Did you check the king lead as well? Last time I had no spark that was it,
led me to substitute the coil and all sorts. With electronic ignition the
best thing to do is to temporarily revert to a points system to at least
check out the coil, distributor, leads etc.
If you can't fully revert but can lay your hands on a points capacitor, then
you could try disconnecting all the electronics from the coil, connecting
12v to the +ve and the capacitor from the -ve to ground, then alternately
short and un-short the capacitor. This simulates a points system and,
although the car won't run, you should be able to check for a spark from the
coil.
PaulH.
-----Original Message-----
From: Tom McLaughlin <tmcl98@yahoo.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 22 February 1999 18:08
Subject: 77MGB will not start...different than the little engine that
couldn't
>I read the thread on the little engine that would not start as I had a
>similar problem this weekend. About 2 weeks ago I changed the plugs.
>They only had about 3000 miles on them, but I had some new Bosch
>platinums so I put them in (gapped at 0.35"). The car ran fine all
>day. I then did not run the car for 2 weeks. Saturday I tried to
>start it and it just cranked. I was getting fuel so I checked for a
>spark, no spark. So, I had another set of plugs that I bought at the
>same time as they are cheap and replaced the plugs again. Still no
>spark. I do have voltage at the coil with the ignition switch on. I
>checked the primary resistance of the coil, about 14 ohms. A bit high
>according to the manual and I'd never changed the coil so what the
>hell, I went and bought a new one up at the parts store (AC delco that
>looked exactly the same as the one I pulled out of the car that has
>worked for 3 years and their computer said it would work on....what
>was that again...an MG what...who makes that). The primary resistance
>of the new coil is only a couple ohms and about 6k ohms through the
>secondary...both should be okay according to the manual. I checked
>the sparc plug wire resistances through the disti cap. They range
>from 5.3k to 8k depending on length. All within spec. I cleaned up
>the contacts on the disti and the rotor (which looked fine), put it
>all back together and still no spark. With the ignition switch on I
>get 13.2 volts at the coil (its hooked up to another car so not to
>drain the battery during all this cranking) Amature question. The
>maunal says that the proper way to check for a spark is to hold the
>plug "with a dry rag" about 1/4" from the block and crank. Is this
>true or should the plug be touching the block...???
>
>However, there is a crack in the disti cap where the clips fasten
>(more like a hole, not a crack)...and it rained pretty hard a few days
>in the last couple weeks, but the car was not driven so I don't see
>how water could have gotten in there. Is it possible moisture got
>into the disti and it is causing my problem? I'm getting a new disti
>cap today and I'll clean the inside of the disti before installing.
>Do I have to go further than just underneath the cap...meaning, do I
>have to take the rotor off and go deeper than that?
>
>I started to suspect the electronic ignition cause I was running out
>of things to test. Here is why...it has a Piranah system that looks
>pretty beat up. It looks like it was coming apart and the PO used
>silicon to put it back together. I don't know how to test these
>things.....so any suggestions would help.
>
>In summary, new coil, new plugs, plug wires are fine, new cap today.
>Car ran fine 2 weeks ago, sat for 2 weeks and now no
>spark......HELP!!! And please, don't be shy with the details, half of
>what I said above, I learned yesterday from the manual. I saw one
>post that said to take the wire from the coil to the disti off and
>hook a spare plug up to that, close the points and see if you get a
>spark...I don't have points though do I as it has electronic
>ignition....not sure what to do next.
>
>Tom
>77B (ran great until I let it sit for 2 weeks; maybe she's just mad at
>me)
>
>
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