DT75 - can't get it to stay running

[Gas Giant]

Re: DT75 - can't get it to stay running

99yam40, yep. I don't think the guy that was paid to do it actually did anything to the carbs. When I cleaned them, I didn't know what I was doing, hence that area didn't get cleaned that well the first time. I couldn't get the main nozzles out of two of them the first time I cleaned them, so I just sprayed a ton of carb cleaner through them. I learned quickly that this doesn't cure a thing; and unfortunately broke the body on the middle carb trying to get the jet out.

Hopefully the replacement carbs will cure the issues. The person I am buying them from said they need to be cleaned themselves...he said he took the float bowls off and checked inside (and said I am welcome to as well) and said there was varnished gas inside, but none of the white corrosion I saw in mine.

So, if it looks like he is telling the truth, I'll stick them in a bucket of carb cleaner to get the varnished gas out, replace parts as needed and see if she runs this time around. And then I can move onto my lower unit issues.

 

[99yam40]

Re: DT75 - can't get it to stay running

That does not sound good, how much did he charge you and have you got back in touch with him to tell what you have found?

Hope your lower unit problem does not go this way too.

 

[Gas Giant]

Re: DT75 - can't get it to stay running

99yam40, I haven't contacted him yet - I am not sure what it would do, since he is also the owner of the shop, but I guess it couldn't hurt.

Yeah, the lower unit thing has me a bit worried too. Basically, the prop spins (and stops) with the engine regardless of what you do with the shifting mechanism on the side of the engine. It doesn't make any bad sounds or anything, at least nothing I can hear from inside the boat (I couldn't get go of the key, or the choke would open and the engine would die) but it obviously shouldn't be permanently engaged.

But I'll start a new thread for that.

 

[199675hpforce]

Re: DT75 - can't get it to stay running

May as well toss some parts on motor. New fuel pump and or diaphram kit install $35,fuel bulb couldnt hurt. Sounds like she wants fuel to me is the motor smoking oil pretty bad, im guessing this is 2stroke correct. Also carb cleaner is bad idea as there are soft plastics in carbs hidden,mercury quick cleen or sea foam deep creep is ok. Check the needles to see if they are sticking up even after my carb cleaning I had this problem. On mercury force there's orange rubber around the needles maybe the cleaners soft them up and they stick, shoot some deep creep on there. Ethanol is bad for outboards but we have to live with it, there's a product startron that people swear by. Worth a shot

 

[Gas Giant]

Re: DT75 - can't get it to stay running

Picked up the replacement carbs. The guy who was selling them actually described them worse than they actually were - these carbs made me realize just how bad mine actually were! There is a little bit of varnished gas in them (and I do mean a little) but other than that they are sparking clean with no corrosion anywhere.

 

[99yam40]

Re: DT75 - can't get it to stay running

Good to hear, hope they are the correct ones, clean them up and see how it goes.
At least you have some extra/spare parts now if you need some.

 

[Gas Giant]

Re: DT75 - can't get it to stay running

Well, you would think I would have spent enough time looking at these carbs to pick them out of a lineup.

Turns out, the carbs are from an earlier year than mine, I believe they are from an '87 motor. (Mine is an '88). I was too focused on corrosion to notice. They are very similar, but there are some subtle differences that I am going to have to work out. I am sure I can make them work with a few little mods as there aren't any major changes I have to make and I believe the jets are the same.

First of all, I need a way to mount the throttle valve sensor on the middle carb. This should be easy as the mounting holes are there; they just need to be tapped, and I can use the throttle arm from my old carb since it extends out the other side of the carb for use in the throttle valve sensor.

Unfortunately, the biggest problem I have run into so far is the plastic fuel inlets where the fuel lines connect. They are rotated 180 degrees from the ones on my old carburetor - this gets in the way of the throttle valve sensor that I need to install. I am not entirely sure how to remove, or even rotate these plastic inlets without destroying them.

I'm going to talk to the machinist at work and see if he has any suggestions, or if he can make something to replace them out of aluminum or brass. I didn't see these plastic fuel inlets listed as a separate item on Brownspoint's site - or any other site for that matter - so I assume they come with the carb body and aren't available individually.

I'm open to any other ideas as well....of course I am very close to ditching this Suzuki motor and going with something that is easier to find parts for, but I am not totally ready to give up yet.

The good news is that the carb passages are clean, free and clear.

 

[99yam40]

Re: DT75 - can't get it to stay running

my advice would be to find the proper ones

 

[Gas Giant]

Re: DT75 - can't get it to stay running

Well, after a few weeks of mods and messing with the carbs to get them right, I finally got them on the engine, and.....

Viola! She started right up and ran. Ran a little rough at first, but once it got warmed up it ran pretty smoothly. This time, it ran until I shut it off myself lol.

So, thanks to everyone who replied, I couldn't have done it without you guys.

 

[mphelle8vld]

Re: DT75 - can't get it to stay running

Nice job getting your motor back on line and thanks for following up with your results, many never bother once they're back on the water and it's a shame since it's the only payoff the heavy posters on this forum receive.

 

[99yam40]

Re: DT75 - can't get it to stay running

Well done, and I hope your modifying will not bite you later on.
Now to see if you have a lower unit problem.
Did you say it had good oil in it?

 

[Gas Giant]

Re: DT75 - can't get it to stay running

99yam40, its funny, before I fired it up yesterday, I tried moving the prop with my foot. It would spin one way making a clicking sound, and not spin the other. So I moved the shift lever on the engine to what felt like a detent, and in that position the prop would spin freely in either direction with no sound. Moved the shifter to the opposite position and the prop wouldn't spin either way.

