No fuel to carburetor

[Pbassjr]

I have a1990 Larson with a 5.0 Merc that didn't hit the water last year, and the year before sat in the water as a floating dock as as soon as I dropped it in the water I realized the gimbal bearing needed replacing....anyway, I am not getting fuel from the tank to the carb. I changed the fuel pump a couple of years ago and it has about 1 hour on it...this is also true for the rebuilt carb. I changed the anti-siphon valve at the top of the gas tank today and still...no fuel to the carb. I changed the fuel filter and filled the filter with fuel before installing....I even filled the line from the tank to the filter with gas before re-installing the line. Today I cracked the fitting on the fuel pump line that goes to the carb and had my son turn the engine over...it is not spurting fuel from the fitting. If I fill the bowl in the carb it will run for a couple of seconds until the bowl is empty. Usually I will moisten the gasket on the fuel filter with motor oil before installing, but I didn't do that this time...don't know if that could be it. Also this has an after market fuel tank from mohler and the fitting (to which the anti-siphon valve is affixed) and tube will pop from the top of the tank when medium upward pressure is applied.

Thanks in advance for reading!

 

[gm280]

:welcome: Pbassjr, reading your thread I see nowhere where you talk about a primer bulb. Is there one to prime the fuel from the tank to the fuel pump? Also, are you certain you are using the proper fuel pump inlet fitting and not the outlet that should go to the carb? :noidea:

 

[Pbassjr]

Thanks for your response. There is no primer bulb. Today I removed both hard lines from the fuel pump to check for obstructions. In so doing, I discovered that the screen filter at the carb was completely filled with sludge and some had gone into the fuel line as well. I am hoping that my not seeing fuel spurt yesterday had more to do with me not cracking the fitting far enough...I did see some minor debris come out of the intake line, but think it may not have been enough to obstruct. I will clean out the lines and screen and reassemble tomorrow PM and cross my fingers. I'll let you know how it turns out. One thing I'm wondering about is how so much sludge built up in the screen with virtually next to norunning hours on the carb since installation...

 

[HT32BSX115]

Thanks for your response. There is no primer bulb. ...................... One thing I'm wondering about is how so much sludge built up in the screen with virtually next to norunning hours on the carb since installation...

Howdy,

Welcome aboard!

1. I/O's never have a "primer bulb" USCG regs do not allow it. They're only approved in "above deck" (usually outboard motor) tanks.
2. That "sludge" was likely always there. It just took an additional year to solidify.

If you have "sludge" in the line, you need to get yourself a suction device to apply suction to the fuel line to ensure that it's clear. You should probably also have a look inside the tank and see if there's water, debris or other "stuff" in there. Water(if present) will mix with phase separated ethanol to produce a mess if left long enough.

An easy way to clean out the tank is to expose the gage sender hole by removing the 6 screws and carefully pulling it up and out of the tank. (go to your favorite marine place and get a new gage sender gasket and screws for when you put the sender back in)

You can then siphon all the gas out of the tank by using a clear piece of 3/4-7/8" vinyl hose long enough to reach from the bottom of the tank to a container outside of the boat on the ground.

It's also convenient to have a ball-type valve (gas valve from Home depot etc) on the ground end of the hose so a helper can shut it off when switching from a full container to an empty container. Connect a piece of 3/4" plastic pipe to the end of hose in the tank and use it to move around and "vacuum" out the debris and water etc. If you tip the bow up, most of the debris and water (if present) will flow to the back of the tank for easy vacuuming!

If you can see the fuel pickup screen(in the tank) you might see that it's covered with debris too. remove it and thoroughly clean it.

(The tank will be easier to clean out if you can remove it from the boat.)

Disconnect the battery, do all of this outside, and have a fire extinguisher handy!

Incidentally, you should never have to prime anything. If the fuel pump will not "prime" the lines or filter, you either have leak prior to the pump or it's defective and you need to replace it.

Cheers,


Rick

 

[JerseyBoater]

I had that same issue today after changing the fuel filter in the pump, and I filled the filter bowl too. After the engine ran with the carb it then died out, took the filter off and most of the fuel was still in the filter bowl. At a guess it looks like a vacuum leak, so I reseated it, and tightened it more that I did before. It then all started working so give that a try. Oddly it didn't leak or anything like that, just enough to stop the pump pushing / pulling the fuel through.