1987 1/2 ton silverado no start 460k miles og

[Jheald65]

Ok , so I worked til it got dark and had a rather odd finding, long story short , I put the old fuel pump relay back in , now .. when the keys turned on , the right pump comes on and cycles for 2-3 sec, and shuts off ... turn the key off , switch the tank selector switch , turn the key , the other pump does the same ...... just like it’s supposed to .....?...... I changed nothing .... but I put gas in the throttle body and tried to fire it up but it won’t fire ,... done for the day , battery is in the charger, I’ll tomorrow...

[Irish_Alley]

Honestly I think you're going down the wrong path. If it was a fuel related issue it should have started on starting fluid

[Jheald65]

I agree

[roundhouse]

You've verified that the pump is putting 12 psi of gas at the TBI with a pressure gauge ?

Purchase a noid light and verify that the computer is telling the injectors to squirt

https://shop.advanceautoparts.com/p/otc-gm-tbi-noid-light-otc7187/17632201-p?c3ch=PLA&c3nid=17632201-P&c3apidt=27667980540&gclid=EAIaIQobChMIsrX2ou-e1wIVSGV-Ch2-vQncEAQYASABEgLtGvD_BwE&gclsrc=aw.ds

Timing chain ever replaced ?

If the timing chain gets worn and jumps a tooth or two it will spin over but won't run

An engine needs compression , proper amount of fuel , and spark at the right time

Put a fuel pressure gauge at the TBI , to verify that the pump is working right

Put a noid light on the TBI

And check the compression with a compression test gauge

Post up the numbers you find with the psi and compression

Do NOT use a normal test light at the injectors
The injectors always have 12 Volts and the computer grounds them to make em work

You can buy a LED test light that's safe for using with computes but that usually doesn't work with injectors since the electricity pulses so fast

[bd]

I wondered how long it would take to come back around to this.  Earlier, you claimed to have spark and fuel.  With 460k miles, do this before investing any more time or money in other tests... How to Evaluate Timing Chain Condition.  Scroll down to "Checking the chain."  If valve timing is far off, the engine will play dead.  Everything else is subordinate.  Under the circumstances, only after you verify valve timing should you proceed with other tests.   

[Irish_Alley]

You know be after you posted the idea of the timing chain I was pretty sure that would solve the problem. But for some reason I forgot about it and was helping trouble shooting a fuel issue which I was sure from the beginning wasn't even the issue since it didn't run on starting fluid

[bd]

I walked into a very remote, long abandoned mine out in the desert early one Summer, being very attentive to watch for aging dynamite, rattlesnakes, rotted shoring, loose ceiling blocks, camouflaged raises and other fatal surprises.  It was very bright outside, shortly after noon.  I was studying the mineralized veins oriented along a fault which the drift followed.  After about fifteen minutes I became troubled, because my eyes simply wouldn't adjust to the low light.  Even using a bright flood, I struggled to see and became really agitated as I began to worry I was going blind.  Eventually I gave up and exited the mine.  As I walked outside I realized I was still wearing my dark glasses.  They were quietly riding the bridge of my nose and I hadn't a clue.  So, I know exactly what you mean....

Of course, there's no assurance that valve timing is the culprit.  It needs to be checked.  But, if it isn't the cause, it oughta be.      Haha!

[Irish_Alley]

just like my quote from S.H.

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

[roundhouse]

I used to have a truck that wore out the timing chain and would jump time about every 10-12,000 miles , or about once a year at the rate I drove it

I got pretty good at changing it .

I was penniless at the time , couldn't afford a new engine ,

The crank bearings were so worn out you could see the crank pulley move when you pushed in the clutch
And you could see the oil pressure spike on the gauge when you took you foot off the gas suddenly and changed gears
Because the crank would move up in the  block

[VileZambonie]

Was her name Lucy? 

Crank no start simple checks: spark, fuel, ignition timing, mechanical timing, compression.

[Jheald65]

Thanks for all the advice.. I’ve been out of the state , and coupled with bad weather have detoured the assessment process ... I’ll be back on it in a couple days ... and will share my findings

[jetman]

Put a compression tester on 'er!  The suspense is killing me..

[Jheald65]

The only operation I had time to do today was to check the elongation of the chain as specified in the link ...
I have degree marks on the timing tab , and when rotated counter clockwise , I get a solid 8 degrees of movement before the distributor rotor slightly moves..
I repeated the test 2 more times and got the same results

[VileZambonie]

You are going about this all wrong. Follow these recommendations previously mentioned:

Crank no start simple checks: spark, fuel, ignition timing, mechanical timing, compression.

As in validate consistent spark from the coil wire and at more than one plug wire. Validate that you have injector pulse. If all is good, validate fuel pressure. If good, check compression. That's all you need to do to determine where your problem lies.

[Jheald65]

Thanks for all the help