TJ40ELESR surges and won't idle after new fuel pump.

[tloc1000]

The motor was running like a champ one weekend, then ran rough, wouldn't idle and couldn't get her in gear the next weekend. I put some fuel in a jar but to me it didn't look like there was water in the fuel.

The fuel line into the VRO was leaking fuel so I was going to check that connection but broke the nozzle when trying to remove the fuel line. I replaced the VRO with a regular fuel pump and pre-mix. When I pre-mixed and rechecked the fuel for water, I saw a distinct water line so that may have been my problem the whole time.

I've taken the carbs off and cleaned and reset the idle screws. She will only start after opening the primer solenoid and giving about half to 3/4 throttle. Then surges and as you try to throttle down to idle she dies.

 

[Joe Reeves]

Doesn't the Fuel Primer Solenoid engage when you have the key set at ON or START and push the key in to engage it?

As per your statement... " She will only start after opening the primer solenoid and giving about half to 3/4 throttle. Then surges and as you try to throttle down to idle she dies." Are you leaving the Fuel Primer Solenoid RED lever in the MANUAL position after that engine starts? If so, that causes the engine to flood out!

 

[fhhuber]

Sounds like it might be pulling air from a bad fuel line connection or bad fuel line.

You can test PART of the system for leaking by just pumping up the primer bulb hard (engine in normal running position so the floats will close the little valves in the carbs) and looking around the fuel pump. But there are a few places it can leak this won't test at all.

If there is any sign of age cracking, just go ahead and replace fuel line.

 

[tloc1000]

Joe- Sorry, I wasn't clear. The previous owner ripped all the wiring out and I have not rewired the key "choke". I manually flip the red lever. It fires for a second, then I put the lever back down, then put it in half throttle and then she fires up.

Fhhuber-. The bulb gets firm when pumped and I see no leaks. I checked everything from fuel pump to carb but I'll check it again.

 

[tloc1000]

Still no luck. I rechecked compression-125 on both cylinders. I'm getting spark to both plugs. I replaced all the fuel lines with new hose. I replaced all connections with new connectors (no zip ties). I replaced the fuel filter. I recleaned the carbs. It doesn't surge anymore but I think it's only running on one cylinder. The top plug is dry when I take it out and the bottom one is wet. I'm kind of stumped now.

 

[tloc1000]

I got an inline spark tester and it lights up on both cylinders when cranking it over. How bright is the light on the tester supposed to be? I can see the spark but it's not super bright.

 

[hardwater fisherman]

No Title

You are probably better off with a tester like this one. You can then see the strength of the spark by making jump the gap. You can also make your own.

 

[tloc1000]

Ok. I know that I am new to wrenching and this has been an awesome learning experience, but I feel like a total dumbass.

I finally got the motor working!!!! She is purring like a kitten and idles smooth and quiet again. The problem????

The idle adjustment screws were not set properly!!!!

When I originally got the boat, I had to clean the carbs and got her working. I set the idle adj screws at 1.5 turns out. She ran great for a few weeks then started to idle rough and wouldn't go into gear. After putting on a new fuel pump, all new fuel lines (which it probably needed anyway), and carb cleaning again, I set the idle screws at 1.5 turns out again but this time she wouldn't run. I had my cousin come over to help trouble shoot and as I was going over everything I did, I thought about the idle adj screws and said maybe I can try to re-adjust them. I opened them up a few turns and then the motor started running better. I finally got her purring pretty good.

Just curious...why would the settings change? Is the new pump putting out less fuel than the VRO so I would need more opening for the fuel mixture?

 

[racerone]

Fuel level in the carburetors is controlled by the float / float valves.-----Not really a fuel pump pressure issue !--------1.5 turns is an " old term " some newer carburetors require more turns out.

 

[tloc1000]

Fuel level in the carburetors is controlled by the float / float valves.-----Not really a fuel pump pressure issue !--------1.5 turns is an " old term " some newer carburetors require more turns out.

Thanks! I can't remember where I got the 1.5 turns out but I know it was on this forum somewhere...LOL.

 

[Joe Reeves]

Just in case.....................

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.