Major injection pump issues

[Ocean Hound]

We have blown 3 CAV/Delphi injection pumps on a Perkins 80hp, all after 3-4 hours running. The first was after winter layover in Sweden, the engineer diagnosing the problem. New injection pump supplied, she fired and off we went 60 miles up the coast. the engine died coming into port. Same engineer came up, bled the system, made some adjustments and away she went. same thing happened at the next port, engine just died coming in. Contacted a new engineer who reckoned the lift pump was not working fully and thus not supplying sufficient fuel to the injection pump. was not able to replace the lift pump but put an electric lift pump in line which did the job - plenty of fuel now to the injection pump, bled the system thru but still non starter. Contacted the original engineer who ordered another new injection pump, together with a new lift pump. Came and fitted both, made adjustments, bled the system and away we went, until 3 hours later - yes you guessed it - engine died on coming into port ( by this time we had become quite proficient at sailing into a strange port and stopping 26 tons without hitting anything. We had also become very proficient at stripping down and analysing the fuel lines and found everything Ok up to the injector pump but not beyond which leaves us with the problem of what caused the problem in the first place. On adjusting the first replacement pump the engineer, whose English was limited, indicated moisture or dirty fuel. We have however a generator which runs off the same fuel tank and fires up beautifully although we have never run it for more than 2 hours. We are wondering if the problem may lie in the return fuel side of the high pressure system where the injectors return unused fuel back into the system. In the meantime we are immobilised in Oskarshamn some 200 miles from the original fitter, awaiting word. We have asked for the first two pumps to be analysed to see if they throw any light on the problem, but none of the original providers are answering their phones or emails. Before we engage the services of a 3 rd engineer has anyone out there got the slightest idea of what may be the cause. One issue in Sweden is the amount of rape seed oil added to desiel, but that doesn't not apply as last bunkering was in the GDR and anyway the generator seems very happy with the same fuel. There is the possibility of moisture in the fuel - the layup yard was asked to fill the fuel tank to the top before winter - this they did not do, but again the genny works so that blows that theory. Any advice at all would greatly appreciated.

 

[Tiercel]

Silly question, but have you changed the fuel filters. We had a similar problem due to some duff fuel from Sardinia which gave us a bad dose of the diesel bug. This caused the engine to slow and stop. A change of filter was a good temporary cure until we could disinfect the whole system with Grotamar 71.

 

[TonyS]

Do you have a water separation filter. It usually has a glass bowl although it can have a metal one if fitted in the engine room. This filter has a screw in the bottom to drain off water. If there isn't one fitted then I suggest you use an oil extractor pump such as a Pela and put the end in the bottom corner of the tank and look what is sucked up. If it is clean fuel you have no water or diesel bug. If it is cloudy/dirty then extract that fuel and discard or filter it.
The generator will have its offtake higher than the engine so it may be in clean fuel but the engine offtake is in the bottom of the tank where water and diesel bug collects. I hope your engineer was changing the engine filter every time he was changing the pump?

 

[tinkicker0]

When I used to work for a living as an HGV Techie instead of sitting behind a desk dreaming up new ways of making a simple job more complicated /forums/images/graemlins/wink.gif, I came up on these symptoms a couple of times on CAV distributor type injection systems many moons ago.

The first was simple: A Bedford truck was brought in that couldn't sustain an idle for more than a few seconds before cutting out.
The fitter had changed the pump with one he had spare with the same result. Transfer pump pressure was regulated in one of two ways.
1. A metered orifice in the pump return line banjo bolt.
2. A sprung ball valve in the same banjo bolt.

It turned out that the spring had broken in the bolt ball valve, allowing transfer pressure to bleed off faster than the pump could supply it when idling.


The next was a Perkins 6354 fitted in a Dodge truck that would run okay for a few minutes then lose a cylinder when idling, then begin running very rough for a couple of seconds before cutting out and refusing to start.

This particular CAV rotary did not have delivery valves fitted in the distribution block banjo's.
Bleed the motor and it would start right up, get warmed up, a worn injector needle would stick open and the pressure of the combustion sequence forced gas back into the injector pipe and eventually into the pump, cutting out the motor.

A new needle set, regulator spring and pressure adjustment cured that one.

Both were one offs and difficult to detect.


I hope you find yours is as inexpensive to put right.