93 4.0 crank no start

[Stutgrtguy]

1993 4.0 XLT 4x4 manual tranny

So few weekends back, went to go to work, truck started for a second then went *puh* and died. gave it a few minutes went in the house to ponder as she never ever does this, when I went back out the cab smelt bad like the air you let out of an air mattress, pop the hood no smell.
Tried again nothing.

I figure fuel off the bat so I check the inertia switch, it's fine. So then I thought fire, tested 4 cylinders all firing 3 on 1 side 1 on the other. Tested all fuses all fine. Squirt of starting fluid, she fires but won't stay goin, ok, fuel pump I guess.
So next weekend comes lets do this, pull the bed off replace fuel pump. Nothin, same deal, starting fluid it fires. test all fuses again and all relays, all fine but I can hotwire the fuel pump relay and now I have pressure, so I buy a new relay, still nothin. Put new fuel filter in,(i didnt before as i had already done it last year) Nothin. Crank no start.

So wore my battery down stuck a spare in began again, now I have no spark figure the coil pack is dead, . New coil pack fires first try and dies immediately. So try the starting fluid again fires up, dies. So I do it again and keep the truck running with fluid but once you stop with the spray she dies. Now I have a bit of smoke comin from drivers side under steering column under the hood, again it stinks like air mattress air. Check all lines for leaks and found none. Pull the new fuel pump out and hot wire it, fires up fine, test the old one fires up better than new one. Check all electrical connections again, all fine, no wires are hot to the touch and all have continuity that need to. shook all wires under the dash and pull the inertia switch off to check for continuity, all good.

So it's definately a fuel issue, maybe plugged lines from filter to fuel rail? Can I put compressed air to these and blow the lines? Do I need to break em loose before the rail or can I just blow the whole system out? If so reccomended pressure? will I mess anything up. Otherwise any suggestions on just wth this might be? I'm at a total loss, and with the tank wide open atm Ive come close to tossin a match in there, but I need my truck! so that option is out.

Anyone out there can guide me to a new direction I'll try it.

Thanks!?

 

[RonD]

You should HEAR the fuel pump run for 2 seconds with key on, each time you turn key on fuel pump should run for that 2 seconds, its not quiet, you can hear the HUMMMM from the tank

If you don't hear it then check the 20amp fuel pump fuse in the engine fuse box, test it
There is also a Fuel Pump Relay in that fuse box
To test relay find the OBD1 plug by the engine fuse box, and look here: https://www.therangerstation.com/tech_library/OBD_I.shtml

2nd drawing down is the OBD1 plug, and Fuel Pump slot is labelled
That slot can be grounded to turn on the fuel pump relay manually
So use a jumper and ground that slot then turn on the key, relay should click closed and fuel pump should be on full time, well when key is on
If not then replace that relay

The computer is in the engine bay but on drivers side down between inner fender and firewall

I would pull it out and have a look at it, it is "cooked" you could smell that in the cab
Its out of warranty so pop the top and have a look inside


Just FYI, you can't test for spark on these systems, well you can but it WILL BE hit and miss
Do what you are doing, spray fuel into the intake to test for spark, if it fires you have spark AND at the right time, so much better info than testing a spark plug wire

 

[Stutgrtguy]

Thanks for the reply but basically everything you said I have done in duplicate if not triplicate. All I got from that was check if the computer is dead.

As I said in post I have tested all fuses and relays a few times, and even replaced them just bein paranoid.

I'll yank the computer out tomorrow check it, anyone else have advice for purging out my system or is that just reachin for straws?

 

[RonD]

So the fuel pump is confirmed to be running with key on?