tamd41a Penta stop solenoid

[petrolhead63]

Hi, off to do some work tomorrow, the stop solenoid is energise to stop, can anybody clarify if it retracts or extends the plunger to stop and therefore in the default run position is it retracted or extended.
Many thanks.

 

[Assassin]

It will retract when energised and the retraction shuts off the fuel and shuts the engine down and its normal position is extended.

Unlike automotive engines, marine engines are designed to run as any fault on the stop solenoid on an automotive engine will stop the engine, this is classed as dangerous on a marine engine where the vessel can be at sea and in danger from a stopped engine through a fault, therefore they are designed to run so they can get to a safe haven before they can be closed down or run out of fuel. Modern craft rely upon many functions from an engine and a loss of electrics will quickly discharge a battery and lose everything from navigation lights to navigation equipment, hydraulics can mean that everything hydraulically controlled can fail and potentially the boat can capsize.

 

[spannerman]

Sorry but that is totally incorrect, if you take out a Volvo stop solenoid you will see that its normal position is retracted and it has a small helper spring under the piston to keep it in the ‘run’ position. When power is applied the piston extends closing a port in the injection pump and stopping the engine.

 

[volvopaul]

Sorry but that is totally incorrect, if you take out a Volvo stop solenoid you will see that its normal position is retracted and it has a small helper spring under the piston to keep it in the ‘run’ position. When power is applied the piston extends closing a port in the injection pump and stopping the engine.

My thoughts exactly, one other possibility is that when the spring goes weak the fuel demand at full throttle can suck the plunger down partially blocking the fuel flow port into the cam head area if the pump.
I had this on a kad 300

 

[petrolhead63]

Thanks for the correct answers, Volvo Paul already knows I have located one issue haha. However, I want to check the solenoid and spring.
The spring then must be a contraction/pull spring to help keep the piston retracted.
I can see that spring could easily be weak after 30 years and perhaps replacing them if available is worth doing,

 

[spannerman]

No the spring is separate and sits down the hole in the pump under the piston pushing it up to keep the port open allowing diesel to flow.

 

[petrolhead63]

No the spring is separate and sits down the hole in the pump under the piston pushing it up to keep the port open allowing diesel to flow.

So the spring is the correct length so in run position with piston retracted it is neither in compression or extension.

The spring must be attached to the piston so it holds it back and in the body of the solenoid?

 

[Assassin]

My thoughts exactly, one other possibility is that when the spring goes weak the fuel demand at full throttle can suck the plunger down partially blocking the fuel flow port into the cam head area if the pump.
I had this on a kad 300

Have also had this, also some springs tend to snap their ends off on rare occasions.

 

[spannerman]

The piston in the run position is retracted into the solenoid body, the spring sits below the piston holding it up in the solenoid. When 12v is applied the piston extends downwards compressing the spring, when the voltage is removed the piston retracts helped by the now compressed spring, all very clear when you take it out.

 

[petrolhead63]

The piston in the run position is retracted into the solenoid body, the spring sits below the piston holding it up in the solenoid. When 12v is applied the piston extends downwards compressing the spring, when the voltage is removed the piston retracts helped by the now compressed spring, all very clear when you take it out.

Got it! I think having looked the springs are available so I feel it is worth replacing them. If weak I can see how it could partially restrict fuel flow and that is a possible cause of something we experience.

 

[superheat6k]

It will retract when energised and the retraction shuts off the fuel and shuts the engine down and its normal position is extended.

Unlike automotive engines, marine engines are designed to run as any fault on the stop solenoid on an automotive engine will stop the engine, this is classed as dangerous on a marine engine where the vessel can be at sea and in danger from a stopped engine through a fault, therefore they are designed to run so they can get to a safe haven before they can be closed down or run out of fuel. Modern craft rely upon many functions from an engine and a loss of electrics will quickly discharge a battery and lose everything from navigation lights to navigation equipment, hydraulics can mean that everything hydraulically controlled can fail and potentially the boat can capsize.

Whereas I like the idea of your latter statement, on my Cummins the stop solenoids are energise to run, and a badly fitted one caused me months of engine start trouble last year, I even re-wired the entire 12v distribution (not before time I would add), but the issue was a dislodged solenoid pintle return spring, about the size of a biro spring. That was one expensive spring !

Also I will now not be using a Southampton based diesel injection firm again, as it was they who rebuilt the pump prior after the problem first started occurring, so it was they who did not ensure the solenoid was properly assembled. AND since their support has been non existent, emails unanswered etc.

 

[Assassin]

Whereas I like the idea of your latter statement, on my Cummins the stop solenoids are energise to run, and a badly fitted one caused me months of engine start trouble last year, I even re-wired the entire 12v distribution (not before time I would add), but the issue was a dislodged solenoid pintle return spring, about the size of a biro spring. That was one expensive spring !

Also I will now not be using a Southampton based diesel injection firm again, as it was they who rebuilt the pump prior after the problem first started occurring, so it was they who did not ensure the solenoid was properly assembled. AND since their support has been non existent, emails unanswered etc.

You do get some strange set up's and in most cases you can swap solenoids from automotive to marine variants and vice versa, one of the most memorable for me was several years ago when a batch of industrial engines were being commissioned and at the last minute several were required to be used as fire fighting pumps; the industrial engines were the standard power to run but the solenoids on the fire pumps were power to stop. Industrials were run and commissioned and then run in on the bench, but the fire units ran fine but wouldn't stop and they merely reduced their revs from 3000 RPM to around half that and had to have their fuel taps closed to stop them.

The only common denominator was the fuel shut off solenoids and when I pulled one apart I found the needle in them was either too small, or the fuel port was too large and when they were energised they engaged, but being mismatched merely restricted the fuel and wouldn't shut them down and these solenoids were straight from the factory, we never used them again either.