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Old 22-02-2014, 17:23   #166
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Re: 50hp Perkins won't rev past 1900rpm

"now undo the HP at injector #1, if that doesn't change the speed, and cause rough running that cylinder is firing proper. Now go through each cylinder one at a time. If any cause the engine to drop speed and run rough then, that is a problem cylinder, start by removing that injector for inspection."

Surely if loosening an injector pipe causes that cylinder not to fire, (rough running) then it was firing with the pipe connected and is therefore OK?

If loosening the injector pipe causes no change then surely that cylinder is the faulty one?

Maybe I misunderstand. It is past my bedtime...
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Old 22-02-2014, 18:31   #167
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Re: 50hp Perkins won't rev past 1900rpm

So. I am here again. So far no start but there was definitely air in the IP. Bled it.
I am going to bleed all of the injectors again.
But if all was well theoretically I shouldn't have to. It should self prime. Is that correct?

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Old 22-02-2014, 18:49   #168
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Re: 50hp Perkins won't rev past 1900rpm

While bleeding each of the injectors No1 (front of motor) has been dribbling not squirting as mentioned earlier, when cracked for bleeding, it has no effect on the engine turning over all the other's do. I think that injector is faulty.
Looks like it's time for the mechanics.
Am I correct in assuming that the motor should start even if one of the injectors is stuffed?

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Old 22-02-2014, 19:57   #169
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Re: 50hp Perkins won't rev past 1900rpm

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Originally Posted by Hoohaa View Post
While bleeding each of the injectors No1 (front of motor) has been dribbling not squirting as mentioned earlier, when cracked for bleeding, it has no effect on the engine turning over all the other's do. I think that injector is faulty.
Looks like it's time for the mechanics.
Am I correct in assuming that the motor should start even if one of the injectors is stuffed?

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Yes, once you get the air out of the fuel system.
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Old 22-02-2014, 19:58   #170
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Re: 50hp Perkins won't rev past 1900rpm

It will run on 3 cylinders.
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Old 22-02-2014, 20:00   #171
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Re: 50hp Perkins won't rev past 1900rpm

It probably won't run on 2 cylinders.
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Old 22-02-2014, 20:45   #172
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Re: 50hp Perkins won't rev past 1900rpm

If it's not even trying to fire - and I mean, not even chugging - you might check the stop solenoid.
In your photo 1390879240762.jpg it's the device with the red wire and that solenoid has to be energised all the time the engine is running. Without that 12 Volts it's like trying to start an older diesel with the stop button pulled out.
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Old 23-02-2014, 06:38   #173
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Re: 50hp Perkins won't rev past 1900rpm

Post #154 gives the sequence for bleeding the 4-108. The idea is to get the air out of the fuel as you move down stream. ie after the fuel filter is purged...slack hydraulic vent screw on injection pump and then tighten...slack vent screw on governor housing of fuel injection pump and then tighten....and finally slack the union nut at the fuel injection pump inlet and then tighten. All of this is done operating the hand priming level. It seems to me that the fuel injection pump inlet comes PRIOR to both the head locking screw and the vent screw on the injection pump?
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Old 23-02-2014, 12:10   #174
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Re: 50hp Perkins won't rev past 1900rpm

Looked more closely at your photos:

Fuel hoses look a little tired & soft at the clips - or maybe just too big for the hose tails. Replacing those hoses and clips would be on my "to do" list even if the engine was running perfectly.

The paint around the lift pump shows that it hasn't been dismantled for service since the engine was last painted. New lift pump is about 25, service kit is about 10. Not saying it's the cause of this problem, just that it'd have been on my list.

A gravity feed tank with fresh diesel from a busy gas station connected using new hose directly to your injector pump connection will roughly "half-split" the diagnosis. Don't forget the lift pump will still run...

With unfamiliar systems and if circumstances allow it's better to change only one thing at a time and then test. If the fault appears cured change it back to confirm that the fault recurs - enough times to be certain of the diagnosis.
Then look for other factors which might possibly have contributed to the failure.
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Old 23-02-2014, 12:47   #175
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Re: 50hp Perkins won't rev past 1900rpm

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Originally Posted by bornyesterday View Post
"now undo the HP at injector #1, if that doesn't change the speed, and cause rough running that cylinder is NOT firing proper. Now go through each cylinder one at a time. If any cause the engine to drop speed and run rough then, that is NOT a problem cylinder, start by removing that injector for inspection." I originally left out Not in 2 places, I thought I typed it, don't know what happened. Also should of said, start by removing the injectors that cause rough running/speed drop.

