Thread: Defender Td5 burnt out fuel pump relay

Originally Posted by jbe

Over the last couple of days, my Td5 Defender gradually lost power and the engine began to run very rough. So, my problem had the hallmarks of oil in the engine loom or some sort of fuel starvation.
Long story short, after changing the oil filter, cleaning the air bleed valve, cleaning the gauze filter behind the FPR and changing the injector loom, the engine started and ran fine for 30 seconds and died all-together.
This made me think that the fuel pump might have an issue. I checked the fuse and it was good, but when I had a close look at the fuel pump relay, I noticed that it was charred, in fact it was dead. I replaced the relay and the engine runs fine now.


This problem seems to be not uncommon as the same happened to a friend of mine in the middle of a trip through Kings Canyon. I think it is worth wile checking this relay on a regular basis.


I still think that the fuel pump relay is getting exceptionally hot (i.e. can’t touch it) though. I tried to google the issue, but it doesn’t look like anyone has come up with an upgrade for this.


So, my question for the brains trust is: has this happened to you and what have you done to fix it.


I’m also wondering if the fact that I have this part of my electrics in the Mulgo box contributed to my problem or made it worse. There is not a lot of air in the box and it gets a lot of heat from the gearbox below. Mind you, I put heat insulation at the bottom of the box to address this.


Cheers
Joachim

Can you not hook up a small 12v computer fan as a extraction fan in the mulgo box to extract some heat

The Mulgo box isn’t part of the problem.
The same relay lives in the much hotter engine compartment on the D2.

I’d be checking the loom for high resistance.

Originally Posted by rangieman

Can you not hook up a small 12v computer fan as a extraction fan in the mulgo box to extract some heat

Was thinking about that. I was actually more worried about the ECU getting too much heat.

Originally Posted by strangy

The Mulgo box isn’t part of the problem.
The same relay lives in the much hotter engine compartment on the D2.

I’d be checking the loom for high resistance.

The fuel pump draws 11A consistently. I put in a new socket for the relay with new contact plugs. Might have been some sort of corrosion on there. I'll keep on watching it.

11 amps isn't that much. Dirty contacts would account for much of the heat.

Dirty contacts or the pump is failing and drawing much higher current.

Originally Posted by Tombie

Dirty contacts or the pump is failing and drawing much higher current.

Any idea what the current draw of the pump should be?
11A doesn’t seem to be exceptionally high.
The new relay still gets quite warm, but so does the one next to it. Considering, it has to run all the time, it might be expected.