no start problem

[84jag]

ok.i'll try that.i'm getting plenty of fuel to the regulator and fuel rail.

 

[84jag]

hey guys,got some life out of my jag today,turned over and tried to start.when it tries to start,it'll run up to 10rpm then quit.any sugestions.really close

 

[Michael J.]

Although the gas in the tank may be fresh, It might be worthwhile to disconnect the fuel line at the rail and pump a few quarts into a jar.

How does the fuel look in the jar? Clear? Cloudy? does it separate into layers?

I still think pulling an injector and testing the spray pattern will be helpfull.

Although you mentioned that the fuel regulator is alright, have you considered installing a "tee" with a fuel pressure guage to see what the pressure is while turning over the engine?

 

[84jag]

the fuel is nice and clear.i was going to pull an injector until it tried to start,it could be just the cold start injector shooting gas.i'm still not hearing the injectors or fuel pump when i turn the key.on my 280zx i heard the injectors run.whatever sends a signal to the computer to power the fuel pump and injectors i think is the problem.what do you think about the temp sensor.it seems to be connected to alot of stuff .when i hooked up the fuel pump wire under the console to a fuse it worked.the diode and fuel pump relay test for power.brand new ignition switch,fuses are good,cleaned turminals and grounds.i'll hook up a gauge to the fuel.later

 

[Michael J.]

I have attached a wiring diagram from the sheet of diagrams that is with my 87 owners manual. The smaller circuit depicted is for the fuel injection system alone.

Hope this helps.

 

[John S Farrington]

The series 3 XJ6 fuel injectors are actuated through the ECU by a signal from the ignition coil negative terminal. Make sure that the wire from the negative side is OK. The fuel injector signal wire is white and black striped along with the signal from the ignition amplifier. There is also a tachometer drive signal that is white and blue striped coming from the coil negative. These wires get heated in the engine compartment, get brittle and break.

 

[84jag]

ok,thank's.i thought the coolant sensor sent the signal.i'll check the wire's.

 

[84jag]

ok replaced the wires,they were brittle but not broke.waiting to get the pressure regulator before i try to start it again.keep ya posted

 

[84jag]

ok,no fuel coming out of the injectors,but fuel before and after the regulater.replaced the coil wires going to ecu.think its the ecu.and do the ecu numbers have to be the same if i replace it.thank's

 

[Michael J.]

Before you replace the ECU, I suggest checking the wiring diagram that I attached on July 12th. Click on the underlined word "Attachment" and the diagram should open right up. Look at the two fuel system relays and confirm that you have power where it needs to be at the relays first.

Verify which wires for the Power resister get power as well. Even though the ECU sends the signal to the injectors through the power resister, if the power resister is bad, changing the ECU will not solve your problem and you will have spent $600 plus and not have solved your problem.

If you have power where it is supposed to be, then you will have no choice than to swap the ECU.

I would rather change a $12.00 relay than a $600 ECU.

 

[84jag]

no fuel coming out of the injectors,have fuel in the fuel rail.ecu ?

 

[Michael J.]

If you have fuel at the fuel rail, but the injectors are not "clicking", you are not getting power to the injectors. Each injector has an internal solenoid that acts like an electromagnet. It works the same way a relay does, except instead of the magnet pulling a switch contact, the magnet pulls open a needle valve in the injector. If the fuel is under pressure it will spray.

Were you able to open the wiring diagram attached above, and were you able to find power to the correct relay contacts with the ignition switch on that supply power to the pump?

On July 8th, you indicated that the fuel pump was not running with the ignition on.

You may have done this already, but I suggest checking the following steps again. The pump has to be running or there will be no fuel spray at the injectors.

On the right side door frame under the Dashboard console is a black rectangular box. The cover snaps on. Pull the cover and make sure the red button on top is in. This is the inertia switch that shuts off the fuel pump in the event of an accident with impact.

If the red button is in, go to the two fuel relays and confirm power at the terminals that supply power to the fuel pump.

Verify that the ground connection for the fuel pump black wire in the trunk where the spare tire is located is not corroded or disconnected. Is there power to the other pump wire (with the ignition on) to the pump?

It may be the pump if the pump is not running with the ignition on and you have power to the pump. Check the ground connection first, it is cheaper to clean the ground than to replace the pump.

When was the fuel filter in the trunk last changed? Check for obstruction if the pump runs by loostening (do not remove) the hose clamp on the outlet side of the filter. Fuel should leak here if under pump pressure. The filter will have a directional arrow on the side. Make sure that it is not installed backwards. If it is, the internal element will collapse and block the flow.

 

[jessebogan]

If you are testing under the hood , an easy way to verify fuel pump operation is to remove the air filter canister. Switch key on, and push the flap in the airflow meter open. This is the signal to the ECU that the car is running, and should activate the fuel pump. This will test the entire circuit. You can hear the fuel circulating in the lines. If you get nothing, you can unplug the relay and see if it is being switched on with a test light. There are two terminals opposite each other, that are oriented 90 degrees from each other. If you make a jumper lead, and connect these two terminals,( in the connector body) the pump should run. Good for testing only, do not leave it hooked up like this.

 

[84jag]

i have a new fuel filter on the car.with ignition switch on the relays on the firewall have power.no power with the fuel pump wire though.injectors have power .i'm running the fuel pump with a jumper wire from the relay to the fuel pump with ignition on.enertia switch tab is down.i have opened the diagram but could not read it.i have a book now. i have a computer on the way.i'm going to try the airflow meter and see what happens.thank's

 

[84jag]

ok,i push the flap open with the key on.the fuel pump worked,what's next.

 

[jessebogan]

Plumb a fuel pressure guage into the fuel line by the battery. Verify that you have pressure, and it should be approximatly 35 psi. While you were there, it would be a good time to take a fuel sample.

If you take the white W/ red stripe wire off of the starter relay, and jump it to battery hot the engine will crank. Make the obvious safety steps, verify in park, block the wheels, etc. Crank the car while holding the flap partly open. Any results? Also, I may have missed this, but does the car start if you spray starter fluid?

 

[84jag]

have not tried the starter fluid.i've replaced the gas in the tank's already.keep ya posted

 

[John S Farrington]

If I were you I would get an EFI schematic and trace the wiring and signals that fire the injectors. The injectors are fired by a signal from the ignition coil (negative side same as the tach drive) that signals the ECU that sends a signal to the injectors. The other side is positive 12 via some power resistors. This is all from memory and could be inacurate. Get a EFI schematic and use it!! Also the fuel pump 12 volts is turned off by the collision sensor as well as supplied power via the master relay on the fire wall. This relay is the large one that also is the starter solenoid signal. Schematics will answer all of these questions.

 

[84jag]

i've replaced the wires that were frail.i opened the flap and it runs the fuel pump with key on.i've cleaned the neg coil wire that signals the computer to operate the injectors.i've pulled 2 injectors and tried to start it,no gas coming out but got gas coming thru fuel rail.i replaced the computer today and still the same problem.anything else run the injectors.

 

[jessebogan]

If I remember correctly the injectors have power, and the ECU switches ground in groups of three. Has it sat for a long time? It is possible, but not real likely that the injectors have failed. Enough water in the fuel, over a long enough time could cause it. If in doubt,look on line for Jaguar Fuel Injection Service in Florida. I have used Daves services many times, and the injectors always work great. Does the tach "jump" when you crank the car? You can take a test light and connect it at the coil neg. and crank the car. The light should pulse.There is also a product called a "noid" light that connects to the injector connector, and it will pulse when the injector fires. This is a good way to be sure that the circuit is OK.