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BoxMN

Did carb kit, started great, but bogs on throttle?... 25hp Evinrude

32 posts in this topic

Hey all,

I put a new carb kit in my '96 Evinrude 25hp 2 stroke. All went well, not missing parts or extra parts smile It started great on Saturday, first turn of the key.

Totally new non-oxy gas, correct oil mix. Starts and idles GREAT! The problem is when you give it some throttle. I "think" it might be as easy as an air leak in fuel line, but not sure, since I did the carb and I am not what you call a mechanic wink

I leaned over and pumped the bulb and if I keep pumping it seems to not bog, but if I leave it alone it will bog with throttle, but will troll all day long just fine.

What else "could" it be if it is not the fuel line from tank to motor, including bulb? No fuel leaks inside or outside the motor.

Also, is there only the one jet adjustment on this motor? I could only find one, but I do see a red adjustment lever on the black part (not sure what it is) that is attached to the starboard side of the carb.

Thanks for any thoguhts. The fuel line was new last year, but it is the cheap gray one from some store, rather than a good one made by OMC (tried that last year thinking my old one was bad). I will be getting a new one, but can't test till next weekend. Thanks!

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yes it is the fuel line. have a 25 evin. and had the same problem. had to keep squeezing the ball..replace it and yes dont do the cheap plastic one like i did at rainy last spring.. they get stiff as a board in cold temps in the fall...

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it might also be the fuel pump. but i would check the fuel lines and replace them 1st because fuel pumps are spendy...i looked one up for my 6 hourse johnson and that was $70. ouch!!

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I agree with the above post... start with the fuel line. It could be the fuel pump as well, but I'd start with the line.

What were the indications before your rebuild that prompted you to do a rebuild? The same problem you have now?

marine_man

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Thanks guys. Nope, it was different. It would run fine under power, but would continually kill trying to idle or troll. It acted much like my honda bike when the carbs were all gunked up smile It was also hard starting.

I did try the new fuel line last summer, the cheap gray one, and it didn't help, so I kinda new/thought it was just time for cleaning, etc. Now it starts awesome, and idles perfect...

I did reuse the fuel line fittings though last year, so this time I might just get a whole new fuel line, fittings and all, just to make sure.

What/where is the fuel pump? Is it the little round black piece that attaches to the starboard side of the carb? With the red "lever" and the "air stem" on the top? (Can you tell I am not a mechanic? wink But I have been getting into more of my stuff nowadays, it is fun learning and doing it myself.

Thanks!

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No, that is the primer. Just follw the line from the motor connecter to the fule pump or follow the line back from the carburator.

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Ahhhhhh.... hmmm...

I don't have a pic of the starboard side, but where is ti in relation to the primer? Here is best pic I have, and it is at cabin so can't take another try until next weekend.

resize800_IMG_0862.jpg

I can see the fuel line coming in from port side, going under the primer area, but can't recall where/how it connects...

Thanks guys, learning a lot on this project smile I was going to do a little report on my project, but until I get it running perfect don't want to stick my foot in my mouth, ha!

edit, whoops, I do have a pic of starboard side, but not great. Here it is, after I put carb back on:

resize800_IMG_0891.jpg

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It will be just aft of that terminal block. It will be shaped kinda like a house. You'll know what I mean when you see it.

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Thanks tons all you guys! Hopefully new hose will fix it, but I know where to check next. Can a pump be rebuilt, or is it a replacement type "fix"?

Thanks!

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Cool, I did that to my lawnmower this past winter, I suppose it is similar system to that? I did get another gasket in the carb kit, but it didn't look like it fit anywhere... here is a pic of it, I just figured it was for a different application of the carb kit to another motor...

IMG_0890.JPG

It doesn't look like a diaphragm to me though, at least not what I put in the mower...

I actualy put all the pics I took up... heh. I seem to have questions all day long smile

Thanks boatfixer!

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nope, thats the gasket for the top part of the carburater.

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Hmmm... they must make this kit for more than one application then, because there was no gasket of that shape on my carb. Trust me, I looked smile because I was nervous.

The other gasket in the kit fit properly. But all parts I could find to take off, I did, and cleaned it good, and then put new parts back on. New float and seat and all O rings that I could find.

I think I know pretty much what you mean about the house shaped pump housing, as I held this gasket up to it to make sure it did not go there, ha!

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Yeah, many of the kits are now "one size fits all". I've got small boxs full of odd gaskets from kits.

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Ok guys, I thought I was going to be able to come back and say all is well... but I am back to say I must be a lowsy mechanic smile I need your help once again.... ha!

I started with the new fuel line, OMC spendy one. Same thing. It still starts GREAT and idles and trolls GREAT! But when I give it some gas it starts to rev, then bogs and will kill unless I pull it into Nuetral quick. I can ease it just a hair over idle and it will goa hair faster, and sort of just go into a minor "surge" of slightly higher then lower then higher etc rpms, but just a hair over idle. If I give it any more throttle it will kill.

I brought the fuel pump rebuild kit just in case, and I did that. It was pretty easy, and I am sure I got it all back together properly, springs and all. The old check valves (little red rubber things) had one crack in one, so I thoguht AHAAA! that is it... but when I tested it after, same dratted thing!!!!! Arghhh.

