Fuel Injection Pump Problem

[aleggert52]

Hello Compass 790,
Thank you for your reply. I have a Racor with a water separator for fuel filtration. a simple but good system for filtration.
thanks for letting me know the scope of a pump testing machine.

[aleggert52]

Hello Skipperpete,
I have had the pump which has 1,700 hrs. to the lab 4 times and each time they said the pump was tested and ready to install. Each time I installed the pump I could not get it to spurt any fuel. I cannot understand this problem other than possibly the pump was taken apart and not put together correctly? I am told the pump testing machines do have the ability to test both volume of fuel and pressure but as of yet I have had no positive results. I will check into the governor to see if there is an issue there but with no fuel coming out of the injection pump when turning the engine over still leads me to think it is an injection pump issue. This has been an ongoing problem now for over 6 months. I sincerely hope it has remedy.

[SV_Galateia]

Any chance there is something restricting the flow of fuel to the pump.

Feed pump

Filter

Clogged at the tank

etc...

*** I have no experience working with diesel engines ***

[Wotname]

It sounds like the fuel rack isn't opening when the throttle is advanced. Although you have removed the injection pump a few times by now, perhaps checked the regulator spring / governor / fuel rack is operating correctly.

If the fuel rack is remaining in the idle position, the fuel delivered will be minimal. It is very unlikely the injection pump is faulty after four trips to the service centre, it more likely there is a problem with the regulator spring / governor / fuel rack interconnections.

In case you don't have the service manual I have some screenshots to show what I mean.

[MBWhite]

Have you checked the "plunger head gap" ? If something has happened to the "plunger head shims" it could be the injection plungers are not moving enough for you to get your proper volume of fuel, which could explain why the pump tests good at the shop but you aren't getting your correct quantity.

[Wotname]

^^ Reasonable point, the injection timing should be checked any time the injection pump has been removed and refitted after a workshop service. However I can't see the timing (pump shims) could make enough difference to give the reported fault.

[MBWhite]

Totally unrelated but I was called to troubleshoot and fix a M939 6X6 5 ton military truck that had sat a winter with biodiesel fuel that had algaed everything up. The owner had cleaned the tank and filters, etc and was still no start and virtually no fuel, just some weeping at injector lines when engine was cranked except for one that would spit. Engine was a Continental multi-fuel and the injection pump was somewhat interesting as there was only one pump piston and a metering chamber that rotated not unlike an ignition distributor.



The culprit turned out to be a little steel button that fit on the top of the plunger shaft, or was supposed to be a plunger button but this one was completely missing and as a result even though plunger travel was in spec the gap created by the missing plunger reduced fuel delivery to practically nothing. Put a new plunger button on and engine went back to behaving. I still don't know what happened to the old one, my hunch is the biodiesel cemented it to the pump piston and that pulled it off and it was then crushed up into powder.



Anyway, since we are stabbing in the dark here it seems possible that gradual engine wear could possibly affect plunger travel. I'm not familiar with a 2QM15, I do have a 3GM30 in the shop but don't think that will really help at all. Also not mentioned so far would be removing the governor cover and inspecting the governor assembly for wear and play.

[skipperpete]

Hey wotname , thanks for the Governor pics, I missed that it was a 2QM15 and my suggestion re camshaft endfloat was of bugger all use, I was looking at the 2QM 20 Governor.
After looking at your photos I’m wondering if the rack pin missed the yoke... but on the safe side rather than the self destruct side, normally on the “safe side” there is no start at all but perhaps on this pump there is enough delivery to idle.

[skipperpete]

Originally Posted by aleggert52

Hello Skipperpete,
I have had the pump which has 1,700 hrs. to the lab 4 times and each time they said the pump was tested and ready to install. Each time I installed the pump I could not get it to spurt any fuel. I cannot understand this problem other than possibly the pump was taken apart and not put together correctly? I am told the pump testing machines do have the ability to test both volume of fuel and pressure but as of yet I have had no positive results. I will check into the governor to see if there is an issue there but with no fuel coming out of the injection pump when turning the engine over still leads me to think it is an injection pump issue. This has been an ongoing problem now for over 6 months. I sincerely hope it has remedy.

The usual tests and settings for your injector pump would be a “phase and calibrate” and a static leak down test for each element then a fuel delivery volume test for a specific number of shots at a specific camshaft rpm so yes your pump must have shown delivery to pass these tests by the tech.
Is there any chance at all that the pin on the injector pump missed going into the linkage yoke?

