2.25 Diesel - fuel delivery issue under load

[Cap]

Hi all,

So I have been driving the 2a around loads lately, loving the crap outta it. Since I had rego, I have had issues with the diesel 'power' on hills (and tassie is full of them). Now I know you cant expect much from these little motors, but I think theres something quite not right that I like opinions on.

So far I have:
1) changed the lift pump to a new one - luckily I did as the old one was flogged but still no major difference
2) removed the gauze mesh on the pick up tube in the tank. The base was collapsed and I think it was partially blocking the tube under suction. This made some difference but not resolved the problem
3) pulled the top inlet cap off the pump, inspected it and the gauze filter was impeccable. In fact it was spotless!
4) checked all linkages on the pump to ensure full range of motion, both throttle and stop
5) made sure air filter was not a factor - removed the pipe to the inlet all together so was breathing without the tube/oilbath filter - no difference
6) injectors where serviced before installation
7) new fuel filter when initially installed, although ill change that soon anyway but this issues was from when the filter was new
8) checked that no brakes/handbrake was binding
9) No black smoke at all, even under load - this is where my suspicions start re fueling starvation
10) played with pump timing to get it running crispy
11) asked her nicely to perform a bit better - but not listening

Right - so the current running:
1) starts up first crank, cold or hot. Even with todays freezing weather, 12 seconds or so on the glow plugs and fires up
2) initial throttle for take off is strong, can wheel spin in the dirt in first gear
3) on the flat, can easily reach 60mph with overdrive

Symptoms:
1) when pushing past 1/2 throttle position (going to WOT), this is where I get nothing extra regardless of gear im in and even on the flat
2) whilst driving, I can pull out the stop leaver about half way before any noticeable throttle loss (as its pushing the metering valve back) - this is interesting, could the metering valve not travel fully in open position therefore restricting fueling at that position? Hard to know why it would stick part way tho.
3) going from slight incline to hills, speed drops off dramatically as if there was no more fuel to give - again NO black mist indicating fueling as one might expect under load

Plans:
1) I will work from the tank forward, making sure all fuel lines are clear
2) lift pump is new and working
3) then... pull the pump lid off and check the metering valve movement and travel?

Anything else I can do, or you may think of? I dont expect oodles of power, but given its a 88" running 7:50s and they used these diesels on 109s carrying load, shouldnt there be a bit more to give?

Cheers,

[JDNSW]

Small air leak on the suction side of the pump? Typically a rust pinhole on the pickup pipe with the screen on the bottom.

Another possibility is that you may have the wrong fuel pump. The petrol and diesel pumps are not the same, the diesel one is higher pressure. I can't find the numbers though.

[Cap]

The one I ordered is 563146 and looks identical to the original one. Ill check the fuel lines next as I said, hopefully a simple enough fix!

[JDNSW]

The pumps look identical - the only difference is the strength of the spring, and the diesel is supposed to have a red diaphragm (but aftermarkets may not have this).

And that part number is not the one in my parts book for either the petrol or diesel, but the book may have been superseded and a new, slightly different, part supplied.

Check how easily the hand primer is to move on both the new and old pumps.

[Gippslander]

