Motor stalling at low idle

[iggyw1]

Same motor, same problem after making some changes. I have an Evinrude, 1991 model E6REIA, 6 H.P. Not many hours on her at all. Had a new fuel pump put in last year and had the carb rebuilt at the same time. I was running it off of a water separator with my main motor, but I took it off of the separator (because of he problems I was having trying to get it to troll) and it is running directly out of the gas tank under my floor in the boat now, same tank as my main motor.

The kicker motor runs fine at 1/3 or more throttle, ( still hard to start though) but when I try to slow it down to troll, I get a little backfire type noise and it quits. Cannot tell if the backfire is from the carb or the exhaust, but being the exhaust is under water, I am leaning towards the little "pop" is from the carb. When is pops it stops running instantly, and even though the motor is warmed up after is has been running at half or more speed to get where I was going on the lake, I need to choke the motor when I pull the cord or she absolutely will not start unless I choke it. I turned the slow idle screw in and tried adjusting that today, and it actually made no differance at all where I turned it out to. Still had the same problem. Anyone that can tell me what to try next, I am greatful. Thank you!

 

[kbait]

The pop /quit is a lean sneeze.. not enough fuel at idle. If you cannot enriches the mixture enough with the low speed needle, your low speed circuit in carb is gummed/clogged, requiring carb clean. This is assuming you have good fuel and carb bowl is full. You could try pulling the low speed needle completely out and blowing compressed air in that hole w/air nozzle/rubber hose attached. This will sometimes clear the circuit and motor will perform normally..

 

[racerone]

Step # 1 is a compression test.----What are the numbers ?

 

[iggyw1]

Will do a compression test and blow the air thru the port when I pull the needle out as well. I failed to mention that I did spray a lot of carb cleaner thru the carb when I was running wide open today. It will be a few days but I will post my results when I do these things. Thanks! NOTE: Could it be a faulty fuel pump issue again?

 

[racerone]

LOL----Spraying carb cleaner through a running motor does nothing !!!!------The carb cleaner would never reach the metering passage ways deep inside the carburetor !----How does your motor run when you operate the manual pump ?-----Those fuel pumps are ultra reliable and rarely fail.

 

[iggyw1]

LOL----Spraying carb cleaner through a running motor does nothing !!!!------The carb cleaner would never reach the metering passage ways deep inside the carburetor !----How does your motor run when you operate the manual pump ?-----Those fuel pumps are ultra reliable and rarely fail.

Manual pump??? The only fuel pump I know of on my motor is the fuel pump that the gas line goes thru and the primer ball on the gas line that is outside the motor. It is not an electric start motor, but has a pull cord. My big outboard (main motor) has an electric start and I have to push the key in on a cold start. Is that what you mean by the manual pump? I am thinking that is a choke, correct? Is it helpful at all to spray the inside of the carb with carb cleaner when the motor is off, then take my air compressor to it tomorrow after the cleaner sits in the carb overnight??

 

[racerone]

The primer bulb on the hose is a simple manual fuel pump.----It moves fuel into the carburetor when you squeeze it.----It can tell you a lot about operation of your motor.

 

[iggyw1]

The primer bulb on the hose is a simple manual fuel pump.----It moves fuel into the carburetor when you squeeze it.----It can tell you a lot about operation of your motor.

I understand now. Yes, I operated the ball to make sure it was full of gas when I was having the issues of the motor stalling out when I lowered the RPMs with the throttle to troll. It really did not change anything. Motor still backfired & quit. Would it hurt anything to spray carb cleaner into the carb with motor off and also into the needle hole after removing the needle, then blow it out tomorrow morning with my compressor? Probably needs another rebuild on the carb?

 

[KG ON]

Adjust the mixture screw at the top center of the carb, turn it in until it seats but dont force it further, turn it out 1.5 turns out from the seated position. From there adjust it in slowly in until you hear a slight cough then back out 1/4 turn. Lower the idle as your able to when adjusting.

Goodluck.

 

[racerone]

There should be no need to rebuild a carburetor every year !!-------Find the real problem with some trouble shooting !

 

[iggyw1]

Raceone, you suggested a compression test to start with. I did that today. Went out a got a good screw in tester, and the top cylinder I got 100 p.s.i. the bottom was ALMOST identical at just a shade below 100 p.s.i. This was a dry test on a cold motor. I can take it out to the lake later today and run it for test after it is at operating temp. if you think it is necessary. This motor is a 1991 model and I don't think it even has 100 hours on it yet. I also bought two new spark plugs and put those in so when I go out again, they will be new. I gapped them at .030.

