VRO (3 wire vs 4 wire)

[WestPoint]

Does anyone know what the real difference between the latest VRO (or OMS) pumps are? I see 5007420 (4 wire) and 5007423 (3 wire) being sold, and someone on Ebay motors is selling what they say is a combination of both kits.

Does the 3 wire kit 5007423 upgrade you to 4 wire? I understand that these pumps are basically the same. The 3 wire 5007423 kit looks like it has more parts- then why is it always cheaper than the 4 wire 5007420 kit?

And what kit is the guy on Ebay probably selling- do you think he is adding parts to make it have what both kits have?

 

[countvlad]

Re: VRO (3 wire vs 4 wire)

Does anyone know what the real difference between the latest VRO (or OMS) pumps are? I see 5007420 (4 wire) and 5007423 (3 wire) being sold, and someone on Ebay motors is selling what they say is a combination of both kits.

Does the 3 wire kit 5007423 upgrade you to 4 wire? I understand that these pumps are basically the same. The 3 wire 5007423 kit looks like it has more parts- then why is it always cheaper than the 4 wire 5007420 kit?

And what kit is the guy on Ebay probably selling- do you think he is adding parts to make it have what both kits have?

if im not mistaken the 3 is the VRO and the 4 wire its a VRO2... but im not 100% positive.. i think the 4 wire on the VRO2 was the low flow alarm

 

[WestPoint]

Re: VRO (3 wire vs 4 wire)

I've read that the 4th wire was introduced to provide 12V power for the alarm circuit board, since the previous 3 wire versions use rectified voltage from the gray wire that was less reliable and/or triggered false alarms.

I have a 4 wire pump now and want to know if I can purchase the cheaper kit (5007423) and save $.

Looking at product photos, it appears that the 4 wire kit (5007420) has four 90 degree fuel fittings and one straight, and the 3 wire kit has one 90 degree and one straight.

I guess that some of the extra fittings might be to cover different hose sizes and rigging, but I need to make sure I get 5/16 fittings that are all straight, except for the one 90 degree output at top of pump.

 

[dajohnson53]

Re: VRO (3 wire vs 4 wire)

I will be able to answer this question definitively later today or tomorrow! I ordered a 5007423 ($299 + shipping) and it should arrive soon. When I get it I will describe package contents by posting to this thread again.

I do know that the 3 wire vs. 4 wire not the difference between VRO and VRO2. My (current) VRO2 pump is 3 wire. The difference between VRO and VRO2 is the mixing ratio and some general incremental design and material improvements.

Relevant to nothing, I've also been looking at replacement oil thanks and the difference one needs to know there is "system check" vs. non-system check alarms as it changes the wiring connection for the alarms at/near the fuel pump and the way the low oil sensor works. That happened in 1996. It looks like the change from VRO-OMS (and 3 wire-4 wire??) happened in 1993. A big FWIW, just taking the opportunity to spew some knowledge I probably wish I'd not had to gain.

As usual, this article is always worth reading and re-reading:

http://continuouswave.com/whaler/reference/VRO.html

 

[WestPoint]

Re: VRO (3 wire vs 4 wire)

Today I emailed www.usavemarine.com, one of many online sellers, with the same question.

They responded and said the correct pump is 5007423 which replaces all other numbers. Now I'm really confused, since other sellers state one is for existing 3 wire pumps and the other is for existing 4 wire pumps, and still others say 5007423 will upgrade you to the 4 wire from 3 wire.

Thanks for your reply- I really look forward to your description when you get it. I can't believe this has to be so confusing.

 

[dajohnson53]

Re: VRO (3 wire vs 4 wire)

Today I emailed www.usavemarine.com, one of many online sellers, with the same question.

They responded and said the correct pump is 5007423 which replaces all other numbers. Now I'm really confused, since other sellers state one is for existing 3 wire pumps and the other is for existing 4 wire pumps, and still others say 5007423 will upgrade you to the 4 wire from 3 wire.

Thanks for your reply- I really look forward to your description when you get it. I can't believe this has to be so confusing.

The pump I received yesterday is actually from USaveMarine, fwiw. Excellent service and price by the way.

I think I understand why he said what he said... read on.

There are now three pumps and actually this is well explained on their website, I believe:

5007420 replaces 4 wire pumps, 1991 and newer

5007423 replaces 3 wire pumps and includes adapter to change to 4 wires (see below).

