Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Fuel Pump Not Working!

Brendan, at least you seem to be getting somewhere. On the assumption you have found the relay, have you identified if it is being fed with 12 volts...?

There will perhaps be two feeds at the relay, one for the coil which I suspect energises the coil only when all the safety/security switches are closed, thus without the engine running or the ign key held in the start position, I might expect that relay coil feed to be dead..?

However the feed for the pump which is switched on to the white/pink when the relay coil in energised... should perhaps be live and sitting waiting to be switched through to the pump, if/when all the other safety/security switching has taken place for the coil to energise/click.

If any of the above is correct then whatever coloured wire is waiting at the relay to give the white/pink a supply may be available to be connected to the white /pink at the relay to then feed through to the fuel pump...?

If there is no supply at the relay perhaps best to check the fuses..?

Should you find a blown fuse, it is possible there may be a problem with the pump or on the white/pink from the relay to the pump that may have taken out a fuse,

perhaps best to pull the pink and white at the tank and keep it away from earth and check to see if the relay clicks with the IGN key held in the START position..?

if the relay clicks, check for voltage on the white pink at the relay, and if you have it at the relay then try to see if you get 12 volts at the white/pink at the tank....

If you get 12 volts,on the white/pink at the tank having replaced a blown fuse, then chances are you have a pump issue...?

Looking at things from a different angle... The pump is quite a high current draw and loose or dirty earth connection can fail under load.. i.e, the white /pink can give a 12 volt reading with a volt meter across a live and the earth, but when the load of the pump is connected, the earth can partly fail causing the voltage to drop to the extent that while the full 12 volts might be available on the white/pink at the pump... the pump it`s self requires a good earth to make use of the voltage provided by the white/pink.

All just using logic, flawed or otherwise, in the hope it might be of some help...?

Good luck Brendan.

Havent had time to read the whole thread. But recently had a pump replaced on 2002 4/4 due to pressure drop BUT it also failed after that as the earth was faulty (I had suspected it but they thought OK). There was no earth to rear of car like others and went back in loom. We (Allon White) have now made a new earth direct to rear chassis and touch wood seems OK..

Keith,
I think on Ford pumps they often have a separate earth rather than going to that common earth on the rear of the chassis.

Interesting thing was there was no earth for the lights either they all 'disappeared' to the front via a loom. Allon White were surprised.

That is odd as they earth on the inner valance on the driver's side. It might be worth cleaning up the engine to chassis earth & the earth at the battery. Do I remember rightly that you had an earth issue a few years ago on the New Forest trip?

Electrically the ground connection should still work as it passes through the rear loom connector albeit it on a single cable! Poor practice though as apart from extra length in circuit you have combined rear light current through one cable plus contact resistance and potential unreliability in the plug/socket to rear loom. Later models still have ground fed through the rear loom connector but also two ground eyelets each with multiple cables to supplement ground locally and individually.

Where is Brendan in this drift on discussion of "separate earths," ground, return and chassis etc.etc...? (-:

I have a basic understanding of matters electrical, but for most folk I suspect anything electrical can be looked upon as being part of a black art, which at best would seem to be simply off-putting..?

Perhaps when trying to help folk out it might be worth thinking of standardising terminology to some extent..?

My thinking would be to try to drop the terms ground or earth, when discussing vehicle circuitry given they seem to have more relevance to household and industrial electrical wiring systems, and as such may have no place in a motor vehicle electrics which in general are in no way connected to either the earth or ground... unless one has a trailing lead in an attempt to dissipate static build up..? (-:

The kiss principal works well for a simple thinker such as I, and as such, given that most folk will be aware of the positive and negative battery connections, the requirement to observe correct polarity, and additionally may well understand a simple light bulb circuit with a switch, then perhaps in discussions it might be worth adopting NEGATIVE as a standard term for the part of the circuits route back to the battery negative terminal...?

I used the term route in that unlike a simple circuit with one length of black wire connecting the "light bulb" directly to the battery negative, in a car chances are that to save on wiring costs it has ever been the habit to use the metal of the chassis or monocoque instead of a black wire from each and every electrical component returning directly to the battery.

In order for the chassis to perform as an electrical wire might, the battery negative connection is directly attached to the ideally clean/bare metalwork of the chassis.

If the above makes any sense then this possible cost cutting measure introduces potential for poor connections to develop over time, given corrosion of chassis is quite normal, and never more so if you drill a hole through the painted metalwork to achieve a point of reasonable electrical connection, and in the process have removed the layer of metal protection which provided a good electrical connection when new but may well be the reason for so many vehicle wiring faults as corrosion sets in to the bared metal...?

Yeah just another ramble, but hopefully may present a route to basic understanding for those who are put off by unnecessary complexity relating to seemingly confusing and different terminology. to describe the same thing.....Wotcha fink..?

“Fink” you are bang on George. Well explained.

How would that work with positive earth cars?

Hi Folks - not been into the garage for the last couple of days due to the rather low temperatures but you have all given me lots to think about! What makes matters worse for me is that the same thing happened last winter too. I tried all the usual checks to no avail and replaced the relay - naturally, then one day the pump suddenly kicked in and away we went - I have absolutely no idea why, but she ran beautifully for 9 months before this episode. I put it down to being a Morgan but clearly there is a gremlin to be found lurking somewhere! I will post again when I have news.