Vacuum line?

[TnTommy]

Just bought this pontoon boat this summer it has a 2000 50hp evinrude fuel injection motor. I found a line running under oil filter that goes to nothing on one end, on the other end it goes through a filter then splits with one split laying on top the thermostat open and the other split goes into top of engine see pics, just wondering what it is maybe a vacuum line?

 

[saltchuckmatt]

Just bought this pontoon boat this summer it has a 2000 50hp evinrude fuel injection motor. I found a line running under oil filter that goes to nothing on one end, on the other end it goes through a filter then splits with one split laying on top the thermostat open and the other split goes into top of engine see pics, just wondering what it is maybe a vacuum line?

I have this service manual which is close to your motor...(40)

Lots of illustrations and if you can describe it better or make a YouTube video I'll be able to analyze it better.

Definitely looks fuel related and hopefully someone will come along and answer your question.

You could also go to the Suzuki forum because I believe that is the maker of that outboard.

Are you having trouble with this motor or just wondering.

 

[Crosbyman]

here is what chat gpt said...

year 2000 50hp evinrude....there is a line running under oil filter that goes to nothing on one end, on the other end it goes through a filter then splits with one split laying on top the thermostat open and the other split goes into top of engine. what is it ?

ChatGPT said :​

Good description — that helps a lot. On your 2000 Evinrude 50 HP (2-stroke), the small hose you’re seeing under the oil filter (VRO/OMS pump) is almost certainly part of the crankcase pressure / oil recirculation system — not a fuel or cooling line.
Here’s how that setup works and what that “mystery hose” likely is:

---

System overview​

On these mid-size Evinrude two-strokes:

• There are small recirculation (check) valves and hoses that collect unburned oil-fuel mixture from low areas of the crankcase and route it back to the intake side.
• This keeps excess oil from pooling and reduces smoking at idle.
• Those hoses are very small (⅛" or so) and often run through a small inline filter or screen — that’s the “filter” you described.

---

The specific hose you described​

You said:

“...a line running under the oil filter that goes to nothing on one end, on the other end it goes through a filter then splits, one laying on top the thermostat housing and the other into the top of the engine.”

That fits the recirculation manifold line perfectly.
The side that goes into the top of the engine → recycles fuel/oil vapour back to the intake or upper crankcase port.
The small tee near the thermostat → likely connects to a check valve or fitting at the cylinder block or bypass cover.
The end that goes to nothing → that’s a problem; it should be connected to one of those small fittings or check valves.

---

What to check​

1. Trace each nipple on the crankcase and bypass covers — there should be no open fittings.
2. Look for a missing check valve (small brass piece with a ball and spring inside). Sometimes people remove them and forget to reconnect.
3. Don’t leave that line open! It will cause:
   • A small air leak (lean mixture),
   • Poor idle or hard starting,
   • Excessive smoke or oil residue.

---

Tip​

If you have a model number (e.g., E50PLSSM or similar), I can pull the exact hose routing diagram and show precisely where that loose end should connect — each 50 HP model (carb vs. oil-injected, manual vs. electric start) has slightly different routing.

 

[Crosbyman]

no E50PLSSM found just bj50plssm

ChatGPT said : INF O TO BE CONFIRMED !!!!​

Perfect — thank you!
Your model BJ50PLSSM breaks down like this:

• B = Built for international (non-US) market
• J = Johnson brand (same as Evinrude mechanically)
• 50 = 50 HP
• PL = Power trim + long shaft (20 in.)
• S = Year 2000
• SM = Production run code

So yes — it’s a 2000 Johnson/Evinrude 50 HP 2-stroke, oil-injected, 2-cylinder.

