# 1979 Evinrude 25 hp tiller



## PikeSlayer (Mar 12, 2012)

So I bought an old boat and motor rig from an old farmer who lived near by me. He told me that he ran it up every year, then ran stabil through it and packed it up for the year as he didn't ever have time to take it out fishing. Low and behold, I took it out this weekend to run it up in a garbage can of water and I could not get it to start. I put fresh gas in and I pulled and pulled until my fingers blistered and my arm was sore and didn't get so much as a pop. I called the guy back and finally got the truth from him, that he hasn't run it in 3 years! I'm wondering where to start as taking it to a local marina is probably going to be a pretty decent hit to the wallet. I figured to start by pulling the plugs and making sure they're not all fouled up. I also figure if I can get someone to help me hold the plug against the block and pull it through I can make sure I have spark. What else, if anything, would be good to go through on it? I didn't get any kind of a book with the motor so I'm not sure what else to do with it. Any info or tips would be much appreciated. The motor does pull through so I don't think anything is seized up. Thanks!


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## Johny25 (Mar 12, 2012)

Probably needs a carb clean or rebuild even. Fuel and spark will be the issues you need to address by the sounds of it. If you have fuel and good spark then you can move on to other possible problems. May want to think about replacing all fuel lines also. Especially if they are original lines.


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## PikeSlayer (Mar 12, 2012)

I'm not sure if this is normal or not, but when I pump the bulb until it builds pressure, I can pull the motor through a few times, and if I go to pull the fuel line off the motor, there is still pressure in the line so it squirts out a bit. How else can you check to make sure you are getting fuel to the cylinder? If I pull the plugs and let it dry out, then prime the bulb, pull the choke, and pull it through a few times, there should be fuel in the cylinder?


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## bbstacker1 (Mar 12, 2012)

First thing I would do is a compression test, once you've done that and assuming you have good compression, I would think it should be at least 100 psi and within 10% of each other. I would then check my fire, if none we then find out why and fix that, if there is good fire and it will not start, squirt a little premix into each cylinder and see if it will fire, if it does we now have to figure out why it is not getting gas to the cylinders. Been setting 3 years, almost without a doubt going to have to rebuild the carb. Should also replace the water pump impeller even if it seems to be pumping water good, that is cheap insurance.


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## xbacksideslider (Mar 12, 2012)

Take the plugs out, hook them up to the ignition wires, use alligator clip jumper wires to make sure that you have the body of the plugs grounded, turn off the lights and in a dark room, pull the start cord, if you see a spark, then proceed to the carb.

Check the vacuum tube that transfers crank case pressure to the carb's pumper diaphram for disconnection or leaks. 

Gas dries out, leaving a residue that clogs jets and orifices. Take the carb off and dissassemble it, take pictures of each step along the way so you won't mis-remember how it goes back together. With fine wire and compressed air, clear all the passages. Take care with the pumper diaphram and inspect it for holes/leaks that might prevent it from pumping fuel. You might have to buy a rebuild kit to get the washers and seals that time and your disassembly have rendered unserviceable.


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## PikeSlayer (Mar 13, 2012)

I checked online and it looks like I can find a carb kit for less than $20. I can also buy a water pump repair kit, which appears to be all the parts for the water pump, for less than $40. I can also get a whole new fuel pump assembly for about $50. All of the lines appear to be in good shape on the engine itself. Assuming that compression is good on the cylinders, do I just start shotgunning parts at the motor? Or do I try to go bit by bit, start with making sure I have spark to the plugs. I'm still not sure of the best way to make sure I'm getting fuel to the cylinders. I figure if I can at least get it to light off, then I can determine how good or bad its running before I start to throw parts at it. I know things will need to be replaced, and I understand motors need upkeep, but at this point I really want to get on the water. Am I being unrealistic and should I just replace all old parts? What parts would be recommended replacement on an older motor? Thanks guys!


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## Johny25 (Mar 13, 2012)

I would check compression, then make sure you have good spark, then rebuild carb (and even if fuel lines look good on the outside I would still replace ALL of them if they are original lines, the old OMC fuel lines were not meant to run ethanol and they deteriorate from the inside out. And for around $10-15 bucks for all lines it is a cheap way of eliminating concerns about that. Little tiny black pieces of rubber can clog carb jets easily.) I believe after you do these rather cheap fixes and it still doesn't run you can proceed to other possible problems. 

