VRO Pump - low oil consumption

[dajohnson53]

J200TXESM.

Condensed version: local shop replaced air motor diaphragm on VRO2 pump, installed new pulse limiter and now it is burning oil at 100:1 rate. Was at about 60:1 before this. I will call shop about this Monday, but in the mean time would like to get IBoats wisdom and advise.

Long version:
Bought engine last year, very low hours, very clean. Appears to have original VRO2 pump. Ran perfectly - good start, good idle, good accceleration, good cruise, proper WOT RPMS.

Marked oil tank and it was consuming oil at an average of right about 60:1 which seemed normal to me because this VRO2 pump is supposed to go 100:1 at idle and about 50:1 at WOT.

Since this was an old pump, based on things I've read here, I decided to replace the VRO2 pump with a current OMS pump and replace the old (black face) pulse limiter with a current (blue face) pulse limiter.

Brought to a reputable local shop and after looking at the pump, and hearing my experience, they suggested I save $$ - he suggested that they simply replace the fuel motor diaphragm because the old one was delaminating... a $41 part rather than the expensive OMS pump. According to the work order they:

Replaced Air motor diaphragm (p/n 435921)
Replaced pulse limiter and pulse hose
installed proper clamps
Used 50:1 fuel w/ on -water test
Water test - Verified oil delivery
verified "no oil" alarm.
Reinstalled, purged, etc. oil line.
Also checked compression 92-95 psi all 6.

I've been running 50:1 and will continue to run at least 75:1 until I get this sorted out.

I ran 56 gallons through it over 2 days this weekend and burned approximately 2.25 quarts of oil (between 2 and 2.5). This is almost exactly 100:1. My usage was about 75% fast cruising at ~4,000 - 4,500 rpm, and about 25% idle rpms (~800-1,000). I would have expected 60:1 oil burning rate again.

I got 2 or 3 "no oil" alarms (1 sec. intervals) first day which went away with a quick squeeze of the oil bulb. Second day, I pumped the oil bulb before first start, but not again, and didn't get an alarm all day. Several starts, rests, and a lot of running time (at least 2-3 hours).

Engine ran perfectly both days: easy start, good idle, good acceleration, full WOT rpms. No overheat or fuel restriction alarms.

I'll double check the oil line for anything that could be causing the no oil alarm, but I'm not too concerned with that at this time as it seemed to resolve and is easy to "fix" on the water. Frankly, I'm glad to know it works!

I'm concerned about the oil consumption. What would cause such a low mixing ratio? It seems "stuck" at the 100:1 idle ratio and not increasing w/ higher rpms.

Like I said, I'll call the shop Monday, but in the mean time, I'd like to know what you-all think and maybe even solve the problem myself. I do have an OEM shop manual.

If the pulse limiter/hose or air motor diaphragm they installed weren't working correctly, wouldn't that affect the gasoline as well as the oil flow rate? Wouldn't I be seeing general fuel delivery issues, not just the oil side? I can certainly visually check the connection of pulse line.

Do you think it's at all related to the pulse limiter and pulse line?

Do you think the oil side is just worn out and it is only a coincidence that it happened after the work the shop did?

Do you think the shop made a mistake and I should expect they give me priority service and fix it for free? This is a place with at least a week waiting time normally. I'd rather continue to mix the fuel and wait until fall rather than lose use of the boat for 2 weeks in July!. Or if there's some simple possible solutions, I would rather just fix it myself.

If so, and I decide to go ahead with my original idea of putting on a brand new OMS, it seems like that's a pretty straight forward DIY? Looks like it to me. The only reason I brought it to the shop in the first place, was because on my engine getting to the pulse limiter looks like a tough job for an amateur (removing other parts to get at it... that always causes trouble for me!) and I decided to let the pros do it. I think that if it's only a new fuel pump (OMS), everything looks straight forwrd.

 

[kenmyfam]

Re: VRO Pump - low oil consumption

If you are averaging 100 to 1 then something is amiss in my opinion. To the best of my knowledge an OMS pump mixes at a constant 50 to 1.
Could be easier and more cost efficient to go premix.

 

[dajohnson53]

Re: VRO Pump - low oil consumption

If you are averaging 100 to 1 then something is amiss in my opinion. To the best of my knowledge an OMS pump mixes at a constant 50 to 1.
Could be easier and more cost efficient to go premix.

Thanks. This is actually a VRO2 pump which mixes 100:1 at idle and then gradually up to 50:1 at higher RPMs - "variable rate oiling". That's why I have this idea that it's "stuck" at the idle mixture rate and for some reason is not ramping up as it is supposed to. I'm trying to figure out if there's something easy to look for.

