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mercury 2+2 check valves

flcusat said:
That's the way I though originally, but your post this morning got me thinking in how those two cylinders get lubrication at iddle,and before hitting the 1800 RPM (which by the way the 1800 RPM I guess is related to the adjustment of the cam follower and the throtle cam (page 2C-6 of the service manual)

When you tested the check valves after the issue with the primer bulb, did you have the throttle at iddle for the gas to go out of the check valves when you pressed the primer bulb, or it was at a position where the trigger on top of the acceleration pump was pressed?
Unfortunately the service manual it is not to clear about how the acceleration pump works.
I will do the test pressing the primer bulb with the throtle at iddle (trigger of the acceleration pump out) and at the position of the trottle when it is full depressed and see what the difference is.
Definately those two cylinders must have some sort of lubrication before the carburators kick in.
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I had throttle at idle when I tested check valves. Yes those two cylinders do get lubrication before accel pump kicks in. Let me know how u make out
 
I got home and did the test without the check valves. Pumped the primer bulb and gas came up out of both hoses going to the check valves. Then asked my son to press the trigger on top of the accelerator pump and gas came out out of both hoses.
I said to my self "now what, is the accelerator pump damaged?" after a few seconds I realized that must likely the gas came straight from the primer bulb from the T at the check valve for cylinder # 4, althought that T has a flow restrictor.
I'm trying to upload a picture of the acceleration pump flow diagram but it is not uploading with a good resolution.
 

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flcusat said:
I got home and did the test without the check valves. Pumped the primer bulb and gas came up out of both hoses going to the check valves. Then asked my son to press the trigger on top of the accelerator pump and gas came out out of both hoses.
I said to my self "now what, is the accelerator pump damaged?" after a few seconds I realized that must likely the gas came straight from the primer bulb from the T at the check valve for cylinder # 4, althought that T has a flow restrictor.[/QUOTE

You're in good shape. Gas should be coming out of both of those hoses that go to check valve when u prime the bulb. And also when u press trigger on accelerator pump. Fuel system is all connected from that primer bulb. All of those lines should fill with gas when primed
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Mattc8821 said:
You're in good shape. Gas should be coming out of both of those hoses that go to check valve when u prime the bulb. And also when u press trigger on accelerator pump. Fuel system is all connected from that primer bulb. All of those lines should fill with gas when primed
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Yeah, but I don't quite understand what the acceleration pump is supposed to do then. And odbiously there is a reason for the check valves, since you have an issue when one of yours was open. Unfortunately there is no much explanation about all this in the service manual though.
 
After leaving all the parts in Gunk carburetor cleaner for 24 hours I reassembled them this morning, connected them to the hoses amd pumped the primer bulb.
Definately one of the valves is not working properly, it takes several pumps of the primer bulb to have gas coming out of it, and the flow it is never as strong as the other one. I interchange them to make sure that it wasn't a hose issue and the problem is always with the same valve.
I reopened the valve and inspected, but couldn't see anything wrong with it, so at this point I'm going to play save and ordewr both of them.
 
The new check valves arrived yesterday and I installed them this morning.
As you can see from the picture the new valves are larger then the original valves
I tried pressing the primer bulb several times, but i guess the pressure from the primer bulb it is not strong enough to open the check valves by itself, because even when the primer bulb was really hard the gas never flow out of the valves.
I'm planning on going out this weekned and will see if I get any mprovement on the RPMs at WOT like Mattc8821 did.
 

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Mattc8821 said:
Well after cleaning out bad check valve connected to cylinder 4 this has fixed my issue! Saw 5200 rpms today for the first time since getting this boat. Spark plug color looks good.
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I am having the same issue. Matt and I are attempting to look at the check valves tomorrow. Do I have to remove the plate that holds all the coils to Get access to the check valves?
 
flcusat said:
The new check valves arrived yesterday and I installed them this morning.
As you can see from the picture the new valves are larger then the original valves
I tried pressing the primer bulb several times, but i guess the pressure from the primer bulb it is not strong enough to open the check valves by itself, because even when the primer bulb was really hard the gas never flow out of the valves.
I'm planning on going out this weekned and will see if I get any mprovement on the RPMs at WOT like Mattc8821 did.
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I'm curious if the new check valves fixed your problem like it did for Mattc8821. I have the exact same issue and went through the exact troubleshooting that Mattc8821 did. Compression is good, carbs cleaned/rebuilt, new plugs, new filters, new CDMs, new stator, new trigger, rebuilt fuel pump, rebuilt accelerator pump.

I've thrown a ton of parts at this trying to figure this out, but didn't replace the check valves yet. Before I tear into it again, it would be great to hear that it solved your problem. Not sure I understand why they would cause the behavior I'm seeing, but willing to try almost anything to get this running better again.
 
GeneralIke said:
I'm curious if the new check valves fixed your problem like it did for Mattc8821. I have the exact same issue and went through the exact troubleshooting that Mattc8821 did. Compression is good, carbs cleaned/rebuilt, new plugs, new filters, new CDMs, new stator, new trigger, rebuilt fuel pump, rebuilt accelerator pump.

I've thrown a ton of parts at this trying to figure this out, but didn't replace the check valves yet. Before I tear into it again, it would be great to hear that it solved your problem. Not sure I understand why they would cause the behavior I'm seeing, but willing to try almost anything to get this running better again.
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After looking over where the check valves are in seeing how much is involved to gain access I decided to run some sea foam through the system, and I repeatedly pumped the accelerator pump to try to force that through the check valves. I loosened up the whole plate that holds all the coils and switch box and pulled it away about an inch from the block. That gave me a shot at seeing the check valve location but I was far from being able to remove them or work on them. I’m going to run it through her three days in a row hard and see if it miraculously clears up. I just got a quote this morning on re-powering the boat with a new Merc! Not sure if all this aggravation is worth it!
 
