No fuel - bulb gets hard - fuel pump works ????

[100es72r]

My 72 100hp Johnson will only start on fuel/oil mix sprayed into the carbs. The bulb gets hard. I did a fuel pump check and it looks ok. Is there anything in the carbs that would cause it not to get fuel out of any of the 4 barrels. It will not start on any cylinder. I would really like to use this boat this weekend and I don't have a carb rebuild kit availiable so I don't really want to tear down the carbs unless it is the only way. Even after choking the unit for several seconds, when I take the plugs out, they are dry and I don't smell any gas. Got any ideas?

 

[KYHunter2]

Re: No fuel - bulb gets hard - fuel pump works ????

What ob said and,

I'd go over the whole fuel system again.

If you have an on board tank . Disconnect it and try using a portable tank.

Are you sure your getting fuel to the pump??

Make sure the bulb is ok. and there are no restrictions in the fuel lines.

KYHunter

 

[ob]

Re: No fuel - bulb gets hard - fuel pump works ????

Yep.Fouled carburetors.They will need to be removed and dismantled to be cleaned properly.

 

[F_R]

Re: No fuel - bulb gets hard - fuel pump works ????

Take one of the hex head plugs out of one of the carburetors (preferably the bottom carb). Look at the end of it. Is it shiny clean or does it have a coating on it? If it has a coating on it, you can bet the carburetor is gummed up and needs cleaning. Pay special attention to the high speed orfice plugs which are down deep in the holes that you took the plug out of. They require a special screwdriver to remove wihtout damage, but you don't really have to take them out if you clean them with the right stuff. The best stuff is the carburetor cleaner that comes in a gallon can with a dip basket. You get it at an auto parts store. Leave the parts in there a couple of hours.

 

[100es72r]

Re: No fuel - bulb gets hard - fuel pump works ????

I appreciate your responses. Using portable tanks. Fuel pulses out of line out of fuel pump when engine is cranked so I believe the pump is ok. I don't doubt that the carbs could be gunked up as I don't think they have ever been cleaned. One thing though. Is it likely that all four barrels would clog up at the same time? I would think that one or maybe 2 could clog at once but not all 4. What do you think? Even in the fuel pump is bad, if I pump the bulb by hand, I should be able to get enough fuel to the bowls to get it to fire shouldn't I? How do I know for sure shich carb kit to get from iboats? I have ordered parts from them before but I am having a hard time identifying the right carb kit.

 

[F_R]

Re: No fuel - bulb gets hard - fuel pump works ????

You are correct in your thought about the fuel pump..it doesn't have a cotten-pickin thing to do with the motor starting. You fill the carbs via the primer bulb. After the motor starts, the fuel pump comes into action to keep the carbs full as gas is drawn out of them.

As for all 4, actually there is only two float bowl chambers, two barrels drawing out of each. Old gas laying in the carbs is what gums them up. And the same batch of old gas lays in both carbs. That's why I suggested you inspect the hex plugs....to see if there is gum in there. If there isn't, and clean gas runs out, you probably don't have carb trouble. Just trying to get you to troubleshoot a bit before tearing into something which might not do you any good.

 

[mrcombel1963]

Re: No fuel - bulb gets hard - fuel pump works ????

Also if you have a water fuel sepperator it would'nt hurt to replace that or those filters either, with junk and water mixed up in your filtraltion system, it does no good to pump that crap into your fuel lines and or a clean carb after you've done all that hard work to get it right. also a fuel tank treatment might be in order if you have never done it before. never know whats up in yur tank after all that time.

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When all else fails, post your question on iboats forums.com for your quik reply.

Stacks

 

[100es72r]

Re: No fuel - bulb gets hard - fuel pump works ????

Thanks for the time FR. I put the unit in a tank and started it on the spray bottle again and kept spraying the fuel to it for a few seconds. Then it ran fine on its own. I did check the drain caps as suggested and they looked pretty good and clean fuel ran out. I think I have a problem with the pump bulb in the fuel line as it is very hard to get it to get hard and it sounds a little too "wooshy." Took the boat to the lake this weekend and it ran fine both days but I did have to start it on the spray bottle the second day. I think I will get a new fuel line and/or bulb.

J

 

[clint]

No fuel - bulb gets hard - fuel pump works ????

I had the same problem with my fuel line and primer bulb. For $12.00 it solved the fuel problem and check fuel line connectors for air leakage. I did also rebuild my carbs, which were spotless. Use the 6 gallon portable tank with fresh gas and see how she runs.

 

[KYHunter2]

Re: No fuel - bulb gets hard - fuel pump works ????

I allways try the easy stuff first. ie: bulb, vent, hoses , filters, etc.

Carb rebuild every few years , good idea though.

Cheap insurance , just like water pump.

Just to clarify , I am aware that the pump isn't needed, for starting.

My statement wasn't clear , when I said make sure theres fuel getting to pump, has to get there to reach carbs .

Regardless of whether crankcase pressure to pump, or forced there by bulb.

A tip , in your onboard tank, there's a neat little , piece of junk.

Called an anti-siphon valve.

A safety device , that works about like my ex. , only when she felt like it!! LOL

This is just MHO, but even if its not causing a fuel delivery problem yet.

I'd unscrew the fitting, and take the ball, and spring out ,and use them for sinkers , next time your fishing.

When they mess up , as they often do .

If your not aware of the thing, it can be a pain to figure out.

I'd still find out when carbs were rebuilt last, and if you cant find out.

I'd rebuild them too.

As long as it runs well , you can wait until end of season.

Keeping an eye out for a lean condition.

KYHunter