50hp Perkins won't rev past 1900rpm

[Hoohaa]

When I bought my boat, over 2 years ago now. The engine had a reving problem. It would not rev over 1900rpm, we flattened the batteries one day and had to leave the motor running for a couple of hours to get everything fully recharged. At the same time we got a mechanic to call in and have a look at the reving problem. He came on board after the motor had been running for a couple of hours and when he revved it up, presto. She rev
ed over 2200 rpm. The problem had fixed itself..
Well, it’s doing it again.
The engine will only rev to 1900rpm while in neutral (cable connected and disconnected) and only t 1100rpm when under load.
The only difference this time is that there may have been a trigger for it. The last time I filled up, I forgot to put the fuel back on when I motored away and promptly sucked air into the fuel system. It took quite an effort to bleed the system as the air was right back to the valve on the fuel tank. She eventually splattered back to life and runs smoothly ever since, but at reduced revs?
Does anyone have any ideas what could be going on??
You can rule out accelerator cables and linkages.

Its a 50hp Perkins
104-19
Engine number KR30332U or ZU.
Code 907649C
Here are some pics.



Thanks Jeff

[Ocean Cowbuoy]

try removing the air filter and see how she revs...best to do it under load rather than neutral. Possibility your air filter needs to be upgraded to higher volume.

[Hoohaa]

Thanks. I have a brand new filter fitted and am almost certain that I have done tests without the filter in place the first time this occurred.
But will try it tomorrow.

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[builder dan]

sounds like it is starving for fuel have you checked the fuel filter?

[Hoohaa]

It did start again after the system was bled. Could this have damaged the fuel filter.


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[Freedom45]

There are three things for a diesel engine that could cause that.....fuel, fuel or fuel.
Check intake lines from tank on up. You have some crud in there somewhere.

[Hoohaa]

Originally Posted by builder dan

sounds like it is starving for fuel have you checked the fuel filter?

Originally Posted by Freedom45

There are three things for a diesel engine that could cause that.....fuel, fuel or fuel.
Check intake lines from tank on up. You have some crud in there somewhere.

Hmmm, soo you think it could be the fuel??
I will attack it tomorrow and let you know how it goes. Just need to figure out what the fuel filter looks like and how it all works.
Thanks, fingures crossed it solves it..
Jeff.
Do you just buy a fuel filter off the shelf?

[Hoohaa]

In my first photo. Can someone tell me what the second/smaller oil filter looking device is? Is this the fuel filter?

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[Oceanride007]

I'm almost certain its the morse control. (Red control rod thingy) could be sticking, over stretched, rusty, loose. Check both ends. May even pay to disconnect it completely take it out run some WD40 thru it, until for sure it moves freely. FYI this is speeder control ie indirecly does it effect fuel, rather it pushes on top of a spring that is balanced by centrifugal weights of the governer (or the electronic or hydraulic equivalent). Best not to run engine at high revs without load.

[Dynamo1181]

Originally Posted by Hoohaa

In my first photo. Can someone tell me what the second/smaller oil filter looking device is? Is this the fuel filter?

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Lower canister is oil filter. The upper left is fuel filter.

[JusDreaming]

check to see if there is a screen on the pick up tube in the tank. If possible try feeding fuel from a jug rather than tank.

[shane malone]

The easiest way to bleed air out of your fuel system. Step #1 find the line going to the injectors #2 start engine get too a hard idle 1200 rpm ( is my recommendation ) #3 just loosen the connection at the fuel rail and injector ( with a rag placed under ) the retighten when you see only fuel coming out the air will bleed off first.
PS it may take more than once but it will bleed out any air out of your lines.

[boatpoker]

As you have owned the boat for two years and were just told where the fuel filter is today, I have to assume you you have never changed the filter.
I wonder how many years it has been since fuel filters were changed.
You likely have three filters ... A. primary (somewhere between the fuel tank and the engine) B. secondary (the one already pointed out to you) and C. mesh screen in your fuel lift pump.

If you don't have a primary (filter/separator) one should be added to the wish list.

Always try the cheapest easiest thing first.

After changing the fuel filters (primary and secondary if you have both) if the problem is not solved, open up your lift pump and make sure the mesh screen is not all crudded up. Suggest you hire a mechanic and watch over his shoulder while he does these simple tasks. In some primary filters it is very easy to put a filter gasket in improperly and defeat the whole exercise.

Sure sounds like a fuel supply issue

[glenn.225]

1+ on filters. Also pumps, do you have one or two? I have seen applications where an electric will feed a machanical and one pump will fail, some fuel will get through but not enough to go to max RPM. In cases it will go to max at no load but not under load.

[perchance]

The date on the secondary fuel filter says 2010. Time to change it out.