John Mackay

I have an all stock '72E with MFI, points, etc., but a Permatune not Bosch CD (came w/ it, not my choice) and I know their rep is not nearly what the Bosch's is.

I have noticed in VERY humid weather (de rigeur here in summer in Wash DC) that the car will start up on a couple of cranks as normal and then cut out very abruptly and crisply--almost as if the ignition switch was shut off or killed, after a minute or less of running. It then cranks and refuses to start until it sits for a while--anywhere from 5 minutes (like it did tonight) to a day.

The car had a full tune up less than 2k miles ago with a valve adjustment, oil change, new plugs, points, cap, rotor, etc. and is driven daily to and from work--mostly in town but I "blow it out" for a brief period on the highway. The plug wires are in good condition and the car has a decent battery (removed #2 with one good sized battery and removed the 2nd cable, etc.) and a new hi-torque starter. The grounds are ok but not new. The car has a mickey-mouse "kill switch" installed via the rear window defroster switch in the Tach line which seems to work fine but these recent quirks have got me thinking about either removing it altogether or replacing it with a switch specifically made for this purpose in the trunk area and trying to get my defroster back.

Anyway, is it symptomatic of the Permatunes to sporadically die before they go dead altogether or do I probably have some other kind of problem?

With the ignition switch on tonight, I couldn't really hear any whine coming from it and for about 5 mins, I was stranded.

I should also mention that the MFI pump is wearing out and I think I have some small leaks in or around the stacks as once it warms up, any backfiring ceases. The pump is adjusted now so that it's smooth across the entire rev band but I know it is not running as crisply as it should be. Saving up now for the pump and throttle body rebuild...Not sure if this is contributing to the starting problem or not. I have not measured the fuel pressure, changed the fuel filter or checked the CO but I know from my 12-15 mpg that its probably not in the 2-3% range as is spec. There is NO gas smell in the oil and for the most part--90% of the time and 100% of the time last winter, the car runs very well. It's only been this summer that I've noticed/experienced this problem.

Any ideas on how to trouble-shoot this?

Thanks, John

Kurt V

John, I too have a 72E with the Permatune Ignition, which I installed after the Bosch unit failed and the PO just tried to run on standard points and coil. The Permatune does not have the "whining" noise the Bosch unit does. It is completely silent. From chatting with other Permatune owners, they do not appear to partially fail. They either work or they don't. I think you've pinpointed the problem the "humid weather". However, I'm not sure what is happening. On less humid days do you still have the problem? If not then I still find it curious that the car will start then die. Normally moisture in the electrics keeps a car from starting period. I would definitely check all grounds and connections, including that "kill" switch.

As for the MFI, how do you know it is wearing out? The reason I ask is that I thought mine was worn out, but most of the MFI experts on the Pelican Board believed it was just way out of adjustment. They were right. I purchase the Gunson "Gas Tester" to check for CO, made the proper adjustments, and solved my problems. Also, John Walker has stated that the factory setting of 3% CO results in too lean of a mixture and recommends a CO at 1000rpm of 5%-6% and at 3000rpm of 6%-7%. That is what I have mine set at. You might want to do a search on MFI topics on the Pelican Board.

Thom Fitzpatrick

Regarding your cutting out issue, I had the *exact* same problem with my '77 - it would just die for no apparent reason, and not start for up to 20 minutes.

I'd switched to a Permatune a couple years prior, when chasing an ignition problem, and left it in.

After replacing the fuel pump, relay, 3 tow truck rides, etc, etc, I *suspected* it was the permatune, but could't prove it. So I put the appropriate tools in the car, along with the original CD unit. The next time it died - which was the next day on the way to work - I got out and replaced it that minute. The car started perfectly. I immediately put the Permatune back, and the car wouldn't start. Again I put the Bosch CD box in, and it started. Proof enough for me. The car ran like a champ from that day on until a friend of mine overreved it by mis-shifting...

John Mackay

Thanks Kurt and Thom both. Kurt, occasionally it happens on not so hot days but basically this has been a summer-only problem. I did not have an instance of it until June or July when it often gets to be 90%+ humidity here and especially below ground in my work and home garages.

The reason I think (and have been told) that the MFI pump is wearing out or failing perhaps more correctly is that when I adjusted everything to spec--all control arms, etc, it was very flat from 2500-4500 and popped a lot until it was warm, when it would even out. I haven't sprayed to find any leaks around the stacks but those are probably part of the problem. As my mechanic anticipated, as I tried to lean out the rich setting on the pump, it actually made the popping worse. When it's warm the way I have it set now, its pretty smooth but still seems rich and not crisp.

In any event, I need to track down this electrical problem and I'm going to look at all the grounds, etc. I had a new voltage regulator put in this spring and the battery was new and my tech said the alternator was charging fine on his analysis but now I wonder.

Not familiar with that Gunson CO meter but will try to find out.

Thanks,

John