DT225 Runs great but dies after long idle.

[Spruill242]

Hey guys new to the forum. My father in-law just purchased a 23' Sea Craft and we've been haveing a little issue with the engine. I would guess it's from the mid '90s. Either way.... Motor starts right up. Never had a problem with that. But if you let her sit too long she'll start to get really quiet and eventually die. Again I can start her right back up but I'll need to put het in neutral and rev her up to get her to stay running. Makes a decent amount of smoke but not bad. Not fogger truck bad but more than the first start up. Running at 4500 or 5000 rpm she does great. No skips or hiccups at all. Just a nice steady run. After a good run like that, she'll idle for 15-20 mins and go back to dying again. And I run through the whole process once more. At no wake zone speeds she isn't very smooth either.

Replaced spark plugs with NGK units one step hotter. I thought it was fouling plugs and thought a hotter plug would stay cleaner. No change. We had the fuel tank flushed and cleaned but haven't changed the filters yet. No change. Few tanks of injector cleaner made her run better at WOT but did nothing for the dying at idle. Any direction for this would be great.

Thanks
Kyle

[Solarman]

dt225, mid 90ish??

I might check the TPS, it might be breaking down at lower throttle settings, but work fine at higher throttle. Could try unplugging the tps, to see if it idles for 20 - 30 mins, and if monitor throws a code? You can't run fast unplugged, but if idles better, or longer, or smoother that might tell you something? Do not try removing/ adjusting the tps, as it takes special connectors to set up properly, read manual first.
Good luck, let us know what you find.

[Spruill242]

Solarman thank you sir. I might get a chance to mess with it tomorrow. Will let you know. In the searching I've done I notice you help out more than your fair share. Thank you for that.

[artdf175]

might ask what the reason was you flushed the tanks?
seems if you are suspecting something with fuel issues, the filters are the first thing you replace.. so change the water/fuel separator and make sure the fuel filter just before the fuel pump is also clean
Art

[Spruill242]

Wasn't sure of the age of the fuel or any past maintenance on the boat. Left the filter to catch any stuff that may have gotten dislodged after cleaning. And not clog a good filter. Will be replacing soon. Boat had the same problems before and after tank cleaning.

[artdf175]

a few bucks for the fuel filter.. even if you might have to change it twice sometimes is a pretty cheap cure
should be changed every year regardless and after flushing the tank there should not be enough of anything left to clog the filter

I scratch a date on the top of my filter as well so I know when it is installed without having to dig out my log book.

I don't know your motor, maybe someone else with more DT experience might answer this question.. is the motor fuel injected type? if so there is a high pressure pump with another filter that should also be inspected and cleaned

[mhill1955]

I have one that does the same thing. When mine idles for a while the engine will shut off and the primer bulb on the fuel hose will be soft. I have to pump up the primer bulb to get it to start back up. I have changed all the fuel lines on the engine and replace the fuel lines all the way back to the on board tank.

[Solarman]

dt225, mid 90ish, running issues at idle

Am starting to think the tps may not be the problem.
Another test you can do is a fuel pressure test at the top of the fuel rail. Your manual should give you procedures to do this. Pressure should be steady at all speeds, if pressure drops at idle then possibly a regulator, or high pressure pump problem.

Have you looked at plugs after keeping it running at idle (as long as possible) till it stalls out, to see if any water, or oil is on plugs (you did mention smoke when starting up)?
You also mentioned running rough in low wake zones. If one cylinder has a slight oil leak in a valve seal, it may be enough to affect idle, contaminate plug, but not higher RPMs? Sorry, dt's don't have valves. Lol, my error.
Just thoughts, but trying to read your info on your problem. Good luck, keep us posted.

[Solarman]

no info given

Mhill1955,
Your problem may be similar, or same, but then could be something much different. please start your own thread, and give all your motor info and I am sure many will read your thread, and if anyone can help you resolve your issue they will. It is not easy to focus on solving one problem, if we have multiple motors and people involved. Each issue a motor has can be identified, but each motor is different. If something had solved a problem you've had with your motor, and your issues were similar, your input is greatly appreciated. Thnx for your understanding. Good luck.

