84 carrera wont start

[j9carrera]

New to this awesome forum.
Just picked up an 84 carrera coupe, sunroof. Owners son left sunroof open, flooded ECU, car would not start. Dumped car, I bought it. Just installed new ECU unit and no spark or fuel.

Need to replace something else? Relay, I have looked at tons on the forum that could be checked, but what is the most logical one, considering the car ran before the water incident?

Also, I was taking out this fancy alarm system from the car and may have cut out a wire that goes to something important. I put this red wire to power and I think I heard a whirling sound from the fuel tank. Is this is the fuel pump power line? If so, where does it go on the fuse block? What is the best manual to buy for this car?

Thanks for any replies.
dab

[Zef]

Ho...So reconnect that power red wire and retest...And welcome to the board...Waynes 101 projects and the Benthley are the books to have...!

[Zeke]

Yes, sounds like the alarm had a fuel shut off. +1 on the Bentley, but it's pricey. For basics (and, surprisingly, more) a Haynes is good. 101 is good all around, not Carrera specific. There is a relay under the seat and it likes to fail even w/o water. Look into that. In fact, buy one to swap in. You'll need it sooner or later, even if the current one is good. Most Carrera owners keep a spare in the car.

Be careful about connecting wires hot.

[mackskibum]

You may need a wiring diagram to pinpoint how the alarm was installed. When operating properly the fuel pump does not run unless the engine is cranking.

1. Check that you have power at the ECU- key on.

2. Check that you have power at the fuel pump while cranking engine.

3. check for spark and injector pulse.

If you have all of these, the car should run. You are missing one of the above due to another failed item or the modified wiring due to the removed alarm.

FYI, there are pages and pages of info on how to troubleshoot Motronic injection, as well as "workaround" ideas for testing. Try the search function.

Welcome to the forum

[j9carrera]

Thanks for the help guys, on what fuse block does the red wire for the fuel pump go, or should I get the manual and look it up?

[j9carrera]

So....the fuel pump does not need power after the engine starts or does it need power when the motor is running? Just thought of this Q after reading reply from mackskibum.

[SoCal70RSR]

This is wiring from an '85 so it should be the same. The DME reg/green wire goes on top of fuse 6 couting from left to right as you look straight at the panel (as in the picture). The fuel pump wire is on the bottom. At least that's how mine is wired... but then again... my car is not running yet (long term project)

[mackskibum]

The fuel pump does need power when the engine is running. It just does not run until it sees a signal from the reference sensor- that is why it doesn't run with just the key on.

All of this is controlled by the ecm.

[DonMo]

must have dme relay working to make up power to fuel pump. I say buy a Bentley's also. Best $85 I ever spent. It has a good diagnostics for DME.

[j9carrera]

I can thank everybody for the comments.
Does the dme relay control the spark also, I dont have spark from the plugs., Thanks,

I will be working on the fuel pump re wire after I get the manual and the new relay.

[j9carrera]

One more question, the oil pressure guage is at stuck at the high point of the number on the guage, that is , is showing there is oil pressure with engine off, part of the dme relay issue....? Bad guage.
Thanks again for all the help.

[tonythetarga]

Originally posted by j9carrera
One more question, the oil pressure guage is at stuck at the high point of the number on the guage, that is , is showing there is oil pressure with engine off, part of the dme relay issue....? Bad guage.
Thanks again for all the help.

check the oil sender on the motor or the one on the tank in the right rear wheel well. Typically it is either the ground in the wheel well or a bad sensor that pegs the gauge.

[j9carrera]

Thanks everybody, will post the results from this weekends work next week, thanks again,

dab

[boyt911sc]

Originally posted by mackskibum
The fuel pump does need power when the engine is running.

So what kind or source of energy drives the fuel pump when the engine is running? As far as I know, 911 fuel pumps are driven by a small electric motor and needs power to operate. So please help us understand the above statement. Pardon my ignorance because I don't buy it. Thanks.

TD

[futureboy]

subscribed (sorry, nothing to offer - good luck j9carrera).

[SoCal70RSR]

The DME relay sends power to the fuel pump at cranking and while started. There is a power cable from the DME/Relay straight to the battery. Because of this, the dme relay can then send power to the fuel pump.

[mackskibum]

I just thought of something- did the car have a factory alarm? If so there may be some wiring that needs to be "modified" in order to bypass the alarm module. Look for the key hole in the driver's door jamb.

Also, check the two reference sensors in the engine compartment-maybe one of the plugs is loose.

[450knotOffice]

j9, welcome to the forum. You are seeing how helpful so many people on this board are, which is why it's such a great resource.

Good luck with the problem. I'm guessing the clipped wires are your issue, along with a possible DME relay needing replacing. The relay sits right next to the DME and as Milt said, can fail without warning, so you should buy a spare anyway. When they fail, the car becomes a 2700 pound paperweight, which is why most of us carry the relay and a wrench in the glovebox.

Show us pics of the car, btw. That's a tradition around here.

[j9carrera]

Thanks for the help everyone,

MACKSKIBUM: Yes has factory alarm, dont have key for the lock in the door jamb, any help with what wires, where they went, etc. I need to check out the current issues and replace the dme relay first, maybe the problem will be gone.

Also, does the dme relay give spark to the plugs, no spark or gas on trying to start, thanks, dab

[mackskibum]

J9- i happen to have the underhood area apart right now. I can take a photo of the alarm module and mods to get around it- that might help your issue.