: 1985 4-Door Brougham Fuel Injectors



Justsomeguy
05-25-13, 06:11 PM
Fuel is not getting into the engine. We removed the injectors and when we turned the key fuel is making it TO the injectors, because it spilled out all over, but it stops there. With everything in place the car won't turn over, so the gas is making it to the injectors and no further.

Using a 6-12V test light we checked the power going to the injectors and found that the positives are always hot, but the ground which we were told is supposed to pulse does not come on at all. It was suggested that the current is less than 6V, so we need a smaller tester to see it and that it is in fact pulsing and that the problem is that the injectors are clogged from sitting for so long. But even if the current is under 6V shouldn't it have at least made the light come on dimly if there was any power?

So, seeing as I already know that the injectors need to be replaced if it IS pulsing and we just aren't seeing it, my question is this:

If we test it with a tester that can pick up smaller voltages and find out for sure that it is NOT pulsing, what could be causing this lack of pulsing?

Our first guess was the ECM, but everything else the ECM controls is working, so is it possible for just this one function to have stopped working or is it something else? We've already checked all visible wires under the hood and don't see any that appear torn, loose, or chewed.

We checked the fuse box under the steering wheel, but none of the fuses specifically say "Fuel injectors" despite the fact that everything else is labeled and I don't have a specific diagram for this exact model's fuse panel, so I'm not really sure which one to be checking.

Thanks ahead of time for any help you can offer.

(On an unrelated note, I have gold painted keys. Is that standard issue? This is my first Cadillac)

jayoldschool
05-25-13, 08:23 PM
Gold keys were optional. I would suggest picking up the Factory Service Manual for your car. It will have trouble shooting flow charts for the work you are trying to sort through, and can save you a lot of time. You can check all of your fuses without removing them in less than one minute by probing both sides with a DVOM set to beep for continuity.

http://www.ebay.com/itm/1984-Cadillac-ELDORADO-SEVILLE-FLEETWOOD-DEVILLE-Shop-Repair-Service-Manual-FE-/350672390092?pt=Motors_Manuals_Literature&hash=item51a5b407cc&vxp=mtr

Justsomeguy
05-26-13, 12:38 AM
Gold keys were optional. I would suggest picking up the Factory Service Manual for your car. It will have trouble shooting flow charts for the work you are trying to sort through, and can save you a lot of time. You can check all of your fuses without removing them in less than one minute by probing both sides with a DVOM set to beep for continuity.

http://www.ebay.com/itm/1984-Cadillac-ELDORADO-SEVILLE-FLEETWOOD-DEVILLE-Shop-Repair-Service-Manual-FE-/350672390092?pt=Motors_Manuals_Literature&hash=item51a5b407cc&vxp=mtr

Will that particular one work for mine even though mine is an 85, or was that just supposed to be an example of what I need?

SafariOne
05-26-13, 03:23 AM
Injector circuit is not in fuse panel, it is in the relay convenience center. There will be a 3 amp. fuse for each injector.....Are you getting any codes coming up on the DIC center??

jayoldschool
05-26-13, 12:48 PM
Sorry, yes, that one will work, but buy the 85 one, there will be examples on ebay.

The Ape Man
05-28-13, 07:58 PM
If both injectors have power for a test light the pair of 3 amp fuses should be OK. The ECM gets an ignition signal form the ignition module.

Trouble trees are best way to go.

Vladillac Khrougham
05-29-13, 01:19 AM
It may be better to use a digital multimeter (http://en.wikipedia.org/wiki/Multimeter) (around $20 at Radio Shack or hardware store or even cheaper if available at a pawn shop or more rarely a thrift shop), you can obtain accurate voltage readings and also I think I remember something about using a test light on a vehicle equipped with an ECM can possibly damage the ECM under certain circumstances unless the test light is rated as "computer safe".

Also buying a GM shop manual that covers my specific year model (91-92 Brougham) is one of the, if not most useful tool/accessory I ever purchased for this car, buying one sooner would have saved me a LOT of headaches, frustration, money and time. Plus in is almost infinitely more useful than the vague Haynes manual that is much thinner and covers all rear wheel drive Cadillacs from 1970-1993 (1993?) and I got mine used (it looked brand new when I received it) on amazon for around $20.

Justsomeguy
05-29-13, 01:48 AM
Sorry about the delayed reply, I was distracted on the road of life.

I ordered the manual but it'll be a while before it gets here.

I found the FI fuses in the relay panel(Was looking in the wrong place the whole time, d'oh) and replaced them all. I figure even if they weren't bad, the car has been sitting for a while so replacing them can't hurt.

I went ahead and rented the Noid Lite to test the fuel injector harnesses, and it blinked as it was supposed to meaning they are getting the correct power.

