50hp Perkins won't rev past 1900rpm

[d design]

Originally Posted by Coops

Buttered fuel pumps are not easy to get hold of.

Coops.

Hahaha lolol

[Andrew Troup]

Originally Posted by Oceanride007

Sailor chick whats a "clogged mixing elbow".

Exhaust/cooling water injection/mixer gooseneck/elbow, notorious for clogging on some engines in particular, (because sudden temp change causes condensation inside, which in turn encourages particulates to build up, notably carbon)

The constriction will cause back pressure and prevent a motor from revving freely.

[FlyingCloud1937]

Irish,

This not your fathers style Perkins. It's 100 series, and bares no resemblance to a 4-108.-107, nor a 4-236.

Second the secondary filter is not a CAV, it is already a spin on fuel filter as noted in the picture.



#3 rd, the primary fuel filter also is not a CAV, its a Racor.



Lastly, the Fuel Injection Pump, is not a the same style as your typical, Perkins CAV DP pump.

It's a cartridge/cassette style pump, so all the peeps advising the OP to bleed it the same as a 4-108 -4-236 or any other style DP pump, is fruitless.

These are the exact same style modern Yanmar, and Kubota use, it origins are Bosch.

Lloyd

Originally Posted by Irish rambler

In reference to this problem I posted on here a while ago about a modification to the engine fuel filter to help make the diesel bleeding easier on the Perkins engines, here are the details for anyone who's interested.
To change the split CAV filter to a 'spin on' type you will need conversion kit part no 302040.
To fit a fuel primer pump on the intake side of the spin on conversion you will need part no 302066.
You will need a longer Banjo bolt part no 302059 with new brass washers part no 302099.
These parts are available from ASAP supplies.com. Approximate cost £56.00 plus shipping.
I hope this helps someone.

[sailorchic34]

Originally Posted by Oceanride007

Sailor chick whats a "clogged mixing elbow".

Oh a mixing elbow or discharge elbow, where the raw water discharges into the exhaust. The cool raw water cools the exhaust gases. This causes the carbon in the exhaust gas to condense and build up over time. The minerals in the raw water also will drop out due to the hot exhaust gases. The carbon builds up over time, increasing back pressure, until the engine can not operate at full speed. Mine was 1/2 blocked after 800 hours, though still ran fine.

One of the symptoms of a clogged discharge "mixing" elbow would be an engine not able to reach rated RPM's.

It's a maintenance item on my boat that I check every 300 hours or so. I'll take it off and run a hose stream of water through the exhaust gas side, should be no backup at full flow. I use a small dog chain snaked through the elbow, with a sawing action to clean the rocks out. I've gotten pretty big chunks out of it.

[Hoohaa]

She's finally running. 2 or 3 of The injectors on the pump needed to be tightened up. Once tightened she fired.
Sounding pretty sweet at the moment.. Will post some .more detsil later today.

Sent from my GT-I9505 using Cruisers Sailing Forum mobile app

[d design]

Originally Posted by Hoohaa

She's finally running. 2 or 3 of The injectors on the pump needed to be tightened up. Once tightened she fired.
Sounding pretty sweet at the moment.. Will post some .more detsil later today.

Sent from my GT-I9505 using Cruisers Sailing Forum mobile app

At the injector housing or the high pressure line?

[Cap Erict3]

Glad to hear it. I hope you get back out sailing soon.

[Uncle Bob]

Originally Posted by Hoohaa

She's finally running. 2 or 3 of The injectors on the pump needed to be tightened up. Once tightened she fired.
Sounding pretty sweet at the moment.. Will post some .more detsil later today.

Sent from my GT-I9505 using Cruisers Sailing Forum mobile app

Im guessing the pump fittings that the injector lines connect to, ?

[Hoohaa]

Here is a pick which will clarify what was wrong.
Does anyone know what the correct name is for it?
The mechanic disconnected all the pipes so he could access the botom bolts and tightened all of them up, there was at least 2 which needed a bit of a turn to tighten.
I did have a crack the one on the right in the beginning, which may have
upset it.
The injector that I said previously was no good (dribled) was just not getting enough pressure from the pump to make it work.

[Andrew Troup]

Originally Posted by Hoohaa

Here is a pick which will clarify what was wrong.
Does anyone know what the correct name is for it?...

I've always called it the 'delivery valve housing' but I've heard others call it the "injection pump outlet union"

I'm not sure if there's a single agreed term, more likely as many terms as forum members!

But thanks for trying to pin it down.
The main problem with the term you used was that the word "injector" (unless qualified by the word "pump") suggests something at the OTHER end of the High Pressure fuel line, which is where the injector lives.

I'm surprised no fuel emerged from that loose connection to the 'delivery valve housing'. Thinking back, do you think it might have been doing so, undetected?

BTW this has been a very instructive thread. Thanks to you and all the very knowledgeable people who chimed in. Wisdom of crowds doesn't always work well on a forum (and in this case, we didn't come up with the right answer) but there were a huge number of plausible possibilities generated, some of which I'm sure would have eluded ANY individual troubleshooter.

