Perkins Perama M30 Volvo MD2030 Low Revs in Gear

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lyleknab

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Hi,

I have a Perkins Perama M30 (which is also identical to a Volvo MD2030) having problem of low revs while in gear runs perfectly in neutral with plenty of revs.
Problem first appeared after changing fuel filters but this may be co-incidence.

I suspect being caused by lack of fuel getting to the injectors but have tried various things with no success and I have now run out of ideas, hoping someone
can offer some more advice/suggestions.

What I have tried so far:
Shaft spins freely with hand when in neutral
Checked exhaust elbow for blockage - completely clear
Swapped lift pump (because I happened to have a spare) although the lift pump was new a year ago and seemed OK.
Bled the system several times.
Removed the fuel filters to check for twisted gaskets or any corrosion where gaskets sit.
Installed another set of filters (just to be sure)
Put a clear plastic pipe on the fuel return line to check if there was air bubbles in the return and guess what absolutely no fuel going through the return either running full speed in neutral or as fast as it can go in gear..
So, that makes me think the problem is lack of fuel.
Disconnected the output pipe from the primary filter and put it in a bottle of clean diesel to try and rule out any problems with fuel tank, pipe from fuel tank and primary filter. No change in the symptoms with fuel being fed from bottle of diesel.
Replaced all copper crush washers on banjo fittings.
One thing I notice when I operate the lift pump manually I cannot get fuel to squirt out at the various bleed points (although it squirts when engine is turned over)
Could I have 2 x faulty lift pumps - seems unlikely. With lift pump removed and operate it by pushing on the buttom pluger get plenty of suction when put finger over the IN.
If I crack open each injector in turn engine slow down so assume each injector if operating OK (injectors were refurbished by Perkins dealer last year)

Think I am out of ideas now - help please
 
Hi Lyleknab,
I have a very similar problem with my engine and would be very grateful if you could share with me your final conclusions and (hopefully) cure. Panamajack.
 
I have a similar problem with a Perkins M20 with it going in to low revs mode when put in gear with increased vibration.I just increased the tickover a fraction to allow for it,did wonder if it was the governer sticking.
 
I have these symptoms too. Has anyone actually sorted it? 4000rpm in neutral. max 2000rpm in gear (tied to the dock or at sea). Seems to have been gradually getting worse over the last few runs. Changed the pre and main diesel filters and made no difference (there was evidence of bug on the pre-filter). Engine not smoking or making noises. Throttle moves to the same place when in gear as when in neutral. Don't know what to do next.
 
seajayare said:
I have these symptoms too. Has anyone actually sorted it? 4000rpm in neutral. max 2000rpm in gear (tied to the dock or at sea). Seems to have been gradually getting worse over the last few runs. Changed the pre and main diesel filters and made no difference (there was evidence of bug on the pre-filter). Engine not smoking or making noises. Throttle moves to the same place when in gear as when in neutral. Don't know what to do next.
Click to expand...

First thing is that it should not rev to 4000 rpm. It should be limited to 3600 if it is an M30 or a 2030.

If it only revs to 2000 rpm with a clean bottom and propeller then it is likely that the propeller is wrong. If it is getting progressively worse then the most likely cause is a fouled propeller.
 
I have a similar issue with my Volvo, although much less marked (2600 max revs in gear under way with clean bottom, been the same since new).
It has occurred to me that under way at speed, the exhaust outlet, which is under the counter, is under water at speed.

QUESTION: Would the exhaust outlet being under water cause back pressure and limit the revs???
(apologies if I should start a new thread for this - but I thought it may be relevant to the OP)
 
Exhaust under water is common and usually makes no difference. You do not say what engine you have, but on any of the engines from 200X, 20X0 or D1 that is far too low. Depending on model you should be able to achieve anywhere between 3000-3600 rpm and cruise comfortably in the range 2000-2500.

If it has been like that from new then it is most likely fitted with the wrong prop.

More detailed advice if you can provide exact model of engine/drive and boat plus size of prop if known.
 
Thanks Tranoma,
Details: new D1-30. (Note: had exactly same issue with previous 2030). 38ft cruiser racer, 6.5 tons (very similar to a sigma 38). Prop is 2 blade folder 17x11.
I realise I am slightly over propped, but this is intentional for relaxed cruising in flat water and I like that the engine is loaded even when doodling along at 6 kts at 2000rpm [happy to be corrected on this]. I don’t believe the slight overpropping accounts for revs reduced to 2600 (?). Actually I should have said, it’s closer to 2700.
No difference with engine cover off, so it’s not air supply. New filters. Boat and prop clean. Tachometer checked.
An earlier thread alerted me to the possibility of partially blocked exhaust hose, which might be 30y old (was not replaced with new D1-30).
PS: other than the numbers, I have no problems with the engine - ample power, no smoke..
 