5007421 for non-oil mix applications. Does not mix oil.

5007423 is the pump I just received. My old pump, the one I'm replacing, has three wires: tan (looks kind of orange), black and gray. These three wires end in a three pin male "amphenol" connector. This in turn connects to a female amphenol connector and the same color wires come out of the female side and are already connected to various places in the engine.

The new pump has 4 wires coming out of it: tan (also kind of looks orange), black, gray and the new wire: purple. The 4 wires end in a 4 pin male amphenol connector.

My new kit includes what I would call this a "pig tail" adapter type of thing. It is a female 4 pin amphenol connector with a SINGLE purple wire coming out if it and 3 empty holes.

The installer (me, you) then moves the three wires from the old 3 pin female amphenol connector to the 3 empty holes in the new 4 pin female connector, matching up with the corresponding colors on the male (pump) side. Those three wires are already connected to appropriate places on the engine, so the only new connection is the purple wire and the instructions then tell you where to connect that purple wire.

This is where I believe the two kits differ. The 020, intended for replacement of 4 wire pumps, does not need that pigtail/adapter and I will assume it does not have one. (don't know for a fact though). The pump must be the same as the "023" with 4 wires terminating in the 4 pin male amphenol connector. The engine, already set up for 4 wire system, already has the female 4 wire connector with all 4 wires already hooked up where they belong. It's just plug and play.

[edit]. Another thing I just discovered. The actual pump in my "23" kit is labeled 5004554. In reading some other posts on this subject (VRO/OMS P/Ns), I've found out that the "020" kits as well as some equivalent, superceded kits also have pumps in them labeled 5004554. Obviously, the kits have the identical pump, differing only in the small pieces included.

That is why I think you could use the 023 to replace any 3 or 4 wire pump. You just wouldn't use the pigtail adapter.

 

[WestPoint]

Re: VRO (3 wire vs 4 wire)

Thanks very much for taking the time to describe it. I wonder why most retailers have the 5007420 kit (4 wire) always priced higher, since it probably has less parts (assuming the pump itself is identical).

Just one more question if you don't mind- what hose fittings were included? I need straight for pulse, fuel in and oil in, and a 90 degree for fuel out.

That's funny about being labeled as 5004554- that is the number of the pump I am replacing. I couldn't exactly read the last number on mine, since most of it was cut off, but it did look like a 4. But 5004554 did not come up as a valid number on any site I tried it on.

My pump bench tested good, but I was told on another forum that it should output a constant psi somewhere between 5 to 7 psi. I ran clear hose on input side of pump and found no air bubbles, and verified no fuel restrictions. Ran clear hose on output side of VRO and pressure tested. At 800 RPMs the pressure would gradually drop from 7 to 3.5 PSI within 15 to 18 second cycles. Each time pressure reached about 3.5 PSI, I noticed a very small group of bubbles (very small- probably combined would make one 1/16 in diam bubble) that pass out of the fuel outlet. Just as I see the tiny bubbles pass out, the pressure would immediately jump back to 7 PSI. Then the cycle repeats again.

Before purchasing a new pump, I will open it up and see if I can find a leak, such as a pin hole in one of the diaphragms. If so I might order a rebuild kit. If not, I'll assume its the housing and order the 5007423 pump.

 

[dajohnson53]

Re: VRO (3 wire vs 4 wire)

...Just one more question if you don't mind- what hose fittings were included? I need straight for pulse, fuel in and oil in, and a 90 degree for fuel out...

I glanced through the installation instructions today an it struck me that there is every fitting and small part you'd need. There are no long hoses.

I don't have any way to scan the instructions right now, maybe you can find a set - all the parts are named.

 

[WestPoint]

Re: VRO (3 wire vs 4 wire)

Since this turns out to be the same pump as the one I'm replacing (5004554), I can also use fittings off my old one as needed.

Thanks again for your posts- I'm sure it will help many others who are trying to figure out what to purchase.

 

[dajohnson53]

Re: VRO (3 wire vs 4 wire)

You're welcome. That's why I tend to be so verbose in this stuff - a brain dump kind of thing, hopefully of value to folks who have the same questions I've had.

 

[Bbrazy2k4]

Re: VRO (3 wire vs 4 wire)

Thanks, that was a huge help I was stuck on that issue for days not wanting to pay 300 bucks on something I couldn't use.