300x Oil Pump Output test

[JOSEPH SHULMAN]

I'm priming oil pumps on twin 300x engines using a Rinda TechMate Pro. During the oil pump output test, the bar graph shows 0–40% and completes in 41 seconds. When refilling the onboard oil reservoir to my marked level, it takes only 45 cc of oil, not the 110 cc specified in the manual. Each tube is pulsing oil, and both motors show identical results. I believe the ECU is acknowledging the oil pump is primed and completing the auto-prime early at 40% and not going through to 100%? Should I continue troubleshooting, or should I throw that crap away and mix the oil like my 2.5s? Any advice would be greatly appreciated.

[David - WI]

That's not how the oil output test works on the other 3L motors... don't you have to unhook the oil line and run the motor at 1500rpm on premix to test it?

[JOSEPH SHULMAN]

That's not how the oil output test works on the other 3L motors... don't you have to unhook the oil line and run the motor at 1500rpm on premix to test it?

This is the test i'm trying directly from the book. Any advice would be much appreciated.

• Using a DDT to activate auto prime, the oil pump should discharge 110ml (cc) =/- 8 ml CC during the auto prime period.
• To check the oil pump output.
• Verify the on-board reservoir is full.
• Release any pressure (loosen cap) from the remote oil tank in the boat.
• With engine not running, use a DDT to activate the auto prime.
• Using a ml or cc granulated container, record the amount of oil needed to refill the onboard oil reservoir.
• Retighten cap on the remote oil tank in the boat.
• Above is the procedure in the book. But my DDT is only performing 40% of the test and saying the test is complete? So I am not seeing the full cycle of oil need to see the pump output of 110 cc.

[Chaz]

Joe you ask a very interesting question. Lets break it down into a few sections.
First, I'm glad you have two motors to get a baseline with.

Both pulse 41 seconds. So the PCM drivers are consistent. Beyond that, they have no idea how much oil was primed / moved.

All 3.0 / 3.2L pump body, electromagnet / piston's are the same. The outlet / hose arrangement is the only thing that is different.

The 225 / 250's have 1 outlet that fills the VST tank.

The 300x has 7 outlets. 1 each hose to the reed adapter plate and the "spare" 1 to a block before the inlet side of the pump.

I always thought it was odd that Mercury would use full oil on the fishing motors and trim back the amount on their Hiperf model. During any rebuild I did, I would just clean the pump and light sand any scuffing on the piston and bore.

Back in the day of reflashing, they turned up the oil pump driver because on fresh rebuilds when the motor came off of double oil, there was a good chance it might seize.
Myself, I've never done the cc / test. But I have blocked off the "seventh" line. (uses a lot of oil and smokes like crazy)
I have made little brass jets to go in line to restrict flow (best option in my book)
Used a 225 pump and a small loop line while mixing gas and oil in the tank.
Taken the pump off and put a resister in place of the pump.

I would be interested to see what the results were if you were to block the "seventh" line and do your flow test again ...

[JOSEPH SHULMAN]

Chaz, thanks for your input. The pump only cycles to 40%, not completing, and the 110cc/test is inaccurate at 45cc. Pumps seem fine since the port motor matches cc output. If issues persist, I may delete the oil pump and VST canister. What size resistors work for their electrical leads? Thanks!

[Chaz]

So what your saying is that your putting the PCM in break in mode, hanging the 7 lines into a ratio-rite (or some type of graduated beaker) and running the priming (line filling portion of break-in) and one motor pumps 110 cc and the other only 45 cc ?

Every pump I have ever run (in break in mode) sounds like it's putting a gallon of oil in the motor .. clacking away at a million miles an hour. First start-up, fog city.

I don't have a pump and meter handy at the same place right now. But it's just like an injector .. either 2 or 14 ohms.