Fuelpump - confusion
 

HI there, I have a XJR SC from 1998 which will not start..same symptome as in all the other fuel pump threads (no sound from pump, have checked relay´s, cranks fine, full battery). Before I order a new pump I was hoping you guys could guide me these issues here:

- since I have a supercharged some tells me that I have two pumps - and should change them both. If correct, I do not know where the other pump is located (besides the one on the tank) ?

- When I search online for a pump it seems like there are BIG price differences...do i need an original part or what quality"level" would be ok ?

Last I cant find the part no for the fuel pump(s) in my manuals - so I am not sure if I search for the correct part here.

Sorry I am a rookie on this, but hope you can send me in the right direction. thanks
-

The fuel pumps are JLM20529, superseded by C2N3866. SNG Barratt sell both, the genuine (GBP 175) and quality aftermarket (GBP 65). And yes, you need two pumps. They are sitting next to each other inside the tank. As these pumps are also used in a number of other cars, there are many aftermarket types, some as low as USD 35 or so but I would not go for the cheapest. Those about USD 70-80 are probably fine.

It can be a difficult job the first time, and you really need to change both fuel pumps because sod's law dictates the 2nd pump fails not long after.

Some pumps need a link lead connector, I don't recommend this and you can usually find OE fitment pumps a lot cheaper than Jaguar. This one for example,
https://www.britishparts.co.uk/jagua...uel-pump-p1996

I'm echoing the above comments, along with having the correct pipe disconnect tool and someone with thin forearms does help when releasing the tank from underneath. Please don't be tempted to remove your interior and start cutting a hatch in the back like some people have!

Before pulling the tank, check your Engine temp sensor, disconnect it and spray a contact cleaner on both parts. Located near the T stat housing.

There is the one fuse that provides power to close both pumps

https://cimg4.ibsrv.net/gimg/www.jag...4a2414c9b4.png

Hi bongobrown,

I agree with Sean that before you pull your tank and replace the fuel pumps there may be further diagnostics worth conducting. The fuel pump priming burst can be hard to hear. Is there any chance you got some contaminated fuel and the fuel filter is clogged, possibly even causing the fuel pump fuse to blow?

You mention that you've checked the relays for the fuel pumps - do you mean that you've confirmed the fuel pump #1 relay is receiving battery power at terminal 3 of its socket, and that with the engine cranking there is battery power at terminal 1 of the socket? Fuse #15 (20A) in the same trunk fuse box is also in the circuit of fuel pump #1. You can swap in a similar nearby relay, such as the Side Marker & Plate Lamp Relay or the Heated Backlight Relay.

If you confirm that terminal 3 of the fuel pump #1 relay socket has battery power, you can bend a large paperclip into a U and use it to jump terminals 3 and 5 in the relay socket to force the pump to run. If it doesn't, check the wiring between the fuse box and top of the fuel tank before condemning the pump. Fuel pump #1 receives power on the Blue wire with Red tracer line and is grounded via the same Black wire as pump #2.

The relay identification diagram is on pdf page 30 and the wiring schematics for the fuel pumps are on pdf page 45 of the Electrical Guide, which you can download here:

Jaguar X308 Electrical Guide 1998

If fuel pump #1 runs when the relay socket is jumped, check your tachometer while cranking. If the tach reads 0 rpm while cranking, suspect your crankshaft position sensor (CKPS), another common failure point.

Cheers,

Don

Hi again and thanks alot for all the useful advise. Indeed the most competent forum I´ve joined.
Seems like I have a lot more to do and try before pulling out the tank. I am an officeguy with a jag and limited basic knowledge about electricity but not affraid to get into small repairs.

About relays I have only checked with an amp-meter..so I am not sure about the "you can bend a large paperclip into a U and use it to jump terminals 3 and 5 in the relay socket to force the pump to run" - are the terminals the slim holes in the socket when taking out the relay ?. And does "jump" meen I simply insert the ends of the clip in each hole ?

I will for sure buy two pumps in reinstall as you guys suggest - furthermore I will try to check the wired between trunk fuse box and tank

One question: the special "pulling the gas cables out"-tool. Is this a do-it-your-self thing and if so, has anyone a picture or advise how to make this.

No matter what I realize that I need friend to help since it seems like a two person job.

I will get back with updates as soon as there is progress. Thanks again for all the advise.

..in case I did not really answer the q about what I have checked:
I used my standard ampmeter - put it on Ohm and checked the 4 connections back on the relay 2x2. Both pairs told me "0.10"..not completely 0,00 - should it be 0.00 ?
I also used the amp meter to check all fuses in trunk fuse box. They all work and can reach 0.01/0.00. I did not check all fuses on heel-box. I will do that.
I would really like to check all I can before ordering and changing the pumps. So I hope you guys can guide me in this "jumping wire" to kickstart the pump.
thanks


So

You can jumper socket 3 to 5 or put power on 5 which is the wire to the pump

https://cimg9.ibsrv.net/gimg/www.jag...3140cfa9ad.jpg

BongoBrown,
This link, courtesy of many here, this time Highhorse, gives a primer in what these fittings look like and how to service them ----when you can even see them!!
The "tool" you're needing is a metal or plastic, ~12mm OD piece plumbing fixture connection tubing--split like the plastic fittings shown in this article, but, still long enough to reach AND not hit the sponge rubber pad at the tank's outlet fittings, WAY under the car!!
Good luck
https://www.hotrod.com/articles/how-...ct-fuel-lines/

@NEECAPR thanks for the link - but for some reason I cannot open the link with the tool example..site redirects me because I log in from a EU country..(wierd)...anyway I have decided to take it to the mechanic shop to help me check all wirering and eventually help me change the pumps.
Before going there I will go check the inertia switch just to be sure and will go for the jump start with a clips. (thanks for the pic..helped)

