Fuel pump relays

[sad parot o'doom]

Having a problem with these again. Exactly the same symptoms as before, engine not getting any fuel. Its a stupid little fault, with likely an extremely simple solution.

These are 2 new relays, only a few months old. Its either a dicky connection on the connectors, or just bad luck.

Now this has only started happening since a couple of weeks ago, when the loom was brought out to diagnose the ECU (misfire, fixed with new ignition leads).

Anyone got any tips on how to clean the connectors (on the sockets)?

I know its the relays or sockets for sure as fiddling with them for a few seconds cures the fault (until you go over a few bumpy surfaces where the problem returns).

[andy-w]

I know this is blindingly obvious...but its got to be a loose connection somewhere...try bending the terminals out on the relays so it forces them into the sockets a bit tighter???

[Parrot of doom]

Yeah something like that is probably a good idea. I just wanted to find the world's thinnest nail file or something to scratch the thin layer of oxide away from the sockets terminals

[seasider]

Parrot of doom said:

I just wanted to find the world's thinnest nail file

You Chimp guys

[griffter]

Parrot of doom said:

Yeah something like that is probably a good idea. I just wanted to find the world's thinnest nail file or something to scratch the thin layer of oxide away from the sockets terminals

Try fine wet and dry paper folded over for rigidity - but really the connector should be tight enough that the blade on the relay disposes of any dirt/corrosion as it's pushed into place.

[andy-w]

How about a cheap set of needle files???
They should do the job...!!!

[GreenV8S]

There's no point trying to take a file to the inside of the connector, simply fitting the relay will clean the bits that matter. It's worth checking the terminals are tight enough (just put an ordinary male spade connector in each terminal to feel how tight it is) and squash the connector a bit tighter if necessary.

[Parrot of doom]

Another question - would a worn throttle pot cause the revs at idle to dip slightly (for a split second) when the accelerator is pressed (ie moving away from lights), when the engine is hot?

[david beer]

I would make up a small loom to replace the relays during driving, that way you know if it the low cuurent side or the main. You will then know which way to look. If you look at the bottom of the relay, the three in a row should all be joined together, of course un-plug after stopping! I have one made up if you wish, i always keep it under the seat, knowing how unreliable these relays seem to be, in a TVR.

[Paul (93 Chim)]

When the problem is sorted would it be a good idea to smear the teminals with Vaseline to prevent any further corrosion as these cars are not exactly water/damp tight?

Paul.

[Parrot of doom]

Mine is

[GreenV8S]

david beer said:

I would make up a small loom to replace the relays during driving, that way you know if it the low cuurent side or the main.

That's how I sorted out the electrical problems on mine. I've got a relay socket doubler (glorified 'Y' piece) so I can run a relay in one socket and then monitor what the circuit is actually doing on the other. It was a great help to show which problems were caused by the relay, and which weren't.

[Paul (93 Chim)]

Parrot of doom said:

Mine is

So is mine, but with it being a drophead they are more prone to the intake of moisture, so corrosion is more evident.

Paul.

[hugepiece]

I was thinking of replacing the relay holders on mine as I get an issue where I stop for petrol for example and the car won't start. fiddle with the relays and bobs yet uncle car starts. I replaced both relays so it's not them, I assume its a connector in the socket, may be easier just to replace them. Anyone got an ideas where I could get a pair from???

[mongoose]

hugepiece said:

I was thinking of replacing the relay holders on mine as I get an issue where I stop for petrol for example and the car won't start. fiddle with the relays and bobs yet uncle car starts. I replaced both relays so it's not them, I assume its a connector in the socket, may be easier just to replace them. Anyone got an ideas where I could get a pair from???

Vehicle wiring products-about a pound each or something silly

[Parrot of doom]

hugepiece said:

I was thinking of replacing the relay holders on mine as I get an issue where I stop for petrol for example and the car won't start. fiddle with the relays and bobs yet uncle car starts. I replaced both relays so it's not them, I assume its a connector in the socket, may be easier just to replace them. Anyone got an ideas where I could get a pair from???

Sounds more like the classic warm-start problem to me....

[hugepiece]

I don't think so because sometimes the car can be left overnight and ten it does it. sometimes I hear the fuel pump prime, sometimes I don't. I remove the relays or just jiggle the loom and then it is fine

[hugepiece]

also the car turns over no problem so it's def not the starter

[GreenV8S]

Almost certainly no need to replace the socket, just make sure the connectors are all clamping properly. (Because there are several connectors on the relay, you won't feel one loose one unless you test them separately.) You can squish the connectors in situ to tighten them, or remove them from the connector for easier access if you prefer.

[perma-grin]

still a newbie in posting terms, but had a similar issue with my 500 last week - replaced relay's, didnt resolve the issue. Started to think the fuel pump was giving - popped the car on ramps and started poking around by the fuel pump to find that the connectors to the fuel pump terminals were barely clinging on, and that the terminals themselves were filthy.
Cleaned the terminals, put on some contact spray, slipped on the connecters and crimped gently - all sorted...
turns out that the bible refers to this as a potential problem... knew i should have read it cover to cover rather than resting mugs of tea on it