3.2 non start help

[ninepfourteen]

Track last weekend.
'84 motronic 3.2 won't start but runs all weekend if push started.

Back home this weekend and change:
both crank sensors
cht sendor
starter

Still won't start.

Did discover that throttle position microswitch is broken and therefore not making contact when throttle is closed.

From what we can tell all other voltages/readings are right.

Help please. Thanks.

[Zeke]

It wouldn't have run at all if the position sensors were bad. I don't know why you replaced the starter, only you know why. The CHT and TPS would affect cold start enrichment and hot start canceling, but seems like you got that figured.

I assume it cranked, or didn't crank by the starter? I'm sure you know not to touch the gas pedal when cranking.

[ninepfourteen]

gear broke on high torque starter in the middle of tring to get it to start at the track.

Turns over with starter.

[rusnak]

I'd guess that probably the positive battery clamp is corroded, and you are not getting enough voltage to the motronic until the alternator kicks in, or something is loose/bad connection. I'd re-check all connections for tightness and cleanliness. Leave the battery on a trickle charger overnight, and my guess it'll fire right up.

[Bill in OKC]

I assume you checked the dme relay. Have you checked voltage from the AFM?

[rick-l]

What do you mean by

Originally Posted by ninepfourteen

won't start but runs all weekend if push started.

?

[ninepfourteen]

I mean it wouldn't start with the starter, but would start with two guys pushing it and letting the clutch out it third gear.

[rusnak]

This is only a theory, but I think you are not getting the full voltage to run the motronic. When the starter is engaged, the current drain causes the motronic to not run. I think either you have a low battery, or as I mentioned you have too much corrosion buildup or a bad connection.

[robhamster]

Can you turn the key all the way until you feel the springy part of the switch to engage the starter. That happened to my '84 and I had a local guy , Eisenbud, rebuild the switch to remove the safety catch that prevents the starter from being deliberately engaged while the engine is running. Sometimes it moves into the safety postion and will prevent the switch from getting far enough to the right to engage the starter. Mine could be push started as well.

[ischmitz]

ninepfourteen,

your messages are confusing. First you say the car starts fine when you push-start it. But you can not start the car with the starter. That points to either the starter being bad or the system is not delivering enough current to operate the starter. (battery, wiring) Next you say the gear (starter gear?) broke and it still turns over??? Then you went ahead and replaced the starter and several sensors for the Motronic.

Why did you change the crank sensors and the CHT? If one of the crank sensors is bad the engine would not start and run properly no matter how you start it. Push-start or using the starter doesn't make a difference. If the CHT is bad the engine runs rough when cold becaue the DME always "sees" a hot engine. Once up to operating temperature a broken CHT is not that big of a deal.

You need to check whether your battery can supply enough power to operate the starter. Measure the voltage directly at the battey terminals while cranking. If it drops from 12.5 volts to single digits your battery is toast. If not measure the voltage at the starter while cranking. If it is more than 0.5 volts lower that what you measured at the battery while cranking you have a bad connection (ground strap, positive cable) If not your starter is on its way out.

Cheers,
Ingo




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