One motor stalling at extended idle-fuel starvation....

R

Reddog

New member
OK, so as I continue to sort our new to us boat out, I have come to this situation:
2002 Tomcat with carbed Honda 90 HP Outboards. At extended idle times (something like over 3 mins., the port motor will start to stumble. If I go to squeeze the primer bulb, it is soft and after a few squeezes, it gets hard and the motor picks back up. The motors run fine at speed and do not falter.
I have replaced both primer bulbs with BRP units (correctly oriented regarding flow and upright attitude), tightened all hose clamps, checked all filters and associated lines.
It seems that I must be sucking air somewhere, but I'll be darned if I can find it or understand why this only happens at idle.
All suggestions greatly appreciated!
 
Happened to me at idle and it was the fuel clip at the engine where suction was being lost. You must be leaking air somewhere. Have you thought about replacing all of the fuel hose? Given your fuel bulb is getting soft leaking air would seem to be the culprit, and replacing hose/or a thorough checking for leaks in hose and fuel filter would be the first place to look.

Possibly the fuel flow at higher RPMs is enough to counteract the suction loss.
 
Do you have external fuel filters like Racor?

Fuel filter head in and out fittings need gas resistant sealant like Permantix. Maybe it is fuel filter gasket at the top and bottom or the O ring used if using a bowl at the bottom of filter. They changed O ring material and have new light color but that was a few yrs ago and maybe back to black.

on edit I agree with ZoeB
Check the clip.
I may have one or the hose goes directly to fuel filter under the cowling

Hard for a blind squirrel to find nuts
 
Switch fuel hoses temporally, if you can. See what happens. lots of places air can get into the line. Any connections, the in and out of filter, O rings, etc are all suspect all of the way to anti siphon valves---lets hope its not that--it was on my Tom Cat 255.
 
all good info and suggestions.
Last week, while looking for the culprit, I was laying on the rear deck looking at the Port Raycor (engine not running, not underway....) and noticed it pulling air around the thread of the clear bowl and the top of the gas in the bowl "blipping" each time the bubble chased around the threads.
I tightened the bowl slightly and the bubble stopped as did the "blipping".
I have looked at that since and do not see it doing this again.
I may re-seal the fitting at the Raycor, I am inclined to think that is where the issue is.
 
Reddog":7gnerizl said:
all good info and suggestions.
Last week, while looking for the culprit, I was laying on the rear deck looking at the Port Raycor (engine not running, not underway....) and noticed it pulling air around the thread of the clear bowl and the top of the gas in the bowl "blipping" each time the bubble chased around the threads.
I tightened the bowl slightly and the bubble stopped as did the "blipping".
I have looked at that since and do not see it doing this again.
I may re-seal the fitting at the Raycor, I am inclined to think that is where the issue is.
Click to expand...


I Once had similar symptoms with a carbureted Honda BF90.
The fuel hose between Raycor & Squeeze Bulb was collapsing,
restricting flow. Just another place to look?
Good luck on your search.
 
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