[mghamms]

I have a 1987 spider that died on the way home from work.
Got it towed to my house and started looking for the problem.

Ecu, fuel pump, relays,fuses and air box changed with know good units 1 at a time.
Tested the fuel injector wire with a nod? tester and no signal from ecu.
battery good 12.5+ volts
cranking volts 10.5+
Low volts to fuel pumps was 8.5 I fiddled under the dash looking for the wires that go to the ecu fuel pump and now 0 to .5 volts at the fuel pump.

Any ideas why to low 0 volts?
What could be under the dash that could effect this?

Also probably unrelated ? I have low volts to my windshield washer pump under load but 12.5 v with the pump disconnected. the pump is new and works fine.

HELP PLEASE

 

[Con Gusto]

Did you check the inline fuse under the parcel shelf near the ECU? It is an 8A bullet fuse along the wires leading to the ECU (not with the general fuse block under dash). I had one of these blow on me on my '89 recently.

 

[mghamms]

yea fuse is a ok

 

[Tifosi]

Dunno about the no start, but:

Ecu, fuel pump, relays,fuses and air box changed with know good units 1 at a time.

Seems a bit excessive a way to go about it but I suppose if you've got the stuff laying around and none of the more conventional diagnostics stuff worked. :shrug:

Tested the fuel injector wire with a nod? tester and no signal from ecu.
battery good 12.5+ volts
cranking volts 10.5+
Low volts to fuel pumps was 8.5 I fiddled under the dash looking for the wires that go to the ecu fuel pump and now 0 to .5 volts at the fuel pump

Cranking volts needs to exceed 10.5 for the ECU to come online.
Fuel pumps only run for about 1/2 a second upon turning the key from off to on, then remain unpowered unless the key is turned to start (then de~engergize again if the engine doesn't catch and the key is returned to run) or the engine is running.

The pumps will do the 1/2 second run thing regardless of the ECU as they are tied to the ignition (coil specifically) for thier activation, not the ECU. Basically the fuel system is seperate from the ignition system and injector system other than the last link in the chain that follows:
The coil comes on and pulses (field collapse) when plugs fire, the drive relay comes on when the coil pulses, the the pumps come on when the drive relay comes on, the main relay comes on when the drive relay comes on, the main relay powers the injectors and the ECU then controls the ground for the injectors to fire them.


Per Con Gusto's referencing the fuse under the panel and the reply that its good, if you've not actually changed it with a known good NIB piece that you bought recently, don't count on its appearance or ability to pass a multimeter check as actual fact that its a good fuse. The older ones, especially the silver strip type (as opposed to the copper strip ones) can have a nasty habit of looking good and even checking fine, right up until voltage is put to them, they warm up a bit, and the hairline crack it grew a week ago opens up and breaks continuity.

Shotgun approach:

As you say you changed the pump, what is the condition of the ground wire?
How about the wires in general on the pump?
Does the in~tank pump have the same voltage issues or is it strictly the main pump?
What is the condition of your charging system?
Ground wire by the ECU?
What is the condition of the two flywheel sensors? (ignition related. no sensors = no ICU = no coil = no drive relay. no drive relay = no pumps & no injector power)
Ground wires on the cam cover clean and tight? (ECU related. no ground = no ECU = no injectors firing regardless of fuel flow)

Tests for various items in your system, including the flywheel sensors, can be found by clicking the L-jetronic diagnostics link in my signature block.