Lumpy Land Rover 90

It originally was just a little lumpy when driving in 5th at about 50 – 60mph. As it was about time for a filter change (oil, air, fuel) and new oil I thought I’d start by doing that. This didn’t improve the lumpy running. It’s getting progressively worse with other noises and behaviour beginning to show…

Symptoms

Harder to start – Engine will turn but doesn’t want to fire. After a long crank or shorter multiple cranks it will fire up.

Ticking sound that turns into a twittering sound when engine warmed up – It seems to be accelerator / engine speed related as when I press or ease off the accelerator the twittering changes.

Loss of power – it seems like I have to press harder on the accelerator to make the same progress as before this started.

Lumpy – particularly up hills, pressing the accelerator will make it thump harder and it will accelerate but it’s struggling.

I’ve deluded myself into thinking it’s the lift pump packing in. I read on this fine site that loosening the filter head banjo bolt while the engine is running will show whether the pump is working or not. If it’s not working, will I just see a slow dribble of fuel or nothing out of the filter head?

Can anyone help me get to the bottom of this problem?

Thanks

just some ideas..

1. 'Harder to start – Engine will turn but doesn’t want to fire. After a long crank or shorter multiple cranks it will fire up.' Check your glowplugs, may be ageing, also the in-line electrics are all well insulated and dry, the plastic on these tends to perish and crack after a while....

2. 'Ticking sound that turns into a twittering sound when engine warmed up – It seems to be accelerator / engine speed related as when I press or ease off the accelerator the twittering changes.' Could be many things, from the bearings in the gearbox to something as simple as one of the belts need tightening up, hows your battery doing...if you have a guage does it drop when you use heater, high-beam etc..?

3. Loss of power – it seems like I have to press harder on the accelerator to make the same progress as before this started.

Lumpy – particularly up hills, pressing the accelerator will make it thump harder and it will accelerate but it’s struggling.

For the above two i'd take the easy route 1st...again check plugs, change airfilter and bleed fuel filter, better still replace it, and the engine oil...give it a basic service and see if theres a difference before you go hunting for something else...oops I see you did this already...try the plugs!!

Mark

eye, that's why I did the full filter change & oil change to rule that out.

starting was 'normal' up until a few days ago, battery is fine (got more amps than Jimmi Hendrix). Glo plugs, 20 seconds and away it goes.

The reason I'm suspecting the fuel lift pump is when I did the fuel filter it took an age to prime it manaually. Far longer than the last time I had to do it.

Its difficult to pinpoint the ticking/twittering as its only evident while driving but to me it sounds like a failing pump.

Thanks for the help, I'll extract a glowplug or 2 this weekend and check condition.

First check the self-bleeder banjo on top of the filter head.
Take the bolt clean off, and make sure the pinhole through it is clear.
Does no harm to poke the hole and make it a bit bigger.

Now pump the lift pump by hand to makes ure it skooshes diesel out the top of the filter.

Replace the banjo bolt.

See if that helps. All your symptoms suggest air getting in, and/or air not getting OUT through the self bleeder.

Also, suspect lift pump may be on the way out.

CharlesY

Thanks CharlseY. I''ll be checking it over this weekend. I'll check the pinhole and purge the fuel system fully. I'll do some testing on the lift pump too.

As always, thanks for the advice. Lets see if the 'old bugger' will get me home..

Found it! Took the banjo bolt out and the pin hole was clear of blockages. Gave the lift pump a couple of pumps and quickly realised that the fuel filter wasn't full to the top with fuel as it usually is. The problem was the fuel filter rubber seal, there was what looked like a very old knackered rubber seal still in the filter head. It must have been there for a decade at least. I've done 3 filter changes on the 'old bugger' and never even noticed.

Removed and cleaned the filter head unit, put the new rubber seal and filter back in and reassembled, bled the fuel line and it started as good as it did before.

The lift pump felt ok initially when pumping, good splurges of fuel coming out but it soon starts to feel softer when pumping.

So I'm back to the start again now. Slightly lumpy under load, up hills, at 50 - 60. I'm gonna live with it for a week to see if I can work out whats wrong. It feels almost rythmical at times.

Thanks for the help,

sounds like the injection pump not metering the fuel correctly. Take it to a diesel specialist and not to a Landy (Franchise) delaer.

Sounds like a 1987 landy 90 going up a hill at about 50-60ish...and its red, theres a giveaway!

I am fairly sure that the fuel system is drawing in air while the engine is running, AND that the self-bleeder banjo on the filter head is nor able to separate all the air from the fuel, thus some air is going to the pump causing lumpy running.

The ONLY places that AIR can come IN to the system is from the tank to the lift pump which is always under a slight vacuum while running. If the mesh filter in the pickup pipe in the tank is choked, or if a pipe between the tank and the lift pump is squashed, the vacuum will be much higher and the amount of air drawn in may be a lot greater.

From the lift pump to the injectors the system is pressurised, and any leak will show up as a fuel leak outwards.

I suggest you take the fuel supply (from the tank) off the lift pump and blow down it as hard as you can. Stick another hose on it to save having to get your head that far into the engine bay. You should be able to blow in and you should be able yo hear bubbling in the tank. If not, pickup mesh blocked or fuel pipe squished.

Next, drill a 1mm hole through the filter head banjo nut.

Next, make sure the lift pump really is working properly while the engine is running. It may hand prime fine, but the INNER operating lever that runs on the camshaft may be bent / broken / worn away, and may not be pumping properly.

Then report back .

CharlesY

Great advice CharlesY, as always. I'll do the checks as suggested. It won't be till Saturday so I'll let you know at the weekend.

Storm99...guilty as charged, surely evryone loves an old red land rover? Does anyone know who started the 'red land rovers don't go up hills'? I bet it was Slob or grippa or MHM....

dirty hands said:

Does anyone know who started the 'red land rovers don't go up hills'? I bet it was Slob or grippa or MHM....

Click to expand...

no guilty, m'lud - it was here way before Grippa and I joined - it disappears way into the mists of antiquity.

Hell, if it was old when you were a junior member it must be almost legend now after your mamoth 27,368 posts.

Jesus, it's taken me a while to get round to doing something about this. I've continued driving it every day and listened to whatever the problem was get worse. I drilled a new hole in the hollow filter head bolt. This improved performance and smoothness but the squeek remained. I tried to fit a new lift pump but i couldn't get the new one to seal properly so I put the old one back on again. I think the old one is working well. I started checking over the fuel lines and replaced some 'temporary' joins with whole lengths and clamped everything down well. It's running much better. The squeek turned into a screech and was......you guessed it......UJ's

Anyway, nearly sorted

God bless old Land rovers for keeping on going.

hi dirty
i had simular problem missing hard on fuel and very lumpy between 50 -60 i had it pluged in to computer and couldnt find a problem but was told on this site to check fuel pressure regulator for leaks changed this and it runs like a dream now,hope this helps

So hold on dirty... can everyone on here jus re read that... a UJ squeaking...

Those pesky little critters....I was convinced that the twittering was coming from the engine. Once i heard clunking as well as twittering I thought it was time to give the UJ's a good grease. The front prop gear box end has loads of play. Thanks for the help fellas.