Stalling at Idle and Idle Speed

[Scode68]

new problem found yesterday. While I'm idling or just just in gear at low speed in a No Wake Zone the motor stalls like I'm running out of fuel. While running at speed the motor runs normal and doesn't stall. Fuel primer bulb is soft but not collapsed. Have a vent fuel cap but when cracked open the same thing happens. Filters are changed out and I don't see air in the fuel line.

What do you think?

2001 Aquasport with a 200hp Johnson 2-stroke

 

[mr 88]

I think you should post this in the Johnson/ Evinrude forum. Maybe post your rpm numbers at idle and if this is a new issue or you just bought the boat etc . Could be something as simple as turning up your idle to a carb rebuild .

 

[Scode68]

I was going to but I have a feeling this isn't motor related. Had the mechanic at the Marina (Mercury Guy) look at it back in August for a non-running issue. Then I pulled the boat and brought it to my Evinrude guy that rebuilt the carbs and tested the ignition and fuel pump.

Yesterday it was stalling while trolling and making my way up the creek in no wake zones. If I pumped the primer bulb the motor would steady out. Bulb was soft but not collapsed.

 

[mr 88]

If your asking questions about your motor , which you are , it's motor related . So when pumping the primer bulb the engine ran ok ? If so , I would start out replacing at the very least the primer bulb . Myself , I would replace the fuel hose as well . If the bulb is breaking down , the hose isn't too far behind .

 

[Scode68]

Since the motor has been ruled out I’m pretty sure I’m asking about the fuel related system. Fuel cap to the primer bulb. I’m looking to find out what in the fuel system would cause a fuel starvation at low rpm, but not at higher rpm’s.

 

[Mad Dog 2]

The fuel assembly (quick connects, primer bulb and fuel line) gray fuel line has a inner liner the degrades and breaks apart.
My fuel line inner liner came apart this summer. I replaced the fuel assembly, engine filter and external mounted spin on filter. The spin on filter did not look that bad.
Runs much better.

 

[racerone]

Test run with another tank and hose.-------Bulb does NOT need to be hard when motor is running.-----Sounds like a small air leak on fuel system------Fuel pumps run off the crankcase compression pressure.-----There may be issues there.----Posting cylinder compression values can help with determining motor health.

 

[Texasmark]

I see 4 possibilities: Fuel line from tank to engine including bulb which these days has gotten to be a big problem after the EPA stuck its nose into the mfgr. of that line, fuel filter in engine clogged, RPM set too low, old fuel lines (23 years old) with leaks either within the hose or at the ends where clamped to a barb.

 

[Captain Caveman]

If I'm reading this correctly, you had a no-start issue in August, got it fixed, and therefore you have ruled out that it's a motor issue? This is October. You could have a new issue with the carburetor. Lots of mechanics skip steps, like rebuilding a carburetor without replacing the needle and seat, or checking the floats, or truly cleaning/clearing all the little passages. Different parts of the carburetor control idle versus full throttle.

It can't be the fuel filter in the motor or the RPMs, since you ruled out motor issues.

You should easily be able to see if it is leaking fuel from the ends of the hose. At 23yrs old, just feel it to see if it is brittle.

 

[Scode68]

If I'm reading this correctly, you had a no-start issue in August, got it fixed, and therefore you have ruled out that it's a motor issue? This is October. You could have a new issue with the carburetor. Lots of mechanics skip steps, like rebuilding a carburetor without replacing the needle and seat, or checking the floats, or truly cleaning/clearing all the little passages. Different parts of the carburetor control idle versus full throttle.

It can't be the fuel filter in the motor or the RPMs, since you ruled out motor issues.

You should easily be able to see if it is leaking fuel from the ends of the hose. At 23yrs old, just feel it to see if it is brittle.

Carbs were rebuilt by me and then an Evinrude Johnson mechanic. BPR kits were used both times and mechanic an ultrasonic cleaner. He is good and would trust him with any work.

 

[Scode68]

Been under the weather this week so I havnt done much. I swapped out the primer bulb with no difference observed. I even ran the boat with the fuel cap cracked open and no difference.

This summer the carbs were rebuilt, all fuel lines from the tank to the fuel pump were replaced and I replaced the filters again. I'm wondering if it could be the pickup tube. Its the original Moeller tank and pickup tube. Are the pickups known to go bad at all?

By the way, when I say it stalls while idling or traveling in gear at idle speed it's after running for 10-15 minutes.

 

[Crosbyman]

engine mdl # ????

 

[Mad Dog 2]

Some pickup tubes have fine screen on them. Water and trash builds up on these fine screens (also trash builds up at any restrictions at 90 degree elbows, fuel quick disconnects and etc).
When suction stops (when the engine is shut down) often trash and water on the screen is released back into the fuel tank. If you’re problem returns “after running for 10-15 minutes.” it could be trash and water being sucked back up on the pickup screen.
Working on boats and heavy equipment my practice has been to remove these screens so that trash and water travel to the engine aux. spin on fuel filter and to be captured there. Also on commercial equipment the recommended practice is to cut the end of the pickup tube at a angle.
You may have fuel phase separation. (Ethanol and water in the tank). I would drain my carbs and fuel filters catch the fuel in a see thru container and let it sit in the sun for a day see if water separates out.
Quick test is to drain the carbs and filters, run the engine directly off a tank of ethanol Free gas.

 

[Scode68]

J200VXSIF 12/2000

I didn't pull that pickup tube yet but couldn't get a straight answer from anyone if there was a screen at the end or not. Tried multiple time contacting moeller but they never returned my calls or emails.

I haven't found water in the fuel yet. Nothing collects in the water separator and I havnt seen anything while sitting in a jar. I could be wrong but I think the key to the puzzle is the soft primer bulb even with the gas cap cracked open. Maybe at higher RPM the fuel pump is drawing enough fuel to fill up the fuel bowls?

 

[saltchuckmatt]

Racerone is on to this, most likely fuel pump but follow his steps.

Not sure why others are not giving this advice.

If I pumped the primer bulb the motor would steady out

This tells the story.

 

[Scode68]

Racerone is on to this, most likely fuel pump but follow his steps.

Not sure why others are not giving this advice.

If I pumped the primer bulb the motor would steady out

This tells the story.

The compression is 100psi +- 1 or 2 psi. I'll have to test this with the 6 gallon tank for my 20 Merc when I feel a little better. So you think it might be the fuel pump?

 

[mr 88]

Racerone is on to this, most likely fuel pump but follow his steps.

Not sure why others are not giving this advice.

If I pumped the primer bulb the motor would steady out

This tells the story.

Read post #3 and #4 above .

 

[saltchuckmatt]

Read what? Read that you recommended changing the primer bulb?

Fuel pump is not a primer bulb.

Maybe I'm not following you correctly.

 

[Crosbyman]

OP said fuel pump was "tested... by EV mechanic". symptom still indicates possible bad pump if " hand pumping" steadies the engine !

 

[Scode68]

Read post #3 and #4 above .

Read post #11.