So, I put it in the neutral position when I fired it up, and the prop didn't move while the engine was running. After I got done running the engine, I adjusted the shift cable per the manual and all seems to be well with the lower unit.

I was thinking of taking it on a sea trial today. (perhaps I should say river trial, this thing isn't going on the ocean until its proved itself and I have a SeaTow membership....) But when I drove by the boat ramp it was crowded, and I'd rather do my first launch when it isn't a holiday weekend, in case there are any surprises I haven't discovered yet.

 

[James R]

Re: DT75 - can't get it to stay running

Very pleased to hear that you got to the bottom of the problem with the carbs.
I have been watching your progress and it has been a long journey, not quite finished yet.
As a precaution and seeing as we are not yet confident of the motors ability and to avoid a tow, you might want to consider simply backing the boat the boat into the water, leaving it attached to the trailer and running the motor test that way before putting to sea.
Good luck.

 

[Gas Giant]

Re: DT75 - can't get it to stay running

Well, you hit the nail on the head. I won't go into too much detail, but it didn't want to run in the water. Wouldn't idle. A friend tried revving it up a little while starting it, but somehow got it stuck at full throttle - so the engine ran at full throttle for about 5 seconds. :facepalm: (Didn't die though, at least until I yelled to shut it down)

Gave up at this point and decided to drag it home.

Started it the next day, and now its running badly. Its missing, and running rough. Prior to the full throttle incident, when it started, it would rev up automatically for a few seconds (maybe 15 or so) and then slow the idle down. It still does this, or at least tries to - it revs up, sputtering and shaking as it does, then when it slows down as it is supposed to, it sputters, backfires, and revs back up. Then the cycle repeats, and will continue to repeat until you turn it off. (I will also note that the engine still fires up as easy as can be, despite it not running well.)

I also noticed that the "pee stream" from the engine kept changing direction (about 15 degrees worth), and was so hot it had steam rising from the water as it exited the engine. When I saw that I shut the engine off. I wasn't able to find a blockage in the opening, which is what I assumed was causing the stream to shift.

I checked the compression later that day, and got less than 30 on each cylinder. The spark plugs were dry and showed no signs of oil on them. When I checked it, I had all the spark plugs removed at the same time and the engine had cooled off from running it earlier in the day. Perhaps I did the test wrong?

So, something has gone horribly wrong. I'm going to pull the head and check the gasket this weekend. I don't want to believe that all 3 pistons would ruin their rings by running at full throttle for 5 seconds, but honestly anything is possible. I will note that the engine never made any out-of-place or bad noises while running at full throttle, and sounded very strong (and it sounded pretty damn cool, if you ask me )

I'll post what I find for any interested parties, or for posterity. Any suggestions on what else to look for is appreciated. (And yes, I've started poking around for replacement engines but don't have a lot of $$$ available at the moment, and I was really hoping to use this engine since my battle with this engine has almost become a personal vendetta!)

Ok, I apologize, I said I wasn't going to go into a lot of detail but I did anyway.

 

[mphelle8vld]

Re: DT75 - can't get it to stay running

Bummer, seemed like you had nailed it. Looking back over the thread, when reviving a motor that's been sitting awhile it's common practice to replace the old gas with a fresh 50:1 mix until you can verify that the oil pump is still functioning, or that the oil hasn't jelled, by monitoring the level of oil in the tank given the amount of fuel used. Hope this wasn't the case but would explain the loss of compression in all cylinders, let us know what you find.

 

[99yam40]

Re: DT75 - can't get it to stay running

You can always try a different gauge just to be sure yours is not the problem.
At 30 I would not think it would fire right up

 

[Gas Giant]

Re: DT75 - can't get it to stay running

That is also a good point. The one I checked it with was a rented Autozone gauge....who knows if it worked properly.

 

[James R]

Re: DT75 - can't get it to stay running

You can get a new gauge on Ebay real cheap. If you only have 30 the motor will not fire.
Good point about the oiling. When I am testing I run on 50:1 out of a jug to be sure that we have oil. I then go thru the procedure to check oil rate and oil at each feed tube. I'll go thru that with you if you need it.
The heating doesn't sound good. Sounds like you have a lean condition. The water jet may change direction if the water is overheated.
Need to back up to the throttle, cable, carbs thing.

 

[Gas Giant]

Re: DT75 - can't get it to stay running

I did get the throttle unstuck, and fixed the issue that caused it. Doesn't stick anymore.

The day before the boat ramp incident, I ran the engine for about 20-30 minutes on the hose in my yard, with no sign of trouble - ran as smooth as a sewing machine, no bad noises, was steady as a rock.

Immediately prior to the boat ramp incident, I did the same thing - warmed it up on the muffs for about 20 minutes, and it behaved the same as before - started right up, purred like a kitten, etc. No signs of trouble at all.

So something had to happen to it at the boat ramp that made it angry.....perhaps the boat needs an exorcist!

 

[halas]

Re: DT75 - can't get it to stay running

Did you get some smoke from the exhaust? And some oily water running down your driveway while running it on the muffs? You should have. Reading this fascinating development I would hate to see your oil pump clogged up. Since the motor was so neglected I would take the oil tank out clean it and replace the oil filter. Is that small oil filter connected to the alarm on your motor? Follow the instructions on your Suzuki Manual to get the pump primed. Use a small portable tank with 50:1 mix. make sure that each clear tube is filled oil and not air.