sick 1978 mariner 140hp

[joshgar8]

hey guys,

After weeks and weeks of seaching the forums I have decided to post on here with the issues I am having with my engine. This will be a lenghty post but I hope to have all required info and history to fill you guys in so we can try and get this thing going.

I bought the engine on a old rotten boat just for the engine alone. I get it home and do a compression test and all cylinders are 145psi. I then replace the timing belt, water pump, fuel pump diaphram, gear oil, and all spark plugs. The engine set about three months for me to find a nice boat to hang it on. I found a 1990 astro quickfire 18fs. I got the engine installed, all electrical components installed along with power trim and fuel line. I then took the boat to a well known old school boat mechanic for final setup and tuning.

I tell the mechanic that I want the boat dependable, and trouble free. I want everything serviced that needed it and all the systems went through. I also want him to take this thing to the lake and run the p1ss out of it to verify all is complete and it good shape.

After three or four trips to the boat mechanic, he finally got it "right" In attempts to get it "right" he put two different sets of carbs on it, 3 different triggers, a special tune job on the last set of carbs and a timing job that I would never have to worry about cooking the pistons. I will admit, she ran perfect. I didnt think it was exactly right though so I began to look into it myself.

On initial investigation, I found that the carbs idle mixtures was set at to 3/4 out, mid and bottom 1 1/4 out. The timing was set at 30-34 befortop dead center degrees @WOT and around 5 degrees before top dead cent @ idle. I only ran the boat twice before finding these issues, a total of an hour maybe. I did verify the .464 was right along with the tdc.

since finding these I have the idle mixtures the top is @ 1 1/2 out and the bottom 1 3/8 out. it seems if I go any richer, its to rich and idles like crap and it very difficult to dock, load/unload. I also backed the WOT timing back to 23 degrees, which i know is still to much but I am trying to work my way back down to the right settings. The timing at idle is still around 5 degrees, and idle speed is 1,100 in neutral on the muffs, 900 in neutral in the lake and 700 in gear in the lake.

I cannot get the idle screw to make the engine speed go up or down, and dont know what I need to do to fix the problems. I have attempted the link and sink several times and still have issues understanding it all. based on the info, can you guys point me where to start. I am sure there is allot of info I have forgot about so ask away with the questions. I just want this thing right, and want to know I am not going burn it up in a day on the lake. Thanks in advance,
Josh

 

[joshgar8]

Re: sick 1978 mariner 140hp

I forgot to mention, I did run the boat sat. I know that the timing set at 23 BTDC will burn it up however with the settings being so far off and me adjusting the some much at one time I wanted to be sure I was going the right way on my tuning. It was set at 23 BTDC WOT and 6 BTDC @ idle. The mixture screws was at top 1 1/2 and the mid and bottom was at 1 3/8. It ran good except alittle sluggish off idle, and would die when idling in gear trying to load and dock. I'm spinning a 21p prop. WOT is about 5200 rpm.

 

[joshgar8]

Re: sick 1978 mariner 140hp

I think my problems all evolve around the trigger being one tooth off. I get confused in the link and sinc process at the point it talk about the pointer pointing towards the three dots on the flywheel. My flywheel doesn't have three dots. It had one for on the sticker and that's a punch mark very close to the .464 mark and it appears to have one more punch mark underneath the sticker long before TDC. It is in abou the same location at the start of the timing sticker. I would like to post some picture but am having a hard time with that also.

 

[Chris1956]

Re: sick 1978 mariner 140hp

Idle pickup timing s/b 4-6* BTDC. Remove spark plugs 2-6 and install them into their wires and ground them to block. Now crank motor and adjust throttle until timing light reads 4-6* BTDC. Adjust distributor collar until carbs are closed, but ready to open. Tighten dist. collar. Now advance throttle to full and adjust max spark advance set screw to read 21*BTDC. Now adjust max throttle set screw to stop carbs from hitting their stops. Install spark plugs and take motor to lake. Run her until warm and adjust idle mixture screws for smootest, fastest idle. Adjust throttle cable and idle stop set screw to achieve about 900 RPM. Now try to accelerate. if she stumbles or stalls. open idle mixture screw on top carb 1/8 turn and try again. If she still stumbles, open mid carb idle mix screw 1/8 turn and retest, follow with bottom carb screw. usually the upper carbs will have screws adjusted mor open. Recheck idle speed.

