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1991 Evinrude 115 2 stroke primer bulb looses pressure....

D

danielarand

New member
I have a 1998 Evinrude E115TSLECM that the primer bulb looses pressure idling for an extended time( let's say 15 min or more at no wake speed).

Pump the primer up on cold or warm start up, motor starts & idles fine, goes under way with no hesitation, runs excellent.

Idle through a no wake zone for a while, and when I throttle up, the motor starves for fuel.

Check the primer bulb, and it has lost it's pressure.....pump it up, and the motor again runs excellent. It always pumps up rock hard.

This is what I've done so far:

Changed the primer bulb twice, both times with name brand primer bulbs.

Changed the fuel quick dis-connect at the motor.

Any suggestions?

Thank you!
 
Check for air leaks / loose hose connections. I suspect your fuel pump diaphram has a small crack / tear. repair kits are readly available. Cheaper than buying a new one.
 
Your primer bulb is working fine, as your own testimony confirms. It pumps up. That's all it is supposed to do. You probably are on the right track, looking at the fuel pump. If not that, the pump probably is sucking air from some small leak anywhere between it an the level of the gas in the tank. Or a dirty filter. Or a bad anti-siphon valve (if you have one).
 
The bulb wont stay hard .
If it is tending to be sucked flat check your tank venting and the fuel pick up for obstructions. Otherwise check the fuel line for air in-leakage.
The quick disconnect from the motor is the prime suspect except that you have already replaced it.
Check it again, esp if you did not fit a genuine OEM part.
Check also around the fuel pump and filter.
The fuel pump itself could be defective of course.
Easily being able to keep it going by pumping the bulb points to either a defective pump or air in-leakage rather than to bad fuel pick up or tank venting
 
Thank you for the reply!

The bulb never goes flat, and yes if it did a venting issue would be present.

I'll recheck all connections again, and any part I use is only OEM.

It'll run perfectly at any speed except an extended idle, I'm going to check/rebuild the fuel pump anyway since it is original.

Thanks again!
 
Idle only would create lower pulse speed for your weak fuel pump, thereby the fuel supply problem. No ethanol, brother......not good for rubber composition. I have a host of photos of damage from ethanol destruction, could start with VRO's.........
 
Ok, rebuilt the fuel pump, checked all hoses connections, fuel filter/seperator.

It does seem to run better, however it did need to have the primer bulb pumped up after just a few minuets with the motor shut off.....perhaps normal???

Also, ever hear anyone using a low pressure electric fuel pump to assure constant pressure in the fuel lines?

There are solid state pumps available that only produce 1 to 5 PSI, and could be wire as to only run while the motor is running.

Any thoughts on this?

Thanks!
 
Do not use an electric fuel pump on that. When you start your motor the fuel pump takes over the primer bulb goes soft absolutely normal. The primer bulb will not hold pressure because once the fuel pump starts working it is pulling fuel through the line. So the pressure releases in the line and turns into a vacuum line the primer bulb then is only a check valve it is not a fuel pump for the motor. If you run the motor for a few minutes you should not have to use the primer bulb again as the carbs are already full just start and go. The primer is for when the motor sits for a good length of time or after it has been tipped up and the carbs have drained.
 
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The fuel pump is driven by crankcase pulses.--------A positive pulse and a slight negative pulse.-----A cylinder compression test may help in determining if there are internal mechanical problems.
 
racerone said:
The fuel pump is driven by crankcase pulses.--------A positive pulse and a slight negative pulse.-----A cylinder compression test may help in determining if there are internal mechanical problems.
Click to expand...

Thank you for your reply, I do understand the operation of a vacuum actuated fuel pump after spending many years in the powersports industry.

Cylinder compression is good and even in all four cylinders.
 
Ok thanks; I understand the primer bulb thing.

It's only after sitting about 15 min it requires bulb pump up, then it runs absolutely perfect. The bulb is the second brand new one I've installed, used an aftermarket product the first time, name brand on the second. It's only a couple months old....

I've only had it out on the water once since I rebuilt the fuel pump....I'll try it again this weekend.....
 
You should not need to pump it up after 15 min of sitting. You do not need to pump up the ball every time you start it. When I take my boat out I only use the primer for the first start after that I may need to use the choke or the fast idle if it sits for a while but that's all. Is this motor new to you.
 
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