Hi, I have a 1988 Ford escort xr3i cabriolet. When I bought it the fuel relay was bypassed so pump on all the time, it works but I'd like to get it fixed.

When I looked at the relay holder a couple of the wires were disconnected and joined together. I've put the relay holder wiring back to how it should be, got a new relay and put it in. It operates as it should, primes, stops and runs engine when started but it makes a loud buzzing. I got another relay, this time a black aftermarket one new, does the same.

I suspect there is a problem with one of the feeds to the relay. Before I start looking further at it, does anyone here know exactly what this is?

Youtube video of relay buzzing: https://youtu.be/XGdpIjstfvM

Any help appreciated before I start pulling everything apart.

Note, fuel pump is working fine. Engine runs fine even with the buzzing.

 

Update on investigation so far.

I have checked all the pin outs and the groud one is going directly to the fuel pump feed.

I have set it all up correctly now and wired it back to how it should be and the noise has stopped BUT ... It is clear this was done because of an issue as it now primes fine and stops but does not turn back on when the engine is cranking so won't start.

Fortunately I have wired it in such a way I can quickly override this to how it was bypassed originally so I can still use it, the investigation continues.

I'm going to try replacing some of the components, starting with the fuel overrun valve on the airbox, reason for that is it was unplugged when I got the car. I will work my round the components if it is not that.

I'll post an update when I have one but if anyone knows what this is before, feel free to let me know.

 

Do you have the original wiring diagram for your car?

 

Yes, using Haynes manual. Further development, the speed sensing module doesn't seem to be preset, I couldn't find it but could find empty grey connector. Im going to check the wiring on the connector to confirm its for that but I've ordered a new one anyway.

Beginning to suspect there was a problem with it so instead of replacing someone took out and had overridden.

 

At least you know how to wire it correctly. K-Jetronic is quite simple.

Speed sensing module? Are you talking about the black Bosch one that has "Drehzahlrelais" on it?

This could be the cause. The pink relay primes the pump when ignition is turned on and when the Drehzahlrelais gets a hall signal from the distributor it switches ground on to activate the fuel pump relay.

 

I have now got to the bottom of the problem and will share this with you incase it helps.

So the original problem was that the pump was on constantly. The previous owner had obviously had an issue and wired it directly.

The ignition positive to the relay had been diverted directly to the fuel pump and the ground to the relay had been cut and tied off for some reason.

Firstly I wired the relay back to how it should be or so I though which made it work but it was buzzing. Turns out that the ground wasn't wired back up correctly so check the wiring if this is the problem.

Once this was done it was quiet and primed but did not re-engage the pump when cranking so it would just stall, i suspect this was the original problem and the reason the former owner had directly wired.

I took an educated guess and changed the speed sensing module, it was a pain to get at but has sorted the problem out.

it is now working properly.

 

Thanks for posting up the fix, so many don't bother.