New Suzuki 150 losing power and running rough under load

[Jaybord]

Hey everyone, I’m new to Suzuki’s and this forum. I have a new Suzuki 150 with 21 hrs on it. It has run fine since new. I did the 20 hr service on it last weekend and was able to get it on the water today. Idled out from the ramp and brought it up on plane and ran it with no issue to our first fishing spot. Trolled for about 20 minutes and stopped and fished about 45 minutes. Started the motor and got the boat on plane again but after about 100 yards the mortor started to blog down and run rough. Trolled it for awhile as I headed back to the ramp with no issues, tried to bring it up on plane again but it started to bog down and run tough. If I put the throttle in neutral and rev the engine it will do the same thing.

bringing in to have it looked at on Tuesday, the dealer said it sounds like it’s going into safe mode. Any thoughts?

[artdf175]

fuel tank venting would be my guess
or the hose connection to the fuel tank-
they build in some type of anti-siphon with a spring and ball bearing
this is not letting fuel flow through and creates a vacuum
punch it out

[Jaybord]

fuel tank venting would be my guess
or the hose connection to the fuel tank-
they build in some type of anti-siphon with a spring and ball bearing
this is not letting fuel flow through and creates a vacuum
punch it out

Checked that already, they remove that spring and ball when they did the installation of the tank and fuel lines since that is a common problem.

[artdf175]

were you able to check the fuel bulb ?
one other thing check the small inline fuel filter pre low pressure pump -- any air in this? like maybe half full?
if you run the engine off a hose watch this filter to see if you see air bubbles

what rpm is the engine at when it starts bogging down?

[Jaybord]

The fuel bulb is fine, arrow pointing towards the engine. Not sure where that small inline filter is. My system is like this, fuel tank to fuel/water separator to prime bulb to engine. I can squeeze the prime bulb full.

i wasn’t paying much attention to the rpms, but I would guess it’s around 3000. I took a video of it running but i can’t seem to post it here.

[artdf175]

need to check the prime bulb at the time the engine is acting up
your engine is identical to mine
the inline filter is on the starboard side in the back with just a short fuel line up to the low pressure pump
run the engine until it boggs down
first check the fuel bulb - see if it is all sucked in
it should be hard and not able to pump additional fuel
then check the inline filter - no air should be full of fuel

one other thought would be the water/fuel filter- did you change this ? just wondering if it is seated correctly

the 3000 rpm level is where the engine limits itself if one of the sensors is not reading correctly. are there any alarms happening?

[Jaybord]

I didn’t change the water/fuel filter. No alarms going off.

[Jaybord]

The boat is back in the garage, later this afternoon (when it cools down outside) I’ll get it out and run that test with the bulb and check that filter. I know what filter you’re talking about now.

[Jaybord]

need to check the prime bulb at the time the engine is acting up
your engine is identical to mine
the inline filter is on the starboard side in the back with just a short fuel line up to the low pressure pump
run the engine until it boggs down
first check the fuel bulb - see if it is all sucked in
it should be hard and not able to pump additional fuel
then check the inline filter - no air should be full of fuel

one other thought would be the water/fuel filter- did you change this ? just wondering if it is seated correctly

the 3000 rpm level is where the engine limits itself if one of the sensors is not reading correctly. are there any alarms happening?

Went out tonight and hooked the motor up to the hose, pumped the ball up, cranked it up and let it idle for a minute. Put it in neutral and brought it up to 2500 rpm. Fuel ball stayed pumped up, no bubbles in the inline filter. The motor ran well and did not run rough or miss.

however, the motor was cold when I started it, much like when I went out the other day, it didn’t start running rough until I had ran it for a distance. Tonight I noticed that there was an intermittent stream of water coming out of the pilot Hole under load. Could it be that there is an issue with the water pump? I didn’t run it a long time at 2500rpm, the temp read 128 degrees when I shut down.

[Jaybord]

---

Taking the boat to the Suzuki dealer tomorrow morning, I’ll post a follow up on this.

in the meantime, I hooked the motor up to the hose and cranked it up and let it idle for a minute. I then put it in neutral and brought the motor up to 2500 rpm, no misses or rough running. The fuel ball remained filled. I did notice that there was an intermittent stream coming from the pilot hole while under load.

i think the problem is the motor is over heating, the motor was cold when I ran it tonight, and it was cold when I first went out the other day, it didn’t start acting up until I had ran it a distance. I will let you all know what the dealer says.

[artdf175]

on the hose-- needs a lot of pressure there are two sets of intake holes on the gear box
the screened intake and a set of holes to the front side- so the pump maybe pulling on a little air
the water coming out the pee hole has not run through the head

it may take higher rpm than you can run off the hose to recreate what I perceive is a fuel problem
Art

[Jaybord]

on the hose-- needs a lot of pressure there are two sets of intake holes on the gear box
the screened intake and a set of holes to the front side- so the pump maybe pulling on a little air
the water coming out the pee hole has not run through the head

it may take higher rpm than you can run off the hose to recreate what I perceive is a fuel problem
Art

Art, should the water coming out of the pilot hole be hot? It was.
if it’s a fuel issue, wouldn’t it act up every time? It apparently doesn’t when it’s cold.

[artdf175]

hot water
no it should be close to the temp that goes in
one exception - off the hose it may not have sufficient water flow
the back side of the port/water jacket that the water flows through before going to the head is the exhaust chamber
it should be passing through quick enough that it doesn't have time to warm up
again, when you run off the hose most muffs are round and fit over the intake screens
when you turn on the water you will see water being pushed out the the other area directly in front of those screens.
when running you should still see some amount of water-if not your water pressure is too low and you could be heating the engine up but would not think it would be to a point of over heating
-unless the thermostat is bad
take the thermostat out
put it in a pan of water slowly heat the water
use a candy thermometer or one of the digital laser thermometers and see what temp it opens at
the temp rating is usually stamped on unit
that way you can rule out that issue

[Jaybord]

Thanks Art, It's at the dealer now, I'll let you know what they find out.

[Jaybord]

Just spoke with the dealer, motor shows no codes on the computer, they’re checking the fuel system now.