Force 125, thought I had a bad reed valve

[redfury]

Yeah, I bought one of the infrared heat detectors from HF as well, comes in super handy. I'm going to upload some video to youtube and post it here for reviewing. I'm wondering if I'm not overloading the fuel recirculation system or if one of the fuel pump valves is bad. All I did was replace the diaphram, screen and gaskets. I have all three valves now, so I'm going to completely rebuild the pump with all new parts since it was cheap and then I can eliminate the pump from the equation.

 

[redfury]

 

[redfury]

 

[jerryjerry05]

The valves in the pump don't usually go bad?
​Not saying they never do but I've seen only one that actually fell apart when I removed the pump to replace the diaphragm.

​Surging: could be sucking air around the intake side, the carbs not synced, a restriction in the fuel lines, the fuel tank vent line partially clogged,
​timing off, motor running hot, the recirc system clogged,

​Try spraying starting fluid around the intake side and the base of the carbs.
If it makes a difference in the way it runs? then it's sucking air someplace??

 

[redfury]

I usually use a water bottle with a pin hole in the cap to spray around gaskets, and I had done that off the lake without any real changes...I'm not a fan of spraying atomized fuel around a running motor. I will probably have to see how it's running once I get the carbs back on in the spring and put a fresh battery in it. I ran it without the fuel tank cap fully sealed to avoid sucking the tank down in case the vent was bad ( this is one of those plastic tanks with the newer click type cap with the anodized vent buttons that you can press to release pressure and unscrew for operating. ) I do have my permanent tank installed, so I may fill it with fuel and have both available when I put it on the lake to compare results.

 

[rk970]

Humm .02. I have a 1969 merc 800 that would run great until a few min at WOT. Engine would "sag" and rpms would drop. Thinking it was going lean I replaced the fuel pump check valves, diaphragms, removed the anti-siphon valve, new fuel filter/separator, fuel lines and primer bulb.. After all that it was doing the same thing.. A set of new float needle/seats cured the problem. The fuel level in the carbs were rising at WOT causing a really, really rich condition because the float needles could not control fuel level at higher pressures/flow..

 

[redfury]

Well, I pulled the head today ( finally got warm enough weather and enough snow melted to get at the boat ) and to be honest, I'm not convinced the gasket was bad. It was well sealed on 2 and 3, 4 was loose after pulling it, but that could have been due to the way it's torqued initially from the center out and the fact that the head pressure as I pulled bolts was at the bottom. It came off the boat well, but I had to scrape gasket material off mostly in the center. I'll put a new gasket on it since I have it, but I'm concerned that I haven't found the issue with the boat yet...won't know until I put the head back on, the carbs on , synch'd and on the water for a test. So, I will have a rebuilt fuel pump, rebuilt carbs and a new head gasket on this motor. All because of a backfire due to a cylinder flooded because of a ruptured pump...

The good news though, looking at all of the cylinders, I can still see honing marks evenly across all cylinders, so the piston/cylinder wall health appears to be good.

 

[jerryjerry05]

From redfury's last post.(

I usually use a water bottle with a pin hole in the cap to spray around gaskets, and I had done that off the lake without any real changes...I'm not a fan of spraying atomized fuel around a running motor)

I've been doing this for years and never had a problem.
I also have a fire extinguisher close by when I repair anything having to do with the fuel system. Being as the intake side is sucking in, the SF gets ingested in the motor and doesn't cause a problem. ​

 

[redfury]

I get what you are saying JerryJerry. On the lake, with the airhorns off the carbs and a squirt bottle with some premix in it, if it starts surging again, I'll be looking at giving it a squirt to see if the throttle improves.

I do have a question though, is there any possibility that the newly reconditioned fuel pump was over running my floats and causing a rich condition? That might explain the smoke. I plan to install the Atwood valve to keep the pump from being able to over run the carbs, as well as a filter after the pump as insurance against anything from the pump. I have to order the parts yet...going to get a new fuel line and bulb as well as the filter and regulator.

 

[jerryjerry05]

No way the pump can over power the floats unless the floats/carb bowls are full of crud.
The pump is at max about 2-3#
A car pump is about 7#
The pump is so low powered that's why they use the squeezie.
It wouldn't be able to draw fuel from the tank when starting.
Or it would take 20-30min to get enough fuel from the pump.

The needle and seat: are they a matched set?
Some needles have a rubber tip and a solid seat.
Some have a solid tip and a rubber seat.
Lots of rubber seats will swell and shut off from additives.
Some rubber tips get a groove in them and cause a leak.

 

[redfury]

Well, I may have stumbled upon my problem. I replaced the starter, put a new fuel line on it, fresh battery and she popped right off with the initial carb settings, however, I was detecting a misfire and started investigating further...found the number 2 coil has no continuity between the secondary lead and ground whereas the other 3 have good readings. I'm going to order a new coil, run in my tank and muffs at home and see if it cleans up. If the engine purrs, it's off to the lake for a tune and test. I'd love to replace all 4 coils, but that's not in my budget right now....I'm more interested in seeing if I've cleaned up this surging issue. It would make sense that it would run great on 3 cylinders initially and then the recirculation system must be getting loaded up from the non firing cylinder. I didn't see any damage or indication that there were any mechanical issues with the rest of the engine, so hopefully this discovery will lead to a fix.

 

[pnwboat]

Make sure the metal contact clip on the end of the wire is making good contact with the center conductor in the wire itself. I've found a few times where the metal clip was badly corroded where it pokes through the insulation to make contact with the center conductor resulting in no or intermittent spark for that cylinder.

 

[jerryjerry05]

Try swapping the coils and see if the no spark follows the bad one??
In all my years I've only seen 2 maybe 3 bad coils.

