2005 Suzuki DF50 rough idle after blockage, please help!

[Skiffmate]

Hoping all of you can help me. I have learned a ton from this site and had troubles getting registered but finally got approved to make a posting here! You folks are awesome at helping the users out. Thanks in advance!!

My father in law has a low hour 2005 Suzuki 50hp four stroke mated to a Carolina Skiff. The motor has been a flawless runner. Always started, idled like a dream, ran out at higher rpms with no issues, sipped gas, very fun to run and very quiet for trolling. This boat was used only a few times every summer in freshwater lakes in MI and stored in a non-heated garage in the winter. The motor is a bit undersized for the heavy fiberglass boat. With 2 people in the boat it planes out great, with 3 adults or 2 adults and 2 kids it struggles. I have added planing out fins which works great and has helped. We also tried a 4 blade prop with slightly different pitch from the standard 3 blade prop and that has helped. All of these changes have nothing to do with the problem at hand but is just a bit of the history of how we have made a few modifications from the original setup.

We noted early this spring on first trips out on the water that it was act like it was running out of fuel at higher rpms. This was not going into limp mode but just bogging down and completely quitting when running at high rpms. Stop, pump the bulb a little and it started right back up. We had to run on idle back to the dock a few times as it seemed to only get a small supply of fuel at a time and could only run at idle.

Started tearing into the fuel system....
Replaced low pressure filter, high pressure filter (both seemed unplugged), low pressure fuel pump (didn't know how to test this) and the fuel water separator filter. The fuel water separator actually was quite clean but quite old so just did it as a 'good measure'. When we retested we had no change in our problems. We then inspected plugs (slight signs of wear and easy to replace so we did) and inspected fuel injectors. The bottom of the 3 injectors had sticky ethanol deposits and the O ring between metal threads and the injector (cushion) broke in half as it was removed. Replaced 3 injectors although they tested good on ohm test figured it was the 15 year maintenance time anyway. Bummed that injectors don't ship with the bottommost O-ring or cushion and had to order those separately. Got that all fixed, still no joy.

Removed manifold and inspected high pressure pump and checked the filter on the bottom of the pump and the fuel expansion housing for crud. Float was good, chamber was pretty clean and old pump looked pretty good though stained. Still changed pump and cleaned everything just because I didn't want to tear manifold back off again.

All filters and pumps changed still no good. Then started swapping tanks (we use an external plastic 6 gallon tank since we don't go far) no change so blockage wasn't in the tank or the tank fuel barb. Swapped fuel line connector clip on ends, no change. Then took off the access cover to the electrical lines and fuel lines that go down the center of the floor of the boat and pulled out all the tubing, undid zip ties going under the back live well and to the motor and found someone had put an inline brass barb splice in the fuel line near the rear. It was never visible unless you removed all the hose. Removed the splice and tested the various segments of fuel line that we had uncovered and found one was plugged, probably the one right downstream from the barb splice!!

I was feeling good about finding the problem!! I relocated the fuel/water separator to under the rear seat so that the hoses going from the plastic fuel tank to the filter and then to the motor were much shorter than having the lines go all the way to the center console and back like they did before. With clear lines, new filters, new pumps, spark plugs and fuel injectors we had to be all set and smooth motoring in the future right!

In the process of removing things the idle speed thingy that threads in and out and controls engine idle was removed. I don't know exactly how to set that back to the proper setting. I tried a few settings till it ran on muffs at a nice low idle. Certainly on muffs it ran better at higher rpms now but it seemed like no matter what we did we could not get it to idle well. It now had a NEW shake at low rpms and would not run smoothly.

Took it out on the water and it started a little hard and would shake and run like it was running lean or running on 2 of 3 cylinders at low rpms. Once we gave a little rpms beyond 2000 it evened out and ran great. At high rpms it is smooth as ever so can't imagine a cylinder miss. I found the idle set point on muffs was OK but when running it in water it needed a little higher idle to keep it from shaking and stalling. Turned idle speed thingy in slightly till a little higher idle was achieved. Still didn't fix the rough run condition at low rpms

We have no engine light and I don't believe any past codes either.

All the boat shops are on 3 week wait time due to COVID and lack of parts. We are going on vacation and REALLY want to get this fixed.

I've read about gunk in the cooling system on this forum so I took thermostat out, no gunk, tested it in a pan and it opened between 140 and 150 deg F (60-70C)

Last night I dropped the foot and inspected the water pump system. It did seem to me that pressure of the water stream out the tell tale was a bit weaker when we last used it and maybe even a bit intermittent in the stream when watching it this spring. We had no evidence of overheat. The rubber impeller was not damaged and ends seemed to look OK, but the rubber was stiff and pretty much stuck in the swept back position. Housing was in great shape not warped or cracked. I saw a little bit of rubber stain on one side of the housing so maybe the rubber did get hot at one point? I cleaned housing with a little steel wool, replaced gasket, metal wear plate and impeller and added a little silicone grease. While foot was off I inspected the poppet valve which I could only see but not get at. It was closed, no debris, nothing stuck in the opening like others found.

