Car won't start , fuel pump is not working or not getting power, please HeLP

 

Stun, let me get home to look at my diagrams and I can help you out. If you are suddenly having fuel problems, odds are it is a fuse issue. BUt, I can also help you out if you want to test the whole system. 2 questions though. 1) do you have a car that was built on/before March 2004? 2) how good are you with using a multimeter?

 

Last week I left work car wouldn't start, weird hunch so I reset the inertia switch, bingo car started right up , with CEL on,,, a few days later the CEL cleared itself , I tho kool but weird, a few days after that went to start up and nothing it just turns over and CEL is back on, I had a similar issue last year and I ended up buying a Fuel Pump Driver Module off a Junkyard, change it and no problems till know I'm heading home now I'll give ya tha exact year/Month it was made ... Any help would be awesome thank u

 

Stun, looking at the diagrams, other than the location of a fuse, it appears the rest of the wiring is the same. So, lets see where we go from there.

First, check to make sure that you have have power to the fuel pump by checking fuse F17 (post early 2004) or fuse F81 (pre early 2004). You can verify that you don't have a wiring problem by verifying you have 12 VDC to pin 9 of the plug on the fuel pump control module. From there, install a fuel pressure gauge to the fuel rail under the hood. You will also want to have a multimeter connected to the fuel pump (pins 10 and 3 of the plug on the module. What you should see is that when you turn the key from Off to the RUN position (don't start the car), you should see 12 VDC appear on the multimeter for a few seconds until the pressure is built up to 40-50 psi and then the voltage will drop off. If you don't see the pressure build up and no voltage on the multiemter, then we are looking at a bad fuel pump module. If you get voltage but no pressure build up, then it is a bad fuel pump.

If you are suspecting a bad module, first, do a check of the inertia switch. What you need to do is to access the inertia switch and you will see 3 wires going to it. You are after the green/red wire (pin 2 on the switch). You should see 0 VDC on it. If you see 12 VDC, then that is a sign that the inertia switch has been activated and it is sending a signal to the instrument cluster to shut the car down (ie, kill the fuel pump). Unfortunately, there is nothing on the instrument cluster that I see that would tell you the inertia switch has been triggered.

Hope this helps you get going in the right direction.

 

Quick question since my fuel pump driver module was frOm another vehicle did I need to goto a jag dealer and have them reflash it

 

Stun, to the best of my knowledge, that module does not require any programming to make it work. So, it should require nothing more than unplugging the old unit, removing it, installing the new unit and then plugging in the new unit.

 

Ok what happened the fuse that powers the pump and relay wasn't getting power .. I piggy back off another fuse and the car started and runs ok with CEL on .. What would cause that one fuse not to be getting power

 

Stun, it can be 2 things that I can think of. You have a break in the bus bar that runs inside of the fuse box. Highly unlikely, but it is possible. The more likely thing is that the bus bar has a bunch of male posts on it and then there is a female to female connector that the fuse then plugs into. This for some reason is not making contact and leading to the no power condition. Unfortunately, your options are fairly limited. You can try putting a screw driver into the fuse slot (make sure you protect any exposed metal when you do this) and then give the slot a slight twist. This will force things to make contact. Sometimes it works, some times it don't. The other option is to open up the fuse box and re-bend the tabs on the female to female connector. This can be done once the connector is out of the fuse box using a small screw driver (aka, jeweler's screwdriver). Unfortunately, to get to the connector, you have to dismantle the complete fuse box which you will find out is quite a joy/job.

 

One of the relay on the passenger fuse box was broke , put a new relay and cars runs and CEL has gone away , thank you very much for all Ur helpful info ..gratefully appreciated

 

if u have 12 volts on pin 2, how do u clear it?

 

robdawg71, you will need to reset the inertia switch. If the inertia switch will not reset (ie, you are still having 12 VDC on Pin 2), then you will have to replace the inertia switch.

 

thanks thermo. With the 3 pin wiring harness disconnected, I still have 12v. Also, the trouble light on the cluster won't go off. Can't seem to seem to reset the code from the cluster

 

robdawg71, if you disconnect the switch from the inertia switch and you still have power on the inertia switch itself, then you have a definite wiring problem and something is making contact where it shouldn't. If you measure the plug itself, you should only have 12 VDC on 1 pin of the possible 3 pins on the plug and then you should only have 12 VDC there if you have the key in the RUN position. If you turn it out of the RUN position, all 3 pins should be dead. Again, if you are finding voltage with the key not in the RUN position on any of the 3 pins in the plug, you have a wiring problem. We would need to figure out where that voltage is coming from.

As for the code that you have, that is what is causing the trouble light. If you can get the code(s) read and put them here, this might help me narrow down where the problem lies.

 

thanks thermo. That is the issue. With the key in the run position there is 12v there. Off it goes away. I will check the inertia switch and post it. Thanks for all of your good advice.

 

I went ahead and hauled it to the jag dealer. Will update u on what they find. Thanks again