[Spruill242]

I'm going to try to keep you guys posted. Weather hasn't been very good here so I haven't gone down to the boat. Fuel filter, and un plugging the TPS is an easy try. Will let you know if it changes anything. I'm going to get the boat in a rack and idle it till it dies. Pull plugs and see if my fuel primer is soft.

It's just strange to me that even after it dies. It will start right up without me touching anything. I do have to rev it to clear it out but it will start right up. When it does restart it's about as much smoke as it has when I first fire the engine cold. Nothing crazy.

[Solarman]

dt225, idles then stalls out

Another, good possibility, your oil injection system may not be working properly at low speeds/ close to idle, but work fine at slightly higher speeds. Causing your motor to load up on oil till it stalls. then when starting up, the ecm automatically raises RPMs for 10 - 15 seconds, maybe just above oil malfunction problem.
If you don't understand oil injection system, it should be adjusted/repaired at a Suzuki repair shop.
Good luck. This scenario seems to fit best with your motors problem.
keep us posted on what you find.

[Spruill242]

Took the boat out last night. The stalling wasn't as frequent. However, I am reving the engine in nuetral every-so-often to prevent it from stalling. This helps alot but obviously not optimal. I have noticed a heavy buring oil smell at low speed and idle now (put curtins up for the winter and it's trapping the air at the rear of the boat.) But at cruise speed it isn't present. I've owned many diesel trucks and know the smell. If it does stall, the engine will try to high rev on it's own after a re-start. So you may have narrowed it down further.

Between the filters, rusty/old FPR, and new plugs there are a few things that need to be done anyways. Are there gasket/o-ring kits for the oil system? I can change out hard parts just fine. Re-calibrating the system will be done in the shop if need be.

[Solarman]

dt225, stalls when idling

I have chatted here with a number of owners, but, have heard one or two that have taken apart their oil systems and cleaned them, due to their motor problems. Am not certain what parts might be involved, but if I can look it up, ill pass your name off, and see if he can give you some pointers.
Ill get back soon as possible.

His handle on the forum is: chackett
Ill see if he gets a message to look you up, give some pointers.

[chackett]

Hey - Sorry it's been so long since I checked here. It's been such a long time since I removed, disassembled and reassembled my oil injection pump I honestly can't remember too much about it. What I do remember was that it was remarkably simple and pretty easy to get apart and back together again. Also, I remember the pump and parts to be in remarkably good and clean condition when I took it apart. I guess all that oil and detergents that must be in it are doing their jobs well. If my memory serves, there is a pretty simple linkage between the throttle and the oil pump so that oil delivery is directly tied to throttle position. I'm sorry it was so long since I have checked in here and I hope you got it worked out. I'd be curious to know whatever became of the issue.

[Solarman]

Still having problems?
If you are still having same issues. Try removing VST, carefully mark positon of throttle valve sensor on top, only if you have to remove the sensor. If you can soak the top without removing the sensor, leave it. Soak the bottom and top just below the sensor. Once soaked, blow each passage, every tiny little hole in both parts till dry. Once dry re-install float needle valve seat and float assy (always reset float level height per manual. Put VST back together, and check if you have a small screen in-line filter inside the fuel line going to the high pressure pump (small cone shaped cleanable screen filter).
Once all done, re-install VST, if you have the idle stop screw still in place don't change. Once started and warmed up well, check rpms at idle. If adjustment of idle is needed, adjust idle power manual for your motor.

Mid 90's is not a good date for your motor. Take a pic of the ID serial number plate located on the motor clamp and post it. The 90's had many changes frequently in those years, many sensors changed, computers changed, everything was changing in those few years. So accurate dating helps us better understand what you have okn you'r motor. Or, if it is actually the right age?

Good luck, post back to let us know what you find.