I was considering filling the thermostat housing and water system from the top down with strong vinegar solution as I don't have a barrel big enough to do a vinegar circulation but I can't say that will help since we don't have a overheat condition. This motor was never in salt water and I see no corrosion in the water lines.

Bottom end gears? Seem to shift between gears fine, I changed lower end oil last fall at winterize time and looked good only a hint of milky white, rechecked oil level now and oil is still clean and full. Motor is always trailer transported to and from a boating event and never sits parked in the water.

I have no access to suzuki diagnostics but with no code would that even help?

What makes a the engine shake at idle and then smooth out at about 2000-2500 rpms and run with great smoothness and power at higher rpms? What about changing fuel filters, fuel pumps, spark plugs and injectors with all new parts would make a new problem? Certainly fuel flow should be like new.

It acts as if the engine is trying to compensate from a one time low idle or is getting confused on rich/lean or air/fuel mixture and computer is running it too rich or lean at low rpms.

I read on the forum that an exhaust leak somewhere can do this as well, I can't seem to find any holes and would be shocked that the motor in this good of condition would have a breach somewhere in the metal shell.

I've read the idle air control sensor could be a culprit but would that not throw a code? I can see that sensor and hoses are hooked up and it looks OK but how to test?

If the impeller was the problem and we didn't have good water circulation then I can HOPE that when I get it out on the water again that it might be better but I'm not so confident. One post I read online it was a poor water circulation issue that caused a rough idle or poor engine performance at low RPMS.

IF I need diagnostics I might be able to twist the arm of the local dealer to just scan my outboard codes even though they are swamped with other work.

Thanks for reading this far!

[Skiffmate]

Update day #2
Tested thermostat and it worked. I put some strong vinegar solution down the thermostat hole and it ran out the bottom. That probably isn't the best way to circulate through the engine.
In looking everything over I noticed a little gas puddle under the relocated fuel/water separator. It is BRAND NEW! It came already assembled so I didn't think to test the connections. I can see when applying pressure to the fuel bulb that fuel is leaking between the metal filter housing and the clear plastic bowl on the bottom. I still had the old fuel/water separator housing setting here which we had though was plugged (now we know the fuel line was plugged) so I spent time swapping the old system back in and remounting in the new location. A little more fussing with the seals on the old setup and got it airtight and not leaking under normal fuel pressure.

Put muffs on and struggled to get water to come out the telltale hole. I have round muffs and rectangle shaped muffs and plenty of water but it is a challenge to get the water directed just right I guess? I knew the impeller, plate, gasket, everything was new, clean and lubed, water should come out! I looked in the tell tale hole, can someone tell me is there a metal plate or valve that opens and closes? I piece of string trimmer line doesn't easily go in the tell tale.. I see some remnant of rubber in the opening. Was there a rubber boot or grommet that fits in the hole? My top tell tale hole has no rubber rim or ring just a opening and looking in a aluminum vertical barrier? Turned motor off, adjusted muffs and then I did get water out the tell tale.

Most outboards have a strong, small pee stream like a man with a young healthy bladder and prostate. My water output is more like a wide waterfall under low pressure. It as if you are pouring out of a one inch hose, a fair amount of volume but low pressure and coming out at various speeds and volumes. Was there maybe a rubber grommet that narrows the stream originally?

The more important thing is HOW the engine ran. It seemed to run more smoothly and the shake at low rpms seems gone. By this time it was pitch dark and didn't want to bother the neighbors. So only ran it a few minutes and packed everything up for the night.

I was searching youtube for a video of what the tell tale stream is supposed to look like in a suzuki 40 or 50hp four stroke. I'll try to search on the exploded parts list to see if a rubber grommet is missing.

Ultimately I need to put it in the water and see how it runs and see what the stream looks like with the lower end dunked underwater.

I was ready to pull off the intake grates on the foot and see why it was hard to get water to circulate and I didn't see much water come out of the prop, most wanted to come out the two holes in the front and top of the foot (I understand these are just drain holes once the foot fills up with water) Isn't most of the water pump water output supposed to come out the prop hole and the tell tale?

I hope I don't have to drop the foot again and re-inspect the water pump. The housing looked mint but maybe I still need to worry about that...

Thanks for all who have read this!