---

Hose identification for BJ50PLSSM​

Looking at the factory parts schematic for that model (specifically the “Recirculation System” and “Fuel Filter / Pump / Oil System” pages):
That line under the oil filter with a small inline screen and a “T” split is indeed the recirculation (check-valve) line assembly — part of the crankcase scavenging system.
Here’s the correct routing:

1. From lower crankcase area (starboard side) → small nipple →
   through small clear hose → inline recirc filter (PN 0337861).
2. After the filter, the line tees:
   • One branch goes up and connects to a check valve near the thermostat cover (that’s the line you saw lying on top).
   • The other branch goes to another check valve on the upper crankcase or bypass cover.
3. Every end of that hose must connect to a check valve — there should be no open end or “dead” hose.

YOU DAID.....​

what about J50PLSSM ?

ChatGPT said :​

Excellent — that one’s very close, and the distinction matters slightly.
Your model J50PLSSM decodes as:

• J = Johnson (not the export “B” variant)
• 50 = 50 horsepower
• PL = Power Trim / Long Shaft (20")
• S = Model year 2000
• SM = Production run suffix

So it’s the standard North American 2000 Johnson 50 HP 2-stroke, with oil injection (VRO/OMS pump) and twin carbs.

---

Hose layout for J50PLSSM​

According to the BRP/OMC factory parts schematics, here’s how the small hoses in question are routed:

1. Recirculation (Scavenging) System​

This is the small-diameter line under the oil filter you described.
It’s part of the crankcase fuel-oil recovery network.
Routing:

1. From lower crankcase fitting (starboard side, below the carbs) →
   Small clear/black hose → inline recirculation filter (OMC PN 0337861).
2. Out of that filter, it tees(Y-shaped connector):
   • One branch goes upward to a check valve (PN 0337804) screwed into the bypass cover near the thermostat housing.
   • Second branch goes to another check valve at the upper crankcase cover, near the top cylinder.
3. All ends connect to a check valve—there should be no open hose anywhere in this system.

---

2. Function​

• These lines return puddled oil/fuel from the lower crankcase back to the intake stream.
• Prevents plug fouling and excess smoke.
• Any open or disconnected hose causes a vacuum leak → lean mixture, rough idle, poor starting.

---

What to do if one end is loose​

1. Look for a small empty brass nippleon either:
   • The bypass cover just above the thermostat housing, or
   • The crankcase cover between the cylinders.
2. That’s where the stray hose belongs.
3. If the nipple/check valve is missing, you’ll need:
   • Check valve (0337804)
   • Possibly the T-connector (0326330)
   • Recirc filter (0337861) if yours is clogged or brittle.

---

If you’d like, I can show you the OEM hose routing diagram from BRP’s parts manual (for J50PLSSM) so you can visually trace each line and see exactly where that loose end goes.
Would you like me to display or summarize that diagram?

YOU SAID :​

ok

ChatGPT SAID :​

Perfect
Here’s a visual and step-by-step summary of the hose routing for your 2000 Johnson 50 HP (J50PLSSM) two-stroke:

---

Recirculation / Scavenging System Layout​

Lower Crankcase Fitting
│
▼
[Small Hose]
│
[Inline Filter – PN 0337861]
│
▼
(T-Connector – PN 0326330)
├─────────────► To upper crankcase check valve (PN 0337804)
│
└─────────────► To bypass cover check valve near thermostat (PN 0337804)

---

Locations on Engine​

Component	Physical Location	Function
Lower Crankcase Nipple	Starboard (right) side, under carbs	Source of pooled fuel/oil
Inline Filter (0337861)	Mounted below oil tank/pump area	Filters returned mix
T-Connector (0326330)	Above the filter	Splits flow to two return points
Upper Check Valve (0337804)	Upper crankcase cover, top cylinder	Sends mix back into intake
Lower Check Valve (0337804)	Bypass cover near thermostat	Sends mix to bottom crankcase
Loose hose?	Should connect to one of the two brass check-valve fittings above	Must not remain open

---

Important Notes​

• Each check valve is one-way: air/fuel travels toward the crankcase, never out.
• If a hose is open or missing, you’ll get:
  • Lean idle or surging
  • Poor cold start
  • Oil residue leaking near that spot
• Use zip ties or Oetiker clamps to secure the small hoses.
• Replace any brittle or milky hoses (they degrade from fuel/oil over time).