Put some 50:1 mix in a spray bottle and spray it down the carb to start if it doesn't start right away. Then you will know fuel is going through the intake to the reeds. You can also spray a little bit through the spark plug holes to lube up cylinder walls and what not since it hasn't been ran in so long. Thats my 2cents at least


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## bbstacker1 (Mar 13, 2012)

I pretty much agree with Johny25, if you just want to hear it run make sure you have fire and squirt a little pre-mix into the cylinders you should at least get a pop. In the end you should replace all the mentioned items even if they seem to be OK. When I go thru an older motor (most of mine are late 50's to early 60's) I replace all fuel lines, do a carb kit, ignition system, etc. One thing I alway fix/replace is the water pump impeller, it may seem like it is working fine and it may for some time but then again it may loose a blade at any time too. Just remember, you might be on the lake and you loose fire or have a fuel issue, most likely the engine will just stop running, if the water pump stops working it may stop running and seize up which is generally not a good thing.


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## PikeSlayer (Mar 17, 2012)

Well I've got the carb kit and new water pump on order, should be here next week. I'm still trying to get it to pop off while I wait, and I've so far confirmed spark, and I've traced fuel up to the pump through the filter. I pulled off the air box and I've pumped and pumped the bulb, choke on, and pulled through dozens of times. I'm not getting fuel to the carb. I'll have to keep digging, but I don't know if the issue is that the pump is bad, line to the carb is clogged, or if the valve and float are stuck. Any other tips for this would be appreciated. Thanks guys


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## bbstacker1 (Mar 17, 2012)

I guess you could go ahead and pull the fuel line just before it goes into the carb, if you are getting fuel thru it, when you pump the bulb, then you pretty much know the carb is not letting any fuel in. My guess, you will find the needle stuck closed when you open up the carb. Did you try pulling the plugs and squirt a little pre-mix directly into the cylinder to see if she will pop?


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## PikeSlayer (Mar 19, 2012)

You were right bb, I pulled the carb off and I could squirt fuel through the line leading to the bowl, but nothing further than that. Once I took the bowl off the needle was shelacked in its guide. I was able to clean it up pretty well. I soaked it all in carb cleaner and flushed it out as best I could. Threw it back together and BLAM, she started right up. Took me a while to get the idle adjustment right. I'll be doing a carb kit on it anyway when it arrives this week. I'm assuming I'll need to adjust the idle setting again. Is there any reason to do anything with the fuel pump if the motor is running fine as is? I found where I can get a new fuel pump, but I just don't know if it is necessary or not. Also, how difficult is it to change out the water pump? I have one coming this week, but I've never changed one before and am not sure how difficult it is. Thanks again guys!


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## Johny25 (Mar 19, 2012)

Johny25 said:


> Probably needs a carb clean or rebuild even. Fuel and spark will be the issues you need to address by the sounds of it. If you have fuel and good spark then you can move on to other possible problems. May want to think about replacing all fuel lines also. Especially if they are original lines.



That is what the first person who commented said to do :wink:


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## benjineer (Mar 19, 2012)

You have no idea how old the fuel pump rubber stuff is. It's probably old enough to be allergic to ethanol. I wonder how much of that stuff on my '78 is original???? I'm betting the fuel pump was redone at some point or it wouldn't be working, but who knows about the lines.


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## Pappy (Mar 20, 2012)

If you are running alcohol in your gasoline you will be living on borrowed time with your fuel lines and fuel pump (vintage) but you have the option of running non-ethanol fuel or replacing your fuel lines and putting a kit in that pump. There is no additive that will rid today's fuel of alcohol.


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## PikeSlayer (Mar 23, 2012)

Carb kit is done, new water pump installed. Checked fuel lines etc... The motor runs AWESOME until I put on the airbox. Then it doesn't seem to want to run right. It runs rich (I think) and when you try to accelerate, it bogs down and dies. I figure there must be something in the air box. There was some mouse nesting material in the bottom of the engine compartment. I can't figure out if there is any way to get inside the airbox to see if it is clean. Is there a filter element inside or can I just blow it out with compressed air?


