Evinrude 225 vro pump pulse?

[Mofuk]

I have a 1988 Evinrude 225 (E225TXCCE)

I can not keep the engine running without the use of the prime bulb. I have checked the VRO pump for vacuum leaks and all checks good, the condition of the diaphams seems to be in good, not hard, no cracks, and move back and forth with no restriction. The only question here is there dosen't seem to be enough pressure/vacuum coming from the crankcase port to work that VRO diapham, I already replaced the limiter from the black to the blue and the pulse seem not enough to work the VRO pump. Cylinder PSI range from 75-85 psi. Is there a range for that crankcase port to work that VRO pump?

 

[Capt Ken]

Re: Evinrude 225 vro pump pulse?

There is valves hidden in the forward part of the VRO and its possible that they are not working properly. I usually take a vacuum pump and start pulling a vacuum and you can hear the diaphram work if everything is good. You can actually do the same by mouth. Doesn't take much vacuum.

 

[multimech]

Re: Evinrude 225 vro pump pulse?

I concur with the information already posted. If you are interested I can give you the exact test Evinrude describes for these pumps.

Get a vacuum and a pressure guage. With the pump in hand off the engine, put your finger over the outlet port (fuel to carbs port) put the vacuum or pressure checker hose onto the pulse fitting on the VRO. Pull a vacuum 15 lbs, keeping your finger covering the outlet, pull of the vacuum (or pressure) hose from the pulse fitting on the VRO. Then release your finger, you should here a click. The same test follows for a pressure check. 15 psi for that check as well. That tests the integrity of the diaphrams to hold pressure and vacuum.

Another test and the first one to be done IMO is to put a pressure gauge after the fuel pump and run the engine. You should have 5-7 psi from the pump, with no air bubbles (use a clear hose to connect the guage) If you do, then the problem is most likely not your VRO. I have never had an engine that would not produce the pulse for these VROs. Not to say it couldn't happen.

 

[Faztbullet]

Re: Evinrude 225 vro pump pulse?

I have never had an engine that would not produce the pulse for these VROs. Not to say it couldn't happen.

I have seen several of these motors that the piston/cylinder clearances would not produce enough pulse to drive the pump at idle.If this just suddenly happened the air motor has a problem on VRO.

 

[Mofuk]

Re: Evinrude 225 vro pump pulse?

I concur with the information already posted. If you are interested I can give you the exact test Evinrude describes for these pumps.

Get a vacuum and a pressure guage. With the pump in hand off the engine, put your finger over the outlet port (fuel to carbs port) put the vacuum or pressure checker hose onto the pulse fitting on the VRO. Pull a vacuum 15 lbs, keeping your finger covering the outlet, pull of the vacuum (or pressure) hose from the pulse fitting on the VRO. Then release your finger, you should here a click. The same test follows for a pressure check. 15 psi for that check as well. That tests the integrity of the diaphrams to hold pressure and vacuum.

Another test and the first one to be done IMO is to put a pressure gauge after the fuel pump and run the engine. You should have 5-7 psi from the pump, with no air bubbles (use a clear hose to connect the guage) If you do, then the problem is most likely not your VRO. I have never had an engine that would not produce the pulse for these VROs. Not to say it couldn't happen.

I applied vacuum by mouth to the pulse side and it does hold vacuum/pressure! But I don't understand the reason for the finger over the outlet side as it does nothing, once I quickly remove vacuum/pressure I hear the diaphram slap back is this the clicking you speak of? I also applied pressure to the outlet side and it blocks flow now when I apply vacuum it passes through from the inlet. I will have to get back with you on the air bubbles test.

 

[Mofuk]

Re: Evinrude 225 vro pump pulse?

I have seen several of these motors that the piston/cylinder clearances would not produce enough pulse to drive the pump at idle.If this just suddenly happened the air motor has a problem on VRO.

the engine runs well with no backfires, excellent throttle response. is it possible carbon build-up could be restricting the pulse? how does this port function?

 

[multimech]

Re: Evinrude 225 vro pump pulse?

But I don't understand the reason for the finger over the outlet side as it does nothing, once I quickly remove vacuum/pressure I hear the diaphram slap back is this the clicking you speak of?

As you are testing the integrity of the diaphrams, your finger holds the vacuum or pressure. When you remove your finger it is like the opposite side of the pump working correctly. If you have your finger over the outlet, pump the vacuum gauge up and hear a click the pump has failed. I hope this helps.

 

[Faztbullet]

Re: Evinrude 225 vro pump pulse?

is it possible carbon build-up could be restricting the pulse? how does this port function?

No carbon could block this port and it works off crankcase compression and vacuum. This pump is different than a regular fuel pump and only discharges fuel when you hear it "click".

 

[daselbee]

Re: Evinrude 225 vro pump pulse?

No carbon could block this port and it works off crankcase compression and vacuum. This pump is different than a regular fuel pump and only discharges fuel when you hear it "click".

A healthy fuel pump will click every few seconds as the engine idles. You can hear it over the engine running. I have never seen the fuel pressure stay at an even 5-7 lbs. It always varies, in that it goes down as the engine idles, and then the click, and it shoots back up.
It varies all over the place, sometimes getting quite low (1-2 psi). I have done alot of testing and alot of VRO rebuilds, with testing afterwards, and all the pumps I tested behaved similarly, but not exactly the same.
This was only idle speed testing.

 

[seahorse5]

Re: Evinrude 225 vro pump pulse?

Here is a link that is quite old but explains how the "VRO" really works.

continuousWave: Whaler: Reference: VRO Fuel-Oil Mixing