Fuel Injection problems, strange Options

[86motoman]

I have a fuel injection issue. I bought the car not running. It has djet (?) Fuel Injection. It hasn't run for about five years, though they said it was running when it went in the garage.

It does start and run, but strangely it seems to run after I unplug the fuel pump relay. The fuel pump relay is mickey moused. Meaning it has a hot wire coming from the coil and wrapped around one of the relay posts and then plugged in. Without that wire the fuel pump does not turn on.

With the fuel pump running the car does not want to start. After unplugging the fuel pump relay it starts good and runs good for a few seconds.

I know little about fuel injection but am willing to learn. I really want this to work for me. I have a multi-meter. What should I check first?

[Dave_Darling]

If the car has a 1.7 liter or a 2.0 liter engine, it's got D-jetronic FI. Look for a silver "hand grenade" thingie over on the right-hand side of the engine bay, with one vacuum hose and one four-wire electrical connector plugged into it.

If that's what you've got, check at http://members.rennlist.com/pbanders for all the D-jet info that exists, just about. There's a link there for a troubleshooting flowchart for the fuel pump...

--DD

[lapuwali]

When you say it won't start, you mean it will crank but not fire? I'm guessing that the jury rigged wire is grounding the coil. Try running a wire directly from some source of switched +12 directly to the fuel pump and see if it will run that way. Make sure the wiring at the pump itself is correct (not reversed). If you can get it to keep running, then go through the wiring around the relay board and do it up properly. There are plenty of wiring diagrams and relay board diagrams on this and the Pelican boards to guide you, as well as the Haynes manual.

While you're there, take a very close look at all of the rubber hoses from the tank to the pump to the injectors. If it's been sitting like that for some time, chances are good the lines are old and cracked, and can easily leak fuel. High pressure fuel and dodgey electrics mean very nasty fires.

[86motoman]

I found the hand grenade thingy with a hose and four wires so I do have the djet for sure.

I am checking the flow charts now.





It does crank fine. With and without the fuel pump running. The wire that is jerry rigged is a hot wire from the positive side of the coil running right to the bottom end of the relay. Wrapped on a post of the relay.

I disconnected it from the coil and went straight to the positive side of the battery post. I confirmed it would start and run well (for a few seconds) with the fuel pump off. As soon as it started to die I could keep it running by firing up the fuel pump for about a second and then pull it off. If I left the fuel pump running while the engine is running it would die in a matter of about a few seconds. Along with starting to spew black smoke. Appears to definitely be flooding the engine.

[Mike D.]

Fuel injectors are stuck open. you can pull them out and soak them overnight in gasoline. While they're soaking you should try to find out why power is not getting to the relay board; fuses, bad wire, ect.

good luck,
Mike D.

[86motoman]

Fuel injectors are stuck open. you can pull them out and soak them overnight in gasoline. While they're soaking you should try to find out why power is not getting to the relay board; fuses, bad wire, ect.

good luck,
Mike D.

Right on, I will do that.

The flow charts are very nice...it looks like I have a lot of work to do!

[mike_the_man]

Check Brad Anders site. It could be that the Manifold Pressure Sensor (MPS) is not working. Thats the grenade looking thing. If you have a vaccum pump, pull a vaccum on it and if it leaks, its defective. A leaking MPS can cause the car to run really rich. Also, it could be a bad Cylinder Head Temp sensor (CHT). All of this is explained on Brads site, with trouble shooting procedures.

Good luck, and keep asking question.

[bondo]

It could also be a stuck pressure regulator or kinked/plugged return line. Easy to check with a fuel pressure guage. Stuck injectors are probably more likely though.

[86motoman]

I believe I have ruled out the stuck fuel injectors. I currently have the pulled but before I did I disconnected them from the intake but left them connected to the fuel line and electrical. had the key turned on. They all gave a little spurt when the key was turned on and then nothing. I then had the engine turned over for just a second and they did pulse while the engine was turning over. So if I understand the system well enough, I believe it is not the fuel injectors stuck.

Before I replaced the fuel tank I tried to start the car by using a couple bottles full of gas. It was circulating, or returning, gas back to the tank. Does this rule out a plugged return line or stuck pressure regulator?