Yea, I know that pre-mix is always an option, but I'm not interested in that. BTDT for many years and I'll go with a mixing pump, either fixing this one or buying a new one.

 

[tashasdaddy]

Re: VRO Pump - low oil consumption

i would never fix a VRO2, i would go OMS, or premix.

 

[kenmyfam]

Re: VRO Pump - low oil consumption

Thanks. This is actually a VRO2 pump which mixes 100:1 at idle and then gradually up to 50:1 at higher RPMs - "variable rate oiling". That's why I have this idea that it's "stuck" at the idle mixture rate and for some reason is not ramping up as it is supposed to. I'm trying to figure out if there's something easy to look for.

Yea, I know that pre-mix is always an option, but I'm not interested in that. BTDT for many years and I'll go with a mixing pump, either fixing this one or buying a new one.

If you are not going to premix then you need to replace with an OMS pump. Dump the VRO2 if suspect.
Good Luck.

 

[seahorse5]

Re: VRO Pump - low oil consumption

There is an oil delivery test in a late model service manual and in service bulletins that an authorized dealer should have.

Also because of the age of your motor, the oil tank should be flushed out, new filter installed and the primer ball and hose condition inspected.

 

[kenmyfam]

Re: VRO Pump - low oil consumption

But "if in doubt throw it out"
Could be really expensive not to.

 

[dajohnson53]

Re: VRO Pump - low oil consumption

Thanks for the advice all of you.

RE: the tank, filter, lines: I did completely flush the tank and change the filter and lines when I first bought and had the engine installed last year - after which the system worked perfectly as I mentioned in the OP. I did follow normal spring maintenance to check for contamination in the tank this spring and checked the lines. All clamps are the proper (ratchet) type, by the way.

RE: when in doubt throw it out: that's exactly what I was thinking and it was my instinct earlier this season when I wanted to get the pump replaced but was talked into the "cheaper" alternative by the mechanic. I think his heart was in the right place, but obviously it didn't work out. The good news is that I do watch oil consumption and didn't get caught unaware.

I think I'll just install a brand new OMS pump and be done with it.

But I still am curious if anyone has heard of the oil side of a VRO (or OMS for that matter) failing in such a way that it mixes at a low rate rather than just failing completely. I'm going to take a look at the schematic and see if I have any bright ideas.

NOT THAT IT WILL MAKE ANY DIFFERENCE! I'll replace the pump, but am still curious.

Thanks again.

 

[countvlad]

Re: VRO Pump - low oil consumption

J200TXESM.

I got 2 or 3 "no oil" alarms (1 sec. intervals) first day which went away with a quick squeeze of the oil bulb. Second day, I pumped the oil bulb before first start, but not again, and didn't get an alarm all day. Several starts, rests, and a lot of running time (at least 2-3 hours).

i never have to prime or squeeze the oil bulb... once the air and the oil line is in place you should never have to squeeze the bulb.... had mine hooked up for 2 years now and everytime i check it its always hard...

if you have to squeeze the bulb you have a leak somewhere or the air purging wasnt done correctly.....

 

[dajohnson53]

Re: VRO Pump - low oil consumption

i never have to prime or squeeze the oil bulb... once the air and the oil line is in place you should never have to squeeze the bulb.... had mine hooked up for 2 years now and everytime i check it its always hard...

if you have to squeeze the bulb you have a leak somewhere or the air purging wasnt done correctly.....

That's what I was thinking too. But I've also read somewhere that it's not all that uncommon to have to give it a pump every once in a while if the engine's been sitting for a while. It's almost always weeks between outings for me. This last outing (two days in a row) I had 2-3 alarms first day, but none the second. Regardless, I've decided to change the pump just because it doesn't seem to be working right and it's 19 years old!

As for the alarms: This is a "3 wire pump". I've read that one of the reasons they changed to the "4 wire pump" was because of false alarms which the 4 wire design eliminated. I wonder if this is the sort of false alarm that was a problem with 3 wire pumps? I have no idea, but my new pump will convert to 4 wire. I'll also carefully re-do the lines and purge, so we'll probably never know if the alarms were poor implementation or false alarms.

Thanks for your comments.

 

[Fl_Richard]

Re: VRO Pump - low oil consumption

Replacing the VRO for the OMS pump is a simple DIY job. Last time I slpurged and had a shop replace it a scored cylinder ws the result. They didnt install the fuel hose completely on the barb and it sucked air.....

If you want somthing done right you've got to do it yourself. I'm a so so smart guy and looking at some of the mechanics I've seen I can do it. I may be slower, but I work cheaper and ultimately do a better job.