What component resets in 7 minutes?

[martinb930]

Hey guys your local problem child again...

At least on a quarterly basis I will be driving (mello and typically on the freeway) AND MY CAR JUST SHUTS OFF... for no apparent reason. So here's the drill... I pop the hood and open my fuse box, pull out my two red fuel pump relays... blow on them, rub them on my shirt... re-install them, wait 4 1/2 minutes and the car fires right up and I'm on my way... until next quarter.

Best guess wins a prize... thanks boys!

[mark houghton]

Originally Posted by martinb930

Hey guys your local problem child again...

At least on a quarterly basis I will be driving (mello and typically on the freeway) AND MY CAR JUST SHUTS OFF... for no apparent reason. So here's the drill... I pop the hood and open my fuse box, pull out my two red fuel pump relays... blow on them, rub them on my shirt... re-install them, wait 4 1/2 minutes and the car fires right up and I'm on my way... until next quarter.

Best guess wins a prize... thanks boys!

A prize? We could win a prize??? Ok then, I'll play: Your 4 1/2 minute waiting time has nothing to do with blowing and spitting on the fuse pump relays. Something heat related I think. Replace the overboost fuel pump shutdown relay. Yellow on my car, on the engine fuse/relay panel. Tall rectangular, if you're not sure. Sophisticated 80's electronics in there, probably getting heat soaked and one of the transistors is malfunctioning. I've got some other guesses, but it's not fair to throw out 50 ideas just to increase my chances of winning!

[martinb930]

You mean this $150.00 relay? Yeap, replaced 3 months ago.

[mark houghton]

Originally Posted by martinb930

You mean this $150.00 relay? Yeap, replaced 3 months ago.

Well then it just has to be toast again, for me to win! Since you replaced it earlier, and the problem (I assume) went away - only to resurface again, perhaps that suggests some bad wires in the socket the relay plugs into. You would have get under the socket to check them out.

OK, one more idea....maybe a stretch. How about the ignition shut off time delay relay (the smaller of the two silver "cans" in the rear)? If it malfunctioned, it could shut off your fuel pumps, just as it's supposed to do when you turn off the key (but it keeps the spark going to burn residual fuel for a couple seconds).

Oh hell...one more idea and I'll quit. Check the overboost sensor (mounted to the back of the boost recirculation valve assembly with a single wire going to it). That sensor should route the wire to ground under normal conditions, and interrupt the ground when boost is exceeded. A bad ground, sensor, or wire would shut your pumps down.

Question: Why are we assuming this is fuel related in the first place? Just because you pull the pump relays and 4 1/2 minutes later she starts? Will she start after awhile even if you DON'T pull the relays? Could be spark related, CDI or MSD.

[martinb930]

Mark: I wasn't suggesting a fuel related problem... more of an electrical problem. When the car shuts down and I pull over I can't just sit there I have to look like I know what i'm doing (even though I don't) it's just part of the routine.

It's suggestions like "boost recirculation valve assembly" I love the most... I'm like duhhh what? I'll check (I mean I'll have the the silver cans thingamajigs checked) so what were the other 47 thoughts you had? kidding... thank you for your prompt reply and humor. :-)

[mark houghton]

Originally Posted by martinb930

I pull over I can't just sit there I have to look like I know what i'm doing (even though I don't) it's just part of the routine.

Now THAT I can relate to! As if it isn't embarassing enough to break down, ya gotta look like you know what you're doing.

Does she sputter to a stop, or just plain quit like turning off the key? You might be having ignition problems, i.e, the CDI or whatever you're using for an ignition module. I don't know how to test them, since I am no longer stock and run with an MSD6AL. Find someone who can let you borrow their CDI for the next quarter and see if it continues to happen.

You need to do some basic troubleshooting next time this happens. Leave the key in the on position, reach your left hand back behind the fuel head near the top and pull the plug from the electrical connection to the switch that is triggered by the fuel head control arm (assuming you're not EFI). Pull that plug, and the pumps will start. If they don't, it's fuel system related.

Damn intermittent things drive me crazy...much easier if they just permanently break.

[NathanUK]

I would say CDI.

I posted some bench tests using a meter on this forum.

My stock 930 coil has a primary resistance of 0.7 ohms. + to -

Originally Posted by NathanUK

OK, here are the resistances

At the CDI connector with it unplugged

Coax to dizzy (green cable) is 570 inner to outer wire.
Brown to White (coil primary) is .7

Coil secondary (coil HT to either + or -) is 649

At the CDI box

31/1 to 31d is 0 (closed circuit)
31d to 15 is 672
31d to TD will charge briefly and then go to infinity (open circuit)
31/1 to TD also charges briefly and then goes to infinity (open circuit)

My CDI is a 930.602.702.00
Bosch number 0 227 300 004