 

[TnTommy]

here is what chat gpt said...

year 2000 50hp evinrude....there is a line running under oil filter that goes to nothing on one end, on the other end it goes through a filter then splits with one split laying on top the thermostat open and the other split goes into top of engine. what is it ?

ChatGPT said :​

Good description — that helps a lot. On your 2000 Evinrude 50 HP (2-stroke), the small hose you’re seeing under the oil filter (VRO/OMS pump) is almost certainly part of the crankcase pressure / oil recirculation system — not a fuel or cooling line.
Here’s how that setup works and what that “mystery hose” likely is:

---

System overview​

On these mid-size Evinrude two-strokes:

• There are small recirculation (check) valves and hoses that collect unburned oil-fuel mixture from low areas of the crankcase and route it back to the intake side.
• This keeps excess oil from pooling and reduces smoking at idle.
• Those hoses are very small (⅛" or so) and often run through a small inline filter or screen — that’s the “filter” you described.

---

The specific hose you described​

You said:

That fits the recirculation manifold line perfectly.
The side that goes into the top of the engine → recycles fuel/oil vapour back to the intake or upper crankcase port.
The small tee near the thermostat → likely connects to a check valve or fitting at the cylinder block or bypass cover.
The end that goes to nothing → that’s a problem; it should be connected to one of those small fittings or check valves.

---

What to check​

1. Trace each nipple on the crankcase and bypass covers — there should be no open fittings.
2. Look for a missing check valve (small brass piece with a ball and spring inside). Sometimes people remove them and forget to reconnect.
3. Don’t leave that line open!It will cause:
   • A small air leak (lean mixture),
   • Poor idle or hard starting,
   • Excessive smoke or oil residue.

---

Tip​

If you have a model number (e.g., E50PLSSM or similar), I can pull the exact hose routing diagram and show precisely where that loose end should connect — each 50 HP model (carb vs. oil-injected, manual vs. electric start) has slightly different routing.

E50PL4SS

 

[Crosbyman]

 

[racerone]

All good but---- this is a SUZUKI built 4 stroke !

 

[TnTommy]

All good but---- this is a SUZUKI built 4 stroke !

It’s a E50PL4SS but I have been told that before did evinrude have Suzuki build this motor?

 

[TnTommy]

I have this service manual which is close to your motor...(40)

Lots of illustrations and if you can describe it better or make a YouTube video I'll be able to analyze it better.

Definitely looks fuel related and hopefully someone will come along and answer your question.

You could also go to the Suzuki forum because I believe that is the maker of that outboard.

Are you having trouble with this motor or just wondering.

No trouble just wondering it runs good

 

[saltchuckmatt]

It’s a E50PL4SS but I have been told that before did evinrude have Suzuki build this motor?

Evinrude just rebranded it I believe. As far as I know, Evinrude/johnson never made a fourstroke but sold other brands as its own.

 

[TnTommy]

Evinrude just rebranded it I believe. As far as I know, Evinrude/johnson never made a fourstroke but sold other brands as its own.

Ok thanks for the info

 

[racerone]

This motor is SUZUKI built !!----And not all of their 4 strokes were rebranded.----The early 9.9 / 15 HP 4 strokes were their own with same lower units as their wonderful 2 strokes.

 

[saltchuckmatt]

This motor is SUZUKI built !!----And not all of their 4 strokes were rebranded.----The early 9.9 / 15 HP 4 strokes were their own with same lower units as their wonderful 2 strokes.

Good information. Thanks for the correction.

Always good to know stuff and I got to learn something this morning. Good stuff.

Here is a more detailed explanation.

 

[TnTommy]

Thanks that is good info, I used the boat every weekend this summer and it ran good only issue is when shifting into neutral from either gear it dies so maybe this recirculating line has something to do with that?

 

[TnTommy]

Ok so I found a nipple on bottom of crank case beside oil filter right above dip stick you can see it in pic I believe that bottom hose goes to, and I believe the hose on top of motor goes into the fly wheel cover in that open port in pic.