Earth Wire

[RogerRust]

After I fitted the electronic ignition I noticed that the engine needed more of a crank to start.

I'd hoped that starting would have improved.

Then I checked the resistance from distributor body to battery earth this was high at 3 ohms. so I worked my way round with the multimeter to find the problem. It turned out to be the gearbox earth strap between gearbox and chassis it was fitted nice and tight but was failing it accounted for the 3 ohms.

Following a suggestion by Willie I put a new strap between a left hand engine mount bolt and the cover that blanks the mechanical fuel pump opening where it is open to inspection.

Problem solved. My guess is that when the starter motor was turning the low resistance of the starter motor windings would be in series with the duff strap and give an unacceptable voltage drop so that the spark is less energetic.

Looking back I think the engine used to start as I let go of the starter and full voltage returned.

[rayofleamington]

Looking back I think the engine used to start as I let go of the starter and full voltage returned.

Ah the joys of modern gizmos - my dad had a new campervan with the same problem. He ended up parking on a slope at home as it would bump start on the first stroke but regularly wouldn't fire on the starter. It took the main dealaer a long time to sort it and they eventually hand made some modifications to the wiring loom.

[Kevin]

Following a suggestion by Willie I put a new strap between a left hand engine mount bolt and the cover that blanks the mechanical fuel pump opening where it is open to inspection.

A useful tip but many engines don't have that opening and cover.

[bmcecosse]

Any part of the engine will do! Timing case bolts are nearby - but use one of the larger ones.

[bigginger]

One of mine had a strap from a head bolt to the battery...
a