One problem or two ???

[bowhuntrrl]

History: Boat and engine sat over 4 years 1986 DT-85

Upon purchase, so far I have rebuilt the fuel pump, replaced fuel pump o-ring and fuel pump block o-ring. Removed and rebuilt all 3 carbs, readjusted the choke solenoid for full pull, checked float levels. Checked compression: 130 lbs +/- 5 lbs . Replaced the plugs with NGK B8HS. Rebuilt the water pump. Emptied out the oil tank, cleaned and replaced oil with new synthetic blend. Checked the oil pump timing/adjustment. Replaced water separator filter with new and connected an external plastic tank with fresh 50:1 mix of 89 octane.

The Problem: After the above work, it ran fine on the muffs. Took it to the lake and it immediately fouled the top plug. Cleaned the plug and moved it to middle cylinder and restarted it. This time the middle cylinder fouled. Thinking it was a bad plug, replaced it with a new one. Took it to the lake. It started fine, but boat wouldn't plane, running on 2 cylinders. The problem appeared to be a fouled plug in the middle cylinder.

Took a trip to the auto parts for another plug, this one a BH7S (just to test). Took boat back to lake. Now the boat would not start. I cranked and cranked, and choked and cranked. All plugs were dry !! Took it back home. The bulb was pumped up hard, there was fuel in all the bowls, and the choke is closing tightly. Fuel does not seem to be sucked into the cylinders. Engine has a nice blue spark when cranking with plugs grounded, carbs have fuel in the bowls, and engine has good compression. Finally got it to fire after a lot of choking and cranking.

What could the problem or problems be ??? Can idle adjustment be the cause?? I've had it from 1 1/2 out to 2 1/4. It idles faster and better when leaner and rough and smoky at 1 1/2. Can I possibly get that many defective plugs??? I seem to remember real bad luck with NGK plugs and snowmobiles from the past.

 

[hopalong]

Re: One problem or two ???

The bulb was pumped up hard, there was fuel in all the bowls, and the choke is closing tightly. Fuel does not seem to be sucked into the cylinders.
Seems like the fuel pump/diaphram has no pressure and or the carb needle/seat/metering not working correctly. Did you actually take the carbs apart, soak them, blow out passeges and install new kits?

 

[bowhuntrrl]

Re: One problem or two ???

The bulb was pumped up hard, there was fuel in all the bowls, and the choke is closing tightly. Fuel does not seem to be sucked into the cylinders.
Seems like the fuel pump/diaphram has no pressure and or the carb needle/seat/metering not working correctly. Did you actually take the carbs apart, soak them, blow out passeges and install new kits?

As stated above: Rebuilt fuel pump, took apart, cleaned, replaced diaphragms, base o-ring and fuel pump plate o-ring. Rebuilt carbs: took off, took apart soaked and blew out passages, checked float levels, adjusted idle jet to specs, and adjusted choke solenoid.

Also, if the fuel pump wasn't working, there wouldn't be any fuel in the bowls. The needle and seat are working properly witnessed by the fact that the bulb pumps up hard when the float comes up and shuts off the fuel.

 

[hopalong]

Re: One problem or two ???

OK, the fuel is coming into the carbs... sooooo the fuel must the leave the carbs... via of the carb metering/devices/passages, something is restricted ...if no fuel is in any of the cyl's then it seems the problem is common to all the carbs.
When you say the plug was fouled, was it oil or gas on the plug that fouled it?
When cranking the motor put your hand over a carb for a second and see if there is real good suction.

Just because you're getting fuel into the carbs does not mean there is fuel leaving the carbs. Go back and track what you did with the carbs and pump. Hope you can find the problem. Good luck

 

[bowhuntrrl]

Re: One problem or two ???

