Four Question on Boat Electrical Problems

[Kovar]

Q1: what is a reliable pump that can be used to replace a RULE 500-[GPH] pump?

BACK STORY

[Sometime prior to now] I purchased a RULE 500-[GPH] pump. It failed soon after being installed. The seller exchanged it for another new pump; that pump failed on Thursday, September 21, 2023.

The battery terminal voltage as 8.0-Volts. I used a battery-jump-pack to jump-start my Johnson 30-HP engine, and I left the that battery connected.

The replacement RULE 500-[GPH] pimp would then run for 30-seconds and stop. Then the RULE 500-[GPH] pump quit and would not run at all.

BATTERY VOLTAGE

Also, with the engine running I only measured 12-Volts at the battery.

Q2: what type of charging should I expect from this [Johnson 30-HP engine described only as being an "old" model]?

I'm unfamiliar with marine power. I assume the [Johnson 30-HP engine described only as being an "old" model] has an alternator.

Q3: are alternators [as used in a old Johnson 30-HP outboard engine] easy to troubleshoot?

Q4: are alternators [as used in a old Johnson 30-HP outboard engine] easy to repair?

--Sam

ASIDE: I am a new particupant in the forum and a new owner of a 1988 Boston Whaler 13-footer.

[jimh]

Re your first question:

Q1: what is a reliable pump that can be used to replace a RULE 500-[GPH] pump?

The RULE pumps are a very common pump used in many boats as a centrifugal pump for lifting water from a sump. That you have had problems with two RULE 500-GPH pumps seems very uncommon. There may be something in your boat wiring or in the duty cycle that is needed in your boat that is causing the RULE pumps to fail.

You do not specify what model RULE 500-GPH pump you have or how long either of them lasted in terms of days or weeks or month, and if the boat was being left in the water and the pump was anticipated to be running frequently. Providing this information would help readers to deduce the cause of their failures.

That the battery voltage was drained to 8.0-Volts sounds like the pump ran for long time, perhaps without having any water to lift. Typically the pump will rely of cold water passing through the impeller to keep the operating temperature of the pump in a normal range. If the pump ran without any water and was running almost continuously, it might have been damaged from overheating.

[jimh]

Re your second question:

Q2: what type of charging should I expect from this old engine?

I am not sure what you mean by "type of charging." If you want to get an estimate of how much charging current can be provided by an old Johnson 30-HP engine, I can only guess: about 5-Amperes on a long term average basis. I would expect that you could cause damage to the charging output circuit if you required it to provide more than about 5-Amperes, and then that load should only for short intervals. Other loads of greater current demand and longer duration may cause damage to the permanent magnet alternator circuitry due to overheating.

The best answer about the capabilities of your particular engine for generating battery charging current will come from the owner's manual.

Also, if you were to provide the model year, then informed readers could give you a better answer.

[jimh]

Q3: are alternators [as used in a Johnson 30-HP outboard engine] easy to troubleshoot?

Yes. Anyone with experience in diagnosis of permanent magnet alternators, voltage regulators, and Johnson outboard engines should be able to assess the condition of the alternator with suitable electrical measuring equipment.

For a person with no experience with permanent magnet alternators, no experience with voltage regulators, and no experience with Johnson outboard engines, and lacking the necessary electric instrumentation and the skill to use them, the diagnosis of alternator problems may not be easy.

As someone once commented about assembly of a child's complicated Christmas toy: "Easy"--for Leonardo.

[jimh]

Q4: are alternators [as used in a Johnson 30-HP outboard engine] easy to repair?

Not always. The coil assembly for the permanent magnet alternator on an outboard engine is usually located under the engine flywheel. The engine flywheel must be removed to gain access. Removal of the engine flywheel, particularly on one that has been attached and in service on an older outboard engine for perhaps 40-years, can be difficult.

[Phil T]

I have never heard of this type of frequent failure of a new Rule pump.

The pump is not being installed properly.

The wiring must be done properly and the splicing must include watertight connections such as heat shrink butt connectors.

See the instructions with the pump.

[Kovar]

[The RULE 500-GPH] pump [that is the topic of this discussion] has a built-in water sensor to [control the] start and stop [of the pump motor.

I'm confident in the wiring, which is direct-to-battery with a watertight in-line fuse.

The "replacement" RULE 500-GPH pump ran for about one summer.

That the RULE 500-GPH pump is a product that is mass-marketed with low cost is an important factor [in the duration of the pump's service life]

I would be happy to pay a premium for a more robust pump.

An experienced boater said he puts a new [pump] in his boat every year. If that makes sense I'll consider it annual maintenance cost of $35-per-year.

[jimh]

On my 1990 Boston Whaler boat there is a RULE pump in aft cockpit starboard sump. As far as I know, the pump is the original pump installed by Boston Whaler. The pump is still working fine. This represents a service life of 33-years. I don't have any complaints about this RULE pump. Notably--perhaps--the operation of the pump is not controlled by the pump itself. The pump only runs when a float switch energizes the pump or a manually-operated switch energizes the pump. Typically the only time water accumulates in the sump is when the boat is exposed to prolonged rainfall. So the pump is not running much, perhaps just ten times per year.

The newer pumps with "automatic" features operate continually by periodically energizing themselves to see if the load on the motor is sufficiently hight to indicate that there is water being moved by the pump impeller. This creates a much greater amount of time for the pump motor to be running than if the pump operation were controlled by an actual water sensor like a float switch. Also, the pump housing contains electronic circuitry that controls the motor and senses the current being drawn. Whether or not the circuitry is designed to be very robust and last 25-years is unknown, but I tend to doubt the circuitry is that rugged and designed for such a long life. Also, the circuitry is continually draining the boat battery with its frequent running to test for water. And finally, being continually connected to the boat battery also exposed the circuitry to all voltage fluctuations of the battery, which might include voltages of greater than 15-volts if the charging source is not well-regulated, and to voltage transients, such as can occur when other electrical devices (such as electric motors associated with the engine power trim system) are operated and shut off. Whenever a DC circuit in which the load has an inductive component has its current interrupted, the collapse of the inductive field causes a voltage spike to occur.

If you want a more reliable sump pump system, you should revert to using a float switch sensor to control the pump. Then replace the $35 plastic disposable pump with a more reliable pump. Here is a possible option for replacement:

https://outboardsmarine.com/product/jab ... 7-gpm-5-5/

[Jefecinco]

I believe the service life of virtually everything on boats is improved by mostly fresh water use. Salt water is an incredibly damaging medium.

[Kovar]

Thanks for the replies.

[Don SSDD]

I have found the RULE electronic sensor pump to be not reliable for me and several of my fellow boaters here [in Nova Scotia in Atlantic Canada].

I had [a RULE electronic sensor pump][omitted a word, perhaps intended to say “fail”]. The replacement also failed inside of one season of use, which for me is from early July to early October. I won’t buy another [RULE electronic sensor pump].

I agree with Jim on having the separate float switch to activate a separate pump, I have had this setup with a cartridge-type red Johnson pump. That combination has been flawless now for four years of use in saltwater.