General DF50 Question

[mindmeld1]

I am troubleshooting a RPM/stall situation after operating my engine (under load). I can get about 3 minutes of service at ~4K RPM, and the engine stalls and quits. I CAN navigate at idle up to ~2K RPM for an extended period.

I've had the VST cleaned (nothing unusual found), filters replaced, water pump serviced, and oil level refilled.

After operating the engine and monitoring using Suzuki software, engine appears to operate normal. All codes cleared and not seeing anything unusual, we shut the engine down to bring back home.

We checked the oil level one last time and the dipstick popped with enough pressure that it sounded like a nice price sparkling wine bottle... A significant POP and rush of escaping gas.

Anyone offering some constructive thoughts will be appreciated.

[Moonlighter]

On the stalling issue, have you checked the basics like the fuel tank vent? Easily overlooked in the quest for more complex reasons for a problem!

Also Fuel lines (air leaks and liner collapsing) and primer bulb - bulb valve can fail.

If you have an underfloor tank, I would remove the anti-syphon barb. They are not required on outboard powered boats and are nothing but a potential problem waiting to happen.

I will leave it to better qualified people to comment on the crank-case pressure issue that you seem to have.

[mindmeld1]

I noticed a very similar post on a similar question. The last time I had the boat on the water, I took the opportunity to loosen the cap significantly before run-up. The engine stalled as before. I did notice that the bulb was NOT firm and it took a couple of squeezes to firm it up. The reduced RPM setting did allow me to navigate a couple of miles before turning back to the launch.

Thanks for your post.

[Elliot Griffin]

1999 DF50 3000rpm limit on water

I'd really like to know the root cause and/or solution to the post. I have a 1999 DF50 which won't go over 3000 rpm on water, but will on garden hose. The bulb begins to soften over 2000 rpm. I changed the external separator filter, changed the low pressure and high pressure filters. I drained the vst and fuel looked okay. There were one or two tiny black specs which came out of the vst, and I can see a couple tiny black specs inside the high pressure filter. No warning lights or beeps during any operation. Battery voltage is fine. I don't have any kinks in the fuel hose. Fuel hose and bulb are new, but tank is original ~2000. Fuel connector to engine is original Suzuki make. My engine is 1999 but with less than 300 hours, it had some long periods of time with old gas in engine. In past I used gas with ethanol and added Stabil. I recently switched to ethanol free. I haven't done the fuel pressure test because it idles/trolls fine, and manual section 5-5 specifies checking pressure at idle. I tried the fuel leak check per service manual (turning key to on 3 times, visual leak check). I'm thinking as a sanity check, I should check supply voltage to high pressure pump with key on. After that I guess the next step is either to get a new tank, or to inspect inside the VST. Would really appreciate some suggestions. I feel like I'm just changing parts without any clue how to diagnose this. I don't have a scan tool, didn't get any warnings, so don't know if that will help or not, saw one on ebay for ~$100. Most of the past issues I had with this engine were overheating warnings, clogged pee lines, seized thermostat. I replaced the voltage regulator once because the original one got burned up due to battery issue. Other than that, it's just been regular maintenance items that I've worked on.

[2014DF25ARS]

DF25A Fuel problems

I'll tell my story of failure on my 2015 DF25ARS. The motor is now a year old. I took it out a couple weeks ago and headed upstream (thankfully) away from our dock with my brother. After about 2 mins the engine died. My brother looked back at the motor and saw that the fuel line had popped off the tank fitting. (I had put it on before leaving, and would swear it was secure.) He put it back on and pumped the bulb for a minute, but I couldn't get the engine to start again. He noticed that when he was squeezing the bulb, fuel was leaking from the O-ring at the tank fitting. We ended up drifting back to the dock and I left the boat tied up for the next couple hours. At end of day, I tried to start it again, but still wouldn't start.

The next morning, I pulled the boat out of the water to try to figure out what was happening. I pulled out the fuel filter - which in my DF25A is a water-separating canister. I dumped the fuel into a jar and it was about 50% water. So I drained it and re-installed it and primed it full of fuel, noticing that the bulb was not very effective at pumping fuel into the filter. As I was squeezing the bulb, I had noticed there was something inside it. I did manage to fill the filter, but still couldn't start the motor.

Next I pulled the fuel hose off the motor & tank & cut the primer bulb in half with a knife. Inside I found that one of the plastic valves had popped off and was what I had felt in the bulb. The other valve seemed to be stuck closed - which may have been why the first had popped off. So I drove out and bought a new primer bulb and installed it. Still couldn't get the engine to start.

