2001 johnson 35 hp 3 cylinder fuel issues

[JoshKeller84]

hi guys, have a 2001 3 cylinder 35 hp johnson. oil mixer removed, fuel line run directly from second fuel pump to fuel filter to carbs. The past two times out, ive noticed that I lose fuel after running a mile or two. motor bogs and then dies. However, it picks up back and continues running for another mile or two if you pump the primer bulb - which leads me to believe its a fuel pump issue. my question is how do i determine which of the two pumps is the problem one? i've noticed my inline fuel line filter stays full, even flows a small amount of fuel to flow through the filter. I also see on the parts diagram, there are two different pumps, but only one rebuild kit - does this mean the internals are the same on both pumps? any suggestions? thanks guys!

 

[hidef]

Have you checked the fuel filter to make sure it isn't plugged and also the screens? The rebuild kit is same for both fuel pumps so I don't know what the difference is between them.

 

[JoshKeller84]

yes, i checked for restrictions. I had to dig around for my manual, and found the port pump is for bringing up fuel from the tank, and the starboard pump is for pumping it to the carbs, which explains why i have flow through my inline filter on the gas line, but none to the motor. I believe this problem occured when my fuel line unknowingly came unhooked while running and ran the outflow pump dry, causing the vaccum and pressure to put a hole in the diaphram. i believe the port pump to be fine, as it still draws fuel up from the tank. sound possible?

 

[hidef]

Yes it does. You should be able to bypass the Starboard pump completely just make sure you plug the pulse line going to the block. The port pump should have more than enough volume to run the engine by itself.

 

[JoshKeller84]

got the rebuild kits in today... tore the starboard pump apart and saw nothing out of the ordinary, however, i reassembled, and unhooked the hose at the internal fuel filter, and turned the key - fuel shot out about 3 feet, so I'm hoping the rebuild kit solved the problem.

 

[JoshKeller84]

took it out this morning and it ran 3 miles before losing fuel. let it run out, trolling motored back, put it on the trailer and went home. Both pumps were empty. Started tearing into the port side pump and the screen was covered with a mud like substance - it was hard to blow through, so i replaced the screen, and all fuel lines. Pulls much more fuel through the fuel filter now. Believe I found my problem.

 

[JoshKeller84]

Still having issues. Motorrad good for 1 mile. Bogged down and then would only run 3800 rpm. two pumps of the primer bulb and it was back to 5800 rpm's. Let it run another mile and it bogged again. this time I let it idle 15 seconds then put the hammer down and it ran back up to 5800. any ideas?

 

[hidef]

Check the port screen again. You could have a fuel line or the hose from the tank breaking down due to alchohol in the line. It sounds like you have an issue with something getting plugged also check the tank for crud and make sure you are not sucking up a bunch of crap. I would also install an in line fuel filter in the fuel hose so you that you are stopping the crud before it gets to the pumps.

 

[JoshKeller84]

I ran it until it acted up then immediately shut it down. Pulled out the drain screws in the carbs and the top one had noticeably less fuel come out than the other two (approx 1/3 to 1/2). Is that indicative of anything?

If the fuel pumps are pumping fuel (and both of my inline filters - one before and one after the pumps) confirm that they are, there has to be a restriction only at WOT that corrects itself when less fuel is needed. Possibly a sticking float valve? Any other ideas?

 

[Bosunsmate]

incorrect float setting, bad pump

 

[racerone]

Run with another fuel tank and hose.

 

[JoshKeller84]

This all happened all of a sudden after accidentally running out of gas. (Fuel line came unhooked). Both fuel pumps have been rebuilt. If they are pumping fuel and both filters are full of fuel after it bogs, wouldn't the pumps be good?

 

[Nissannx]

Can you post pictures of how your fuel lines are routed? I'm having similar issues and the mechanic butchered my lines and I would like to route them to the factory way.

 

[Bosunsmate]

This all happened all of a sudden after accidentally running out of gas. (Fuel line came unhooked). Both fuel pumps have been rebuilt. If they are pumping fuel and both filters are full of fuel after it bogs, wouldn't the pumps be good?

probably but you say priming with bulb manually fixes it
check compression, as that affects the pump pressure

 

[JoshKeller84]

Compression is 140 for all 3 cylinders. Its just weird tgat when it bogs, one single pump on the primer bulb and two seconds later it takes off again. Come off plane and not pump the bulb but let it idle for 15 seconds and itll run like normal again for another mile. Will remove air box and spray carbs one at a time with fuel. Oil mix to see if its always the same carb.

 

[racerone]

Run with a known good tank and known good hose !

 

[hidef]

The pickup in the tank could be getting plugged. You need to try a known good fuel hose and a clean fuel tank.

 

[racerone]

Fuel pumps are run by crankcase compression.------A cylinder compression test does not indicate if crankcase compression is poor.-----Have seen issues with the plastic seal rings on the crankshaft !

 

[JoshKeller84]

replaced all fuel lines and got a new hose/primer bulb, and tore into the carbs today. Nothing seemed abnormal, except for a little black "goo" in the needle and seat area of the top carb. will try my other tank tomorrow after work. Would fuel shoot out 6 feet when the motor is being cranked if the fuel pumps werent getting enough compression from the crank case? My other thoughts maybe to just find a 5 psi electric fuel pump and bypass the engine mounted ones. or possibly try a new fuel pump.

 

[hidef]

Your fuel pumps are fine if they are pumping that much volume you are good. Testing with a good tank that has no junk or crud in it will get you pointed in the right direction. Make sure you use fresh fuel do not dump the fuel from the tank you are currently burning. You want rule bad gas too.