Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

[Merc probs]

Heres the prob..was running fine then the bulb goes soft and rough running low rpms and wont idle.It runs fine at full throttle if i squeeze the bulb.I have to start it by giving about half throttle as soon as i pull the rope.I changed the whole line including ball.New line with fuel filter to carb..Had the carb cleaned.Had this same problem last year until i put a carb kit in it.I havent changed the fuel pump since i had it.So i think its that.But also heard about anti syphoning going bad but dont know where thats located.By the way its a 1989 20hp merc and i looked at the fuel pump and it looks fine.Any help would be appreciated...Thanks

 

[Yepblaze]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

Sounds like it's time to remove the carbs and replace, or maybe blow out the needle/seats again.<br /><br />Perhaps I'm misreading this but It will run at full throttle while sqeezing the bulb, but stumbles and dies as if flooded when you try to idle down(and still squeezing)? <br /><br />Or even when not squeezing, still stumbles and dies with the bulb not building pressure? And takes raised throttle to get it to fire off again?<br /><br />It might just be flooding rather than holding back the pressure of squeezing that bulb. And the pump for that matter.

 

[Fouled Plug]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

The anti-siphon valve is in the fuel line bulb. Since you've replaced it, I would think that's not the problem. Sounds like a bum fuel pump diapragm.

 

[Spidybot]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

If squeezing the bulb helps, it is not a syphon problem. If the tank could not replace used fuel by air (blocked vent), squeezing the bulb wouldn't do any difference but you can remove the tank cap to check.<br /><br />What you do by the bulb is helping the fuel pump so a kit for this sounds right.<br /><br />The bulb is under pressure when you squeeze it and should stay hard until the motor runs. Then the fuel pump (at the motor) sucks the fuel and the bulb is under vacuum. Although some feels rather firm during normal run, it is common that the bulb softens.

 

[dilligafda]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

To try to determine the source of your issue, try a couple of things. First, attach a remote fuel tank with a new primer bulb in a known good fuel line. If the condition remians, then the boat's tank is not the problem. if the situation is corrected then replace the fuel line and primer bulb. If this doesn't correct the issue, then the fuel pump is suspect. Your best bet at that point is to contact your local dealer for information on having the pump rebuilt/replaced. Good luck!

 

[ranger69dv]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

Fuel pump diaphram has a hole in it somewhere. tear it apart and replace it and your in buisness

 

[Merc probs]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

Trying the fuel pump tomorrow.I ordered the only 2 fuel pumps that were made for my mercury online.took them to a repair guy to clean carb and replace fuel pump.Went back and they werent right ones he said.Went to marine shop today and find out my carb is from a 15 horse or something blah,blah.Then went to nappa with the part # i got from him.I have to buy the whole rebuild kit for $35 that comes in tomorrow.And still dont know if its the right part or even my problem.Its a new tank and new jets as i replaced everything last year troubleshooting the same problem.Thats the thing,would a fuel pump go bad like last year then when i put in the carb kit work great again then do the same thing this year?

 

[Hooty]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

I don't have a manual for your engine but I'd bet there's a procedure for testing the fuel pump. It requires a pressure gauge and a tee in the fuel line between the fuel pump and carburetor, Have you tried that yet? <br /><br />c/6<br /><br />Hooty

 

[Merc probs]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

I havent tested nothing just bought new.Thats why i think trouble shooting sucks.I started with the cheapest and now wasted $18 on 2 fuel pumps online($7 shipping).And bought the simplist like hoses and bulbs,but at least i can use them.And hoping my $35 dollar kit from nappa at least has my 1 peice rubber fuel pump that is equal to about .50 cents whole sale.But i will pay it because i want to go boating bad.And my flat bottom goes about 27 mph on the river when running,And that is a awsome feeling.

 

[letsbarbq]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

hey mercprob.<br />sorry to hear about your prob. last time I had a doubt that my fuel pump was working properly I used a automotive fuel pump. Its a 12v little pump you can get at auto zone. I hook that up to the gas line to the motor and I hook it up. If the motor performs like normal then you know you have a fuel pump prob. if it doesnt then you know its something else. I think it cost me 20 bucks and it comes with lifetime warranty. good to have when you are 50 miles offshore.<br /><br />just my 2c. let us whats going on.

 

[letsbarbq]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

sorry one more thing. just yesterday I ran on a test tank and pulled a vacuum and the bulb was collapse flat. the engine bogged and low rpm was very sluggish and rough. found the bulb collapse. re hook to another fuel source then it was fine. point is. it might be a check valve on your gas tank. these valve keep your fuel from returning completely back into your tank when you are not running the engine. sometimes they go bad. A quick trouble shoot would be running on a portable gas tank.<br /><br />sorry, trouble shooting sucks. but its free.

 

[Merc probs]

Re: Fuel prob.Trouble Shooting sucks,Bulb goes soft!!!

I was wondering if it was gas tank problem.But i bought that brand new last year.And the gas tank before that one was new the year before.The thing that sucks is i bought my motor used and they never said carb was changed.I wont take it to the pro shop because they would basicaly do the same thing im doing.Hopefully i will get it running tomorrow,pick my kit up at 4 p.m. eastern.Will let you know...Thanks for all your help!