Where should I start? Carb?

[scrit9mm]

I have been posting problems with my 25R73 not starting for the past week. I have been pulling on it every evening and morning this week with not so much as a backfire. I have tried several different steps before pulling on the cord. The jist is the bulb is hard, the choke is out and I pull once or twice. Push in the choke and pull, by the 3rd pull I think it's flooded. So the next day I would not squeeze the primer bulb, not use the choke and pull and by the 4-5 pull it is flooded. My low speed needle is unturned one and one quarter turn from fully seated. Which is where it was when the motor was running last weekend. I have rebuilt the carb, changed all fuel/ vacuum lines, new fuel line to the tank and new gas tank, rebuilt the fuel pump with new screen and outer cover. When I take my plugs out when I believe it has flooded they are pretty wet with fuel.

Should I take apart my carb, and if so what should I look at?

 

[oldybutagoody]

Re: Where should I start? Carb?

I was perplexed on my 56 Fleetwin after a carb rebuild and it turned out that I had pinched the fuel line between the quick connector on the carb where it goes under the bottom plate and into the engine compartment. I only say that to show that it's usually one small issue. You said it ran last week and you rebuilt the carb and now it does not start so it's likely something in the fuel system. Is the float valve stuck? Sometimes in cleaning you dislodge a piece of gunk and it clogs the main jet. Is the tank vented? Be systematic and you'll find the issue. Have you checked for spark?

 

[robert graham]

Re: Where should I start? Carb?

Your carb float needle valve is working and your float level is set correctly? Are your spark plugs really clean and fresh? Do you have spark at the plugs when you pull the rope? Try pulling the starter rope with the plugs out to see if a lot of raw fuel comes out. Sounds like motor is really flooded and wet-fouling your plugs so they don't fire. Check it out and let us know what you find.

 

[CatfishMN]

Re: Where should I start? Carb?

I posted this in your other thread, but really listen to the previous poster and check your carb float level. On the same model motor I went throught he same thing you did before finally chasing that down as the culprit.

Also - do you have a spark tester? If not, go get one so you can rule that out as a problem as well.

 

[scrit9mm]

Re: Where should I start? Carb?

I rebuilt the carb prior to it running this past weekend. When I rebuilt the carb the manual specified that the top of the float be level with the bowl, and it is. I have checked the spark with the plugs out to ensure that they are both firing. They are new plugs also. What would cause too much fuel into the firing chamber? Explain the vented tank? I was under the impression the tank needed to be sealed to ensure a vacuum to pull the fuel into the motor. I believe the cap on the tank has a screw type vent on it. Should this be screwed tight or loose. I havent fooled with this since it was running this past weekend so nothing changed with the tank.

I am either overthinking this or it's way over my head.

 

[oldybutagoody]

Re: Where should I start? Carb?

Your '73 uses a single line tank with a fuel pump. The vent should be open to allow the pump to draw fuel. The older OMCs (Pre '59 60ish) used two line pressurized tanks that do not vent. Open the vent screw on the tank cap and see what happens.

 

[kbait]

Re: Where should I start? Carb?

Float level is correct when you invert the carb body (float installed/bowl not). If the float is parallel w/carb body, you're good. Make sure you have good compression(whoomp, whoomp when pulling is good), check spark w/tester and get 1/4" blue bolt. Or hold the plug that far away from ground bolt to make sure. If you didn't change out the fuel line from pump to carb, you may have got some gunk in the carb (there's no screen past the pump cover..) Correct plugs? J4C's gapped to .030", I believe.

Tank vent open.. no vacuum in tank. The fuel pump 'pulls' the fuel out, and a sealed tank will eventually reach vacuum that the pump cannot overcome.

Good luck!

 

[scrit9mm]

Re: Where should I start? Carb?

Thanks for the describing the tank situation oldy and kbait. The plugs that came in it when I got it do not have the electrode that you gap, they are just flat. I replaced them with the same model number plugs, they are NKG plugs (BUHW). I will try the tank issue.

Do I have the wrong plugs??

 

[scrit9mm]

Re: Where should I start? Carb?

I checked an online manual and it says to use Champion UJ4J plugs which are not flat, but they are no longer making these.

Should I go with the Champion J4C's gapped to .030" like kbait suggested?

 

[BonairII]

Re: Where should I start? Carb?

Should I go with the Champion J4C's gapped to .030" like kbait suggested?

I would doubt that flat plugs are what the manufacturer recommends. Stick with manufacturer recommendations(including proper gap)....they built the motor, they probably have a pretty good idea what plug makes their motor run best.

 

[nwcove]

Re: Where should I start? Carb?

jmo, but ive never had much luck with ngk plugs in any motor. did you cross reference the ngk's to see if they are a replacement for the uj4j's? have you tried putting a few drops of premix in each plughole? then try to start it. ( without the tank connected)

 

[scrit9mm]

Re: Where should I start? Carb?

I didnt bother checking the manual before I purchased the replacment plugs, I just got the same ones that were in there when I got it. The plugs I have are not the replacment plugs for the UJ4J, I found the Champion 825C is the correct plug. I will stop by the parts store after work and try them out tonight. I hope it's this simple!

 

[kbait]

Re: Where should I start? Carb?

Your motor has points. I looked and found UJ4J champions. Never heard of 'em! If you can't find those, J4C's will work fine, like every other 25 J/E points motor I've seen (coils under flywheel, or coils external). Maybe '73 was different?? Weird. If someone has a reason for the difference, I'd love to be enlightened!

 

[scrit9mm]

Re: Where should I start? Carb?

Thanks for all the info. I stopped by the parts store and picked up two plugs. They were out of the UJ4J's so I got some comparable autolite plugs. Stuck em in and it fired on the second pull. Shut it off and repeated several times. It fired with no choke. I also unscrewed the vent on the fuel tank and it released audible pressure. This thing is running like a champ.

This is why this forum is great!

Thanks a million!

 

[oldybutagoody]

Re: Where should I start? Carb?

Great. It's usually something simple, but figuring it out is the bugger. I spent a half hour trying to make my fleetwin idle smoothly before I noticed I'd left the choke out. Duh!

 

[nwcove]

Re: Where should I start? Carb?

......sometimes things are so obvious they seem to easy! happy boating scrit!