It's driving me nuts, about ready to give up and sell it, even though I just bought it !!! Put 3 new plugs in tonight against my better judgment,because my friend thought I should eliminate that variable. Took it to the lake for another try. It started up and idled rather roughly. As soon as I put it in gear, it cut out on 1 cylinder. I had the boat still strapped to the trailer so I tried to run the revs up a bit. Couldn't get it to clean out. Pulled it out of the water to try to determine what cylinder. When I pulled the plugs, none of them were what you could call fouled, in fact they seemed a bit dry. After that, I checked for spark with my grounding harness and all 3 were firing nicely.

Is it possible for needles to stick closed ??? I've never seen it in 35 years, but for some reason the fuel doesn't seem to be readily getting into the cylinders. As a last ditch attempt, I'm going to pull the carbs off tomorrow and go through them again. I think I will also look at the reeds. Beyond that, sell the boat I guess.

I'm really open to suggestions since I'm pretty desparate right now.

 

[deejaycee_2000]

Re: One problem or two ???

check out you reed valves, are you 100% sure your float level in the carb is correct, and did you sync the carbs? Ideally the fuel/air mix should be 1 1/2 urns outwards from softstop, and lightly from there .... more than 2 sounds a bit heavy .....

 

[bowhuntrrl]

Re: One problem or two ???

check out you reed valves, are you 100% sure your float level in the carb is correct, and did you sync the carbs? Ideally the fuel/air mix should be 1 1/2 urns outwards from softstop, and lightly from there .... more than 2 sounds a bit heavy .....

deejaycee,

I checked the float levels with a dial vernier. As far as carb synch, I'm a bit confused there. The linkage rods are fixed with no adjustment from carb to carb. I looked down the throats and they all appear to react the same to the throttle. Even if there was a problem, I wouldn't know what to do since there is no provision for adjustment, I'm going to pull the carbs again today and check some things. There's is doubt in my mind as to whether it is an '86 or '87 motor. According to Clymer, the idle adjustments and jets are totally different for these two years. I'm going to check the jet numbers to see just what I have. When I had them off last time, I eyeballed the reeds and they looked fine, what else should I do ??? Should I take them out and check the gap with feeler gauges ???

The motor idles much better with the adjustment out around 2-2 1/4 turns, which is the spec for the '87 motor.

Another question: What is under the welch plug in the top ??? On the parts diagrams, I don't see a replacement for it so didn't remove it last time I had them apart and cleaned them. I used 2 cans of carb cleaned and blew through all the passages. At this point, I suspect carb problems, I just don't know why. I've been working on cars, motorcycles and boats for 35 years and have never seen anything like this.

 

[hopalong]

Re: One problem or two ???

I would suggest you try to have patience to find the problem. That motor is a great motor once you get it running. I had an 86 115 since new and had thousands of hours on it. Just replaced it with an 87 DT140! And now I have the 115 back running to use on something another day.
You asked, Is it possible for needles to stick closed, yes it is very possible whenever there is fuel (sticky) residue were the needle moves within the seat.
Please try this out:
I'm assuming when you last tried running it at the lake the boats fuel tank and lines were connected to the motor? If so why not try relocating the fuel line to a temporary remote gas container and connect to the motor and start the motor to see if there is any difference. if no difference do this: I have found that the fuel quick connect that attaches to the motor could be worn just enough to suck air into the fuel line and when this happens the motor will not even hardly fire and if it does it will not fire on all cylinders. And there will be hardly if any fuel in any cylinder. I bypassed the quick connect with a barb fitting connecting it directly to the fuel line from the fuel filter and wha la the engine fired and ran on all cylinders...the quick connect male & female was the problem.

 

[bowhuntrrl]

Re: One problem or two ???

I'm assuming when you last tried running it at the lake the boats fuel tank and lines were connected to the motor? If so why not try relocating the fuel line to a temporary remote gas container and connect to the motor and start the motor to see if there is any difference. if no difference do this: I have found that the fuel quick connect that attaches to the motor could be worn just enough to suck air into the fuel line and when this happens the motor will not even hardly fire and if it does it will not fire on all cylinders. And there will be hardly if any fuel in any cylinder. I bypassed the quick connect with a barb fitting connecting it directly to the fuel line from the fuel filter and wha la the engine fired and ran on all cylinders...the quick connect male & female was the problem.

