1987 f150 4.9l. air pump removed.
Long story! I siphoned some bad gas from my non-functional rear tank to my front tank. made it run like crap, misfire like crazy. have YouTube of it. siphoned tank put in fresh gas and this where it gets weird:

after siphon still misfired:

New plugs, wires, cap

changed fuel filter, no change

took out injectors: 1 ohmed bad with MM

cleaned all injectors using 9v compressed air and berrymans

reinstalled injectors; still missing

took out injectors 2 ohmed bad, bought 6 remaned.

AFTER THIS CHANGE I CANNOT GET IT TO START. JUST CRANKS AND OCCASIONALLY BACKFIRED

​​​​​​Still nothing. Checked ignition system. wasn't getting consistent spark;

changed distributor to rule out pip and TFI

no change.

​​​​​​Won't run with Ether.

tried jumping fender solenoid, nothing.

rotor turns when manually rotate crank and after several turns timing mark and Plug 1 still line up

help? any suggestions. my baby has been down for almost 6 months

 

Gotta be a spark or timing issue if you can't start it with fluid. Ignition coil replaced? Verify a nice blue spark all the way to the plug?

I don't think it is fuel related, but, do the new injectors hold pressure? Have you measured fuel pressure on either tank?

 

idk if it helps but I checked my compression on them and they were all good. idk if timing would mess with those numbers. also had good fuel pressure.

is there a way to check the coil besides a open air gap spark tester? I'm laid off right now so it's a bit tough.

wouldnt timing gears failure be evident when I manual crank engine because the gears would slip and throw off the timing mark to Plug1-rotor line up? I'm kind of a newbie.
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thanks so much I've been posting and fighting about this for months.

 

remove the distributor cap and watch it while cranking...the rotor should turn smoothly...If it does, then pull a plug, stick it back in the wire pocket, lay it against the engine, grounding the threads of it and watch for a nice spark...

this will prove spark and then timing gears are turning without buying more gear.

bests

 

rotor turned with the starter. got a spark, didn't look as blue as I'd like, but it still sparked. I'd assume enough to catch.

 

How are you using the starting fluid ?
Remove the intake hoses from the throttle body, With the throttle plates wide open, fire a 3 second burst of starting fluid directly into the plenum (upper intake).
Turn key.

 

yeah had a buddy spray it with intake tubes removed from TB. did short spray, got irritated and sprayed like a 10 second burst

 

here's some videos of when it was running before it stopped. exhaust: https://youtu.be/2Ioxsuk3YoU engine compartment: https://youtu.be/O0osYRm1bEI

 

If a spark isn't a good blue in open air, then it may not be strong enough to jump the gap when under compression in the motor. Here is a link to a previous post made many moons ago, containing the resistance specs for the coil. https://www.f150forum.com/f10/1995-4...31/#post305996

Suggest if you had a timing chain/gear problem - the motor would sound goofy turning over - loping and irregular.

 

if I attach a video of it cranking can you let me know if it's timing gears? this is my first truck. mostly worked on small engines. any possiblity of a stripped cam gear?