If I pump the bulb while going, it will rev up and run properly, but I mean hanging over the back and pumping while someone else is driving.

so I though, okay, what else could it be that would let air get into the line/bulb, and I thought the tank. So I tighten up the screws on the sending unit (plug on tank, a plastic OMC tank) and still didn't change. So I went to and thought, okay, it can only be the line or tank, and this is my second line, so it must be the tank - $70 tank from a Crosslake boat shop, and still the same thing....

I am going nuts, partly because it stinks to just go trolling speed... and partly because IU thoguht I could do this and I can't figure what the issue is...

So, last things that I can think of is the pulg going into the motor fuel line... but that might just be throwing more money into it (what I ahve been doing I guess) and I just have no clue...

The bulb goes soft when you give it gas...

So, what could I have done when rebuilding the carberator that could cause this? I thoguht I got it all done properly, I was real picky to make sure, and I thoguht all went well. But something isn't right. Any ideas on what I could have wrong or missed, I will buy you beers an clean your fish and wash your trucks.... ha! I am lost, please help!!! smile

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Hmmm... okay, could I be stupid enough to have put the fuel line on backwards?.... I swear I looked at the arrow on the bulb, and had it so it followed the fuel flow.... but now that I recall, the bulb is closer to the tank than it is to the motor, and that just doesn't seem right with how I am used to it.

Boy I hope that is it, as I don't mind being stupid smile especially after buying a $70 tank that I didn't need, ha! I just hope it works. I won't know until Friday.

But any thoughts you have, I sure would appreciate it. Would a reversed fuel line cause the issues I am seeing? Thanks.

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It wouldnt even start at all backwards.

The bulb will lose pressure under normal running conditions. Does it get hard when you pump it not running? Im assuming you have looked everywhere for leaks. The fact that you can pump the bulb and make it run suggests the fuel flow is not restricted. It still seems to be a fuel delivery problem. Just to make sure of things though, I'd take the carb back apart and recheck the float level and needle.

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I'm going to say improper float drop.

I'll go on to explain why I think that is your problem.

Idles fine but when you ask for throttle it bogs and dies.

If you were sucking air or weak pump in most cases there is still be enough fuel in the bowl to give you some acceleration till the fuel in the bowl is exhausted by lack of fuel being pumped. In your case there is an instant bog, that tells me there isn't enough fuel in the bowl to for the slightest bit of acceleration. A plugged main jet would do the same thing but you cleaned the carb.

So did you set the float drop with the rebuild?

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Thanks guys.

Set the float drop... um, not sure what you mean, so I obviosuly didn't smile I just put the new one in and thought that was it. But it makes sense that it is just using up all the available fuel too quickly.

How do I adjust that? I put the new float on, and the little clip for the float needle, and the new seat. The new seat seemed to have slightly smaller hole than the old one. The new one is on the right here:

IMG_0880.JPG

Thanks for helping me!

edit - oh yeah, I did check for leaks and no fuel leaking anywhere, inside motor or out. The bulb does get hard when I pump it, but it gets soft when running, I guess that is normal then, but I never had a need to check it when things run right... When it does do the little "surging" at slightly more than idle, I was kinda thinking is seemed like the float bowl might get empty, then full, etc. I just didn't know there was an adjustment there.

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It looks like you are not getting enough gas to the bowl with the newer smaller seat hole.

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Good point Frank. That also brings up another issue, upside down float. I've seen that as well too.

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Thanks Bruce, but the previous troubleshooting and replies help in narrowing things down too.

The size difference in seats doesn't matter because the needle is matched to the seat.

The float drop is the measurement from the float to the carb body. There could have been instructions in the kit as to where those points of adjusts are measured from and what those measurements should be. If not then post the carb number and they can be looked up. A manual would have them.

When gas enters the carb the float will rise. When the proper fuel level is archived the fuel is shut off by needle and seat.

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ST, I would think that the whole size would matter to the amount of gas that can pass through it. If the motor was made to run with a large seat hole and now you have reduced the volume of it, you aren't getting the same amount of gas in the bowl. So when you hit the gas it may starve the motor?

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BoxMN, I'm not familiar with the newer Evinrudes, but I've had 2 older motors. One required the tank cap to be vented and the other was a closed system. Could it be that your motor is creating a vacuum in the tank and not allowing the fuel to flow? Phred52

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Thanks guys. Here are some answers.

The tank is not vented, so that can't be the issue. (My merc 50 needs it to be vented, so I know what you are talking about though. I wish it was just that, ha!)

The kit did not have any instructions about measuring the float. I am pretty sure about that, as I read it all twice at least. It is at cabin, so will check again. I don't have the carb kit number, but it is for an 96 Evinrude, 2 stroke, remote, long shaft, electric start, no tilt.

I am pretty sure I got the float on properly - here is apic I took of the old one, and I matched it up like this. One thing is that the thin alum that connects the float to the needle and the "hinge" I bent as strating as I could to match how the old one was sitting. Maybe that is the adjustment you are talking about? I might have that wrong?

IMG_0872.JPG

edit - hmmm.... in looking at that pic closer I see there is a slight "upward" bend to that thin arm. I think I might have made the new one straighter.... which would match what you are saying about not letting enough fuel into the bowl for a more open throttle flow.

Drat, now I will have to take the carb off on the water (no public access on the lake, and my normal "ramp" freind is not up yet), but at least I have done it once now so I know what to expect.

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