87 p/u won't start

[DnStClr]

This problem sounds more like a bad ignition module to me. The module can be removed and taken to AutoZone for a test. Also- Do you know how to check for fault codes to see what codes the ecm is throwing?

[Tjerica1201]

It was sitting for a month before I went out to start it and found that it wouldn't start.  I've been trying to fix it for an additional month.  So grand total, it has been sitting for 2 months.  When I parked it, it was running perfect.  I didn't park it intending to leave it sit for a month or anything.  It just so happened through day to day life that I had no need to drive it.  With high gas prices and such, I would always run all my errands in the car leaving the truck to sit.  One day I needed a Christmas tree and had no choice to drive it and went out to start it and it would just crank and crank but no fire.  This is the same thing my Dad's 93 did.  A new dizzy fixed his issue.

The ignition module is in the distributer isn't it?  Yes, I've jumped the A/B wires and its throwing 12.  That is an "everything's good" code isn't it?

Is there any way for ME to test the ignition module?  I'm somewhat versed on the use of a multimeter. 

[Irish_Alley]

the icm can be tested at a parts store. sometimes they have to test them multiple times to heat them up

[78BIG-TEN]

Generally speaking the icm either work or they don't,have you checked for spark at the plugs,and is it continuous while cranking,and yes code 12 is normal

[Tjerica1201]

Ok I will pull mine out and get it tested.  I did not check each plug, just #1 and yes it is continuous through cranking. 

[78BIG-TEN]

So you have spark at the plugs and the injectors are pulsing,that tells me module is probably ok.Are you sure the cap is clean and the rotor is indexed and pushed down all the way

[Tjerica1201]

Yes the cap is clean and the rotor is seated.  I've even pulled all plugs to make sure they weren't all fouled up and they all looked almost brand new (they have like 20k miles on them).  I don't know what else to check, that's the only reason I'm leaning toward the dizzy.  its worth at least checking. 

[DnStClr]

Checking the module with an ohm meter will give weird readings . It can be checked in the truck  (The location of the ignition module is on the distributor plate beneath the cap and rotor.) 
http://www.ehow.com/how_8000853_test-ignition-control-module.html
Did you check your fuses?- particularly the ecm2 fuse? Also, when the injectors are spraying, are they ticking as well? That ticking is the ecm opening the injectors, or better said- it's providing a ground for the injectors to pulse..

[Tjerica1201]

On Saturday I swapped dizzy out of my blazer and it started right up.  I guess it was the module after all.  Now I am having fuel delivery issues.  After I got it started with the "new" dizzy, I shut it off and went in for the night.  Sunday morning I went out and tied up all the loose ends and went to start it and drive it, and it wouldn't start.  No fuel is coming out of the injectors.  I can dump a little fuel down the throttle body and it will fire just fine.  Should I hear the fuel pump kick on every time I turn the key to run? or is there a pressure switch that kicks the pump on only when its low on pressure? 

I went out this morning (Monday) to start it and it fired right up.  When I switch tanks to the new pump, it dies.  I switch it back to the first tank it starts up.  When its on the original pump and running, fuel is pouring out the fuel fill port.  a lot of fuel.  I don't know if the two issues are tied together or not.  As for the truck dying when I switch tanks, I would automatically lean toward the switch that is mounted to the frame under the passenger seat but I changed that out a year ago when I was having other issues (that didn't fix the problem then so I still have the original that should still be good). 

Any ideas?

[Irish_Alley]

http://forum.73-87chevytrucks.com/smforum/index.php?topic=29825.msg249543#msg249543
read this it may help you out. i think my problem was the tank switch having bad connections

[Tjerica1201]

Don't have a lot of time to look through it in depth right now, I just skimmed it but it looks like it that's gunna help.  It ended up being the switch in the end?

I will give it a good read through this evening.  Thanks.

[Irish_Alley]

cant say for sure but i know the 1st one broke apart in my hands as soon as i unplugged the wires. the second used one was all gunked up with dirt and grime brake cleaner helped but it still screwed up from time to time even just dies going down the road. got a brand new one, had the truck running and unplugged it and the truck died like it had been put the new one in and never had the problem again.

[Tjerica1201]

Final Update.  I swapped out the tank selector valve and all the problems went away.  So I am now getting accurate readings out of both tanks (gauge needle was pegged out past full) fuel is no longer dumping out of the drivers tank fill port when that tank was selected, and the switch actually switches between the tanks. 

Only issue I have now is that I think that the drivers tank pump is weak.  When I select that tank, it slowly starts to spit and sputter and eventually dies.  When I select back to the passenger tank before it dies, it picks back up and runs normal.  I'm going to make sure I'm getting the correct voltage at the plug going into the valve and if its good I guess its a bad pump, unless you guys have another idea.  That pump is less than a year old. 

[LTZ C20]

Do a fuel pressure test at the output from the drivers side tank,  if it's below spec then your probably right about the pump being weak.

[Irish_Alley]

could also be the rubber line that connects the fuel pump to the assembly

it comes with a new pump anyway but it can rot and crack and cause loss of pressure.