Fuel or Electrical

[Hvymtl]

1998 Evinrude 90 SPL NON VRO. On going problem (new boat to our family) . Fuel line and fitting changed from tank to engine. New fuel/water filter. New plugs. Good compression all cylinders.

Here goes: Engine will start and run fine. On plane running at about 3400 RPM for about 5 -10 minutes the engine will suddenly bog and lose power..it will continue to run if RPMS are reduced to below 2000 or so. Will not take throttle at all from this point. Fuel primer bulb is pretty EMPTY feeling, but pumping the bulb doesn't seem to really help..... After running at 2000 RPM or below for a time the engine will take throttle once more but maybe for 3-5 minutes before losing power once more and I have to throttle back to keep it running.

I have noticed that the voltmeter starts out at about 13.8 while we're running good but is pushing 15 volts when the problems "SEEMs" to start. Batteries are good. I suspect fuel pump, just don't think a electrical problem would allow the engine to keep running at 2000 or below? Since I never shut the engine off none of the components have time to cool, but the boat will run good "sporadically" after long periods of idling.

I initially thought the fuel lines were too long for the engine pump.... I have about 2 feet from tank to hull fitting, from the fitting to the filter / separator is about 18 inches, and from the output of the separator to the engine maybe 2 feet of 5/16 hose. For a total of 5.5 feet the pump has to pull fuel.


What do you think???

 

[glenn property of pam]

Re: Fuel or Electrical

fuel bulb is going flat indicates the fuel pump is pulling fine and there a blockage. The fuel vent could be blocked by a mud dobber or a problem with the fuel line and bulb. As your from ft myres check the fuel vent first.

addition: does the alarm bleep when you turn the key on to show that its working as there are problems that could cause it to go into slow mode but the alarm should sound to alert you to the problem

 

[Hvymtl]

Re: Fuel or Electrical

fuel bulb is going flat indicates the fuel pump is pulling fine and there a blockage. The fuel vent could be blocked by a mud dobber or a problem with the fuel line and bulb. As your from ft myres check the fuel vent first.

addition: does the alarm bleep when you turn the key on to show that its working as there are problems that could cause it to go into slow mode but the alarm should sound to alert you to the problem

No beeps. fuel bulb is not sucked flat or collapsed, I guess I should have said empty is the feel. I can squeeze it a few time and feel it fill up. Vent is open since I used compressed air to blow the old fuel out of the tank earlier and the excess air pressure was coming out the vent.

Is there any way the electronic ignition (if it has one) is failing)?

 

[glenn property of pam]

Re: Fuel or Electrical

so the warning buzzer does not beep when the key is first turned on?

 

[Hvymtl]

Re: Fuel or Electrical

No buzzer at all (this is a non VRO if that makes a difference). Have ordered a pump rebuild kit.

Would /could a the stator and power pack cause an intermittent problem without complete failure? Again, I never shut the engine off to cool just continue to run it at reduced RPM and then eventually it will take throttle for a few minutes before losing power once more.

 

[glenn property of pam]

Re: Fuel or Electrical

im not a expert so hopefully one will chip in.

im wondering if your model has limp mode (slow mode) so it will run fine until it senses high temp then it will rev limit to 1500rpm. At lower rpm the engine gets a chance to cool down then when the temp drops the engine runs fine again for a few minutes until it gets hot again. Low pressure or no water at the tell-tale would be a clue. Also the test where you try to keep your finger on the head for 3 seconds.
You say the engine has no vro and you have not listed the engine number so im wondering if the vro has been removed. When the vro is removed from a engine the alarm will constantly go off until certain plugs have been removed from the oil system. If some one pulled the wrong plugs or unplugged the alarm then this will cause a problem as the engine will see a overtemp (go into slow mode) and not sound a alarm. I know my engine buzzer will bleep once when key is turned on like a self check and my vro system has been removed.
I surgest you test the alarm to rule out a possible overheat by disconnecting one of the temp sensors in the head and shorting the wire on the boat side to ground while the engine is running. The over heat alarm should sound when the tan wire is shorted to ground.

Ive heard of power packs that die when hot and come back to life when cooled down but ive never seen or heard of one that kinda fails and keeps running but like i said im no expert.

 

[rothfm]

Re: Fuel or Electrical

Same, not expert on the SLO MODE aspect. But sounds like it is doing a slow mode cycle. Others will chime in but its new to you so you might attempt to baseline that motor. Meaning check compression, Check spark, fuel and water flow. Also its really handy to bring along a temp IR gun, to quickly measure temps before, during, and after it acts up. I'm thinking it is a heat issue.

 

[nymack66]

Re: Fuel or Electrical

The mechanical vacuum created my this motor is not adequate for below deck tanks and with a fuel/water separator installed. As a test install a portable tank above deck elevate it level or above the engine run it and see what happens.

 

[Hvymtl]

Re: Fuel or Electrical

At lower rpm the engine gets a chance to cool down then when the temp drops the engine runs fine again for a few minutes until it gets hot again. Low pressure or no water at the tell-tale would be a clue. Also the test where you try to keep your finger on the head for 3 seconds. You say the engine has no vro and you have not listed the engine number so im wondering if the vro has been removed.

My engine was one that came from factory with no VRO, I have felt the water coming out and it is always cool.....hmmm....never really warm (does that mean the water is circulating?).

I suggest you test the alarm to rule out a possible overheat by disconnecting one of the temp sensors in the head and shorting the wire on the boat side to ground while the engine is running. The over heat alarm should sound when the tan wire is shorted to ground.

Don't know if the commercial use 90 had "limp mode" or not. I'll do this today.