I replaced my GPs and the GP relay within the past 3 weeks or so.
Yesterday, the preglow light came on for only a second or less - even
though
it was in the upper 40s and hadn't been started since the night before
- it
was stone cold - it started instantly although it runs like one
cylinder
isn't firing evenly. Within a minute the engine idles & runs smoothly.
That's way too quick. No wonder it ran poorly.
I'm wondering about the possibility of a GP being bad out of the
box?
Certainly. The relay, too. It happens. 'New' relays usually are
new old stock, and the internal components can fail with age, though
not so much as with use. Most likely is the GP, or its wiring.
Also - is there a way to check each GP without removing them
Sure. The quick way is to pull the plug off the GP relay and use a
DMM to measure the resistance to ground of each one. The rated value
is 0.6 ohms, though it can vary with temperature. The important part
is that they all be about the same.
Even better is to use a hefty ammeter to measure the current to each
one. I just did that on the 190D a couple of days ago. Within a couple
of seconds each one dropped from about 28A to under 20A, except for the
bad one that was drawing about 2x normal current. (_That_ is a weird
failure mode.) Most people don't own an ammeter that is good for more
than 10A, however.
The GP's seem to be pretty basic - but I guess the innards could be
bad in
one.
They are pretty basic, but they're not as simple as the old series
plugs.
-- Jim