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I mentioned in a previous post that I have the same problem with a Perkins perama m20,it didnt seem to have this problem when I first bought the boat,I did read somewhere that the fly wheel was to light and assumed the problem had been rectified with later Volvo models.
 
Venus1 said:
Thanks Tranoma,
Details: new D1-30. (Note: had exactly same issue with previous 2030). 38ft cruiser racer, 6.5 tons (very similar to a sigma 38). Prop is 2 blade folder 17x11.
I realise I am slightly over propped, but this is intentional for relaxed cruising in flat water and I like that the engine is loaded even when doodling along at 6 kts at 2000rpm [happy to be corrected on this]. I don’t believe the slight overpropping accounts for revs reduced to 2600 (?). Actually I should have said, it’s closer to 2700.
No difference with engine cover off, so it’s not air supply. New filters. Boat and prop clean. Tachometer checked.
An earlier thread alerted me to the possibility of partially blocked exhaust hose, which might be 30y old (was not replaced with new D1-30).
PS: other than the numbers, I have no problems with the engine - ample power, no smoke..
Click to expand...

2700 is still too low and would not have passed Volvo commissioning which requires a minimum of 3000 at WOT with that engine. Restricting it to 2700 means you are unable to use the last 8hp or so that the engine is capable of producing and you could just as easily used a D1 20!

Your prop is too big. An inch off pitch or diameter would bring the revs up to the minimum level. There is no advantage in overpropping as you have done. Cruising revs are 2200 which will still achieve around 6 knots with the correct prop.

I have the same setup in a slightly lighter boat (but similar waterline length) and a 16*11 2 blade FlexoFold. This achieves 3100 and 7.5knots.

Doubt it is the exhaust restricting revs, but worth checking.
 
I had the boat out of the water to clean the bottom and prop (and grease prop its a featherstream feathering 3 blade, MD2030D, saildrive, 36ft AWB (Dufour 36 Classic)) and there wasn't that much to clean off and it hasn't made any difference.
Looking more closely it looks like 2400rpm in forward and 2300rpm in reverse so maybe there is some info in that.
I've contacted darlow to see if its possible that the pitch can have changed by itself waiting on that answer.
Is there a way to measure the fuel flow to see if there enough?
 
Thanks Tranoma, I think I needed to hear that.
I have not acted up to now, as I had no “problems” — 7.8 kts at 2700rpm with no smoke, and relaxed cruising at 6 kts at 2000...
But I guess if I had to motor into a gale I would struggle.
I will look at reducing prop pitch
 
Hi, I’ve got a 2010 but since I changed to a larger spin on filter, I get a similar problem after changing the filter. I find that I need to bleed it twice before I get full power. I have a bulb on top of the filter housing which helps. My pump on the engine does bleed fuel when the lever is used and when the engine is running fuel comes back from the return. I am surprised this is not happening on your engine as I think the pump should provide more fuel to the injectors than actually gets used.
On this basis either you have some air trapped somewhere or your pump(s) are not working at 100%.
 
image.jpegDarlow got back and have been very useful. I don't think its the prop ( at least not enough to have the boat lifted again at this point). I rembered I took a photo of the prop in June when I lifted her last to investiagte and whilst not spotless it looks ok to me. So I am going to look at the exhaust elbow now (only a couple of hundred hours max since the elbow was last replaced) but it'll be a while before I can do that. If that looks ok it'll be out of the water again
 
seajayare said:
View attachment 73122Darlow got back and have been very useful. I don't think its the prop ( at least not enough to have the boat lifted again at this point). I rembered I took a photo of the prop in June when I lifted her last to investiagte and whilst not spotless it looks ok to me. So I am going to look at the exhaust elbow now (only a couple of hundred hours max since the elbow was last replaced) but it'll be a while before I can do that. If that looks ok it'll be out of the water again
Click to expand...
Good luck, and please let us know the eventual outcome
 
Hi, I still think you have a fuel problem. If you look at the diagram on marineparts.com the fuel pump has a diaphragm. You could check that this is in good condition and not holed or baggy.
 
I have checked the return to the tank and I have fuel returning at all revs ( in gear and out) it's not constant but in gear at max revs there is a very steady flow. I have been assuming that having something making it back to the tank indicates that the fuel system is working OK ( no problems with air, blockages pumps) . Do you think it's possible that the fuel could still be returning to the tank with a dodgy pump or air locks?
 
My son has a Perkins M20 which we fitted about 5 years ago, it came out of a canal barge. On fitting it had a similar problem to that of original poster. I took the cover off the governor mechanism and was amazed how gunked up it was. I think it is on the front of the engine. The gunge stopped the mechanism moving properly. Since then it has been a brilliant reliable engine.
 
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