 

[redfury]

Hmph. well, I replaced the coil with a used one and it started and ran beautifully, until I started giving it some throttle. The smoke was so bad that it was choking me...running really rich...really rich. Seems like the longer I run it, the worse it runs. It's obvious that I'm getting excess fuel and running rich. I pulled the plugs and they were all the same, though cylinder #1 and 4 had a little smoke rolling out of the spark plug hole, which is probably because of were the motor stopped running.

I hate carbs. It seems like any adjustment I was doing didn't really make a difference in how it ran before I changed the coil, not really seeing much of a difference after as I turn the enrichment screws. I reset them lightly and turned out 1 1/4 turns, then turned back in a quarter. I'm at a bit of a loss. It seems like if I let it sit for a little bit, it will run smooth at idle, but then if I start throttling it, it starts to act up. I know that the water pump is getting enough water up to the head...it seems like it's choking itself out.

 

[Nordin]

Have you checked the fuel pump diaphragm?
If it is worn and have small holes the engine maybe get more fuel and run rich.

 

[jerryjerry05]

Does the squeezie get hard when pumping?
Any fuel coming back / spitting through the carbs?

You initial adjustment is about 1 1/4- 1 1/2.
After the motor starts to rev up the idle setting does nothing as the main jet takes over.

The smoke is normal as your not getting it up to operating temp and allowing the oil residue to burn off.

Once it gets faster for longer periods the bad smoking will go away.

Like Nordin suggested check the fuel pump.

Starting fluid: start motor and spray around the intake side.
Any changes?? then it's sucking air somewhere??

 

[redfury]

Fuel pump is brand new. After getting it on the water and getting proper back pressure on the exhaust, I was able to tune it into a nice hum. Apparently cleaning the carbs helped more than I thought, I was just running really rich. I was able to run the enrichment screws in a little further than I had them set at prior to rebuilding them ( the engine sat for 3 years and I had started it up and ran it )

However, the problem I'm having now, after finding that I had a dead coil and replacing it, is a dead coil again...same cylinder. I'm worried that there might be something going on that is causing me to damage coils. It ran great the first outing, the second was good, but the third I could detect a misfire ( slight ) and then at the end of the day I was getting that misfire you can feel at speed...like you are hitting thick water and pushing through it. It would start right up when it died, but it was sputtering pretty bad. Did and OHM check on the coils and sure enough, primary to ground I get nothing...open circuit.

I want to be more thorough on the diagnosis, the coil I put on was from Ebay used with a 90 day warranty...contacted the seller a few minutes ago. But, even if they send me a replacement or I end up buying a new one, I want to make sure that there isn't an underlying cause to this. Is there a way to check the igniter circuit for high impedance or ? I'm not as versed in 2 stroke ignition circuits. I'm going to change the plug on that cylinder just in case ( they were just changed recently ) but I don't think I'm as worried about the plug being the culprit as I am the rest of the ignition system. This boat ran great until I started having this problem. I don't want to keep throwing parts at it because I find a dead component and kill it because I didn't check back far enough.

 

[jerryjerry05]

Looked at the last post, what cyl is the coil going bad?
Always include the year and model#
If it has aftermarket part? the test results can be different on some parts.

I've only seen 2 bad coils in all my years.
One going bad after a short time??
This is when you need to do the trigger output test.

1. Check the trigger resistance, trigger wire sets read approximately 50 ohms between the wire sets (DVA-5V or more), and open to engine ground.
2. If readings are good, disconnect kill wire from one pack. If the dead cylinder starts firing, the problem is likely the blocking diode in the other pack.

I tested a trigger and one lead had 25v on 1 set of leads.
Turns out in the wiring harness the bad wire had worn through and was getting too much power and causing problems.

Also test the leads for broken wires under the shrinkwrap.
I routinely replace ALL the connectors when working on the ignition system.

 

[redfury]

• 1254X7B - 1987 , I was wondering how to test this. The 2nd cylinder from the top is what has been giving me fits. I will test the trigger assembly, as I was concerned that perhaps there was something that was going on. I wasn't aware of the higher voltages.
• When the #3 cylinder was being flooded, I was running the motor trying to get the boat around the lake, I used primarily my trolling motor, but used it to get back to the launch. When I finally figured out that 3 wasn't firing doing a cylinder balance test, I knew that I was getting compression and spark. After I had the problem with the poor running at the end of the last year, I was doing another balance test and I do remember #2 giving me a helluva shock when I pulled the wire ( I was using a test light as a path to ground, but apparently it chose me instead ) and I threw the wire and ran and shut the motor down as soon as I could....geez that hurt good too! I was worried I had damaged the coil by having the motor running without it having a path to ground, even though it was for a few seconds. I discovered the bad #2 coil after rebuilding the carbs over the winter, replacing the head gasket and firing it up and detecting the misfire, which prompted me to ohm out the coils, where I found #2 open. Figuring that was my culprit, I got the replacement and it ran smooth as butter again...I was able to properly tune the carbs at home in my tank, and then tweak on the lake. Boat ran great that day. The second time I took the boat out, was by myself, and I did a bit of playing around, as I had just gotten a new Helix5 sonar. The 3rd time I took the boat out, I could hear a slight miss, and by the end of the day, the motor was sputtering at idle, so I did the check on the coils again knowing that everything else should have been fine. Same coil, same problem. So, when I get the new coil, I am going to put it in a different position, put in new plugs and was thinking that I would need to make sure the trigger wasn't the problem, because I can't think of anything else that could be ruining a coil. Over voltage makes a lot of sense.

Now, when you say disconnect the kill wire in one pack, are you talking about the CD modules?

 

[redfury]

I took pretty extensive pictures of my motor during most of my acquisition or it, and while I've worked on it so I can reference most angles.