Evinrude Lightwin 4HP: Carb problem?

[shaferintl]

I have just overhauled this 1969 engine. New rings, gaskets, one new rod, and tune-up kit. The engine has great fire at the plugs. I can't get it to hit. Not even when spraying ether right into the throat of the carb. As near as I can tell, there is no vaccuum being created through the carb. When I put my hand over the throat (ie seal it) and pull the engine through, I feel no suction.<br /><br />My theory is that no fuel is getting into the cylinders. But why? I have good compression at the plugs.<br /><br />Any thoughts?

 

[ezeke]

Re: Evinrude Lightwin 4HP: Carb problem?

Did you check the leaf plate assembly?

 

[cobra 3.0]

Re: Evinrude Lightwin 4HP: Carb problem?

...that's what I am thinking too. Been there done that!

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

Well, I cleaned the leaf plate assembly up while I had it apart. What else should I have checked?

 

[OBJ]

Re: Evinrude Lightwin 4HP: Carb problem?

Jim....pull the carb and with a wire, GENTLY push on each reed valve to make sure it's not stuck. The put the carb on and give it another shot.<br /><br />Gonna asked a dumb question here.....ya' didn't put the reed plate back in backwords did ya'? The reed stops go in toward the engine.<br /><br />Keep us posted....thanks.

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

OK, it gets checked tomorrow. I'll let you know.

 

[gain11]

Re: Evinrude Lightwin 4HP: Carb problem?

Don't use ether!! It has no lubricants. Try pre-mix in spray bottle. Just relaying what the admirals and gurus have told me!

 

[Xcusme]

Re: Evinrude Lightwin 4HP: Carb problem?

Just some thoughts....<br />Did you replace the upper and lower crank seals??<br />Did you use Loctite 518 or equiv. to seal the powerhead?<br />Are the pistons installed 180 degrees the wrong way?<br />Fuel pump diaphram leaking??

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

>>Was said: Did you replace the upper and lower crank seals??>><br />They were replaced.<br /><br />>>Was said: Did you use Loctite 518 or equiv. to seal the powerhead?>><br />I sealed it with Form-a-Gasket. Don't know if this is adequate.<br /><br />>>Was said: Are the pistons installed 180 degrees the wrong way?<br />No. I was very careful to follow the manual on this one.<br /><br />>>Was said: Fuel pump diaphram leaking?? >><br />No fuel is coming out of the pump. I can't tell if air is getting in. There is no fuel flow. I presume this is because there is no pull (ie vacuum) through the carb. The bowl is full and the consequently, the float valve is closed.

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

I pulled the carburetor and the bowl was full of fuel. I checked the main jet and it is clear (able to blow air through it into the throat).<br /><br />Next I pulled the leaf plate assy and checked it. The leafs (reed valves) are all free and the assy was installed properly such that the reeds were pointing inward toward the cylinders. I put the assy back on, put my thumb over the hole in the plate and pulled the motor through. No suction. Shouldn't there be some suction against my thumb?

 

[Xcusme]

Re: Evinrude Lightwin 4HP: Carb problem?

I think you've already answered your problem. Using Form-a-Gasket on the crankcase could be your problem. GelSeal or Loctite 518 are anaerobic type sealers. They seal in the absence of air. It doesn't take much to seal both halves, but you do have to use the right sealer. When applying the 518, be sure to not get the thin bead of sealer too close to the oil passages, and seal the entire length of the crankcase. Make sure both mating surfaces are flat and clean upon re-assembly. Start tightening the bolts from the center of the crankcase, out towards either end at half torque. Then go back, again, starting in the middle and re-torque to final specifications.

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

OK. I'm going after the crank seal. I'll redo it with the loctite 518. I'll let you know how it turns out. <br /><br />One local fellow asked about the lower seal. This is a bit confusing. The manual shows no lower seal or o-ring, only an upper. When I took it apart there was no lower seal. My gasket set that I order for this outboard didn't have one. Is there supposed to be a lower crank seal?

 

[Xcusme]

Re: Evinrude Lightwin 4HP: Carb problem?

Jim,<br />Just for grins, get compression reading before you pull it apart again. It's a good thing to have some sort of a baseline of figures, before and after.<br />Good question on the lower crank seal, I don't have a parts list for your year. Other folks on the forum perhaps will lend a hand with that info.

 

[BillP]

Re: Evinrude Lightwin 4HP: Carb problem?

Pull the spark plugs and put a squirt of gas in the cyls. Then put the plugs back and crank it. That may help get it going before you do manual labor. Those are normally easy starting engines. I've owned 2 3hp Johnsons and one 4hp Evinrude (69). All are almost identical.<br /><br />My manual with exploded views of the 3 & 4 list no crankcase seals on pre 1969 models. They put an upper crankcase seal starting in 1969 but no lower seal. Put the seal lip down.<br /><br />It says the crankcase should be put back together with "hardening" cement type sealer. They say to set the reed stops at 1/4".

 

[shaferintl]

Re: Evinrude Lightwin 4HP: Carb problem?

>>BILLP WROTE: Pull the spark plugs and put a squirt of gas in the cyls. Then put the plugs back and crank it.>><br />I have tried this and do get a little hit this way.<br /><br />>>BILLP WROTE: My manual with exploded views of the 3 & 4 list no crankcase seals on pre 1969 models. They put an upper crankcase seal starting in 1969 but no lower seal. Put the seal lip down.>><br />That's what my manual shows, also. Upper seal installed lip down.<br /><br />>>BILLP WROTE: It says the crankcase should be put back together with "hardening" cement type sealer.>><br />What is your thought on my use of Form-a-Gasket? I have had two people say it is inadequate.

 

[OBJ]

Re: Evinrude Lightwin 4HP: Carb problem?

Well heck Jim....may as well throw in another .02 worth.<br /><br />The gel seal used between crankcase halves is really just to fill in the voids to disallow air infiltration. I don't think form-a-gasket will squish out enough to keep the tolerances in check. Wouldn't use it anyways.<br /><br />The only think I could see on the parts break down is an Oring at the end of the drive shaft. I'm not real sure how the lower crank is sealed.<br /><br />But it seems you've covered just about all the bases and still it won't fire or suck in gas? I would almost think that possibly you have an ignition problem. Will the spark jump a 7/16" gap with a hot spark? May even want to throw in a new set of plugs regardless even if the ones you have are new. I have on occasion gotten a bad "new" plug. And on these small two juggers, one bad plug will not let the engine start.<br /><br />Keep us posted.

 

[BillP]

Re: Evinrude Lightwin 4HP: Carb problem?

What is your thought on my use of Form-a-Gasket? I have had two people say it is inadequate.

The manual is very specific about using hardening type sealer and not using hardening type may be the problem. I use Aviation Form A Gasket on most parts and it works fine. On older outboards that don't have great mating surfaces I use different brands of the non-hardening and hardening type. Everytime I've had a part that was difficult to seal the hardening type worked best.<br /><br />Did you check the compression? I rebuilt a 1000cc Kawasaki mcy engine once and put low compression pistons and rings in for a turbo installation. The rings had a "top" and I put them in upside down...no compression. I don't think that is a problem with the omc 4 rings but you may want to check anyway.

 

[woofer2609]

Re: Evinrude Lightwin 4HP: Carb problem?

Jim! everybody! sorry to re-open a can of worms, but if we're lost, it's nicer to be lost together! I am having the exact same problem regarding no fuel to cylinders that you had!(except with a 6hp!)<br />hopefully you didn't get too frustrated and throw it off the end of the dock! what was the eventual outcome to your problem? Anybody?