To do a quick check of fuel system with engine stopped try priming the fuel system with the priming pump if there is no air in the system the hand primer should go into neutral position after one pump. This can be best checked after the car has sat overnight. If the priming pump continues to pump there is a likely hood of air in the system, this can only come from the suction side of the priming pump as a leak on the discharge side would result in a leak. If you have no air in the system then my next check would be a blockage on the primary side, i have in the past found rubber suction hoses de laminate and the internal parts of the hose collapse during operation causing a restriction and thus starving the engine of fuel. Symptoms loss of power no indication of black smoke and failure to reach full revolutions. If the blockage is on the pressure side the symptoms can be the same, however to find the issue you will require to insert a "T" fitting on the discharge side of the fuel priming pump as close as possible to the fuel injection pump. Install a fuel pressure gauge on the output of the "T" fitting and when the engine is under load read the output of the fuel priming pump usually around 5-7 psi.
As to other causes of loss of power in diesel engines there are many but systematic elimination of possible causes will eventually reveal the issue. As you mentioned you checked the inlet for restrictions, so should you check the exhaust, a plugged muffler will prevent the engine from reaching maximum revolutions and thus be down on power, your first indication of a faulty exhaust system is a strained exhaust sound driving along followed by an increase in engine temperature. This may not be obvious driving around locally but will show up on extended driving or heavy loading. The fuel pump metering valve is not a likely suspect as a quick test of revving the engine in neutral from idle to maximum revolutions will check firstly the metering valve operation and the governor weight operation. If the engine does this freely and without over speed the governor and the metering valve are operational. There is a small vane pump in the back of the CAV Fuel injection pump the can wear and as a result the injector pump could be down on boost pressure but this is very unlikely the vanes are as a rule quite long lasting, and you mentioned you checked the filter at the rear of the fuel injection pump that sits in the inlet fitting to the pump. By memory it is 15/16" ring spanner and the filter is a small white plastic affair. This could cause issues if it were blocked.

I hope this can help you regards Gippy

[Cap]

Thanks Gippy, I’ll indeed start with the suction side and move forward. Exhaust is new. The joys...

[Cap]

Got confirmation from Lance (Bundy Bears Shed youtube channe (https://www.youtube.com/channel/UCV7jOffH_nDSiWd8Qsfbrqg)l) that the metering valve function I described within the pump is normal. So if I dont find any issues with the fuel delivery to the pump, then the next thing to do is to increase the fueling within the pump itself.

Lance has some excellent videos on how to rebuild these Lucas CAV pumps if anyone running a 2.25 diesel is interested, so much so that I feel confident doing this myself.

[Gippslander]

I would not alter the fuel output of the pump until i had taken it to a fuel injection workshop and had the out put checked, it will cost a few dollars but they can tell you if it is performing as required and if not it is a simple five minute adjustment by them to make the pump output meet the engine requirements.
Remember black smoke is a result of either overloading or over fueling, the first is an easy fix change gears the second can result in burnt piston crowns, washed bores which can result in piston seizure or fuel dilution of the engine oil and accelerated bearing wear.
I did my apprenticeship in a Lucus CAV fuel injection workshop and Land Rovers were a common vehicle for us to repair.

Regards Gippy

[Cap]

Agree Gippy, even Lance doesnt advertise this mod as it can lead to engine issues. In my case I got zero black smoke, its like I am driving a petrol. Its very very responsive on take off and anything around town its a delight to drive. So if I can get this sorted so that it gives me a little more oomph on hills I would be happy.

Ill do some investigation work this weekend and post any findings, I am determined to get this sorted!

[Blknight.aus]

I've been caught out with a crushed return line before today..

also check to see if theres any bubbles forming up in the return line (depending on which configuration you have) that are coming back to the pump via the filter head.

[Cap]

The plan of attack is:
1) check the fuel lines from tank to lift pump - ensure no blockages.
2) check for air leakages from tank to lift pump (and change the fuel filter anyway)

Failing the above, ill get the pump checked by the same person that serviced my injectors. So really a process of elimination.

BTW - I installed an electrical oil pressure gauge (the older RRC ones) with the correct sender (bought through Howard Industries) and im getting steady oil pressure over 3 bar (its a 4 bar - 60psi) gauge and sender. So really happy with this :)

[Cap]

Update - had a look at the fuel lines before the lift pump, all good. I was hoping for a blockage there :(

I then re-bled the top union on the fuel filter housing. Then I re-bled the pump, nice stream of diesel comes out. So I am now thinking its with the pump or possibly a timing issue?

Would timing affect the upper half of the throttle range, even tho its great from idle?

I will rebuild my secondary pump, got the rebuild gasket kit from Bundy Bears Shed so may as well have that one sorted and swap out as a test.