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## PikeSlayer (Mar 25, 2012)

I blew air through the air box and got flow. No debris came out. I can't figure it out. I cleaned the carb initially and I got it to idle well. Then I put in a carb kit and a new water pump, ran the motor with the air box off and it ran and idled perfectly. I put on the airbox and I couldn't even get it to start. When I put the airbox on, the choke lever that hooks to the arm for the choke plate, doesn't allow you to move the choke more than a little bit. When I run it with the airbox off, I can completely close the choke. I've looked at parts drawings and all the parts appear to be right, so I don't get why you can't use the choke properly with the airbox installed. However, now, I cannot get the motor to idle even with the airbox off. It continually wants to die off, but if I flick the choke closed for a split second, the engine will rev back up. I can give it throttle, pop the choke for a second and get it to run smoothly at high rpm. It just won't stay at idle. It also doesn't like to be throttled up from idle to speed. This is a real head scratcher for me. Any advice????


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## jasper60103 (Mar 25, 2012)

I have an '81 25hp with the air silencer like yours. First, lets get the choke lever working properly. The only thing I can think of is when put the air silencer on, its blocking the carb linkage somehow? Also, it can be a little tricky getting the choke lever (#23) mounted correctly. It has to fit correctly with the bellcrank (#1) as well. 
Anywho, I know I put it on wrong a couple times, LOL. Take a good look at it again. Also, I think if the choke detent (#43) or choke knob (#21) is upside down, the choke knob may not slide in/out correctly?

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1979&hp=25&model=25904R&manufacturer=Evinrude&section=Carburetor

edit: Also, I have a few carb pics, maybe it will help. Let me know if need more.


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## PikeSlayer (Mar 27, 2012)

I cannot get photos to post on here. Is there some kind of a setting I need to change or something? I've got pics of my carb in its current configuration that I want to post to see if there is any obvious issues.


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## jasper60103 (Mar 27, 2012)

PikeSlayer said:


> I cannot get photos to post on here. Is there some kind of a setting I need to change or something? I've got pics of my carb in its current configuration that I want to post to see if there is any obvious issues.



They may be too large.
The easiest way is load your pics on a picture hosting website like photobucket, etc.
Then post the image code (or link) in your thread.


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## Pappy (Mar 27, 2012)

As far as not being able to get it to idle properly without blipping the choke just richen your idle mixture screw a little bit and it should run start running properly. Turn the screw counter clockwise around 1/2 turn and see how it runs. You may be able to turn it back in 1/8 turn at a time (allowing around 30 seconds for the new mixture to stabilize the engine) and increase the idle quality until it once again shows signs of running lean. Then back it back out a little.


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## PikeSlayer (Mar 28, 2012)

I looked at my carb. The parts all appear to be right based off the parts drawing. I included some pictures. The first 2 show the carb with the choke in the normal position:
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0353.jpg. 
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0354.jpg
The 3rd shows the carb with the choke pulled out:
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0355.jpg
4 and 5 are when pushing the choke to the full closed position and what it looks like when resting against the choke arm respectively:
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0356.jpg
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0357.jpg
6 shows the choke lever pulled out:
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0358.jpg
7 shows the choke lever pushed in:
https://i1052.photobucket.com/albums/s450/PikeSlayer83/GEDC0359.jpg

You can see that the throw of the choke knob makes the choke arm hit the air box and therefore not actuate far enough. This still doesn't address the idle issue, but like jasper said, I need to take this one step at a time. Thanks in advance for any advice! 
Pappy, I had this motor running perfectly when I first put the carb back on. The only thing I can think of is that something that I didn't get out of one of the passages broke loose and is now blocking something in the idle port. It had origionally idled perfectly, I could shift it in and out of gear, and throttle up smoothly in neutral. This was all done in a barrel though, not on the water. Now, with the airbox off, no matter what I do to the idle adjustment, it wants to die off. I get that applying choke would imply that it is running lean, but I adjusted the idle screw until the motor was smoking like crazy, indicating a richer than normal mixture, but it still wouldn't stay running...


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## jasper60103 (Mar 28, 2012)

Nice pics!
With the choke open (pushed-in), I'm almost positive the choke lever should push the bell crank. I can double check when I get home, but I think that's the problem. You just have to remove the lever and reposition it if that's the case.

Also, I think pappy was just trying to get your idle problem resolved. I respect his advice.


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## PikeSlayer (Mar 28, 2012)

Thanks. Yah, if you think I just need to reposition the lever, that probably makes sense. Also, I hope I didn't come off as being upset or disrespectful towards Pappy. I was just trying to clarify my problem. I get what he is saying about the idle adjustment, I'm more just checking to see if you guys agree with me, and I should take the carb back apart and reclean it since it had been working perfectly, and now it isn't idling.


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## PikeSlayer (Mar 29, 2012)

So how exactly do you reposition the choke lever? I'm worried that adjusting the linkage on the side of the carb for the choke will effect the way the throttle plate opens when you use the choke.