 

[Chris1956]

Re: sick 1978 mariner 140hp

There could be only one dot (punch mark), but it will be on the far right of the decal(looking at the carbs). The dot on the decal is placed over the punch mark.

 

[joshgar8]

Re: sick 1978 mariner 140hp

Ok I am at work now but will verify that dot first thing in the morning. I however do have pictures on my phone of the flywheel and pointer on zero and the pointer has been verified correct with dial indicator. In the pic, the two NIBS, one on the trigger pulley, and one on the trigger housing that's underneath the inspection slot when top support is on is NOT lined up. It appears that the trigger pulley is about one or two teeth off clockwise when looking at it from the top. The dot that's overtop of the punch mark just to the right of the 14 degrees after top dead center is pretty much lined up with the trigger pulley.

Thanks for your advice, and help. I have determined one of these things can very easily drive a man crazy if he cares about the longevity of his equiptment.

 

[joshgar8]

Re: sick 1978 mariner 140hp

Chris, I did all that was described above. First thing I had to move the trigger pulley one tooth to get the arrow to point towards the dot. I adjusted the first pickup to 5* BTDC, I pushed the throttle control all the way forward and then set the max advance to 21* BTDC I then checked and adjusted the throttle cable along with the max throttle stop. After all was setup I was curious as to what the timing light was going to say at idle. I spun it over in neutral with all the plugs still out and it fired at 8-10* AFTER top dead center. I put all the plugs Ina and buttoned it all back up and was going to try it on the muffs. It will not get anywhere close to idling at the current settings. To get it to run I have to use the fast idle and when it does, I checked the timing and it's idling at 6* BTDC and. The carb mixtures are set at 1 3/4 turns out.

 

[Chris1956]

Re: sick 1978 mariner 140hp

There is no spec for the timing at idle. The 4-6* spec simply synchronizes the carbs and timing. Health and carb mixture adjustments determine how retarded the actual idle timing will be from the 4-6* spec. I have seen some of them idle at about 0*. Later ADI modles are a few degrees ATDC. Set the idle speed for about 900 RPM, after the carbs are adjusted, tighten the idle stop to this setting, adjust the throttle cable to push the throttle closed and add some preload, and you are done.

 

[joshgar8]

Re: sick 1978 mariner 140hp

So this being said I should adjust it to idle, for that to occur I believe that the advance/throttle will be alittle beyond the first pickup just to get it to idle. Is that still within spec? Another words the throttle position will never let the trigger get low enough to come off that first throttle pickup @5* I believe I can make this happen, however it takes the first pickup totally out of the picture.

 

[Chris1956]

Re: sick 1978 mariner 140hp

If you have set the idle pickup timing correctly, the carbs will always start to open at 4-6* BTDC. That is all that matters. Set the idle stop anywhere the motor runs at the right speed. Just do not adjust the collar on the distributor, once it has been set to the proper idle pickup.

 

[joshgar8]

Re: sick 1978 mariner 140hp

Ok good deal. I will attempt to get her dialed in on the idle in the morning first thing. I adjusted the collar on the trigger housing (2-5/16 headed bolts) for the carbs to begin to open @ 4-6*. I will leave that setting alone and try to bring the idle up with the most outboard screw on the plate just forward of the trigger opposite the max idle timing screw. My concern is having enough adjustment in the screw, I haven't looked at it again since I had to leave for work but off the top of my head it's going to take several rounds in to get it to idle.

Is it common for these engines to not get back down to where the carbs are fully closed and timing fully retarded at idle? The way this thing is looking, the carbs will always be open some to maintain 900rpm when the pickup is set correctly.

Thanks allot for your help and patience helping through this. I work on aircraft for a living so its second nature for me to double, triple and then check again for the fun of it when trying to get something right when I'm alittle bit uncomfortable with something.