ON EDIT: I'm assuming it was the BOTTOM hexagon you (or some unidentified other) had loosened? Or was it the top one?
BTW: for anyone who didn't know, it does NOT PAY to overtighten the delivery valve housing. It can distort the barrels within the pump, which operate with VERY close clearances.

[Andrew Troup]

The 'delivery valve' is a very cunning little poppet valve which, in addition to slamming shut at the end of the pressure slug from the pump, so the injector shuts of cleanly and does not dribble, also acts a bit like a surge tank (in a hydro-electric generation installation, or a water pumping station - which stops the pipework bursting when a valve is shut off against the momentum of water flow).

There is a pressure pulse reflected back from the injector when it in turn slams shut as the pressure supplied from the injection pump (which is momentarily VERY high) decays due to the delivery valve closing.

That pulse hits the little spindle inside that housing, which acts a bit like a "Whack-a Mole" and dives momentarily even further back into the body, preventing the shockwave from being reflected back towards the injector, or at least softening any rebound.

Injectors do not have any inbuilt timing: they just open when a slug of fuel arrives with sufficient urge, so a second opening could otherwise ensue, which would not be a good thing, especially given there will now be an explosion in full party mode inside the combustion chamber.

Apologies if I have deviated from the gospel truth here: this is just my understanding. I am not a diesel expert by any means.

[FlyingCloud1937]

Originally Posted by Andrew Troup

The 'delivery valve' is a very cunning little poppet valve which, in addition to slamming shut at the end of the pressure slug from the pump, so the injector shuts of cleanly and does not dribble, also acts a bit like a surge tank (in a hydro-electric generation installation, or a water pumping station - which stops the pipework bursting when a valve is shut off against the momentum of water flow).

There is a pressure pulse reflected back from the injector when it in turn slams shut as the pressure supplied from the injection pump (which is momentarily VERY high) decays due to the delivery valve closing.

That pulse hits the little spindle inside that housing, which acts a bit like a "Whack-a Mole" and dives momentarily even further back into the body, preventing the shockwave from being reflected back towards the injector, or at least softening any rebound.

Injectors do not have any inbuilt timing: they just open when a slug of fuel arrives with sufficient urge, so a second opening could otherwise ensue, which would not be a good thing, especially given there will now be an explosion in full party mode inside the combustion chamber.

Apologies if I have deviated from the gospel truth here: this is just my understanding. I am not a diesel expert by any means.

The return lines take all the back pressure from the Injectors.
These are the little tubes that connect each injector. NOTICE THE HP LINES LEADING FROM THE INJECTOR PUMP, the small tubes that are just below the injector HP lines. These are the return fuel lines.


The last #4 injector is connected to a rubber line that returns to the tank.

The 400 series of this same engine, the return has been reworked. In the 400 series the return from the injector, which now ends on the #1 injector is taken to a Banjo bolt that sets atop the fule intake from the lift pump, and finally the return line to the tank from the same banjo.

This affords the the fuel system to be self bleeding when a filter change is made. All you need do is bleed the filter head, and the IP, and injectors will self bleed.

The caveat is if you run out of fuel and you run the IP dry, then you will need to bleed the IP.

So in the end it turns out AIR IN THE SYSTEM. Air can be in the suction side, that won't allow the IP to build the required hydraulic pressure. Or it can be in the HP line to the injector, that won't allow the hydraulic pressure created by the pump to act on the injectors.

When you think of anything hydraulic, think of it as a Steel Rod, force at one end create equal force at the other end of the steel rod.

Now because of air in the system, air compresses, the Steel Rod isn't Steel anymore. It's sponge, which acts to consume all the force that was applied to the beginning. So no force left at the end.

My guess is someone, undid the HP pipes at the injector pump with a single wrench in an attempt to bleed the system. Always use a wrench on each fitting, when they are stacked...especially hydraulic systems.

Lloyd

Lloyd

[FlyingCloud1937]

Yep,

As I just posted, someone put a single wrench on the IP line 1 & 4 as is well demonstrated by the picture. You can see that paint is broken off both 1&4 unions, as well as the tubing, but not 2 or three, and that is because it takes a special tool to access these unions.


You can also see the fuel residue on #1, that will be likely you high rev issue.

Lloyd

Originally Posted by Hoohaa

Here is a pick which will clarify what was wrong.
Does anyone know what the correct name is for it?
The mechanic disconnected all the pipes so he could access the botom bolts and tightened all of them up, there was at least 2 which needed a bit of a turn to tighten.
I did have a crack the one on the right in the beginning, which may have
upset it.
Attachment 76868The injector that I said previously was no good (dribled) was just not getting enough pressure from the pump to make it work.

[d design]

Geez youd need one fancy tool to get to them unions!

[Uncle Bob]

Originally Posted by Hoohaa

Here is a pick which will clarify what was wrong.
Does anyone know what the correct name is for it?
The mechanic disconnected all the pipes so he could access the botom bolts and tightened all of them up, there was at least 2 which needed a bit of a turn to tighten.
I did have a crack the one on the right in the beginning, which may have
upset it.
Attachment 76868The injector that I said previously was no good (dribled) was just not getting enough pressure from the pump to make it work.

Did this curre the lack of revs ?