Logo
FULL SITE MENU

2001 Johnson 25hp, J25EVLSIC carb/ air/ fuel supply, running rough.

C

Captainjac15

New member
I am no certified expert, but I have been around a lot of outboards and I/Os. I have a nice big shade tree in the back yard.

Current problem is with J25EVLSIC, 2001 Johnson 25 HP 2 stroke, runs rough, will idle fine at start up then quit within 1-2 minutes. Give it throttle and it dies pretty fast. 100% sure it is running lean. I can keep it going by choking the front of the carb with 1 finger. Still coughs a lot though. I ran it first time this spring and it fired right up and ran all day. Was stalling at low idle from time to time while trolling and it didn't seem like I was getting full RPMs at WOT... so I pulled the carb and bought a rebuild kit. It was Sierra (all I could find locally) and I will never do that again. Its all over the place. Some of the needle valve seats and micro tolerances were off by over a millimeter in the bowl. I Have set and reset the float to manufacturer specs 3 times now going back to the J/E parts. I Checked fuel lines, primer bulb...looked for air leaks, sealed main fuel lines with hose clamps. Checked compression- Good, checked Spark-good (jumping 1/2"), Installed new spark plugs. Checked fuel pump while turning engine over and delivery line removed from carb- good pressure. Blew out all fuel lines. Checked primer solenoid (modern choke)- good. I have had the carb on and off and re-assembled 7 times now. I am at a loss. Sucking air somewhere? thats all I can come up with for how it seems to be running and coughing intermittently, and the reason I can get it to stay running by choking the front of the carb with my hand. I have set the low idle mixture screw and it runs better if I go out 3 turns, but I know that is farther than it should be. Any help or direction from someone more experienced with this engine would be greatly appreciated.
 
Last edited:
Also wondering if it is a timing issue. The coughs seem to happen at the same time, almost like a clock. Hard to describe in words but here goes.. rum rum rum rum *cough rum rum rum rum *cough, like it misses at the same time after a few strokes. Weird though, I changed the plugs and put in new NGKs. I didn't mess with the ignition system at all yet other than new plugs and checking for good spark while the engine was already running. The plugs were not the exact same as what I took out, but cross referenced at the shop. Can the different plugs mess with the timing?
 
float level is set by holding the carb upside down and making the float level. Did you soak the carb when you rebuilt it? Did you blow out all the passages with compressed air? Did you play with any of the linkages? Did you check the link and sync? Did you over torque the top of the carb? Did you overtorque the float bowl? Does your float require the clip on the needle? Is the clip on correctly? Have you tried a different fuel tank? What is good compression? You are over thinking the micro tolerence thing. The fact you have to cover the carb throat to run tells me the idle passage is still plugged. Put the correct Champion plugs back in your motor OMC motors tend not to like the NGK plugs. Your cough is called a lean sneeze usually caused by the idle circuit in the carb being plugged. Try opening the low speed mix more. It is not a timing issue.
 
Last edited:
Thanks for the reply, and all good questions to ask myself. The float is set within specs, level to the housing when upside down, and 1 3/16" from the housing when turned right side up and gravity pulls the float down. The needle is seated properly and the clip is installed correctly. The needle doesn't stick at all when the float drops. I did not soak the carb, though the idle passage seems to be clear. I guess there could be varnish build up that is just restricting and not blocking. A soak will tell, what would you recommend for a soaking agent? There are a few options out there. I did not link and sync using a timing light, though the linkage is right on. Butterfly Fully retarded at idle position and the butterfly is perfectly flat when the control unit is at the WOT position. The tank has new gas and is clean, the main jet has been removed and is clean as a whistle, same with the idle screw and seat, new O-rings on the screw and housing, all orifices removed and cleaned. Then used compressed air to blow out the carb passages while the orifices where out. I didn't think the idle passage had so much to do with how well the engine ran when above idle, shows how much I need to learn still. I am sure that I didn't over torque the screws, maybe 8-10 Nm applied, but after taking the carb apart so many times I should probably get a new rebuild kit just for the fresh gaskets. There is also a chance that I am not getting a good seat on the intake manifold, could be sucking air there too and Really leaning out, I'll try a brand new gasket there and some focused cleaning on both sides of that connection. I'm really kicking myself over this one, the boat fired right up the first time out and we trolled all day with some WOT in between to prevent plug fouling. It just didn't have the RPMs it should have at WOT and it stalled on me a couple times at low idle even after the engine was warmed up. Now it only seems to have gotten worse since I dove in head first, live and learn, haha.
 