Lastly if all else fails, then its likely just a tired engine and should get the compression checked and live with it as is until a future refurb.

[Cap]

OK, I have SUCCESS!!!!

Now everything I have done was around fuel flow, or rather where it may not flow! Today I had one last item, the fuel filter and housing. Now I knew the filter wouldnt be the issue, but changed it anyway. Fuel inside looked very very clean.

However, this is where it got interesting. The spill rail on top of the housing that has the fuel hose run to the last injector, when I inspected the banjo bolt, there was no hole in it! It means that the fuel never flowed from this spot, and I am thinking there was an air pocket, or perhaps vacuum that did not allow fuel to flow past a certain point.

I drilled the hole, cleaned up it, buttoned it all back together and bam, got fuel/response that was missing. To say that I am happy is an understatement. Funnily enough tho, my spare fuel filter housing banjo bolt also was only partially drilled, so wondering if this is by design or a manufacturing error.

EIrrespective, I now have the 'black mist' on load and response is much better... I recon I gained half a horse (which is like what, 50% extra power [thumbsupbig]).

173010

[Gippslander]

The bolt going into the fuel fitting should have a hole in it, normally it has a spring and ball which acts as a check valve to prevent fuel from the filter going back to the tank. In a normal situation the banjo has a an inlet from the injector return line and another going to the tank, as stated the returns normally go back to the tank but some can go into the filter if needed. This is as I remember the normal fuel flow if your vehicle does not have a banjo with two fittings( one from the injectors and one returning to the tank) then the following may not apply.
As a result of normal injector operation some fuel bypasses the needle in the nozzle due to operational clearances this fuel exits the nozzle and fills the cavity in the top of the injector before the excess returns to the tank. If this fuel canÂ’t return, pressure will build up in the injector and reduce the output of the injector which will effect the engine output. I believe if your system returns to tank you should check with a Diesel Fuel injection workshop and purchase the correct banjo bolt with the check valve as this will keep the correct fuel pressure in the fuel supply to the pump. This will also allow the injectors to vent correctly keeping everything in balance. As it is the fuel priming pump will be pumping constantly to keep the injector pump supplied and the rest will be returning to the tank hence the need for a check valve. Only the injector return fuel should be going to the tank as this is in excess to the system requirements.
i know this is a bit long winded but I am trying to explain the correct operation of that side of the fuel system.
Regards Gippy 😀

[Cap]

Hi Gippy - many thanks for the details, by all means the more detailed the better!

I had another look at the spare banjo I had, and this one has a tiny pin hole (which my other one didnt) as per picture:

https://www.johnrichardssurplus.co.uk/pub/media/catalog/product/cache/1e43497fb5b4e26d33c21d7294d7fe98/1/3/13h1515lnn.jpg

I did put this one in to test, and basically ended up with the same symptoms as with the other non-holed banjo. All checks I have done involve having this tiny pin hoel arrangement, no banjo with ball.

So I am at a loss here, currently with the banjo I drilled with the hole (much bigger than the picture) it performs well. I completely understand what your saying but again the banjo with pin hole arrangement doesnt work as well... perhaps theres another issue I havent come across as yet.

Aside from the banjo, the fuel lines are a stock arrangement, nothing has been modified and as per pic:

https://www.scparts.co.uk/media/catalog/category//1/4/14107.png

[Gippslander]

Hello again as i see it the suction filter (60) is from memory a 7111- 44 suction filter and the item 45 is the secondary filter (45) is a 7111-296 these are the old CAV filter numbers from approximately 50 years ago. So the item number 30 should be the banjo bolt with the check valve and it returns to tank or that is how it was back in my day someone may have altered the arrangement i do not know i will endeavor to find a diagram of the fuel system and get back to you. i will confirm the banjo bolt did not have a restriction as pictured it was free flowing from the injector return line but had a ball and spring to prevent pressure from the secondary filter returning to tank.
Regards Gippy