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.