no power to injectors. power to cold start injector.( steady ), fuses good , bump sw ok, relays work on another car,, runs on carb cleaner, pump was working, tries to start with cold start inj at times,

 

A couple EZ checks before getting into anything weird:

- There's a white/black wire from the coil "-" post that runs aft along the water rail. This a the trigger wire for the fuel injection. Check the wire and connections

- At the rear of the water rail is a bundle of 5-6 ground wires. These are the grounds for the entire fuel injection system. Make sure none are broken and the ground connection isn't corroded

- On the RH inner fender, down low and well forward, is the resistor pack for the fuel injectors. Silver box, about the size of a pack of cigarettes. A little tricky to reach. Check connector plug and pins for corrosion.

Cheers
DD

 

The cold start injector (which operates 100% independently from the regular injectors) should have power (that is, 12 volts positive) only when the key is turned to 'start'. If it has constant power, something is amiss....although probably not related to your primary problem of no power to the injectors.

Cheers
DD

 

To clarify, since I may have misunderstood, you've verified that there is no voltage supply to the injectors? Or, simply, the injectors are not operating?

Voltage supply to the injectors comes from the 'main relay' on the firewall and thru the resistor pack.

Cheers
DD

 

changed out main relay with 2 used ones same thing. no power to injectors, no power to amp, power to cold start with key in run

 

OK, some quick voltage tests at the main relay

- White wire should show 12v with key 'on'
- Brown wire should show 12v at all times
- Brown/slate wire should show 12v with key on
- Black wire is ground

Assuming that's all OK go to the resistor pack and check for 12v at the brown/slate wires with the key 'on'

As for 12v at the cold start injector has someone replaced the red diode pack with an ordinary relay?

Cheers
DD

 

no power at amp, my helper gave me wrong info , cold start power only on crank. wires on relay white /yellow, blue /green, red/ white, brown,forgot other

 

Ignition amp?

From memory one of the wires should be white and have 12v with key 'on'

That's sounds like the starter relay.

cheers
dd

 

doug went back to shop and checked wires on relay c1 w/r, c2 brown 12v, c4 w/u nothing, w1 w/y nothing, w2 b/g nothing . you say w/y should have 12v komo. nothing . what would happen if i jump 12v to w/y? thanks for your help

 

What you are describing is the starter relay. It has no direct bearing on the fuel injection system and wouldn't account for your 'no power to injectors' problem. If the engine cranks when you turn the key to 'start', the relay itself is OK.

However, since we're here, the checks for the starter relay are:

- solid brown wire = voltage supply, 12v at all times
- black/green = should be ground with transmission in P or N
- white/red = output to starter solenoid, 12v with key turned to start
- white/yellow = trigger voltage from ignition switch, 12v with key turned to start
- white/blue = not used/needed, ignore, but should be 12v with key turned to start

On the firewall you should have the starter relay, a red diode pack (for the fuel pump circuit), the fuel pump relay, and the main relay. For a 'no power to injectors' problem you should focus on the main relay. The main relay sends voltage to the injectors and the Air Flow Meter, and powers-up the ECU. I know you swapped it out with another and there was no change but that doesn't prove that the the relay is being triggered. A couple posts back I described the checks for the main relay. Or, just check for 12v at the brown/slate wires at the injector resistor with the key on. If you have 12v here then you know the relay is being triggered

Cheers
DD

 

ok checking wrong thing , back to shop black one next to starter

 

ok now your getting somewhere. white 12v komo, black ground, brown nothing on either one

 

On the firewall there are two "+" voltage junction/distribution posts. One inboard of, and slightly below the brake booster and the other inboard of, and slightly below the battery. Your brown wire should go to one of these posts....probably the RH post but check both. Make sure the connections are tight and clean, wires are not broken off, etc. These posts are 'hot' at all times so disconnect the battery before working on them'

On these old Jags a solid brown wire will always be constant 12v "+" and, one way or the other, go back to these junction posts. "All roads lead to Rome" type of thing.

Cheers
DD

 

ok know them, will that help get power on other brown wire? thanks again

 

All the solid brown wires eventually end up at one or the other of the junction posts.....and the posts themselves are wired together with a heavy cable hidden behind the fiber-board heat panel.

I say 'eventually' because a couple branches of the brown wire circuits have splices or additional junctions....but my memory is foggy on which branches, specifically.

So, if everything is OK at the junction posts you might have to look for a problem downstream. But the posts are 'square one', so to speak.

I suggest you download the S57 Wiring Guide. It's available in one of the sticky threads at the top of this section

Cheers
DD

 

These are the "easy" wires. Start at the battery + post. trace the large cable to the firewall post. Many wires should be there. Caveat, if battery - post cable is not properly connected at the wing wall, you will have zero volts at the fire wall post.

Basic. Proper battery connections proper battery to ground connections .

And,as Doug knows these critters far better than, follow his guidance.

And, Aye, the post on the right side is connected to a similar post on the left side.

For more guidance. white wires are hot only when the ignition key is on...

Do you have the S57 Schematic. Sans it, you are flying almost blind...

I hope??
Carl,

 

i have a wiring dia but i don't think it matches car, colors diff, right on doug they had put a new battery in and messed up the wires on the post. now i have power on brown wire, nothing on other, seems to me if i have power on one wire then turn key on it should go across the relay to other brown. or am i making a mountain out of a mole hill? still no power on brown/slate. it's a 5 prong relay in a 4 wire place. doesn't make sence, but it works in the other 87 that i bowered to switch parts ,will try and get a diff wiring dia

 

None of the relays are intended to carry power from one brown wire to another brown wire.

When you turn the ignition 'on' do you hear/feel the main relay click? If not, it isn't being triggered....which means it isn't grounded or it isn't getting trigger voltage from the white wire

If it works in the other car, you're ok

A 5 prong relay in a 4 wire socket isn't a problem. The 5th terminal on the relay isn't used/need on this particular circuit.

Cheers
DD

 

got power on white wire in komo, grd wire to battery haven't ck'd to see if power on crank , lucky i live 2 miles away back to shop to see downloaded s-57 must have been a pain in a to put all that in

 

got it up and going, power kept dropping out , bump sw kept triping out and resetting ever time i closed door, bypassed and up and ready thanks doug for your help