Surely if loosening an injector pipe causes that cylinder not to fire, (rough running) then it was firing with the pipe connected and is therefore OK?

If loosening the injector pipe causes no change then surely that cylinder is the faulty one?

Maybe I misunderstand. It is past my bedtime...
Nope just a typo, and poor proof reading.

Lloyd

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Old 23-02-2014, 14:49   #176
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Re: 50hp Perkins won't rev past 1900rpm

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Nope just a typo, and poor proof reading.

Lloyd

Hi Lloyd,

I just cut-and-forgot-to-paste a whole paragraph. Been citing the Senior Moment defence a lot lately too...

If it runs OK on the gravity feed try replacing your fuel hoses temporarily with clear braided PVC. Bubbles make it easy to see where air is being sucked in. Hose tails crack, banjo washers seal great until the first time they're undone, hoses too big for the hose tails wrinkle inside when compressed by the clips and leak sooner or later. Olives, o-rings, gaskets, diaphragms... all fail, all need checking.
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Old 23-02-2014, 17:44   #177
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Re: 50hp Perkins won't rev past 1900rpm

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Originally Posted by shane malone View Post
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.
Hello sailors

I have the same problem with my 1968 perkins 4.236 85 bhp engine in my cal 46 sailboat

Thx to the internet I get tips advices and help on how to trouble shoot and fix problems

I seem to remember that I was able to rev my engine passed 1500 rpm before

Recently I'd only go to 1000. The engine starts right away. No black or white smoke. It runs smoothly. No water in the oil. It's not burning oil
It has 1100 hours ( almost new)

I had replaced my secondary fuel filter fearing ( on someone's suggestion) that I had reversed the O ring on the engine-attached fuel filter.... That was okay

But I did see that the O ring on the primary Racor 500 o ring had been TWISTED. After this I bled and ran the engine to 180 F temp and I was able to reach 1500

My stainless steel fuel tanks have been cleaned 5 years ago. The auxiliary
Electric fuel filter is clear and the fuel looks sparking clean coming out of the Racor before it feeds into the engine

Does anyone know why my rpm won't go passed 1500?


Thanks in advance

Edwin
Cal 46 Lahlia
MdR CA
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Old 23-02-2014, 18:25   #178
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Re: 50hp Perkins won't rev past 1900rpm

BORN YESTERDAY, Disconnect exhaust pipe from the manifold (this may make a very small mess) start your engine, careful not to over rev it. I suspect you exhaust hose has collapsed internally due to lack of water flow, thereby burning the inside of the exhaust hose causing it to delaminate and restricting gas flow. Give me feed back if this cures the problem. Ron Fisher, stumpknocker13@aol.com
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Old 23-02-2014, 19:24   #179
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Re: 50hp Perkins won't rev past 1900rpm

Hooha
Back to a few basics, Uncle bob would have ensured you bled the fuel filters, you use the wobble lever on the primary pump to bleed the fuel pump block. You bled the block from banjo which is good enough, the plug slightly better. You have therefore assured that the Fuel pumps are not dry so no damage has been done there. The rest (As Flying Cloud said) should be self priming.
I have to assume priming is not the issue, by now you have done it 10 times over already.

As bornyesterday said about power to the S/D solenoid “is it enengised or have you got a wiring problem”, don’t think so but definitely worth a try.

Left field suggestion is:
Does your engine have a overspeed, or low Lub oil pressure Shutdown. Is there a reset button somewhere.


Check the wabbly pump is it functioning properly? check via the priming plug/banjo on Fuel pump block, pull it apart.


If none of this, it may be the speeder spring in the governor. It would be great if there was a inspection hole (plug) to check the motion of the Fuel pump rack, as in rack and pinion, thats the devise that is fundamental in varying the fuel pump delivery.
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Old 23-02-2014, 19:49   #180
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Re: 50hp Perkins won't rev past 1900rpm

He changed filters and it hasn't run since, as I understand it.
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