As a final test to confirm two dead pumps I jumpered both pump relays and confirmed I have power at the tank connection - dead silence and no pressure so I'm fairly certain both pumps are toast. While troubleshooting the beast I detected an electrical issue that I can't explain. I have battery power to both relay circuits (1), and switched power to both relay circuits (33). Relays and fuses are fine, and all terminals in the block look pristine. With power switched on I get momentary power at the tank for pump 2, then the relay opens which I understand is normal since this pump only comes on line at high rpm. With power switched on I get no power at the tank (or at the back of the board) for pump 1. The relay closes when power is switched on, and opens when power is switched off - just as it should. I was assuming a bad connection or internal problem in the fuse block until I tested my wife's '99 XJR - it exhibits the exact same dynamic except it starts and runs just fine. Any insights will be greatly appreciated.

 

I'd suggest checking and cleaning the connector on the engine coolant temp sensor.

 

Along with Sean's suggestion, when's the last time you replaced the fuel filter? If your pumps have gone T-up, you should have a code to read. If its just pump 1, then 2 should allow it to run in limp mode, but still give you a code. Both mine went T-up at ounce. I'd also check the CPS (crank positioning sensor), it may be dirty, the connector may be damaged or it simply may be bad. Without the ECU seeing the CPS, it won't start.

 

Thank you both for the feedback. The temp sensor connections look solid, and I'm getting some tach movement when cranking so I think the CPS is working. I'm sure the pumps are the problem since I confirmed power and ground to both with no results - no idea why I'm not getting any codes. When I removed the relays to jumper them I got relay faults so at least that part of the diagnostics is working! I ordered two aftermarket pumps from SNG - an English brand I'm not familiar with for $100 each - hopefully they're decent as I see lots of stories here about replacement pump failures. My only question at this point is why I'm not getting switched power at the number 1 pump - including the car that's running fine. Lady P in an earlier post mentioned a safety protocol that requires a signal from the CPS for the pump to reactivate - the relay closes-opens-closes when cranking - but neither car displays this behavior on pump 1 circuit - only on pump 2. I'm missing something here but for the life of me I don't know what it is.

 

What you described is normal, i.e. the start-up "protocol" is: on ignition switch "on", Pump 2 will be activated for a few seconds to prime the system and will be switched off; then, during cranking, the signal from the CPS will cause the ECU to switch on Pump 1 and the engine starts running. Pump 2 is later activated, from time to time, to run together with Pump 1 when the demand for fuel gets higher like during harder acceleration and probably also during sustained very high speeds or uphill driving when, again, there is higher demand for fuel. I believe the reason why Pump 2 is initially used to prime the fuel system is the fact that this pump gets used much less than Pump 1 so it is good to give it a bit of a spin at each start-up which would, at least, give it a bit of exercise in the cases of very gentle drivers.

 

Is this the same Mark II transplant you were working on last year? Maybe go back and review MS' diagram and instruction . . . or get your wife to jiggle some wires again. Sounds like some wire is disconnected or loose.

 

Same transplant project - you have a good memory. Different symptoms this time - before I had power to the tank plug on both circuits - this time just on one.
MS - I was assuming I'd see momentary power with the initial ignition "on" - even without cranking - for both pumps - and then constant power on pump 1 when running or cranking.
If what I'm seeing is normal I'm good with that - fingers crossed the new pumps do the trick.

 

Hey guys new to the forum. We have an 01 xjr. It has been sitting for about a year🙁. Went to start it and the battery is dead. As usuall with these things I bought another battery. After installing tried to start it and it would not kick over. Now when i turn the key on i hear a few systems making noise in the engine compartment. However i do not hear the pumps in the fuel tank at all. Are they noticeable loud or quiet? I checked every fuse in the engine compartment and in the trunk area . Any thoughts? The tach does move when turning over. The tank is half full. Its been in the garage. Where are the fuel filters located? In the previous threads it say the fuel screen was plugged up. Does that mean the fuel tank requires removal. Sorry for all the questions. Im good with a volt meter. Just not sure where to start. Any help would be great. I did try putting the positive and neutral together. With the battery dead could it have cause the security system to lock out starting. All lights work and guages. Also i checked the enertia switch in passenger foot well to see if it was tripped. Thanks in advance.
Gary

 

The two pump relays are in the trunk .... do a search for diagram. Pump one and two -- pump two is secondary when needed except if pump one dies. Mine are quiet --

pumps have attached fleece filters ..... external fuel filter under rear suspension. Pumps fail ... often they pull too many amps and melt the connector --- all inside tank.

Have needed to replace both of mine in both R's ... tank out. Some cut rear deck -- hack into tank .... not my style.

 

Any chance it could be sonething easy in the engine compartment? Is there another hidden relay compartment other than the 2 fuse boxes located on the drivers side?

 

There is a odd fuse that supplies power to the to control and close coils of both relays

This is different then the main power through the relay contacts powering the pumps

Are you on pin 3 to 5 on the relays ?

If you are getting the initial fuel priming of the fuel rail and not the second phase of fuel pump enable with the crankshaft position sensor telling the ECU you have engine rotation , have you keyed it a couple of times to charge the fuel rail , started it to watch if fuel starvation shuts the engine down shortly

t

 

FYI -- the two pump relays are the same ... in fact all the same color are the same. So you can swap them. Although it seems it's never the relays,

Checking the pressure of the fuel rail is the way to determine fuel. then checking for power at the relay. Put you hand on the relay -- have some one turn the key -- should feel the contact.

 

As the fuel pumps fail the connector at the pump can get burnt pins reducing current

The relays power contacts can also pit although it will close and click

the pitted contacts can reduce the needed current for proper operation

The check valves in the pumps can stick open , some have installed external check valves without changing the pump

The fuel pressure regulator can bypass , you can pop the fuel line test port to see if pressure is kept after X amount of time

The # 2 fuel pump should not come on until 4000 RPM and turn off at 3200

If the # 1 does not light off the engine the # 2 will turn on in the starting sequence after a certain amount of ties , this may explain why the # 2 is trying to become active

 

High test fuel goes bad faster than lower grades, could simply be bad gas. Also, check the throttle butterfly, it could be stuck from sitting.

Have you scanned for codes, you should (but not always) get a code if the pump is toast and the second one is trying to be used to start it.

 

Yes i do have some codes. First is a p1230 Low speed fuel pump fault. the second is a P 0730 incorrect gear ratio and the 3rd is a p1111. A generic code for the diagnostics

 

1230 Low is pump #1 I believe. .. obviously with failure rates and labor to do --- you don't replace one pump.

my memory is high seed pump (#2) charges the fuel rail as you turn the key and pump #1 keeps it going -- this way pump #2 is not sitting all the time. It fairly high RPM before pump #2 restarts --think it's 4k RPM.

 

Fuel filter change

Relay swap

pump connector inspection

Is the fuel line retaining the 43 psi after pump shut off , test port on left engine bank but not all X308's equipped

External check valve option

The odd fuse in the heelboard with corrosion

fuel pressure regulator bypassing



bypass the relay control with a jumper from 3 to 5

If you get true # 1 fuel pump operation then you have cut your issue in sections