 

[joshgar8]

Re: sick 1978 mariner 140hp

I think I may have her dialed in to a decent base setup to fine tune in the lake. I got the idle set on the muffs around 1050-1100rpm which I know is high, but my thoughts are the backpressure in the prop and lower unit from the lake will bring it down close to 900......I hope. It took 90% of my throttle screw screw in to get it to that setting and to 90% of my throttle cable had to be taken out for the neutral to fall into place. I double checked the max timing, still at 20-21* I didn't recheck the pickup timing, but haven't touch the two adjustment bolts since it was set. My max throttle still had about .030" play in the carb shaft after hitting the throttle stop. I'm planning on the lake tomorrow if the weather lets me.

 

[Chris1956]

Re: sick 1978 mariner 140hp

There is a link between the throttle arm and the distributor that can sometimes be adjusted to get back some of the idle set screw and throttle cable adjustment. Not sure if your model has it.

 

[joshgar8]

Re: sick 1978 mariner 140hp

Chris, I went to the lake today but was very limited on time due to it getting dark on me. I think I have everything where it needs to be except the idle mixture screws which I just simply ran out of time to try and improve the already good results. It was running very good considering all the major adjustments I made from where it was. I did have to mess with the idle speed alittle bit but it's not totally dialed in until the idle mixture screws are set. The only thing I noticed that seemed out of tune was when I was loading it up on the trailer, I put load on the engine and then when I got it where I thought I wanted it on the trailer I pulled the throttle back to idle pretty fast like and it died. I checked out where I was on the trailer and needed to pull up more, loaded the motor again and went back to idle and it died again.

What are these symptoms of? Lean mixture, fat mixture, or just the nature of the beast with a high strung two stroke. It did take fuel and the load on the engine when loading but died when the throttle was brought back to idle and load removed. Thanks man, Josh

 

[Chris1956]

Re: sick 1978 mariner 140hp

Not sure the exact cause of the stall. I would finish the carb idle adjustments and see if it gets better. Remember the mid carb runs a bit richer than the top carb and the bottom carb runs richer than the mid carb. So the top carb idle mixture is usually turned out a bit more (maybe 1/8 turn) then the mid carb and so forth.

 

[CVX20SPRINT]

Re: sick 1978 mariner 140hp

When you do get your idle sorted I think you will want a different prop.I'm pretty sure you'll want 57-5800 rpm at wot.Thes old inlines don't like to be lugged.

 

[joshgar8]

Re: sick 1978 mariner 140hp

I got it out and ran it a couple hours this morning until the lake got real rough and allot of boats everywhere. When I first put it in the lake and idled out of the no wake, I snapped the throttle forward and it fell on its face bad. I reset all the idle screws to 1 1/2 out and still very very sluggish out of the hole but did come out and plane. I kept messing with the mixtures and got it to come out of the hole pretty good, but still takes longer than expected. I think I may still be alittle on the fat side. What are the characteristics of a overly lean rich condition?

Other than that, I am getting really close on the setup. What's leading me to think its rich is after turning the screws in some, alittle at a time, it was continuing to improve on the holeshot. After I pulled it out of the water, my prop hub was rather black and the vent holes in the prop had black streaming from them.

Although it's much much better and I know I'm not going to burn her down, I just have alittle bit more tweaking to get it perfect.

 

[Chris1956]

Re: sick 1978 mariner 140hp

If you are seeing extra fuel in the exhaust, the fuel pump diaghram may be leaking.

 

[joshgar8]

Re: sick 1978 mariner 140hp

It's not exactly fuel I don't guess it's carbon so to speak.It wipes right off like sutt, but leaves me to believe it is a overly rich mixture based on my experience with regular engines. You can see exactly where the exhaust gasses travels out of the vent holes up toward the following blade. It is also built up on the prop shaft nut. If you was to do a prop change, your hands would look like you have been juggling coal.

 

[Chris1956]

Re: sick 1978 mariner 140hp

You are running a 50::1 fuel mix? You are using TCW-III 2 cycle oil? What do the spark plugs look like? Why did the mechanic swap carbs? Did he use standard jets in the carbs? Why three triggers? You would think one good trigger would be enough. Do you know how much work it is to change triggers?