DeanP said:
After looking over where the check valves are in seeing how much is involved to gain access I decided to run some sea foam through the system, and I repeatedly pumped the accelerator pump to try to force that through the check valves. I loosened up the whole plate that holds all the coils and switch box and pulled it away about an inch from the block. That gave me a shot at seeing the check valve location but I was far from being able to remove them or work on them. I’m going to run it through her three days in a row hard and see if it miraculously clears up. I just got a quote this morning on re-powering the boat with a new Merc! Not sure if all this aggravation is worth it!
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racerone said:
With lots of money to spend there is no need for aggravation.
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You can’t take it with you…..lol
 
Mattc8821 said:
have an 03 Mercury 125 2 stroke. 2+2

These motors have 2 check valves that are connected to fuel lines that seem to run from the accelerator pump.The check valves screw into the block- one screws into where cyl 3 is located, and another right below into cylinder 4.

Can someone tell me what issues it would cause if one of these check valves was faulty?
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If the check valves go bad they will flood either the number 3 or 4 cylinder with fuel and they will not fire or will fire intermittently.you can take the out hook them back up to fuel line,pump bulb if fuel spray out they are bad ..they should only spray when accelerating pump is depressed...
 
Mattc8821 said:
i posted about this before but still didn't figure it out. Here's info below:



2003 Mercury 125 Saltwater 2 stroke (2+2) on 20ft dual console
Boat only getting up to about 4200rpms and 30mph according to gps
Compression 120+ in all 4 cyls
I've determined that it's not running on the #4 cylinder. When I pull that plug wire off, it gets up to the same speed / rpm as if it's plugged in. When I run it and pull the spark plug, it looks a little wet, but there's no color on the plug at all, as if I just took it out of the box. Changed spark plugs around to rule out getting bad plug.


Cylinder is getting spark. I have a spark light and have spark gap tester. Set gap to 7/16 and spark jumps that gap. Spark light lights up when running. Hooked up timing light and it also read same rpms as other 3 cylinders at idle.


Pulled off carb and went through it 3 times. I'm about 100% sure that there are no obstructions in carb. Got rebuild kit also, so needles are new. Float height good also. I even switched floats and needle between carb 3 and 4 to make sure float height wasn't issue, and it wasn't. Still wasn't running on #4. Also primed bulb and unscrewed drain screw on bowl to make sure fuel was in it, and it was.


Thought it maybe wasn't sucking fuel. Pulled reeds out and reeds are 100% perfect. Put my hand over carb when running and felt suction. It also drew some fuel out of the bowl when covered. I also have a steamer - I put steam in front of each carb and had someone crank motor and watched it suck steam into each carb. So suction seems good. Also rebuilt fuel pump.


Had boat on the water and up to around 3500rpms. I sprayed some fuel into that #4 carb and there was no change in speed or rpms.


Regulator is brand new. Trigger is brand new. Stator tested good with meter -did testing procedure in manual. I unhooked rev limiter and ran it and made no difference. I swapped cdms around and ran it which also made no difference. I also traced each wire for each plug that plugs into cdm module and tested continuity on each one, and all wires seem good.


My next thought was that maybe there was some water getting into that bottom cylinder. Maybe that's why the spark plug looks brand new when I pull it out because steam is cleaning it. Maybe plug looks a little wet when I pull it from water or steam. If I run it in driveway and pull out that spark plug after I shut it down, steam does come out of that spark plug hole. Not sure if that's normal or not. Also read that water intrusion will steam out a cylinder will not let it fire even if there's spark.
I pulled the exhaust side cover off of motor and replaced that gasket / water jacket. Thought maybe some water could get into cylinder from exhaust port area . But I ran it this morning and still only getting around 4-4200rpms. These motors seem simple but this is throwing me for a loop


The strange part about my run this morning was that when I first put it in and ran it, my tach said it was hitting 5000 rpms which it hasn't done since this issue began. But gps speed was still saying around 30mph. It didn't feel like it was going as fast as it should be, even though rpms were reading higher. So I pulled that plug wire off and ran it again and rpms only went up to 4200, still around 30mph. I reconnected that plug wire and ran again. Speed still around 30 and rpms stayed at 4200, not 5,000.
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Mine is doing the seem thing just came home from lake m Mechanic said it was fix not even close
 
I have a 2001 with the same issue. Is this the part (image below) ? Is it port-side on the 2001 ELPTO?
 

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I am having a similar issue on my 2001 125hp ELPTO 2+2. No power between 2k and 3k revs. Idles ok, WOT Ok, Midrange and transition to 4 cylinders is terrible. Running options are either under 10kmh or over 30kmph. Fuel hoses replaced after they perished and blocked the carbs. Carbs re-built. My understanding of the Accelerator pump is that its purpose is to shoot fuel only in rapid acceleration, and at other times the check valves restrict fuel flow. Therefore, pumping the accelerator pump should shoot fuel into 3 & 4 cylinders. As dtthomas68 has assessed, squeezing the primer bulb should have no affect. I am assuming that my check valves are bad and letting fuel through at all times, and therefore flooding the ports in 3 & 4 until the carbs open enough to compensate over 3k revs? Could anyone advise how smooth the transition to 4 cylinders should be and at what rev range do they all fully fire? Am I on the right track with the check valves or should I look elsewhere?
 
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