Won't run on carbs. Only runs on primer... HELP

[MrChuckFL]

2001 Johnson 135.

Just like the title says. The engine won't run on the carbs. It will only run if I hold in the the primer button. As soon as I let the primer button out, it dies within a couple seconds.

Here is some history and what I have checked...

Pumping primer ball didn't make any difference.

All 4 carbs were all rebuilt last year.

The VRO was converted to pre-mix before I got the boat. I thought maybe the pump was bad so I rebuilt the fuel side. Same thing.

Thinking maybe the pump was bad, I followed the advice in another thread about converting to dual older style simple pump. Same thing.

Checked compression. 120lb on all cylinders.

So now I am kind of at a loss and looking for ideas on what I might be missing.

Any words of wisdom would be greatly appreciated.

 

[Joe Reeves]

Re: Won't run on carbs. Only runs on primer... HELP

Check to see if you actually have fuel flow to the carburetors (remove hose at carbs, pump fuel primer bulb). If no fuel flow, find the blockage point. If fuel flow exists, for some reason, you once again have carburetor problems.

 

[tashasdaddy]

Re: Won't run on carbs. Only runs on primer... HELP

agree.

 

[cdoliver]

Re: Won't run on carbs. Only runs on primer... HELP

If you pump the fuel bulb and fill the carb bowls with fuel, it should run for a minute on the fuel in the bowls. if it doesn't you have a carb issue. Just because it was cleaned/rebuilt last year, doesn't mean it isn't dirty this year. you can remove the fuel line to the carbs and turn it over to see if its pumping fuel. If it is, carbs...

 

[rusirius]

Re: Won't run on carbs. Only runs on primer... HELP

I'm not an expert by any means, so take this for what it's worth. I recently had a similar problem with my own engine.

With my motor I noticed that the primer pump pulled from the bowl of the carb and shot fuel straight into the intake throat and cylinders. Since it ran fine shooting fuel straight in, but not otherwise it was kinda obvious it was a carb issue.

I stripped the carb down and found it really loaded up with a LOT of black "gooey" stuff. I knew what it was right away. This was the first year that it was impossible to find regular gas instead of E-10. I was pretty sure the fuel tubing was E-10 safe, but obviously it wasn't. The lines running to the pump and also to the carb had turned to mush inside and all the goo had flown straight into the carb and plugged it up.

I stripped it down and cleaned it out the carb and fuel pump, replaced the fuel lines with new ones and now it's purring like a kitten.

Have no idea if this might be your problem, but pull one of the carbs and have a look in the bowl and see what ya see.

 

[MrChuckFL]

Re: Won't run on carbs. Only runs on primer... HELP

I pulled off one of the lines going to the carbs and pumped the primer. Got plenty of gas there.

Since this problem started around the time that the E-10 was being phased in, I also took the advice of rusirius and removed one of the carbs and pulled the bowl. It was full of fuel and a didn't see anything weird in it.

 

[Joe Reeves]

Re: Won't run on carbs. Only runs on primer... HELP

When you had the float chamber off (bowl), did you remove the high speed jet in order to inspect it. Fuel must flow thru that jet before it can obtain access to any other passageway of the carburetor.