Volvo Penta MD2030-D Faulty Injection Pump?

[sailprincess]

Hi All- We've been having an issue with our Volvo Penta MD2030-D for months now and can't seem to trace down the source of the problem to fix it. We ran the motor at 2K RPM for about 8 hours when suddenly the RPMs dropped and started going up and down, then the engine would die. Bled the lines, problem persisted. The engine seems to run well at a steady idle, if we don't touch the throttle, especially when the engine is cold. As soon as we add power and then reduce power, she drops RPMs and dies. If we run at low idle, she dips her RPMs and runs rough every few minutes then has a sudden surge again and goes back up. Lower the throttle, she dies. There is no white smoke or black smoke and water is coming out the back nicely.

We have:
-checked the pickup tube on the tank, checked the fuel quality (it is very clean), ran the engine with the pickup tube and return line in a bucket of diesel (note that there are some bubbles in the return line). This eliminates the tank itself or the vent being an issue...
-replaced all fuel system hoses and fittings
-replaced stock shut-off valve with a new one
-changed the primary Volvo filter 3 times
-changed the secondary (Racor) filter 3 times, then eventually replaced it with an entirely new unit as we found a small leak)
-replaced the fuel lift pump
-cleaned and serviced all injectors
-replaced one injector that was leaking despite being serviced
-replaced all delivery tubes
-replaced return line (as it got a crack from muddling with it)
-checked mixing elbow for clog, it was not clogged. Cleaned it and re-installed it.
-removed and cleaned heat exchanger (hey why not while it's all apart!?)
-changed coolant (it was very dirty)

If we run the engine with an electric pump in place between the tank and the secondary (Racor) filter, it still has the above described issues, but not as bad. It runs better and does not completely die although it still sounds like it is hunting for fuel as the RPMs surge. We are going to do some more testing but we are suspecting the injector pump to perhaps be the issue. We understand from speaking to several Volvo mechanics that they've never seen one fail and they've never even sold one, but hey- there is a first time for everything, right? Our next step will be to pinch the return line a bit to try to push some fuel pressure backwards and see if she runs better, assuming she is not getting enough fuel consistently. Beating our heads against the wall here and hoping for some other opinions! Cheers in advance.

[Odysseus]

Seems you have done everything that would find the fault,  and I agree the pumps are bullet proof and very expensive, i am ex Lucas CAV , they are engineered to a very high spec.

After all that its sound like fuel starvation,  and you have done what i would have, however I did have a similar  problem with my old Scanmar volvo 2003 when motoring for a long period, and like you tried everything. Only when I stripped out the tank  did I find the issue it was bits of hard brown gunk that  was sucked up when fuel was low and boat rolling a lot. Although filter looked  clean there was bits of this gunk in the primary filter each time.and that was reducing fuel flow until sucked through pipes into the filter.

If you are going to get pump checked don't  let the yards do it these pumps are out of their capability. On the South Coast there is a very good company called P.B. ASHER. 02380 3331 39   service@pbasher.com.  they are experts on diesel pumps. Give them a call and talk it through with them.


Hope this helps

Odysseus
Bav 38

[JEN-et-ROSS]

Just a query..
   You noted that when the fuel feed and fuel return lines were placed in a bucket of fuel and the engine run, there were 'bubbles' in the return line.
There shouldn't be? should there?. Where could the air come from, other than the other side of the injector pump somewhere..that would cause rough/intermittent running..
or am I missing something.........?..........Bill