Evinrude vro problem? Or Carb problem?

[Mcombs91]

I'm sure you guys have seen this one a million times. I have a 1998 evinrude 115 carborated engine. Primer bulb won't stay hard. Will start and run as long as someone pumps the bulb until it floods or they can no longer pump. Replaced all the fuel lines and bulb and can apply firm pressure and see no leaks. Without starting it you can let it sit for a short period of time and come back to the bulb and it not be firm again. I took the vro pump off and left all hoses connected and pumped the primer bulb and gas flows very freely. So I took it off and removed the diaphragm but I don't see any visible damage or holes.
If I replace the diaphragm how will I know the pump still works? Should I just buy the whole pump?
Or is it fine and this completely normal?
Thanks!

 

[Mcombs91]

Guys these diaphragms look fine nothing visible. Can't figure out why it still passes gas through the vro when the bulb is squeezed.

 

[racerone]

If the diaphragm is in good shape then operating the primer bulb sends the gas straight through the pump and into the carburetors !!!----That is how these pumps on outboard motors work.-----Look carefully how the fuel pump works as you may have missed a key point on how they work.-----Have you checked the pulse limiter ???----Have you checked for crankcase pulses ??------Done a compression test on this motor ??

 

[Mcombs91]

Yea I actually took it in a couple months ago and had a tune up/check up. Compression test was good. Power pack was good and I complained that the tach had stopped working. He said leaving an onboard charger on the starting battery and the motor terminals hooked up at the same time put constant pressure on the diode and burnt it out so current could travel both directions. This messed up the cdi which he replaced and the tach worked about a month and quit again. I didn't leave the motor terminals hooked up while charging. I'm guessing a weak battery contributed to this with high voltage. Maybe this could play a role?

 

[Mcombs91]

So all he said he could find is the rectifier regulator.

 

[Mcombs91]

No Title

There is two hoses which run from my carbuarators back to the front and connect to nothing. One comes from the top part of the float bowl, the other from a plastic line on the side of the carbuarator. I'm going to include some pics. I can blow into them and cap my hand over one carbuarator hole and tell that it is corresponding to that particular carb. The other with the T doesn't really allow much air to flow

 

[Mcombs91]

Anybody got anything similar?

 

[Chris1956]

Those two hoses may connect to the air box. Normally there is one on a nipple on the lower port side and the one with the TEE is a slip fit into a hole on the upper starboard side of the air box.

Your motor should have a vapor separator and vapor pump. This is the first stop for fuel entering the motor. The primer bulb is supposed to fill the vapor separator, and the inlet needle will close causing the primer to get hard. The fuel is gravity fed to the VRO pump, mixed with oil and pumped to the carbs. The cover of the vapor separator must seal for the vapor pump and VRO pump to suck the fuel.

BTW - using a charger on your batteries will not burn out the voltage rectifier or the blocking diode in the harness. Your mechanic is mistaken or ignorant.

 

[Captain Jeff]

Those hoses indeed connect to the air silencer / air box. Some type of breather hoses I believe.

You should look into the pulse limiter on the bottom cylinder and make sure it is not gunked up or the hose is clogged. It is a blue metal fitting if it is a more recent model or possibly brass. The VRO uses pulses from the lower cylinder to pump fuel kind of like how a car uses vacuum from the engine to power the brake booster and other accessories.

Also, a tip I just learned, try holding the primer bulb vertical with the arrow pointing up while you pump. This helps close the check valve on the bulb. If you get a firm bulb this way, you know the needle is sealing in the vapor separator.

 

[Faztbullet]

BTW - using a charger on your batteries will not burn out the voltage rectifier or the blocking diode in the harness. Your mechanic is mistaken or ignorant

It wont damage the blocking diode but yes it can damage the regulator, If charging is up to spec you should never have to charge starting battery unless something left on.The newer regulators sense voltage thru the main red wire and if it sees voltage in excess it bleeds it to ground, since its water cooled to dissipate the heat and its not running the regulator overheats and fails eventually.It may take some time for this to happen but it will happen, If you going do charge the start battery install a battery switch to disconnect motor from system...

 

[Chris1956]

Hey Fazt, How many amps of charge (or number of volts) would it take to burn out the VR?

 

[Faztbullet]

Anything over 13.5v the VR tries to bleed off to ground, it not the amps that kills them it the heat that cooks em. thus the water cooling thru the heat sink fins on bottom of VR. Merc VR's bleed thru surface contact on divider cover and if you let em get loose,paint the cover or don't use the heat sink compound they will fail too.

 

[Mcombs91]

Thanks guys. Im going to look into these tonight and tomorrow night and will update with what I find.

 

[Mcombs91]

Ok so I pulled the hose from the pulse limiter then removed the brass fitting and put the hose back on the fitting squeezed the primer bulb and fuel flowed great. When doing that I had opened the Schroeder valve half way so that fuel would flow and help clear debris if they were present.

Then replaced the pulse limiter and hose and returned the valve to the 6 o clock position. Pumped the primer bulb until full and held steady pressure with three fingers and the bulb slowly depressed for about ten to fifteen seconds until pushed all the way together.

I can't see fuel leaking anywhere so this makes me think the float needle isn't seating all the way but partially.
Thanks Matt

 

[Mcombs91]

So this evening I replaced my starter because it finally died. I hooked up the battery terminals turn the switch and had a warning horn. Tried to start and the motor would turn and the starter would fall out like the engine hit but would take off. I don't believe it was actually starting because I seen no exhaust or anything like that. When I open the red Schroeder valve to let the gas flow from the carbuarator so see a brown looking stuff flow from the bottom carbs and white stuff flowing from the top carbs.
I drained the tank about 3 weeks ago and ran it through my riding mower with no problems. Put in fresh gas and marine stabilizer. The oil tank and oil looks good.
So I thought the carbs may be dirty and need cleaned and I removed two of them disassembled and everything looks good. Air flows through good and look extremely clean.
Tomorrow I will put them back on and check the vapor separator float.
What should I look for when I do? How do I know if I have a float and needle seat problem as I think I do.
The motor was running the other day and now I have an alarm and won't run?
Thanks Matt

 

[Mcombs91]

Guy I don't know what the hell to do haha. Reassembled everything still have a very weak alarm but all the check lights go out just fine. When cranking the motor it sounds good and acts like it hits then the starter falls out. But I know it's not firing because I can take the plug wires off and it does the same. I can take the plugs out and it crank all day. So I still have the air in the fuel tank problem because the bulb won't stay firm. I feel like it should at least fire and run some. I know the rectifier regulator is bad but it should run without it, it has before.
Any input?

 

[Chris1956]

Disconnect the bad VR. Disconnect the yellow and yellow/grey wires to remove that as a factor. Test for spark. Make sure clean fuel and fuel only gets to the carbs. No brown stuff.....