Hi. First thanks to everyone for the help and expertise in these forums. I have a 93 XJS with 193K miles. I had the fuel pump replaced 6K miles ago, 22 months ago. Car won't start now, engine turns, no problem with battery, though no smell of fuel when trying to start the car. Someone suggested it might be a fuse to the fuel pump. I can't find a fuse in the manual for the fuel pump. Any help appreciated. Thank you.
Paul Shashaty

 

Ahoy. Is there a fuel pump fuse or relay to check on a 93 XJS? Don't see a fuse in the manual. Thanks.

 

Hi Paul

Is your Car a V12 or a 6cyl with an AJ16 Engine?

In any event the first thing to check regardless of whether a 6cyl or a 12cyl is the Fuel Pump Cut out switch, which is designed to trip if you have a crash.

But can sometimes trip if it is jarred or you go over a bump.

On a UK Car it is located on the Left Hand door pillar, almost exactly opposite your knee but could be on the other side on a USA Car.

Its a little Plastic Box with a hole in the top and a spring loaded plunger inside, which if it were accidentally tripped can be reset by pushing the plunger

back down by using something like the end of a pencil. (don't use a screw driver)

You may even be able to do so by pushing it down with your finger.

If your XJS is the 4.0L 6cyl it 'could' be the Crank Sensor that needs replacing, as you are getting into the mileage zone where these things go wrong.

If you have a 4.0L Car, Crank the Engine while you look at the Rev Counter.

If the Rev counter goes to 200 RPM then the Crank Sensor 'Should' be OK.

Again: If you have a 4.0L Car, just to the right of the Battery is a carpeted Trim Panel with a Plastic Turn Button to remove it.

That being the Case remove the Trim Panel, so you can see the inner Wheel Arch and look up into the void above the Wheel Arch, where you will see some Relays.

If you can't see them you're not looking properly because they are in there tucked out of sight at the top.

The Silver one is the Fuel Pump Relay.

If your Car is a V12 then its a different ball game altogether, so lets us know what engine you've got before we go any further.

 

Thanks Orange Blossom. How's the weather in UK?


The sad cat sitting in my garage is a 93 6 cyl 5 speed manual, 4.0 liter, convertible. I think it was the only year they imported to US with a manual transmission! It's fun to drive.


The fuel pump cut out switch looks good. BTW, its on the RT side. I took the cover off and the plunger is down.


When I crank the engine and look at the tach for RPM's, it drops to below the "0" mark. Just tried it again while jumping the battery since it's getting run down.


That being said I looked in the trunk and saw on the RT side two relays, one brown, the other blue. I googled the relay and saw another posting that said it should be replaced by 87 not 87A or 87B. The brown one has 87 on it so I assume that is the relay. How do I test it?

 

BTW, if it is the crank position sensor which I googled and saw it is $95, what's it take to replace that?

 

I found another relay (for the heated seats) same specs and swapped it out. No start. I also checked all the contacts with an ohm meter comparing readings to the other relay. The other relay I found was silver. So maybe when I had the pump changed before, the previous mechanic changed the relay. Anyway, no start. Crankshaft position sensor? JagBits? How difficult to change? Couldn't find anything in the net.

 

Hi Paul

Since the Crankshaft Sensor is an expensive piece of kit, probably best to rule that out of the mix for the moment, in favor of doing the free stuff.

Although I've never changed one myself, I've heard its a reasonably easy job to do though maybe quite awkward to get at.

Since you have a Convertible, it sounds like you have an (in pump tank) where the Fuel Pump goes into the Top of the Tank.

Where that being the Case the Fuel Tank with the Pump in the Top, is located behind that big Steel Baffle Plate in the Boot/Trunk.

So if you need to Change the Fuel Pump, then you need to remove the Baffle Plate and then pull out the Fuel Tank but before you can do that, you need

to remove the Supply and Return Fuel Pipes from the Fuel Tank underneath the Car.

Which requires the use of a Special Tool (unless you can make one) as you have to push and turn the pipes in order to get them off and they are in a

really awkward place to get to.

So taking things a step at a Time, see if you can borrow a Fuel Pump relay from another Car or from a Shop.

I don't know how you Test them but someone on here will (Warrjon would be my best bet)

Then if no dice and the Relay seems to be ok, you need to see if you have fuel coming through because what a lot of people don't realize is that the Fuel

Pump only runs for 3 Seconds at every actuation of the ignition key.

Where its easy to think it isn't working when in fact it might be.

So next go under the Bonnet Hood and (Taking all precautions) with the Ignition OFF, undo the Fuel Pipe and then slip a piece of pipe over this to take it

outside the Car into a Container.

Then Turn the Ignition on and see if fuel comes through.

Not recommended to do this in a garage because of the Fire Risk, so best to push the Car outside beforehand.

In the event no Fuel Comes through, then you 'may' have to remove that Steel Baffle Plate to get to the Wires on the Fuel Pump in order to Test the Relay.

If you decide to remove the Baffle Plate and are able to get to the Wires on the Fuel Pump then I can show you how to Test it.

There may be an easier way to do it but that's the only way that I personally know.

But if the Relay is OK then the Pump may need replacing, which is not exactly a 'Walk in the Park' where depending on your mechanical skill and

enthusiasm, not of course forgetting the size of your Wallet!

You may want to consider taking her into a Shop.

In the event that Fuel does come through, then the next thing to look at would be the Spark, leaving the Crank Sensor as one of the last options.

Weather is quite Windy though not blowing a gale at the moment.

 

I also have a 1993 4.0 5 speed convertible
had the same problem your having and it was the crankshaft position sensor
easy to do but best bet is to remove the bracket from the block just 2 bolts think they were 8mm then remove the sensor as the bolt holding it is probably corroded and the brackets can snap (cast aluminum)

 

I have a 92 Jag 5-speed with the I6. Turned out to be the fuel pump wiring harness.

 

the mechanic found a short in the wiring to the pump. and also the crankshaft position sensor. More reasonable than my last mechanic who was a British vehicle specialist!

 

reading your post #4 I see you found two relays on the right side of your trunk in the fender well. There are 3 of them in the "93 xjs. The fuel pump relay is silver.
The blue relay is the reverse lights relay. The 2nd blue relay is the transmission power relay. quoting right out of my "1993 model year update" released to apprise mechanics of the changes from the 1992 model year. My '93 was built in September of 1992 and has all three. I believe that all '93's after my 185**** serial number would also have them.

 

1992 should have 2 relays in the right rear wheel tunnel.
1) black base is pump relay agu1068, could be brown (Bosch 0332014113)
2) red base is main efi relay agu1070 (Bosch 0332014112) metal with a red stripe