My '87 Blazer all of a sudden wouldn't start as described in this thread on this forum:
https://blazerforum.com/forum/1st-generation-s-series-1983-1994-tech-40/87-blazer-fuel-pump-relay-location-48533/




After thinking I had troubleshot it for a bad relay (as Ohsofly and Swartlkk advised in above thread) I replaced the relay with a new one and the car still won't start. Turns over great but makes no attempt to catch.

This is what I have troubleshot so far:

1. Has new air filter (and sometimes no air filter during testing)
2. Has gas in tank (was already partly full and added 4 gallons)
3. Fuel filter is CLEAR (removed and blew through it fine)
4. With or without relay (old, new, connected or not) female test lead from fuel pump relay (see above thread) hooked to 12V+ makes fuel pump whine - it's not the fuel pump itself, that works fine.
5. When ignition is turned to ON (between AUX and START) I do NOT hear the fuel pump whine (notwithstanding 3) with either new or old relay connected, with listeners inside and outside the car. This sounds like a problem - isn't it supposed to do that for 3 seconds when the ignition is turned to ON? I used to hear it @ ON. (It does sound like the fuel pump whines down after trying to START and releasing ignition -?)
6. With new relay connected and fuel pump test lead connected to 12V+ car does not make any attempt to catch when the ignition is in START (so manually bypassing the relay to get the pump to pump fuel when the ignition is STARTing it still doesn't catch.) I did this after letting the fuel pump work for several seconds to prime the line and tried STARTing it 2-3 times for 5+ seconds each time. This is 2-3 times longer than it usually takes to start the car. Soon I will be jumping the battery...

What else can it be that - after not one starting problem in 2 years - caused one roughish start and then no catch at all nada ever after? Plugged injectors (all of a sudden?) Bad computer? Where to start troubleshooting from here?

Thanks for any leads!

 

I wanted to post my success in determining the trivial problem causing my 87 Blazer not to start all of a sudden. I got really great help from this forum and I hope this will help someone else.

Having chased down all the leads here in 2 forum threads (#48533 & #50354) everything checked out (without advanced tools) but I kept hitting absolutely NO GO! A mechanic friend told me about the ECM-B fuse causing this problem on another Blazer he had worked on - which was fine on my truck - but right next to it is the ECM-1 fuse = and that was way blown!

Scouting around here and googling for 'ECM 1 blown fuse' for this model I found this post:
http://wiki.answers.com/Q/ECM1_blowi...991_S10_Blazer

And that was exactly the problem - someone years ago had mashed the rubber connection on the positive lead off one of the throttle body injectors and it had finally worn/melted through shorting out to ground on the air cleaner housing. So I spliced and insulated that back together, replaced the fuse, truck started right up! Total cost (not counting my educational labor!) less than a buck!

So I hope I put enough keywords in this to help someone here find this possible solution directly - all our problems should be so simple to solve!

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