[Murray]

https://www.boats.net/catalog/suzuki/outboard-by-year/2005/df-50tlk5-beginning-vin-05001f-510001/water-pump

Parts #2,7 and 8 are all rubber that could potentially deteriorate and end up in your telltale discharge. With the engine running use a piece of weed wacker line and shove the line as far in as you can working it in and out to see if you can dislodge the debris. Your pee stream should be like a young bladder with a healthy prostate.

[Skiffmate]

I see there is supposed to be a tell tale 'nozzle' or water indicator tube or something? Can someone help me find the part number or what part of the engine blowup parts list I can find this rubber nozzle? I can see on my motor that there is only small remnants of that nozzle left in the hole.

[Skiffmate]

Thanks Murray for the list of parts. What I don't understand is that looking in the hole with engine off I can't see where the weed whacker line would go in. There seems to be a visible aluminum vertical barrier or plate shutting off the passage about 1/2" in the port hole. Does that plate move or open and close when engine starts running. There are two holes. The top hole higher up has a rubber grommet around it but is the exhaust hole right? That hole is wide open and no water comes out. The lower one where water is coming out no longer has a rubber grommet or cap and is the one that I can't figure out if the water comes to this exit point from the bottom of the hole or the top but straight in it doesn't seem to connect to tubing of any type.

[Skiffmate]

I found the tell tale hole grommet and cap and O ring on the oil pan section of the parts breakout.

https://www.brownspoint.com/store/pc...l.asp?ID=18722

[Murray]

Thanks Murray for the list of parts. What I don't understand is that looking in the hole with engine off I can't see where the weed whacker line would go in. There seems to be a visible aluminum vertical barrier or plate shutting off the passage about 1/2" in the port hole. Does that plate move or open and close when engine starts running. There are two holes. The top hole higher up has a rubber grommet around it but is the exhaust hole right? That hole is wide open and no water comes out. The lower one where water is coming out no longer has a rubber grommet or cap and is the one that I can't figure out if the water comes to this exit point from the bottom of the hole or the top but straight in it doesn't seem to connect to tubing of any type.

Not sure what the “vertical barrier or plate” is unless it’s a flush port for flushing the engine (with engine off). My engine has a garden hose threaded attachment for flushing so it’s obvious what it’s intended purpose is. I wonder if that’s what your looking at? As far as it being an exhaust port as far as I know all exhaust exits out the prop under water. Sorry I couldn’t be more help, hopefully someone will chime in with more experience with your particular engine. I would suggest you purchase a genuine Suzuki service manual. You can find pdf’s for the older engines for a fair price.

[Skiffmate]

I'm trying to find pictures of the rear of the outboard online since I'm at work and can't take a picture. My flush option is a screw hole right next to the top vent hole on the side of the lower shaft. On the rear there are two 'output' holes. The top has a rubber grommet on it, the lower one on mine does not but there is some embedded rubber bits seemingly 'glued' to the metal. I'll try to find pictures or take pictures. It would make sense water would make it up to the top hole as the rubber grommet on the top hole looks like the parts pictures I'm seeing on ebay and boats.net. Maybe both holes at one time had rubber grommet on them?

[Skiffmate]

OK, I grabbed a screenshot from a youtube video. This is a 2010 suzuki, mine is a 2005. You can see the top hole has the rubber grommet thing protruding and water coming out. There is a lower hole that does not seem to have a grommet on it. On my system the water is rolling out of the lower hole but not the top one?? Could that be? Is there a tube that goes to the pee hole that came loose somehow and how can I get to that tube and inspect it?

suzuki 50.JPGsuzuki 50.JPG

[Skiffmate]

Another picture. I'm getting water out of the bottom most hole but not out of the top most hole? What is the bottom hole for and why is water streaming out of that hole but not in a dedicated pointed stream?Suzuki rear.jpg

[Skiffmate]

Tonight I inspected the tell tale hole and compared to pictures above. I was wrong in my earlier post. THe water IS coming out of the top hole BUT! Certainly that plastic or rubber projection seen in the picture above is missing on my motor. I can see right into a hole in the housing and can see an aluminum lined 'cavity' and a tiny entrance hole coming from above into that aluminum space. I'll post pictures tomorrow. I have ordered the water output grommet/tube and a snap in 'cap' and a O ring that goes in between to restore the factory look.

I took the foot off again as I wanted to be sure everything was in there correctly when I replaced the impeller. Opened it up and everything looked good. I carefully put the impeller back in its housing and checked that the rubber seal on the housing that connects to the water tube was in good shape then slid the foot back on the motor.

Ran weed whacker line into that telltale housing but it is very hard to get the weed whacker line to make a 90 degree bend straight up into the little hole that water comes through that heads up towards the top of the engine. I could after some fiddling get it in there but it didn't go in very far.

Put muffs on and ran the engine, very quickly water started coming out the tell tale hole. I'm thinking it comes out like a lazy water fall because the opening is so large versus in the picture above where the opening comes through that grommet and then out a very small hole.

