86 force 125 problem

[bill104]

Ok so I'm new here hoping I post this correctly, freind has a 86 bayliner with a 86 force 125 four cylinder with two carbs, early in the boat season he took it out and couldn't get it to run so they brought it to me (Diesel guy ) so I cleaned the carbs got it running,they took it out and was pleased it ran ok, he went out a month later it was hard to start used a lot of fuel and would stall trying to accelerate, went back tested compression 1,2,and 4 was 135 #3was 115, found pin hole in fuel pump on motor so kitted it and installed all new fuel lines from tank to electric fuel pump with new filter and new lines all the way to both carbs, also found one bad coil which was replaced, took it back out and and hit 35 mph wot ran good then my freind belly slapped across a wake shortly atfer lost power as if running out of fuel but still idled fine,I was able to get it up to 20 mph but it seemed to get worse as we got closer back to dock, electric pump didn't help and once home seemed to have slow flow,so I opened the float cover and found no debris or water in tank so relocated a new glass filter to new loction to watch flow and got good flow again fired it up in a tank at home it seemed to idle ok and while in neutral with no timing advance ( meaning controlled the carbs at the throttle arm) it seemed to have a good response although I didn't rev it high or for more then a couple of seconds due to not advancing the timing and not wanting to hurt anything I did notice it seemed to pop if I gave it to much throttle as if hitting a rev limiter, all was good, then Saturday my freind ask me to go out again,so to be safe I fired it up in the tank before heading out and it had a hi idle but ran smoothly so I lowered the idle at the rod at the tower like the book says back to where it was closer to 750 or so ( no rpm gauge) took it out launched fine good idle even went in gear without stalling then tried to throttle up and it just fell on its face didnt matter if I slamed it to full or eased it up it just acted like it was loading up ,took the cover off and same thing, as a side note after cleaning the carbs both times and setting the idle screws at 1/14 out from seat,it runs there but doesn't matter how far in or out I trun the screws nothing changes it just idles the same,any ideas other then using it as and anchor.

 

[pnwboat]

Normal idle setting is usually about 1000 RPM's in the tank or on muffs. This will get you about 800 RPM's in the water in gear at idle speed.

Check to see if you're getting good spark to all 4 cylinders. You may have 1 cylinder that's not firing. Clean the plugs and take it out and check the plugs afterwards. Normal plugs should have slight carbon build up on them. A clean plug is an indication that it's not firing.

 

[bill104]

No all cylinders are firing, he's running the plugs without to arm so there's no adjustment possible but all plugs are dry and burning a light tan so no fouling, read here about a plastic part at the timing advance arm that would miss things up, also going to look for exhaust leak,also something I read about here,thanks for the input.

 

[Frank Acampora]

Bill: Sorry, but lack of punctuation makes it difficult to read your post. In the future. please use sentences, periods, and paragraphs.

First, go to the top of the page and watch the video: Tutorial. This explains how to synchronize carbs and timing. Also read the sticky: Synchronizing timing and carbs. between these two you should understand how to initially set up the engine.

Trying to trouble-shoot an unknown engine without setting everything back to factory specifications is an exercise in futility because timing is strictly mechanical and carbs must open correctly related to timing advance. Also, because they are mechanical, they are coupled. If one ot the other is not set correctly, the engine simply will not run correctly..

After setting the engine back to specs, then you can more easily try to determine the problem. From your description it does appear that there is a fuel problem so check that first BUT--Don't discount electrical. A misfiring CD box can still have plugs firing periodically and have them looking correct as far as burn color. BTW: He is using a 50-1 fuel/oil ratio with TWC-3 oil, correct?

Also, do not permanently mount an electric fuel pump on these engines. There is no provision for automatically stopping the pump if the engine stalls. This can pose a safety hazard.

 

[jerryjerry05]

"all plugs dry and a light tan" This motor burns gas/oil mix and I've never seen a permagap plug that's "tan" under normal use????
What plugs are in there? Should be Champion UL-18V or the NGK BUHX
The " electric " pump what's the pressure reading or specs on the pump.
Why install an electric after you repaired the pinhole? Get rid of the electric.
#3 cyl operates the fuel pump. Low comp on #3 could be from the excess fuel washing the cylinder???
IF???? The pump is any stronger than 3-4# it could be too strong and causing the needle to lock in place.
Or strong enough to push past the needle and flood the carb.

Carb fuel/air mix screws start at 1 and 1/8th or 1 and 1/4 turn out.

 

[bill104]

Ok the electric pump was installed by last owner in place of a primer blub and he used to drain his tank in the winter, so its only on to get fuel up to the carbs, and its only six psi, I read that number three cylinder could be low compression if mechanical pump has a leak which it need hand a good sized hole in it,so I will retest that now that it's fixed, thanks too the advise given so far, I'm going to pull the carbs and reclean then,and make sure the floats are set correctly, also I found that I was tuning the idle mixture wrong as I was adjusting one at a time instead of moving both equal amounts,which means I could have left them to rich, because I didn't leave the throttle open long once it began to bog down,I'm sorta thinking there to rich, and as for proper timing it is set at 28 degrees with starter,hoping to get time to play with it soon and will update what I find asap,thanks again for the information.