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## jasper60103 (Mar 29, 2012)

PikeSlayer said:


> So how exactly do you reposition the choke lever? I'm worried that adjusting the linkage on the side of the carb for the choke will effect the way the throttle plate opens when you use the choke.



Pike,
I'm going by memory here, but it requires a little patience and dexterity. You are not making any linkage adjustment by doing this. 
You'll have to remove the screw and washer for the choke lever. Then re-attach the choke lever such that the arm extending upward is behind the bellcrank. I'm not sure about this step, but you may have to push and hold the bell crank forward (because its spring loaded) to accomplish this. 
When you get to this point, it will start to make sense. I wish I had some pics of mine, but I didn't get a chance to look at last night.

To answer your other question, checkout the youtube video below. Notice how he is moving the throttle and it doesn't affect the choke. 

https://www.youtube.com/watch?v=8uhNenO6aIQ


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## PikeSlayer (Mar 30, 2012)

I guess I'll just have to dig in and give it a try. Also, I'm guessing a re-clean of the carb may be in order. I just can't figure out why it doesn't want to stay at idle now...


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## PikeSlayer (Apr 3, 2012)

I looked a little closer at the linkage from the choke pull knob to the choke plate linkage and it looked like it was a bit bent and tweaked from previous use. I did a little creative adjusting and got it to where the choke plate closes fully and the throttle plate opens slightly upon fully pulling out the choke knob. Then I took apart the carb and cleaned it again. I didn't see anything specifically come out, but there were a few very small particles floating in the carb cleaner when I was done. I put her back together, fires right up and idles with the airbox on. I still need to do a little more adjusting to get the idle right where I want it, but it runs, idles ok, and will stay at a low enough idle for me to shift in and out of gear. I just didn't get it to idle great with the throttle all the way on the idle stop cause it was getting late and I had to shut her down. Thank you all so much for your help! The advice and motivation/confirmation of ideas helped me to get through it without giving up. I will be creating a new thread shortly about my brother's Merc 9.8 horse 2 stroke that runs and idles, but won't carry a load in gear. I told him I'd take a look at it after I got mine worked out. Thanks again guys!


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## jasper60103 (Apr 3, 2012)

Hopefully, you'll get the idle just right when on the boat. Thanks for the update.


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## PikeSlayer (Apr 15, 2012)

AHHHHH!!!! I got the idle great in a barrel, took the boat out yesterday and the motor absolutely SCREAMED across the lake! It was awesome for about 2 minutes, then it started missing a bit, running rough, and I had to throttle it back because it bogged down so bad. I tooled around with it for a while and it continued to run somewhat rough and it seemed to run a little bit better when I backed just off of full throttle. We anchored, fished for a while (about an hour) and I started the motor again. The return trip it ran much better, but still not as fast as the initial run when it was cruising. I made sure to tool around and took my time getting back to shore to see if the motor would run differently once it was warm. It ran smoothly for the entire trip back, but again, it wasn't as fast as the initial run. Any ideas? I don't want to screw with it too much because it at least pushes my boat through the lake, but I got that little taste of what it could be and now its haunting me :?


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## PikeSlayer (Apr 17, 2012)

I pulled the plugs this evening. I know its been a couple days since I ran the motor, but the brand new plug I installed right before running, are already kind of fouled looking. There is some caked on crap. I don't really get how it could be fouled already unless it's running rich right? I have the idle dialed almost a third of a turn leaner than the recommended starting point. Is there any way to adjust your full throttle mixture? Could this be causing my issue?


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## bigwave (Apr 18, 2012)

Hey Pike this may be a silly question. Did you use new gas on your trial run, and is you mixture of oil correct for the engine? I once over mixed my fuel/oil, fouled my plugs real quick, boat ran like crap. I changed the plugs and gave her fresh fuel and she ran like she was supposed to. This is a cool thread, I am learning through your problems.


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## PikeSlayer (Apr 22, 2012)

Yah, it was fresh gas, and a new tank when I did it. Brand new, 50:1 mix. At worst, I mixed it ever so slightly lean. So I don't think its a fuel mix, but thank you for throwing ideas in to keep the mind running. Good thought!


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## xbacksideslider (Apr 24, 2012)

It might have got hot on that initial run when it "screamed" across the lake.

How's your compression now?