Next day I had to make a 1-week business trip, so the boat & motor basically sat in my driveway for the week. Before leaving, I ordered a maintenance kit from Brown's Point because I thought I might need to change the fuel filter. I also ordered the Racor Suzuki fuel-separating filter canister that Suzuki sells here in the states. (That's a $200 spend to keep water out of my fuel system in the future.) The following weekend I decided to try to start the motor again in my driveway - in a trashcan full of water. It took about 5 minutes to get it started, but once it started it idled fine and would re-start without problems. So I felt like I had finally flushed the fuel system of whatever water seemed to be in it.

A week later, I installed the new water-separating canister and took the boat out to the river with a friend. We headed out of the marina and everything was working fine, though I did feel the motor stutter a couple times as we were idling from the marina... We got on the river and I hit WOT, and we took off without a problem. About 30 seconds later, the engine stuttered to an idle. I turned if off and waited 30 seconds and re-started it without a problem. We idled for a minute and then took off again, hitting full RPM without a problem. About 60 seconds later it stalled again. This went on for 3-4 cycles. It would start & idle and take off fine, but after about a minute would stop. Usually it would idle OK, but a couple times it died completely. Would not run at speed for more than a minute or so. No warning lights or beeps from the engine, except a beep when the motor died completely.

We returned to the marina and I decided to change the fuel filter at the dock. I put in the new fuel filter, noticing as I took off the old one that there was no sign of water in it. But what the heck - it's probably time for a new filter anyway, and I thought maybe there was some obstruction hiding in the filter.

******************
At this point I'll stop for dramatic effect and ask if anyone knows what's really wrong with my [practically new] motor?
******************

After replacing the filter, I starting squeezing my new bulb to fill the new filter with fuel, noticing again how ineffective the bulb seemed to be at pumping fuel through my system. I looked down and found my $%^&* problem:

I had installed the new primer bulb backwards!!! The arrow on the bulb was pointing the wrong way. I had installed it with the hose removed from the boat, and I guess just had a brain fart when looking at the arrow. I pulled the bulb off and turned it around, and we headed out of the marina and spend the rest of the afternoon zipping around as carefree as when I bought the motor a year ago. Fingers crossed for the rest of the season...

Sorry for the thread drift... I hope you find the problem with your motor!

[Moonlighter]

I'll tell my story of failure on my 2015 DF25ARS. The motor is now a year old. I took it out a couple weeks ago and headed upstream (thankfully) away from our dock with my brother. After about 2 mins the engine died. My brother looked back at the motor and saw that the fuel line had popped off the tank fitting. (I had put it on before leaving, and would swear it was secure.) He put it back on and pumped the bulb for a minute, but I couldn't get the engine to start again. He noticed that when he was squeezing the bulb, fuel was leaking from the O-ring at the tank fitting. We ended up drifting back to the dock and I left the boat tied up for the next couple hours. At end of day, I tried to start it again, but still wouldn't start.

The next morning, I pulled the boat out of the water to try to figure out what was happening. I pulled out the fuel filter - which in my DF25A is a water-separating canister. I dumped the fuel into a jar and it was about 50% water. So I drained it and re-installed it and primed it full of fuel, noticing that the bulb was not very effective at pumping fuel into the filter. As I was squeezing the bulb, I had noticed there was something inside it. I did manage to fill the filter, but still couldn't start the motor.

Next I pulled the fuel hose off the motor & tank & cut the primer bulb in half with a knife. Inside I found that one of the plastic valves had popped off and was what I had felt in the bulb. The other valve seemed to be stuck closed - which may have been why the first had popped off. So I drove out and bought a new primer bulb and installed it. Still couldn't get the engine to start.

Next day I had to make a 1-week business trip, so the boat & motor basically sat in my driveway for the week. Before leaving, I ordered a maintenance kit from Brown's Point because I thought I might need to change the fuel filter. I also ordered the Racor Suzuki fuel-separating filter canister that Suzuki sells here in the states. (That's a $200 spend to keep water out of my fuel system in the future.) The following weekend I decided to try to start the motor again in my driveway - in a trashcan full of water. It took about 5 minutes to get it started, but once it started it idled fine and would re-start without problems. So I felt like I had finally flushed the fuel system of whatever water seemed to be in it.

A week later, I installed the new water-separating canister and took the boat out to the river with a friend. We headed out of the marina and everything was working fine, though I did feel the motor stutter a couple times as we were idling from the marina... We got on the river and I hit WOT, and we took off without a problem. About 30 seconds later, the engine stuttered to an idle. I turned if off and waited 30 seconds and re-started it without a problem. We idled for a minute and then took off again, hitting full RPM without a problem. About 60 seconds later it stalled again. This went on for 3-4 cycles. It would start & idle and take off fine, but after about a minute would stop. Usually it would idle OK, but a couple times it died completely. Would not run at speed for more than a minute or so. No warning lights or beeps from the engine, except a beep when the motor died completely.

