No crank after pulling apart tan wire........

[RUN GMC]

So I was driving my pride n joy today when all of a sudden the idle started stumbling to a rough idle..... I was able to drive it home after I stopped and put in some Sunoco premium gas......after getting it home I left it running and retrieved my timing gun to check the timing which showed it to be at about 14 degrees advanced give or take 1 degree or two.....so then I decided to pull apart the tan/white wire on the fire wall to adjust the timing like I ve done before.....upon pulling it apart the tan/white wire it killed the motor at idle and when I went to crank it I got nothing at all....plugged the tan wire back up I still got nothing.....I disconnected the negative to the battery for one minute to reset computer and reconnected it and went to crank it.... it would turn over but not fire up....repeated the process again still no fire......plan to place #1 cylinder to tdc, check orientation of distributor and try to crank it as to try set/check timing again..........the question is has anyone been through what i described ...the distributor is two months old, tps is new, egr is new, ......has anyone had to replace their tan/white wire that you disconnect to set timing.........any help would be appreciated....thanks in advance..............

[franken]

Sorry to be the punctuation police, but that's simply unreadable gibberish.

My recollection is the tan wire is the brake light, but that wouldn't impact cranking.
Might try checking if lights work, and move to measuring voltage to ground. The solenoind controls the starter and needs 12V on the S terminal (and ground) to switch the starter.

[Shady Rascal]

The tan wire he is talking about it used to put the truck into base timing mode so you can adjust your timing. When you reconnect it, the ECM takes back over timing duties.

Original poster, start with checking for spark.

If you do have spark, spray a good shot of carb spray or starter fluid down the throttle body and try and start it.

Off the top of my head, I'm guessing your fuel pump was dying, hence the poor running, then it finally gave up coincidentally when you were messing with the tan wire. The above spark check and spray in the throttle body will show you where the problem lies.

[Dead Parrot]

Any chance that while you were messing with the tan wire that you accidentally disconnected an unrelated connector? Elbows have wondrous trouble causing powers.

[RUN GMC]

Thanks for the responses so far.....first i was in a hurry typing so i could try to get some input on my situation.... I should have proof read my posting (sorry)....I did go over it and corrected errors and punctuation miscues......

Shady Rascal......just got though testing for spark at #1 plug and coil all was good there.....will do the carb spray in a minute but i can do one better for now thanks to your input.....my truck has working dual tanks sooooooooooo.......I will switch to the other and try cranking it again......it never occurred to me to do that.....doh......

Dead Parrot it runs around to the master cylinder where the connection is made on my 87 GMC..... did check wire for any bad spots or breaks and didnt see any at all......and I didnt knock anything loose from what I could tell but will look again......

......now headed out to garage to try other tank first then carb spray, if fires it up I will replace fuel pump relay module since I have a few new spares thanks to Rockauto Clearance emails.....I have stocked up on a few parts for the GMC......back in a few......

[RUN GMC]

Okay switching to the other tank was a no go didnt change anything.......so I swapped to a new fuel relay still a no go.....also noticed Im not hearing the pumps prime up by turning on ignition.....spray in the carb and it stumbled and try to start......so is it odd that both pumps wont run when the used to.....does dash selector switch fail and take out both pumps .......preparing to check wires under dash near ash tray.......I install a new gas tank diverter valve under the truck 2 months ago due to a bad gas leak.....I will keep you guys posted.....thanks again.....

[mongocanfly]

Fuse?

[RUN GMC]

Okay narrowed it done to the dash switch or the oil pressure switch on the back of the motor......while update later..........

[RUN GMC]

Lol I like Blazing Saddles........well didnt have a oil pressure switch so i messed with the dash tank selector switch saw nothing wrong from what I could see of it.....then pulled off plug to oil pressure switch was dirty with back of engine grime....as i laid across radiator to clean oil pressure switch plug I noticed that the tan/white wire was not together since i had reset ecm with pulling negative battery cable.....finshed cleaning off plug to oil pressure switch then reconnected tan/white wire......gave it a try and it fired up ......then I went and got timing gun and connected it.....rotated advance till I got back to zero it read 21 degrees....so then I let it warm up and put back on air cleaner and air hoses......shot the timing again tweaked it to zero and got 24 degrees......sounds nice but with the gun I see( and hear it too) a miss in the timing where it would jump for a second and then return......so I just ordered new plugs (NGK) on Advance Auto online and will install them tomorrow with a set of brand new Taylor spark wires I have on the shelf...........so i guess it was operator error from what i can tell on my part.....thanks again everyone for indulging me in this mental episode i had........

[mongocanfly]

Sometimes its the simple things..