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## shawnfish (Apr 24, 2012)

probally a dumb question, did you adjust both of the idles? i had the same problem with my 80 j25 after removing and cleaning carb and just played with the low speed needle(front of carb through the silencer) and didnt get it right untill i used a tach and adjusted the one at the base of the tiller and the low speed needle....5450 rpm's and mine was singin!..........


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## PikeSlayer (May 6, 2012)

I took my boat back out yesterday for its second trip. The motor ran good cooking across the lake right away. I still don't think its running as well as it did for my very first time out, but with 2 adults and 3 kids, the boat did push along at a decent clip. The problem is, after sitting for about a half hour, I started up and when I cranked up the throttle, it just surged and didn't really want to run above 1/3 of throttle travel. Shut it down, fished some more and then fired it up, ran good again. Sat and fished some more, then took a run across the lake. The motor would run good for a couple minutes, then start surging and loosing power, if you dropped to idle for a few seconds and back up, it would run good for another minute or so before surging again. I started pumping the bulb while cruising and notice it was getting soft. When I continued to pump the bulb it smoothed out some. After sitting and fishing for awhile, the return trip across the lake I didn't have to pump the bulb at all, and it ran for the most part fine the entire way. I do notice around the time it starts to surge a bit, before it surges badly, if you back the throttle off just a touch from wide open, it actually increases RPM a bit. Could it be that the fuel pump is weak and not keeping the bowl full of fuel? I was wondering since with the motor running at idle for a bit, it will run higher rpm again for awhile, like maybe the slower speed allows the pump to catch up a bit? Any ideas would be great guys.


P.S. I have not checked compression yet. I need to get my hands on a reliable tester.


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## PikeSlayer (May 6, 2012)

shawnfish said:


> probally a dumb question, did you adjust both of the idles? i had the same problem with my 80 j25 after removing and cleaning carb and just played with the low speed needle(front of carb through the silencer) and didnt get it right untill i used a tach and adjusted the one at the base of the tiller and the low speed needle....5450 rpm's and mine was singin!..........



Where exactly is the other needle? I'm wondering if that might help it out a bit. The problem is, if I look on youtube, I can find guys with the same motor cruising across a lake and they look like they're going a lot faster and their RPM sounds higher. I'm sure some of this has to do with the weight of the boat, and maybe I'm being too picky, but I really like to go fast! 8)


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## Johny25 (May 6, 2012)

Surging indicates a fuel delivery problem........ can be several things, float not set correct in the carb, weak fuel pump, clogged fuel pump, high speed orifice in the carb clogged, fuel lines sucking air, carb base gasket leaking, fuel tank vent hose not working. 

If you pump the ball on the gas tank and the engine runs better then 99% of the time it is a weak or faulty fuel pump. If not then I would clean carb good and flush lines to be sure they are clean.


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## PikeSlayer (May 6, 2012)

Johny25 said:


> Surging indicates a fuel delivery problem........ can be several things, float not set correct in the carb, weak fuel pump, clogged fuel pump, high speed orifice in the carb clogged, fuel lines sucking air, carb base gasket leaking, fuel tank vent hose not working.
> 
> If you pump the ball on the gas tank and the engine runs better then 99% of the time it is a weak or faulty fuel pump. If not then I would clean carb good and flush lines to be sure they are clean.



I had the carb apart and cleaned thoroughly. I had also flushed the lines as I reassembled everything. The fuel pump is the only thing I didn't mess with. I haven't been able to find a rebuild kit for the fuel pump. It looks like you have to buy an entire fuel pump assembly for about $60. I just wanted to bounce this off you guys before I spent the money on it. Hopefully a new fuel pump helps with the problem. Thanks for your help!


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## PikeSlayer (May 6, 2012)

I just ordered a fuel pump and will hopefully have it on and tested within the next week. I think what I will do the next time I have the boat our is try and take a quick video of it running to see if that offers any additional info for you guys. Thanks again for all your help. God I hope this works.........


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## PikeSlayer (May 12, 2012)

WOW! So here is the conclusion. I got my new fuel pump, went out and got new fuel and vacuum lines. I decided to take off the carb to make it easier to replace some of the lines. When I pulled off the airbox, there was a huge chunk of foam from the upper cowl insulation stuck around the main jet and jammed in the throttle plate. I CAN'T BELIEVE MY ENGINE EVEN RAN WITH THAT IN THERE!!! Needless to say, I already had a new pump and lines, replaced all and took it out yesterday. RUNS LIKE A CHAMP!!!! 8) Thanks for all the help guys!


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