Bad fuel pump?

[denL]

I have a ?75 Evinrude 25hp, model 25552B. I was having trouble with my carb flooding. I rebuilt the carb and replaced the float. The engine started but died after 10-20 sec. I adj. the float because gas was flowing out of the carb. The carb seems ok now but the motor only runs for 10-20 sec. I decided to check my fuel pump. Is this the correct way?

1. With carb still out, I connected a longer hose from the fuel pump to a jar.
2. I removed the plugs.
3. I checked the fuel line by pressing the bulb and gas flows into the jar.
4. I pulled on the starter rope a number of times but no gas flows through the hose.

Is my fuel pump bad? Also, the parts diagram and my service manual show a different fuel pump. Mine has 5 sides and looks like an ?85 model. Should I just rebuild it?

 

[Lion hunter]

Re: Bad fuel pump?

Not sure if the pull rope would create enough pressure to pulse the pump (I never actually tried).

 

[denL]

Re: Bad fuel pump?

I wonder if I should put the carb back on, try to start it and pump the bulb to see if would run? I changed all the hoses but I'll check for leaks, too.

 

[Lion hunter]

Re: Bad fuel pump?

That's what I'd do. The only sure way to test is a pressure guage but there are a couple of tests that that will give you a good idea.

1. Does it have electric start? If so you can crank the engine. That will create enough pressure.

2. Pump the bulb to see if it stays running (easiest)

3. Attach a longer hose to the pump (Just to get it out of the way of any spark). Pump the bulb and fill the carbs. Remove the fuel pump hose and put in a jar (again away from the motor). Start the motor. In the 10-20 sec. it stays running it will tell you.

 

[denL]

Re: Bad fuel pump?

Good news and bad news. The fuel pumps works fine! I did the test lion hunter suggested and gas flowed out of the hose from the pump when I started the motor. The bad news is when I reconnected everything and started the motor, gas flowed out of the carb throat, just like it did before I started this project (mess). I've adj. the float per Joe Reeves' instructions but I'm a rookie so I must not be doing it right. I'll do it again.

 

[Lion hunter]

Re: Bad fuel pump?

Did you rebuild the carbs? All the adjustments in the world won't solve a bad float needle. Easy fix for $25.

Edit: never mind I see that you rebuilt the carb. With the carb upside down try and blow into the fuel inlet. No air should pass through.

 

[denL]

Re: Bad fuel pump?

Thanks, Lion Hunter. With the carb upside down, I did blow into the fuel inlet and no air passes through. Air does pass through with the carb right side up. I dlb-checked my manual and I've been removing the carb incorrectly. My arm on the needle valve is broken so I've been removing the needle valve to be able to remove the silencer. I noticed this time, the red piece came out also. It didn't break so I'm sure it will go back in when I screw in the needle valve. I'm not familiar with carbs so I don't know if this cause my problem. Any other ideas?

 

[Lion hunter]

Re: Bad fuel pump?

Needle valve I spoke of is the float needle. That is correct that no air should flow upside down, air will flow right side up as the float drops and pulls the needle down. THe only way to remove this needle valve is to remove the float. If there is fuel coming out of the carb throat it means that this valve is bad or not adjusted right, or the float is bad or not installed correctly. They are the only things that allow fuel to enter the carb.

I guess I don't understand what you mean by arm is broken. Some pics may help. I assume by red peice you mean the o-ring aorund the low-speed needle.

There should also be a plug at the bottom of the carb. Did you remove that and blow compressed air through? That is your high speed orifice.

 

[crxess]

Re: Bad fuel pump?

If you are getting flooding while pumping the ball, that is possible. The Pressure from you squeezing can overcome the float and excess gas will pass through. I've done that.

Upside down test is nice, but it will not tell you if the float adjustment is correct or the Float is actually floating up and sealing the needle seat.

 

[Lion hunter]

Re: Bad fuel pump?

CRX is right the upside down test will only tell you if the needle is bad. You've got to set the float properly. The link you looked at is the best info available for that. With the carb upside down try the float at level. If there is still a problem raise it a little (With carb upside down) if the needle and float are good you'll reach a point between overflowing and running out of fuel.

 

[denL]

Re: Bad fuel pump?

Thanks for the input. I did remove the orifice plug and blow it out. I'll post a picture of the arm tonight when I get home but it sounds like I just need to keep adjusting the float until I get it right. At one point in the process, I adjusted the float too far and no gas came in (the bowl was empty) so I know it does work. I thought I was on the right track, but when I re-adjusted it, gas poured out of the carb again. I think I was on the right track but couldn't get it correct. I'll go back and give it another try. I'm getting pretty good at removing the carb and putting it back on!!!: Thanks for all the help.

 

[denL]

Pics of carb arm

Pics of carb arm

Here is a picture of the needle valve with the broken arm. I was able to remove the white piece and now I don't have to remove the air silencer. I also attached a picture showing the red piece that came out. It appears that it screwed in just fine though.
I probably won't be back to this project for a couple of weeks because of vacation and other stuff. Thanks for the help.

 

[Lion hunter]

Re: Bad fuel pump?

That is low speed air/fuel mixture valve. The red thing is a o-ring seal. They do come out at times. Never known it to be a big deal. That needle gets set at 1.5 turns from seated (not tight, just seated). Then you turn in 1/4 turn at a time while running to adjust the mixture. I imagine your missing the linkage arm to connect it to the knob on the cowl. Might make it a little tougher to get set right as you may not be able to adjust once the cowl is on. Putting the cowl on sometimes cuts off enough air that it requires adjustement.

But long story short, you float or float needle still seem to be the issue.

 

[denL]

Re: Bad fuel pump?

Thanks, Lion Hunter. Hopefully, I will get this motor running, again!

 

[Lil' Johnson]

Re: Bad fuel pump?

Is it possible that you have a bad float? I am not sure if your floats are solid or hollow, but if its hollow it may have a pinhole leak in it and when the bowl fills up the float will stay down causing fuel to overflow out of the carb. Remove float and place in container of fuel and see if it floats. Sometimes you can shake them and hear fuel inside. Good luck solving your problem.

 

[denL]

All fixed!

All fixed!

Thanks for everyone who helped out. The problem turned out to be the main jet. I took it to a mechanic who determined that the wrong jet was installed. I guess one of the many past owners installed one that he had laying around. How it worked is beyond me!