Last edited:
If you have an air leak somewhere that tends to raise your idle. Use carb spray cleaner and spray everyhole you can find. Pay attention to the main tube tharuns from the bowl to the top of the carb. Take the mix screw out and spray through there also. That carb may need the screw turned out more than 3 turns. You do not link and sync with a timing light. You need the roller on the carb to start moving at the mark on the cam.
 
This is a web link to the link and sync procedure I was referring to. Setting throttle and ignition together. http://www.pbase.com/bmcelya/evinrude_88_idle_and_timing_sync

As far as linkage for throttle alone goes yes the roller lines up with the marks on the cam and low idle and full throttle are set properly. When referring to the holes in the carb, yes the cleaner has been sprayed through and comes out of every hole I can see, including the small pin holes inside the main throat of the carb.
 
I hope there are different pages on that link. The link and sync procedure shown is for an 88 hp motor. Try turning the low speed screw out more. If you still think you have an air leak spray Wd 40 around the carb if you have a leak the idle will pick up.It could also be your crank seals.
 
The crank seals are really what I am worried about, don't want to do that big of a tear down... fingers crossed. That would mean that the fuel pump would not be running properly though as the vacuum in the crank case runs the pump, correct? Thank you again for your help.
 
Are your reed valves good? Have tried adjusting the low speed mix screw more? Did you remove the Welch plug from the top of the carb? Is the air jet installed in the front of the carb? The The fuel pump is not vacuum operated it uses the pressure pulse from the crankcase. There is a very small vacuum pulse. Is it running on both cylinders? What is your compression?
 
Last edited:
I just got home and have a chance to work on the engine again this evening. First, pulling the carb again and soaking it. Next getting new bowl gasket and carb-to-intake manifold gasket. Then reassembling the carb and going ahead with your suggestions from there. I did take a look at the reed valves while having the carb off and they look brand new, no build up or gumming. Next step would be reassess the fuel pump and make sure I have a strong flow. I should check compression again, since the lean sneeze incident and report back. Last check the compression was right around 110 on top and bottom cyl. I will update after the above steps have been completed. Hoping that running lean didn't mess with my rings or cylinder walls. The good news is that the plugs were still a little wet with oil last time I pulled them so the cylinders hopefully haven't been damaged by running too lean.
 
Last edited:
Just removed starter and pulled the carb again. Found some black dust and a small white fiber from my after pump fuel delivery line. Explaining why the low idle jet would run perfect at first then get lean after running for a few minutes. The fuel screen on the fuel pump was pristine. Time to replace all the lines under the cowling. It explains why it was running lean and erratic, but always good at first start up. The main hose from the tank is new and the tank has been cleaned and new ethanol free gas put in. This explains a lot. The lines looked good and new on the outside, doesn't mean ethanol hasn't done what it does on the inside of those rubber lines. I think we're on the right track now. I will still dip the carb body and bowl, also buy a new gasket kit as I have probably crushed the gaskets by taking the carb apart too many times thinking that was my problem. This is the first time I have seen substantial debris inside the bowl. Probably twisting and moving those lines so many times has shown the true problem here.
 
The definition of Stupid... doing the same thing over and over and expecting a different result. Thank you flyingscott for giving me a new perspective and pointing me in a different direction, and making me think about other variables. Sometimes that is all we need. I appreciate the direction and knowledge you were willing to share.
P.S.- I also bought the OEM champion spark plugs, QL77JC4, and put them back in, lol.
 
Last edited:
SOLVED!!!... SOAKED THE CARB in CHEM-DIP

1- Buy the Evinrude / Johnson OEM rebuild kit for the carb. SPEND THE EXTRA $5!!!! the parts and gaskets are the right size and perfect
2- Install to exact specifications being mindful of every measurement i.e. float level to the housing when held upside down, and top of float 1 1/8 " to 1 5/8" from carb housing when turned rightside up and float drops
3- make sure gaskets are perfectly aligned, pay special attention to the small central gasket that seals the venturi tube inside the bowl. This seals the upper part of the bowl from the venturi suction, and prevents air suction inside the bowl, it forces all fuel to be pulled through the main jet at the base of the bowl, and keeps the mixture steady and on point.
4- Connect bowl to carb housing, do not over tighten the screws, make sure you don't crush the gasket, tighten screws in an "X" pattern
5- REPLACE all fuel lines inside the engine housing, make sure all connections are tight with zip ties
6- Buy the OEM Champion plugs QL77JC4
7- Listen to the engine purrrrrrr like it was new.

Thanks again Flyingscott!
 
Back
Top