90 astro 4.3 crank sensor

[ss63]

Hi guys I looked in the 2 places it should be either in front at the crank & in the distributor ! I know what the 2 parts look like & nether is at those locations ! what agnatically happen it just shut off ! like someone turned the key off ! I changed the service parts in the distributor oil pressor sensor was told to change the crank sensor next but where is it ? Thanks

[ChevyTech]

There is no crank sensor on that vehicle.

There is a pick-up coil in the base of the distributor that produces pulses base on the rotation of the distributor shaft.

Stop throwing parts at it and do some testing. The quality of replacement parts is so bad you may be making more problems.

First thing you should do is see if it has spark.

It is common for the ignition module in the distributor to fail. Many parts stores will test the module for free if you bring it in. You must put heat sink compound under the module when installing it or it will fail.

[ss63]

Thank you as your the only one that points fingers at the distributor ! since I could not locate those two parts ok been working on car since I was 15 now 67 did take a know new working module clean & put that special grease under it with new rotor & cap as it went from running perfect to off ! no spark so since I did that is it now the distributor ? or can a coil just let go ? Thanks

[ChevyTech]

You're welcome.

There are not to many people even looking at this board any more.

Pickup coil testing:

500 to 1500 ohms between terminals.

Infinite from one terminal to ground.

When testing the pick-up coil resistance, the key should be off, and the pickup coil should be unplugged from the distributor module.

Inspect the magnetic material on the reluctor that moves inside the inner points of the pick-up coil to see if it is cranking into pieces. It should be one part

NOTE: Being that your truck is injecting fuel that shows the computer is getting a pulse from the pick-up coil. That pretty much rules out a problem with the pick-up coil or magnetic material breaking down.

If it in fact it injects fuel when there is no spark then look at the distributor module, distributor cap and rotor, or the coil & coil wire. Just because the parts are newer does not mean they are good parts. I can't stress enough how bad the quality of new parts is now.

[ChevyTech]

There is another thing I want you to check.
Make sure the white wire between the module in the distributor, and the coil, has good tight connections.
Sometimes the terminals in the connectors get stretched out and do not tightly hold on to the terminals they side over.
The white wire is the wire that grounds the coil to make it spark.

There should be white wire going to a connector that is taped to the harness from the factory right by the coil. That white wire is connected to the white wire at the coil. If you put a test light on that wire with the other end of the test light on a good ground the test light should flicker when the engine is cranking as the distributor module pulses the coil to make spark.

[ss63]

Wow that's a lota good info & many things to check ok I thought giving the year 90 astro 4.3 was enough info ? short of not saying its an automatic which most are again Thanks

[ss63]

Originally Posted by ChevyTech

There is another thing I want you to check.
Make sure the white wire between the module in the distributor, and the coil, has good tight connections.
Sometimes the terminals in the connectors get stretched out and do not tightly hold on to the terminals they side over.
The white wire is the wire that grounds the coil to make it spark.

There should be white wire going to a connector that is taped to the harness from the factory right by the coil. That white wire is connected to the white wire at the coil. If you put a test light on that wire with the other end of the test light on a good ground the test light should flicker when the engine is cranking as the distributor module pulses the coil to make spark.

Sorry for the delay as this vehicle near by / not at my house ok up-date first took wire from coil put spark plug on got spark there , then took one of the wires from a cylinder & it sparked there too next took cap off that pointy thing is turning in another ring now there's black plastic ring around that other ring now it does move but only a quarter of an inch in either direction ! ok anyway not a hint of a start even with ether ! so i would summarize ( from what you wrote its the distributor ). that houses the crank sensor ? again thank you for your input .

[ChevyTech]

You said it has spark, and earlier you said it injects fuel, so the pick-up coil has to be working.

The engine position is determined by the pick-up coil in the distributor.

Did you remove the distributor to do any of the work you did?

Did you rotate the housing of the distributor at all?

Does it have a good hot spark that looks blueish?. A weak spark usually looks more orange then blue.

[ss63]

Morning ok spark is good but not a blueish as I would like also did not remove or turn / rotate dist. in block just did the test I spoke of the other is parts are original ( dist. & coil ) with 222,000 on a 1990 and as I said it was idling perfectly for 20 minutes while I was raking leaves next to it & it was like someone turned the key off ! and never a hint of a start since again thanks

[ChevyTech]

Make sure the battery is charged up so you not getting weak spark because the battery voltage is low.

Make sure the spark can jump ½ inch.

[ss63]

Sorry for my delay as I had computer trouble ! ok I did have a well charge batt. as I kept it on that batt. minder / tender as I was checking the spark ( which was weak ) it attended to start ! so I put the wire back on and then it back fire with a really Big Bang & fire out of the TBD great enough to blow the PCV & other vacuum lines off & blew valve cover gaskets out !! so I quit ! so now its a good parts van ( as it ran very good to the day it just shut off ) and I was trying to get it running again ! so I have All the new ignition parts short of the computer a $150 worth so would like to like 300 as scrap is close to 400 ! and say good by as I'd know it since new ! may 2021 be better ! Thanks for all the input everyone gave me