We returned to the marina and I decided to change the fuel filter at the dock. I put in the new fuel filter, noticing as I took off the old one that there was no sign of water in it. But what the heck - it's probably time for a new filter anyway, and I thought maybe there was some obstruction hiding in the filter.

******************
At this point I'll stop for dramatic effect and ask if anyone knows what's really wrong with my [practically new] motor?
******************

After replacing the filter, I starting squeezing my new bulb to fill the new filter with fuel, noticing again how ineffective the bulb seemed to be at pumping fuel through my system. I looked down and found my $%^&* problem:

I had installed the new primer bulb backwards!!! The arrow on the bulb was pointing the wrong way. I had installed it with the hose removed from the boat, and I guess just had a brain fart when looking at the arrow. I pulled the bulb off and turned it around, and we headed out of the marina and spend the rest of the afternoon zipping around as carefree as when I bought the motor a year ago. Fingers crossed for the rest of the season...

Sorry for the thread drift... I hope you find the problem with your motor!

ROFL!! I needed a laugh this morning!

Nice work on fitting the water separating filter. Absolutely essential on all boats in my opinion.

[Moonlighter]

I'd really like to know the root cause and/or solution to the post. I have a 1999 DF50 which won't go over 3000 rpm on water, but will on garden hose. The bulb begins to soften over 2000 rpm. I changed the external separator filter, changed the low pressure and high pressure filters. I drained the vst and fuel looked okay. There were one or two tiny black specs which came out of the vst, and I can see a couple tiny black specs inside the high pressure filter. No warning lights or beeps during any operation. Battery voltage is fine. I don't have any kinks in the fuel hose. Fuel hose and bulb are new, but tank is original ~2000. Fuel connector to engine is original Suzuki make. My engine is 1999 but with less than 300 hours, it had some long periods of time with old gas in engine. In past I used gas with ethanol and added Stabil. I recently switched to ethanol free. I haven't done the fuel pressure test because it idles/trolls fine, and manual section 5-5 specifies checking pressure at idle. I tried the fuel leak check per service manual (turning key to on 3 times, visual leak check). I'm thinking as a sanity check, I should check supply voltage to high pressure pump with key on. After that I guess the next step is either to get a new tank, or to inspect inside the VST. Would really appreciate some suggestions. I feel like I'm just changing parts without any clue how to diagnose this. I don't have a scan tool, didn't get any warnings, so don't know if that will help or not, saw one on ebay for ~$100. Most of the past issues I had with this engine were overheating warnings, clogged pee lines, seized thermostat. I replaced the voltage regulator once because the original one got burned up due to battery issue. Other than that, it's just been regular maintenance items that I've worked on.

When you say it wont go over 3000rpm on the water, i am assuming that this is with the engine in gear and trying to get on the plane? If so, the key difference would be that the engine is under load in those circumstances.

I assume that you have checked and perhaps replaced or at least cleaned and regapped the spark plugs? Checked the fuel tank breather to make sure it is clear and tank is breathing properly? Have you checked compression?

You dont describe what it is actually doing when you try to accelerate past 3000rpm - is it missing, jumping around, or ??? Is the acceleration up to 3000 strong but just wont go further?

If you can give us some more detailed info and description about that sort of thing it will help someone to assist you.

[Elliot Griffin]

With boat in water, in gear, engine won't go to 4000 rpm. While accelerating above 3000rpm, combustion becomes unstable and engine reduces speed automatically but doesn't shut off. No buzzers or lights. However, with boat in my driveway, in gear, engine will go to 6000 rpm, no issue.

I inspected the spark plugs, no issues.

I inspected the fuel tank (I think it might be a Moeller non-EPA 12 gallon): inside withdrawal tube, seals, inside tank, etc. The cap has a vent screw. When screw is open, I can blow air through cap. I did notice that there is a loose o-ring over the screw thread which tends to fall down and cover the vent slot in the screw, which would tend to restrict air flow. I never paid much attention to that before, but it might be something to look at further. Maybe I should just remove the cap entirely and see if that improves the situation? Bulb arrow points toward engine. My fuel/water separator is just a basic Attwood/Walmart special (10 micron). Please advise what tank breathing check I can do.

I have not checked compression.

Someone suggested the neutral switch (37721-99E01). I did notice that in some other posts (switch gets stuck in neutral position, control system limits rpm because it thinks it's in neutral). I just looked at it, and the plastic switch body has a fine crack in it. I'd like to test the switch as a sanity check, but don't suspect switch could be the root cause since the engine runs to 6000rpm in my driveway without issue.