Click on image for larger view

Click a second time

Put on a flash drive and take to a office supply to print in clolor any size you want

The ECU provides a ground to command the relays closed

See page 16 for wire color codes

http://www.jagrepair.com/images/Auto.../jagxj1998.pdf :icon_dance-disco:

The # 2 relay is not commanded close until 4000 RPM

Tips :

Even though the relay may click doesn't mean the power contacts are good allowing enough current to drive the device , burnt contacts or cat whiskering

The clicks validate the correct command

Check the fuel pump connectors for burnt sockets

Some X308 models have a noise suppressor on the fuel pump connector that can be open

Do change the fuel filter

The crankshaft position sensor on the back of the engine tells the ECU to enable the fuel pump command and can get contaminated on the sensor face with fine metallic particals degrading the CKPS signal

See link , it is item # 3 in the drawing :

https://www.jaguarforums.com/forum/x...cation-128624/ :icon_dance-disco:

Make sure the ground wires are intact along the side of the battery compartment

Chttps://cimg3.ibsrv.net/gimg/www.jag...be2aafb385.png
https://cimg3.ibsrv.net/gimg/www.jag...e7b445c1a6.png

bongobrown
Let's see if you can open this concept sketch of the line receiver fitting. Also, one of many threads on getting at the lines.

https://st.hotrod.com/uploads/sites/...ay-drawing.jpg

https://www.jaguarforums.com/forum/x...-reach-198075/

Test Both
 

BongoBrown,

Adding to Don B.'s excellent paperclip jumper instructions, try that with both Pump 1 and Pump 2. I recently suffered a primary fuel pump failure on my SC Vanden Plas. (Similar drivetrain to XJR) I've maintained my own cars for 44 years, and never before had a 'partial' fuel pump failure. Until now. I could hear my fuel pump running while listening at the fuel filler port, all relays were working properly, and resistance across #1 pump motor was as expected. It wasn't until I jumpered #2 pump I realized how the pump should sound. It will be clearly audible through the front of the trunk. I could then drive the car on Pump 2, saving me a tow and all the trauma angry tow truck drivers can inflict on our Hoopties.

NOTE: My (very excellent) independent Jaguar shop told me I was lucky, many folks with supercharged XJ308's have a non-functioning Pump 2 and don't know it. I didn't argue with him, but I drive in a manner in which I would've been aware, and have given my Pump 2 plenty of exercise. But this gentleman has worked on thousands of Jags (NOT an exaggeration) and is a font of useful knowledge.

CAUTION: If this works, and you do have a defective Pump 1, and jumping Pump 2 allows you to drive the car, be aware you have jumpered OUT all your control logic steps. That pump will run regardless, even if it shouldn't. As soon as you are done driving PULL THE JUMPER OUT. You can leave it handy for the shop to use, but pull it when you shut the vehicle off. When handing it over to the shop, turn off the car and pull the jumper. Show them what you did, but let them reinstall if they wish. You left the vehicle in a safe (if inert) state.

thanks again for all the great input. Despite I have to admit that the electrical diagrams does not make so much sense to me, but checking the wirering, groudn etc..is something I have tried.

The tool for taking our the fuel lines is for me nonsense even though I can open og clearly see the illustration, but proberly relates to me lack of experience with jag fixes. I will tro to show it to the mechanic so see if he can relate to it and make similar.

What I have done:
I tried to jumpstart both relays with a large paperclip. I am sure I inserted it in correct pins/holes even though it sparked when I inserted it. hope it did not damage. With the clip inserted I turned the key, cranks as is should - but no start. Same with both relays. SO I guess this tells me that the problem is NOT the fuel pump relay (?).

And this means I need to go through the complete fuel pump(s) replacement - and will try to convince the local workshop to put in some hours on this, even though the are NOT a Jag shop...

Thanks again for all the helpful tips....feel free to chip in with more suggestions - especially those I need to check before pulling out the tank etc...

Have a great day people.

A better jumper is to use a blade connector jumper available at the auto parts store . This gives you more accurate current to the pump and arcing damage to the sockets if installed with the battery disconnected

Fuel filter change ?

https://cimg2.ibsrv.net/gimg/www.jag...6d0f75000f.png

Having a spark when you jumper the "I' and the "---" pin sockets located at the opposite sides is normal as you are connecting current directly to the pump which draws quite a few amperes. The fact that you still could not start the engine suggests that the pumps have seized. This almost always happens if the car is sitting for a long time (a year or so) without starting the engine. Sometimes, repeatedly briefly putting the jumper in and pulling out can free the pump. You may wish to try this but it is better to use two short pieces of wire with one end of each pushed into the sockets "I' and "---" and touching the other two ends together, approx one second on, one second off, many times. Then tie the free ends together and try again starting the car.

Just saw the reply from "Lady Penelope", much better. If you get two of the terminals shown and attach each to one end of two short pieces of wire, you can plug the terminals into the sockets "I' and "---", strip about 7-8 mm of the insulation of the free ends of the wires and touch them together.

My "Jumper" relay:
https://cimg5.ibsrv.net/gimg/www.jag...dfa81a41f1.jpg
I opened up one of my spare relays and soldered a piece of wire inside bridging the contacts. The relay coil is unaffected by the mod so the ECU will "think" that a normal relay is present and good. I can use it to test the pressure of the pumps (I have a supercharged Jag), run on Pump 2 for a while from time to time to keep it in good form and, if my Pump 1 dies, run on Pump 2 to get home.

ok..I´ll try to connect with running car also. I have a 2amp charger and have been connected 24/7 the last 3-4 days now. The battery should be fully charged then, but I´ll give it a shot from my second car..Wanna try all I can to avoid the full operation with tank out, special tool etc...