Hopalong,

Since I was not sure of the quality of the boats fuel (sitting 4 years), the first thing I did was take a new plastic tank and connect it directly to the water separator (new filter). I will definitely check out the motor connector since that sounds EXACTLY like what I am experiencing.

I went to the auto parts today and bought a gallon of real carb cleaner. Only problem is that I don't know how to remove the plastic fuel inlet elbow from the carb. I don't see them listed in the parts breakdown and can't clean the carb body with it on since that stuff is nasty and eats all plastic and rubber. My intent was to give them a soak in the real stuff although I did blow carb cleaner through all the passages to make sure they were clear.

 

[hopalong]

Re: One problem or two ???

try removing that coupling and connecting the inlet side of the bulb to the gas container and the outlet end of the bulb fuel line directly to the fuel filter/pump.

 

[hopalong]

Re: One problem or two ???

Did you have any luck solving the problem. I noticed in the manual them carbs do have some funky adjustments and procedures to adjust them to sync as deejaycee mentioned

 

[bowhuntrrl]

Re: One problem or two ???

Did you have any luck solving the problem. I noticed in the manual them carbs do have some funky adjustments and procedures to adjust them to sync as deejaycee mentioned

Took a few days off from the headaches !!! I started putting it back together today. I have the coupling out, just need to cobble together a replacement for it tomorrow. I'll let you know when I try it out again. Tomorrow night I will be picking up another 85 hp motor (1989 Force). I know that I can make it run !!! Got it for next to nothing and for a winter project.

 

[deejaycee_2000]

Re: One problem or two ???

man you should just get, a 90hp yam ..... problems solved

 

[bowhuntrrl]

Re: One problem or two ???

Did you have any luck solving the problem. I noticed in the manual them carbs do have some funky adjustments and procedures to adjust them to sync as deejaycee mentioned

Finally got to the lake today with the boat. One of my friends talked me into it even though I was still hesitant. We had a pretty successful run, about 85% I would say. What I did was to eliminate the Suzuki quick-connect and replace with a double sided fuel barb.The only other thing was to replace the carb to manifold gaskets since I had taken the carbs off again to check them. I didn't really do anything to them since when I pulled the bowl on the bottom carb, it was still spotless. I noticed when we went to run it on the hose before the lake that the bulb seemed a bit harder. It started nicely, and then I tweaked the idle jets a bit before we were off to the lake.

I took off and the boat had a tough time planing, but once it did, it seemed to go ok.. I went back and picked up my buddy and we headed down the lake. It has no speedo or tach but seemed to be going between 25-30 mph. We'll check with a GPS next time. My impression is that it needs a 17 pitch prop. The engine doesn't seem like it's revving high enough, that plus trouble planing. I also have a tach to install but have been holding off pending the results of my repairs.

The one negative thing that happened (literally) was that the negative battery cable came loose while we were out and when I went to trim the engine, it killed the motor. I hope it didn't cause any damage, but given my luck, probably fried the rectifier or some other component. I put the terminal back, started it up and made a few more laps of the lake then in.When we got back and were trailering the boat, we noticed that the water screens on the lower were gone, fell off in the lake. I'll have to order some tomorrow.

Now I can resume installing my electronics and other stuff. I may even get out once with the boat this year. Next season I shouldn't have too much to do to the boat. Thanks Hopalong for suggesting the fuel connector, I think that was the problem.

 

[hopalong]

Re: One problem or two ???

Hope that was the problem. Intermittent air entering the fuel supply line can seem like the motor has fuel pump, carb, or even spark problem. When all that is wrong is air in the fuel line or the bulb etc. is not able to keep pressure up to the fuel supply to the pump.
Good luck with the rest of the problems