When I turn the car on I get every error message(No battery, no gas, etc. even though it has a battery and gas), but I can't actually START the car, so I can't tell if it's just doing the "you just turned me on so I'm testing the error lights" thing or if they are actually problems.

j2rossit
05-29-13, 07:42 AM
have you taken a fuel pressure reading?

SafariOne
05-29-13, 11:45 AM
Do you know how to pull the codes from the climate control center????? That can steer you in the right direction. Can you hear the fuel pump running when you switch on the ignition????

j2rossit
05-29-13, 11:57 AM
He said that the injectors were getting fuel, so I'm guessing the pump is running. But I'm wondering if it isn't putting out as much pressure as the injectors need.

Justsomeguy
05-31-13, 06:10 AM
I was going to rent a fuel pressure gauge to get it tested, but they want $150 just to rent the thing, and all the car guys I know told me not to worry about it anyway because they were sure it wasn't a pressure issue(They all think the injectors are clogged from sitting so long with bad fuel in the tank).

carnut
06-01-13, 02:01 PM
The 2 injectors should spray as the engine is cranked over for a few seconds. This is an 85 rear wheel drive? The injectors receive power from the oil pressure switch, If no pressure is read by the ECM, the fuel pump shuts off. Check the harness at the oil pressure switch at the oil filter for being secure. The fuel pressure is less than 11 LB so a weak fuel pump or in tank filter screen clogged can lower it enough not to start.

j2rossit
06-01-13, 03:57 PM
The Brougham is RWD.

If the injectors is powered through the oil pressure switch, wouldn't it die if the pressure switch doesn't register any pressure? I know that it doesn't

carnut
06-01-13, 09:31 PM
A faulty harness or failed oil sender would allow a few seconds of spray while the engine cranks over then shuts them off. Do they spray while cranking or not? I just re read this thread and it appears this engine is not even cranking over, is that true? If just the idiot lights are coming on and the starter doesn't rotate the engine why are we focusing on fuel delivery?

j2rossit
06-02-13, 09:31 AM
But I've had my oil pressure sender completely disconnected and the engine still ran.
And when the oil pump died all together, the oil pressure sender cut the circuit and the oil pressure light came on but the car kept running.
I don't understand how that could be possible if the injectors are fed through the oil pressure switch.

j2rossit
06-02-13, 01:27 PM
I just took a good long stare at my 85 FSM and came up with the following:
The oil pressure sender is a part of the fuel pump circuit. It appears that it has a "normally open" circuit that connects the positive and negative side of the fuel pump relay. So if that circuit closes, the power will short circuit through the oil pressure unit instead of the fuel pump. I'm not sure what would cause the oil pressure switch to close this circuit since closing it due to low pressure would mean the fuel pump was bypassed on start up.

I also found a fuel injector troubleshooting guide and I'll try and post it when I get the time.

----------

A quick phone call to a buddy revealed that the oil pressure switch has 2 thresholds, 1 that will turn the light on, and one really low one that will activate the fuel pump bypass circuit. So when my oil pump went, it must has still been giving just enough pressure to keep the fuel pump going but not enough to turn the light off.
It also makes sense that unplugging the wiring harness would not stop the engine since that just forces the bypass circuit to stay open.

Justsomeguy
06-02-13, 06:25 PM
If we remove the fuel injectors, the car will run because the fuel is getting -to- the injectors, so without the injectors in place the gas just spills out all over the place. But the injectors themselves are not spraying, so once the injectors are put back in, it won't start.

So from my limited perspective it seems like either A. The injectors are bad or B. whatever tells the injectors to spray is bad. Or possibly C. they are getting fuel but not enough pressure, but as I said all the car people I know told me that's unlikely.

I know they ARE getting power because when tested with a Noid Lite it did flash, so a lack of power isn't the issue.

j2rossit
06-03-13, 09:01 AM
I went through the diagnostic chart and I think you're better off waiting for your copy of the manual to arrive. There's no way I'll be able to go through the procedures properly.

Justsomeguy
06-03-13, 11:39 AM
I went through the diagnostic chart and I think you're better off waiting for your copy of the manual to arrive. There's no way I'll be able to go through the procedures properly.

Haha, that's fine. Not everything can be done over the internet.

j2rossit
06-03-13, 05:08 PM
I will tell you that it all hinges on the fuel pressure reading. The chart starts with dividing the tree up between: less than 9 psi, greater than 9 psi and less than 12 psi, and finally over 12 psi.
If it's between 9 and 12 psi and no spray from either injector, then it boils down to checking the exact voltages between the injectors to look for any imbalance. specific imbalances and polarities point to different issues with the injector circuitry.