04 sx230 low rpm stbd motor

[bayratt]

Picked up a project 2004 sx230 late last year and had a mechanic swap in a donor waverunner engine (2002 fx140). Finally made it out and the donor engine generally lagged in rpms with throttle position, and topped out initially around 7800. Backing off a bit it would eventually get to 8200, not erratic, but after doing some research was worried it was the ecm issue (gas smell in oil and level was a bit over the full line). I pulled plugs and found cr8eb's, cylinders 1 and 2 looked ok, 3 a little fouled and 4 a bit more fouled. Cr9eb are the right plugs (put new ones in today), could this have done damage to the engine? Anything else I should be checking out?

I also swapped the ecms between the two engines and both seem to run on hose fine (they ran fine on hose before also, I'm hoping this points towards ecm being ok). The box looked brand new inside including the ecms, so it doesn't look like any water damage there.

On the yds hookup I tested the coils and fuel injectors, all clicked and got good spark on all cylinders from coils.

Hoping to get out on the water tomorrow to test.

 

[bayratt]

Update for anyone looking, it wasn't the plugs. With the ecm's swapped, new plugs gapped correctly, and fresh oil, I'm still only getting up to about 8k rpms on the same motor, so thankfully ruled out expensive ecm.
Any ideas what might lead to low rpms? There's not an overwhelming gas smell in oil, but I think I smell some gas on oil. Idling near a dock I didn't see the rainbow-type evidence you'd usually see with fuel in water, but they're were a small amount of soapy-like small bubbles which could suggest fuel in exhaust.

Any ideas would be appreciated.

 

[dgfreeze]

I’d run compression tests across all cylinders on both engines. Look for consistency. Any single cylinder with a bit less compression will obviously hurt rpm’s.

Check your air filters for any sign of moisture. An oily air filter will restrict the air flow, which will obviously restrict rpm’s.

I highly doubt one step hotter plugs will do any damage. It’s more an indication of potential attempts at rectifying this exact issue by the previous owner. When an engine is getting some carbon deposits on the plugs, a step hotter plug will help prevent that carbon. Maybe that’s what the previous owner was trying to figure out. And maybe not.

Also, your injectors could be starting to go bad. They could be starting to squirt instead of spray.

 

[bayratt]

Going to give compression tests a shot, should I worry about cutting fuel so I don't dump fuel in during cranking? Is there an easy way to do that? I'm assuming disconnecting lanyard cuts spark to the plugs.

 

[dgfreeze]

You should be able to either unplug all the injectors, or even unplug the fuel pumps. (I believe there are two). That said, it's not standard practice, and good chance it throws a code that you should then erase...

The only reason for pause is that these engines are somewhat known for their ECU's failing, and holding an injector open. This would affect the reading. So, pick your poison.

 

[Brad_Ct]

Pull the lanyard at the helm, engine will turn over but all fuel and ignition are disabled. Check to make sure the throttle cable was adjusted properly, it may not be opening the throttle bodies all the way.

 

[dgfreeze]

Pull the lanyard at the helm, engine will turn over but all fuel and ignition are disabled. Check to make sure the throttle cable was adjusted properly, it may not be opening the throttle bodies all the way.

So the lanyard does shut fuel off too? I would’nt have recalled that. And the throttle adjustment is a good call. Sometimes it’s the simple things.

 

[Brad_Ct]

So the lanyard does shut fuel off too? I would’nt have recalled that. And the throttle adjustment is a good call. Sometimes it’s the simple things.

Yes it does, I had a problem with a ground on one of my fuel pumps. After I found the problem for my own curiosity I checked power to the fuel pump with lanyard pulled and there was none.

 

[itsdgm]

Have you tried swapping coils?

 

[bayratt]

Have you tried swapping coils?

With the yds diagnostics I tested each coil with a coil tester, each had strong spark. It's the older style that is one big pack.

 

[bayratt]

Yes it does, I had a problem with a ground on one of my fuel pumps. After I found the problem for my own curiosity I checked power to the fuel pump with lanyard pulled and there was none.

I did compression test today, was getting up to 175 on the first 3 cylinders and couldn't get over 150 on #4. I think you're right about lanyard, wasn't seeing any fuel out of open cylinders when cranking.

Afterwards I saw on a video that I should've had throttle open, it was at idle so I hope that didn't affect readings.

Dropped in maybe an ounce of marvel mystery oil hoping this is a sticky ring issue and letting sit for a day.

Any views on sea foam vs MMO? I read seafoam shouldn't stay in oil for long, and considering oil is changed by pumping out vs draining I thought MMO the better idea since that is ok to be in oil (right?).

 

[Brad_Ct]

I did compression test today, was getting up to 175 on the first 3 cylinders and couldn't get over 150 on #4. I think you're right about lanyard, wasn't seeing any fuel out of open cylinders when cranking.

Afterwards I saw on a video that I should've had throttle open, it was at idle so I hope that didn't affect readings.

Dropped in maybe an ounce of marvel mystery oil hoping this is a sticky ring issue and letting sit for a day.

Any views on sea foam vs MMO? I read seafoam shouldn't stay in oil for long, and considering oil is changed by pumping out vs draining I thought MMO the better idea since that is ok to be in oil (right?).

#4 is definitely low on compression, with the throttles closed you can get lower compression readings then actual.
I use sea foam in everything, I actually read the label on the can I have yesterday and it states to use 1 ounce per quart of oil and states that it has cleaning and lubricants in it.

 

[bayratt]

#4 is definitely low on compression, with the throttles closed you can get lower compression readings then actual.
I use sea foam in everything, I actually read the label on the can I have yesterday and it states to use 1 ounce per quart of oil and states that it has cleaning and lubricants in it.

Thanks for the heads up, maybe as annual fogging routine I'll alternate each year between seafoam and mmo. Just did a follow up compression test and hit 175 twice! Right in line with the others.

Pretty happy right now, but still anxious to get on the water and test. Shooting for tomorrow afternoon for a test run.

 

[bayratt]

Oh man! Getting a little more rpm but still hangs around 8k wide open. Still picks up a little, maybe 8200 when backing off a bit.

Throttle wire is opening the intake all the way (checked at the throttle body), and for some brief moments after cruising for a bit it did get up to 9k (held there for maybe 3 seconds before cutting back down).

My thoughts at this point is to put sea foam in gas tank, I have about 3/8 tank, so maybe 18 gallons or so.

Any advice here? Would it be ok to run in this condition and hope to clean injectors by running through with a can of sea foam in tank? Should I over or underestimate how much gas is in tank (how accurate do I have to be with the 1oz-gallon ratio?). Should I add fresh fuel? Fuel in tank is a few years old from prior owner, and while I thought that could be it the other engine continues to ruin great with 5 times the hours (550 vs 120 on the struggling engine).

All temps seem good so I'm hoping not doing damage running engine this way. I'm pretty sure I don't have gas in oil, I might've mis-diagnosed that last time I don't trust my sense of smell.

Any thoughts appreciated!