The shake at low RPMs is gone. I did inspect the exhaust silencing chamber and where the rubber boot connects from the manifold to the silence chamber there may have been a misplaced edge of the rubber boot. When we put the manifold back on we may not have had that rubber boot exactly sealed on all 4 sides of the air box entry. I was careful to get that sealed again.

The other thing I found last night was that my fuel/water separator was leaking fuel between the metal fuel filter and the plastic bowl under it. It is possible the engine was sucking a little air through that leak? That is now replaced with a fuel/water separator that has a tight seal and no gas leaks.

Perhaps the shake is gone due to the impeller working properly again. I just can't say.

I'm still worried about the engine though. When I ran at idle it seemed to run smoothly but then the water stream coming out of the tell tale stayed very cold from the garden hose but the engine seemed to be getting hotter and hotter. After about 20 sec or 30 sec on idle there was a beep from up by the console, 2-3 sec pause and another beep. I could see no indicator lights on the gauge lighting up so I have no idea what that beep means. Thinking it meant engine overheat I shut down the engine.

I don't know that I ran the engine long enough to open the thermostat but I had already proven the thermostat opens at temps above 140F.

I took the thermostat OUT of the motor, ran the boat on muffs again and could feel cool water circulating up the water hose that leads up to the thermostat at the top. The engine stayed cooler. I didn't hear a beep this time.

I put the thermostat back in and ran on muffs again, each time I get water out of the tell tale but before the engine heats up and opens the thermostat the beep comes back.

People talk about codes like 4-2 or 4-1. I assume a red indicator on the dash dial should be the one flashing? I have no red lights on.

I know those lights should work as a few years ago the oil pressure light stayed on, I knew we had good oil pressure, I replaced the oil pressure sensor and the light went off and has stayed off since.

If the shake at idle was a fuel/air leak or exhaust leak then we should be good on that.

Now I'm concerned about the cooling system and I don't know where to go next. The lines blow freely, the thermostat is opening, the circulation system is brand new and water is coming out the pee hole.

Is there a way to check a temp sensor or idle control sensor?

Right before I shut it down for the night I put it at about 3000 rpms and let it run there for about 10 sec and then when I went back to neutral it wanted to stay at about 1500 rpms. Then I heard a beep and the engine instantly cut down to idle as if it couldn't go back to idle on its own but it was stuck for a bit at higher rpms.

I'm struggling and appreciate any help I can get.

I'd like to back the trailer in a lake, leave boat on trailer and run it with the whole bottom of the motor submerged to be sure it has plenty of water all around to circulate through it.

I don't like using muffs as they seem finicky to get on correctly.

Thanks again to those who have stuck with me this far!

[Skiffmate]

Pictures from my telltale output port. The rubber/plastic parts that project out from the housing are missing. Inside you can see an alumunim cavity and the entrance hole seems to be a tiny hole that enters from the top?

I have what I believe to be the correct parts in the mail, hopefully I can figure out how they snap together and how they snap in the hole. IT appears on the parts pictures they have threads similar ot the exhaust tube but I don't see threads in the aluminum housing hole.



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[Skiffmate]

Can somone describe where the air temp sensor is installed on the DF50? I see the sensor on the blowup of parts but not where it sits.

Today I pulled plugs, brand new and the first 2 threads at the tip had some brown staining on them. Probably from cranking and running on muffs without engine heating to full running temp?

Today I also charged battery, volts on the battery with multimeter and on the suzuki gauge are about 12.5 with key on. With crank the gauge on the console goes down to 10v. With engine running it goes up close to or just a bit above 14.

I had to fuss and fuss to get the muffs just right to get water to fill the housing around the water pump. Once the housing fills, I can tell since the water will leak out the ports at the top of the foot opposite the prop side. Then the water pump starts putting out the tell tale hole.

Idled pretty normally, just a hint of shake once in a while. Then ran up to about 2000 rpms and held it there a little. Seemed fine. Here is what is unusual. When I bring it back down to neutral and put it in neutral then the rpms want to hang at about 2000. They hang there for about 3-4 sec and then the engine suddenly drops down to a low idle and at the same instant the beep, 2 sec pause, beep, 2 sec pause beep, 2 sec pause starts up again. No engine light to give an idea that this is a diagnostic code that I can look up.

It didn't want to stop beeping so turned motor off. With the key just in the on position there is no beep which also makes me think it is not a stored code. Then I started it right back up. I ran it up to 2000rpms for a bit again and then dropped it down to idle and this time it idled normally and didn't beep.

So confused. a single beep, pause x 2sec single beep that starts right after the engine cuts down to idle, what could that be?

Weather permitting will put in water and put in normal driving conditions and see how it does.