I also tested the spark with a spark tester and the spark jumped the 5/16" gap on the tester and it was a bluish spark, so I am assuming no spark issues with this?

 

[racerone]

Compression is not the issue then.----The motor should respond to the low speed mixture needle.-----So that points to fuel issues.-----Does spark jump a gap of 3/8" or more on both leads ?

 

[iggyw1]

Adjust the mixture screw at the top center of the carb, turn it in until it seats but dont force it further, turn it out 1.5 turns out from the seated position. From there adjust it in slowly in until you hear a slight cough then back out 1/4 turn. Lower the idle as your able to when adjusting.

Goodluck.

I did this a few times while out on the lake yesterday, (it did not do anything to remedy the situation) however, since then, in my garage, I removed the needle all the way, shot some carb cleaner into the hole where the needle goes and blew it out afterwards with my air compressor. I will see what that did for me (if anything) a little late today on the lake hopefully! Will report the results. I still have a new fuel line with a new fitting on it for the motor, and a new primer ball coming that I bought on line, and also a new fuel pump coming with that order as well that might do something for me too when it all arrives sometime between June 27 & July 3rd.

If when I get done with all of this and it still will not troll, I will take it back to the repair shop for another carb rebuild. Either way, I will post how we did in the near future on this post instead of a new thread.

 

[KG ON]

Good call removing the needle and spraying a cleaner to remove and blockage on the low speed circuit. One other thing to keep in mind is the packing that goes around the low speed needle, if that is introducing air into the system it will cause a lean condition which could be problem based on the fact that changing your needle setting doesn’t affect the motor. The packing is either the plastic piece or cork, most likely the plastic one based on the year of the engine.

 

[iggyw1]

O.K. I received my new fuel pump today. Looks like the wrong one due to the back plate being a lot thicker, and it still uses the gasket on top of that extra thickness. Has the right parts number on it though. If I get some longer screws, I can mount it o.k., but I will not be able to put my motor hood back on!! If I take just that back plate off of the old one and use it on the new one, will all kind of things be flying out at me because of some springs. or is it an easy removal just to switch the back plate? Everything else matches perfect.

Any way, I still did not get my new fuel line nor the primer ball yet, but I did do something today that I have not done yet. I removed the line going from the fuel pump to the carburator, and I am getting a good flow of fuel coming out of the discharge when I squeeze the primer ball. Does this mean that the fuel pump is working o.k. or does it really mean all I am doing is bypassing the fuel pump under the hood attached to the motor? Also, could I be getting enough suction from the piston at high speed to suck the fuel in and not enough suction from the same piston at a slow speed so it cannot suck the fuel in? Keep in mind, my compression on both upper and lower cylinder were 100 p.s.i. (a shade lower on the bottom one, but over 99 psi.)

edit: The motor runs great at about 1/3 or 1/4 throttle or more. No problems at all after I get her started. Have to choke it to get it started even after it is warmed up, but it runs sweet with partially open throttle as stated with no choke.

 

[iggyw1]

Compression is not the issue then.----The motor should respond to the low speed mixture needle.-----So that points to fuel issues.-----Does spark jump a gap of 3/8" or more on both leads ?

When I tested it for the spark, I had a good blue spark to jump a gap of 5?16". Did not try a 3/8" gap, but I can get the tester from my son again and check it out.

 

[iggyw1]

Good call removing the needle and spraying a cleaner to remove and blockage on the low speed circuit. One other thing to keep in mind is the packing that goes around the low speed needle, if that is introducing air into the system it will cause a lean condition which could be problem based on the fact that changing your needle setting doesn’t affect the motor. The packing is either the plastic piece or cork, most likely the plastic one based on the year of the engine.

Plastic piece at the hole looks like day one, brand new.

 

[racerone]

When you operate the primer bulb the fuel goes RIGHT THROUGH the pump.-------Crankcase pressure pulses operate the fuel pump.----Mostly a positive pressure pulse and a slight vacuum pulse !!----Compression in the cylinder is not the same as compression in the crankcase.----An understanding of how your motor works will help you in trouble shooting.

 

[iggyw1]

Does anyone know if a fuel pump can work o.k. at 1/3 to full throttle and NOT work at an idle speed or is this unheard of???

 

[racerone]

The fuel pump operates with a + pressure pulse from the crankcase.---At idle there is more time for air to leak out of the crankcase and between the 2 crankcases in your motor.------So at idle on a motor in good condition the pump will work just fine..---------BUT----The condition of your fittings and internal fuel pick-up inside the tank also come into the picture !!----Have you checked those items ?