In praise of Lucas electrics
With the Stag running at last, I turned my attention to the E-Type as there were a couple of items that required attention. On my last outing the horn failed to operate, so an investigation and remedial action were required. I suspected the relay, as it’s an original large Lucas item with pressed aluminium housing that’s mounted on the inner guard.
This is the relay that was fitted to the car when I purchased it making it possibly over 50 years old – who said Lucas electrics are problematic..? Firstly the two feeds to the relay were tested for voltage; the purple wire is always live and comes from fuse three and powers the horns. The green cable is connected to fuse six and is ignition switched and earthed via the horn button. Both wires were indicating 12v and connecting the purple to the purple and yellow (horn feed) had the horn operating which seemed to confirm a relay issue.
Just to check I replaced the wires and removed the one to the horn push so I could earth the relay terminal and got a scare as the twin air horns unexpectedly blasted a few inches from my left ear, proving the relay was operational. It appeared the fault lay in the connection from the relay to the horn push button. This includes a brass rod that runs down the centre of the steering column, which is insulated from the column itself and energised via a small spring loaded plunger in an insulated block at the base of the column. I had replaced this plunger and insulation bush a number of years ago when the old insulation material had disintegrated and the horns sounded at random, so it could have had a bad connection.
The horn button was removed to check the continuity of the wire from the relay to horn push and this was found to be okay. Reconnecting the wire to the relay and turning on the ignition confirmed there was 12v at the brass button on the centre rod and earthing it sounded the horns, but the reason they had failed was still a mystery.
One thing I noticed was that some of the relay blade connectors were a bit loose and may not have been making correct contact, so all the terminals were cleaned and tightened ensuring good contact, which will hopefully prevent a future reoccurrence. This just goes to show that one should logically check through the system and not jump to incorrect conclusions based on component age or history.
What I presume was the original SU fuel pump had been rebuilt in the ’90s during the car’s restoration with no issues until around seven years ago when it would sometimes fail to pump after the car had been standing for a while. A swift bang on the inner panel was usually sufficient to coax the pump back into action. In 2010 the engine was removed for attention so I decided to give the pump a second overhaul and replaced the original contact points with an electronic conversion kit to overcome the issue of sticking. However, when I checked with Burlen I found there was little difference in cost between a new electronic pump and the total cost of an overhaul and conversion kit for the old pump. So I ordered a new pump and that was fitted at the same time as the rebuilt engine.
Right from the initial fitment the electronic pump operated differently from the old one. When the ignition was turned on the pump operated rapidly until the carb bowls filled but then continued to cycle slowly, whereas the old pump would remain quiet. The carbs had received a major overhaul in 2010 with many new components being fitted, including new needles and floats, then last year the jets and float needles were replaced.
Numerous checks confirmed there was no fuel leakage anywhere in the system, so I thought the pump inlet valve may be leaking. However, as the years progressed the speed of pump operation under no load conditions has increased, especially when starting a hot engine after a short break when there would be a rapid clicking from the pump and what appeared to be a lack of fuel at the carbs. I phoned Burlen and they
thought that it may be caused by a vapour lock due to the high under bonnet temperatures, or that the pump may be in sucking air, and suggested I tighten the diaphragm clamping screws. On an E-Type this means pump removal, so it was disconnected and prepared for inspection on the bench.
Rather than just tighten the screws I decided to pull the pump apart to check the cleanliness of the internals. It was immediately obvious there was an issue with the diaphragm gasket.
One of the centres for the screw holes hadn’t been punched out cleanly and was probably allowing some air leakage into the pump. The pump was reassembled and bench tested and a length of outlet hose was blocked off with a set screw and hose clamp so that the flow rate could be regulated by adjusting the tension on the hose clamp. When the flow stopped the pump no longer ticked and the speed of ticking increased as more fuel was allowed to flow, so all now seemed well.
I have informed the supplier of the problem and meanwhile I‘ve always found Burlen to be an excellent supplier of quality items. I purchase all my SU and Stromberg spares from this company, as I have found that parts sourced locally here in Australia have variable quality and some of the rubber components have a very short life span.
During the major rebuild I replaced all the fuel lines and there was now a 3/8-inch copper line running under the car and the original plastic flexible lines front and rear had been replaced with rubber fuel hose. This was 20 years or so ago, so while the pump was out I took the opportunity of replacing all the rubber hoses that run from the fuel tank to the pump and from the pump to the copper line. At the front of the car, the hose from the bulkhead mounted fuel filter to the carbs was also replaced.
While the tank top was exposed I removed the eight small set screws that retain the plate on top of the tank to check the condition of the tank’s internals. I was pleased to see no nasties were revealed, just a small amount of sludge but very little rust or corrosion. As there was very little fuel in the tank, I drained it and cleaned up the sludge as best I could with the tank in place.
A can of fresh fuel was poured into the tank, switching on ignition had the pump filling the carb bowls and a test drive confirmed correct operation. Let’s hope the problem is now fixed.