I don't have a vaccum pump to test the manifold pressure sensor. I will see if I can suck on the end to tell if it is leaking. I am not sure if that will be accurate or not...but I'll give it a shot.

I have noticed that there is a wire broken. Not connected to anything. It is a sensor to the cylinder head. Is this the cylinder head temp? Maybe my problem. I didn't see where it was suppose to go...I'll keep looking.

[bondo]

You found it! That wire is quite necessary. The sensor is near the spark plug on the right rear cylinder, and you probably need to take off the air cleaner and move some hoses to get a good view of it.

[phantom914]

You found it! That wire is quite necessary. The sensor is near the spark plug on the right rear cylinder, and you probably need to take off the air cleaner and move some hoses to get a good view of it.

Or the sensor could be on the front left cylinder if the heads were swapped like mine apparently were. <_< Then the wire might not be connected because it didn't reach. The connector the sensor needs to be connected to would be near the right rear cylinder on top of the engine tin.


Andrew

[86motoman]

Right on!

It is on right rear of the engine. The wire is snapped off and I don't see where it plugs in. I will pull out some references.

[john rogers]

Sounds like someone has jumpered the fuel pump relay with the extra 12 volt wire. I'd say check the fuses on the relay board and their connectors, probably replacing the fuses anyways. You could also try another relay or put it in the headlight relay socket to see if the light pops up and see if it is good? When you turn on the key the pump should only run a second and then stop and then run when cranking. You can also check the voltage to the inlet of the relay with a volt meter when someone turns on the key to see if you get a jump. Good luck.

[lapuwali]

Excellent. Yes, the CHT regulates how rich the mixture is during warmup, and with it disconnected, the ECU thinks the engine is very, very cold. So, the mixture is set very rich, and the engine will die as soon as it warms enough. Cylinder head temps rise pretty quickly (like 30 seconds of idling to get to normal temps from dead cold), so the engine won't run long.

Sounds like you have a fair amount of rewiring work to do.

[86motoman]

Does the cylinder head temp sensor just ground on the tin anywhere?

[lapuwali]

It grounds on the head. If you find where it's supposed to connect to and ground that connection, you'll get a full hot reading. Will be difficult to start when cold, and will run like crap until it warms up, but that's also a solution if the sensor is shot until you get another sensor.

[86motoman]

Sounds like someone has jumpered the fuel pump relay with the extra 12 volt wire. I'd say check the fuses on the relay board and their connectors, probably replacing the fuses anyways. You could also try another relay or put it in the headlight relay socket to see if the light pops up and see if it is good? When you turn on the key the pump should only run a second and then stop and then run when cranking. You can also check the voltage to the inlet of the relay with a volt meter when someone turns on the key to see if you get a jump. Good luck.

Nice Job! One of the fuses were corroded horribly. Worst I have seen.

My pump doesn't seem to quit running. It just keeps running as long as the key is on. Is this because it is running off of the jumper wire?

[86motoman]

It grounds on the head. If you find where it's supposed to connect to and ground that connection, you'll get a full hot reading. Will be difficult to start when cold, and will run like crap until it warms up, but that's also a solution if the sensor is shot until you get another sensor.

This is good to know. I am learning a tremendous amount here. This is giving me a lot of confidence in my capability to keep the 914 as a daily driver.

I am still looking for the wire that connects to the cylinder head temp sensor. I haven't been able to find it anywhere in the book or the web. (IMG:style_emoticons/default/wacko.gif) Where does this hot wire come from? The ecu, wiring harness, etc.?

[bondo]

If I remember right it comes out of the harness on top of the engine somewhere. They have a tendency to get brittle and break off right where the come out of the harness, which may make finding it hard.

[john rogers]

If you jumper pins 30 to 87 on the relay or run 12 volts to the relay as you have, the pump will run when ever the key is on. Is this good or bad? Depends since it goes against the factory deign it is not good and if you leave the key on you could have fuel leak past an injector(s). The only advantage to this is to have the ability to know the pump is actually working before cranking so the car will start. Some say you need to do this to be able to push start a D-Jet 914 but not true. Good luck