crimped or bad and fuel vent was clear, removed ASV, replaced fuel tank pickup tube, checked it and 90 degree tank fitting for screens and found none, cleaned fuel tank and didn't find water or a lot of debris, removed all of ethanol gas and replaced with E0 gas, replaced F filter by VST, replaced low pressure fuel pump, replaced fuel filter on high pressure fuel pump inside VST , pulled all fuel injectors to authorized Yamaha repair facility in Punta Gorda, FL for cleaning and performance testing, bought Yamaha Diagnostics Software and cable, then the last item was bypass fuel flow meter then OB ran fine and bought a new one. If you read this far, you have a lot of time on your hands, LOL and sometime, it is takes a lot of patience to troubleshoot
 
Update: I've put another 2.5 hrs on the motor with no recurring power problems. I don't know what the Hell is wrong, but if it never comes back, I'm happy.
 
Well that's certainly good news, hope you're able to enjoy the rest of your season.

Of course your season is all year round, ours is over; Triple J is covered up for the next six and a half months or so.
 
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