Td5 disco hard to start

So it got worse after changing fuel filter on it last year, it’s got bad enough now I have to pump the throttle in the mornings after 10 secs or more of cranking to get it to go, once it goes it drives perfect.

so far, new plugs, new VDO pump, new air bleed valve, new filter, new non return valve, new FPR (repair kit) new genuine injector washers/seals. (No fuel in oil)

before I changed the filter last year it was always on the button

other than new injectors I don’t know what else to try?

upon doing some further diagnostic, i think i may have a starter/crank sensor issue? I am only getting 200rpm cranking speed, i can get it started by giving it throttle, or if i just hold it for a long time, 10sec+. But when it does catch without throttle i can see the rpm going to 300, and from what ive read it needs to see 300 to fire the injectors? can anyone confirm this? the starter sounds pretty healthy as in its turning over fast by sound, and the sound doesnt really change when it shows it hitting 300rpm. So im thinking when cold the starters causing some sort of EM interference with the crank sensor (so ive read this can happen) Ive left it on a step hill round the corner to try and see if it will easily go on a bump start, in which case i will be heading to go get a new starter i think.

seen a denso starter recomended, but theyre not in stock until monday, and the lucas ones are in stock now, but theyre only £80 compared to the £160 denso, is lucas a brand to stay away from or any good?

Fixed this with a new starter

So it didn’t fix it, it is audibly turning over faster, but crank sensor still reads 200rpm, or just below, changed the sensor and it’s the same.. what else can I check?

What is your at rest and cranking battery voltage?

Si Click said:

What is your at rest and cranking battery voltage?

Click to expand...

So today it was slow to crank, then had to jump it to get it going at work

Running only 12v so ordered a new alternator, hopefully the battery isn’t toast.. left it charging and will leave over night, after charging for about 3 hours it’s at 12.2v rest and drops to 9v when I start cranking and steadys around 11.6v whilst cranking.

Will check again in the morning with the battery on a full charge from the mains

I’m guessing I want it to stay above 12v at all times? If not replace?

The TD5 needs a strong battery to start as the ECU powers the injectors. 9v is quite a big initial drop and certainly way too low for start, but 11.6v should be OK. However, if it only achieves that after being charged then it is clearly not in the best of health.

God knows how long the alternator has been on its way out for, as said its only providing 12v whilst running. So unsure if battery is bad or its just not been charged up properly in some time, ive had it on charge since around 5pm now (10pm now), chucked my booster pack on for good measure and went for a start, voltage dropped to 11.6 and was around 12 while cranking for a few seconds (still not on the key like it used to be)... ill measure voltage again when its fully charged in the morning on a cold start.

New alternator should be ready to collect tomorrow so ill chuck that on, really starting to annoy me now...

Freelander1banger said:

So today it was slow to crank, then had to jump it to get it going at work

Running only 12v so ordered a new alternator, hopefully the battery isn’t toast.. left it charging and will leave over night, after charging for about 3 hours it’s at 12.2v rest and drops to 9v when I start cranking and steadys around 11.6v whilst cranking.

Will check again in the morning with the battery on a full charge from the mains

I’m guessing I want it to stay above 12v at all times? If not replace?

Click to expand...

A healthy, fully charged 12v battery should produce a fraction over 13v at rest, and not connected to anything.

You need a new battery.

Freelander1banger said:

God knows how long the alternator has been on its way out for, as said its only providing 12v whilst running. So unsure if battery is bad or its just not been charged up properly in some time, ive had it on charge since around 5pm now (10pm now), chucked my booster pack on for good measure and went for a start, voltage dropped to 11.6 and was around 12 while cranking for a few seconds (still not on the key like it used to be)... ill measure voltage again when its fully charged in the morning on a cold start.

New alternator should be ready to collect tomorrow so ill chuck that on, really starting to annoy me now...

Click to expand...

Alternator probably just can't push much charge through the dead battery.

Turboman said:

Alternator probably just can't push much charge through the dead battery.

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in my experience even with a bad battery youll still get 14volts at the terminals as on other cars ive had, the battery is only 2 years old, so I will try the alternator first, most of my friends with discos have had dead alternators so seems common, then if no joy I will replace the battery. I also checked the crank sensor harness which has a split in the EM shielding, only 1/2mm exposed but unsure if that would make a difference.

Also would a low battery give a low reading on the crank sensor? i keep reading the td5 needs 300rpm to start, even with the new starter its still now showing above 200rpm, even though it is audibly quicker spinning over

Freelander1banger said:

Also would a low battery give a low reading on the crank sensor? i keep reading the td5 needs 300rpm to start, even with the new starter its still now showing above 200rpm, even though it is audibly quicker spinning over

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What any engine needs to start will be dependent on temperature, how good the spray form of the injectors is, how good the compression is, various things.
But the faster the cranking speed, the more likely it is to start even if those things are not quite right.

What I do know is that if the battery is only producing 12v at rest, it is goosed.

Also, the only time my missus Td5 Defender didn't start, it was a dead battery that caused it.

Turboman said:

What any engine needs to start will be dependent on temperature, how good the spray form of the injectors is, how good the compression is, various things.
But the faster the cranking speed, the more likely it is to start even if those things are not quite right.

What I do know is that if the battery is only producing 12v at rest, it is goosed.

Also, the only time my missus Td5 Defender didn't start, it was a dead battery that caused it.

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you are correct my battery is shagged, on charge all night 13.1 volts full charge, soon as I switch ignition on 12.2v, cranking cold drops straight to 9.6/9.9v. So new battery ordered also..

The ECU needs more than 10.5V to work and above 250rpm input while cranking, below any of those it will hardly start.

Thankyou, I’m hoping that is all it is. New alternator on and perfect 14.4Volts at idle now, collect the new battery tomorrow so fingers crossed

So new battery and while it’s 100% definitely a lot easier to start, it’s still not on the button like it used to be

Maybe it's time to get the injectors checked by specialists cos it's possible that they are mucked up

sierrafery said:

Maybe it's time to get the injectors checked by specialists cos it's possible that they are mucked up

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I was thinking the same, it is a lot better now it will start from cold in about 2 seconds, after its started its on the button. Where as before i would drive it about 200yrds to the shop to stop for a coffee in the morning and it would be a pig to get going again, also I've got a puff of white smoke coming out on a first start, so I think maybe I have a leaky injector. My insurance renews end of month and ill have my other car covered form then so I'll probably pull the injectors and send them off once I have alternative transport ready. Rest of the time it still and always has drove perfect once started...