[Compass790]

Originally Posted by skipperpete

Is there any chance at all that the pin on the injector pump missed going into the linkage yoke?

That would be my guess without seeing it too.

[My Wind Lass]

Hello aleggert52, I suspect the fuel lift pump. I had the same problem with my 2QM15 on our old 1980 C&C 32. We were sailing down river in the 1000 Islands and the winds were light so we motor sailed and when I tried to increase the throttle above idle, the engine would not increase in speed. We were caught in a bit of a current heading toward a dam with very little wind. Fortunately with all of the sail up and the engine running at idle we managed to get across the current to the yacht club where we planned to spend the night.
After a number of trouble shooting tests, I realized it was the fuel lift pump that was not feeding the injector pump enough fuel. I had to replace the fuel lift pump which completely resolved the issue. Fortunately we were able to get one within a day so we were soon on our way again.

[patagonik]

Hola,en el momento de dar arranque la bomba inyectora envia un poco mas de combustible que a maxima velocidad(sobrecaudal de arranque)a veces hasta el doble.
Revise su bombita alimentadora o en su defecto coloque un bidon con combustible limpio en altura y conecte dos mangueras directamente a la bomba inyectora,una a la alimentacion y otra al retorno y pruebe asi(el bidon debe estar mas alto que la bomba asi baja por gravedad y tenga cuidado con la cañeria original que no inunde todo cuando arranque el motor)Con esta prueba descartara que no haya problemas en la alimentacion.
Lo otro que me ha pasado alguna vez es que alguien haya soldado los cañitos de retorno de los inyectores y estos se hayan obstruido.(cuando un inyector se carga de presion suele hacer ese problema)
Espero haberlo ayudado
Saludos desde la patagonia argentina
Sergio

Hello, at the moment of starting the injection pump sends a little more fuel than at maximum speed (starting overflow) sometimes up to double.
Check your feeder pump or, failing that, place a drum with clean fuel at a height and connect two hoses directly to the injection pump, one to the supply and the other to the return, and test like this (the drum must be higher than the pump so it goes down by gravity and be careful with the original pipe that does not flood everything when the engine starts) With this test you will rule out that there are no problems in the power supply.
The other thing that has ever happened to me is that someone has soldered the return pipes of the injectors and they have become clogged (when an injector is charged with pressure, it usually causes that problem)
I hope I have helped you
Greetings from Argentine Patagonia
Sergio

[jhulmer]

I had this same engine, if it passed the test on the high pressure pumps it is fine.
Look for a more simple solution - broken throttle cable, or slipping throttle lever. disconnect the cable and see if you can advance the throttle directly at the engine.

Smell the engine oil and check the level. Is it high, does it smell like diesel? bad lift pump - diaphragm has ruptured.
Fuel issues as mentioned above.

[donradcliffe]

You are describing a classic fuel starvation/blockage issue. The engine is getting enough fuel to start/idle, but not enough to develop power. If the injectors and pump have been checked out (which you probably didn't need to do), the problem is in the fuel supply.

I used to check out the fuel supply by running the engine off a jerry jug of clean fuel. Now I find it much faster and better to use an outboard squeeze pump with clear tubing.

Step 1. Take off the line from the fuel tank to the Racor filter, and put on the squeeze bulb, and direct the ltubing from the squeeze bulb to a container. You should be able to easily pump fuel out of the tank, with strong flow and no evidence of a suction developing, and no bubbles in the tubing. If you can't get good flow, you have a blockage. If you get bubbles, you have an air leak.

Step 2. Repeat step 1 downstream of the Racor to see if the filter is clogged or is leaking air.

Step 3. Hook up the output line of the squeeze bulb to the lift pump inlet, bleed with the squeeze bulb, and start the engine, and after a bit open the throttle. If it develops more power when you squeeze the bulb, you have a lift pump problem. Be also sure to look for tiny bubbles in the clear line.

If you haven't found the problem yet, repeat step 2 with the squeeze bulb on the output of the secondary filter.

All of these steps together will take less time than removing the injection pump.

[Dalestr]

I too think you need to look at things common to both cylinders. As others stated, try operate the throttle lever by hand to get a feel. I would look at the complex links of the governor system and that is a complex bunch of springs and levers. A broken spring could do it. You probably have to remove the engine front cover to do this (remove front crank pulley). Being stuck at idle is better than stuck at wide open, another failure mode for a governor mechanism.
If there is any way of actually seeing the injection pump rack movement, like through an inspection port, that would be the first thing, but it sounds like the rack is not moving to increase fuel delivery.