1990 b2 wont start

[jstann]

So i got this truck last year about this time .. guy said it wouldnt run for him . So i put a batery in it cleand some conections and it flashed right up drove it for a few months no prblms sat from easter till sept . Went out started it up and it was running like junk . So i put a new fuel filter cleand the injectors new plugs cap rotor and coil .. still had a miss but it was good enough to drive .. well last weekend i got in it and the battery was dead .. so i jumped it and i could hear the fuel pump run with the key off but it started .. drove to town and it died keyed it on and of a bunch of times and it wouldnt run for a few min then die did it a few more times and then got a buddy to tow me home .. stzrted messing with it checking grounds and conections had 2 injectors unpluged and it would start pluged them back in and it would run till you reved it up and it would die .. pump still runs with the key off ..

Any ideas?

 

[RonD]

Fuel pump relay is most likely stuck closed if fuel pump runs with key OFF
Relays have a spring inside that holds them open, if spring breaks then they are closed all the time

Fuel pump power at the Relay is 24/7(all the time), direct fused connection to battery Positive
So if relay fails closed then fuel pump would run all the time
Relay should be OPEN key off.

Locate fuel pump relay, in 1990 it could be on the underside of engine fuse box.
It will have a Green Base(plugin)
Battery is unhooked I assume
With Key OFF, unplug that relay from it's base
Hook battery back up
Plug relay back in, it should not "click" or make any noise when plugged back in because it is bad relay(stuck closed), but fuel pump will come on.
Replace relay
If relay "clicks" then relay is OK, it's wiring is the issue, this relay gets 12v from EEC relay next to it, Brown base, EEC relay closes with key on, it powers EEC(computer), fuel injectors and spark, along with FP relay.




The TFI modules are known to cause problems as they get older, i.e. as engine/TFI module heats up spark starts to fail, warm engine No Start, is a symptom of that.

 

[lil_Blue_Ford]

RonD nailed it. Start there and report back.

FWIW, Autozone will test TFI modules for free. Make sure when they run the test that they run it a couple times in quick succession to warm up the module. I’ve seen them pass the first test or two only to fail miserably on the rest because the module warmed up. The module is located on the distributor unless someone relocated it and requires either thin wall sockets or a special tool to remove


Sent from my kite using a trebuchet