My 2005 4.2 S-type recently 'ran out' of fuel despite showing just over 1/4 tank on guage. Vehicle Diagnostics showed LHS tank level sender output 110/255 and RHS sender around 40. The car had sat for 12 months with no use and I am guessing the 0.5mm nozzles in the LHS jet pump may be blocked. Has anyone had experience with this fault? Is there a procedure for clearing the jet pump?

I am a newcomer so apologise if I have failed to find pre-existing coverage of this topic.

 

Roger,

I've moved your question from New Member Area - Intro a MUST forum to S-Type forum.

Members here with the same vehicle will be able to advise on the fuel issue.

Graham

 

My 2003 is presently experiencing weird gas level indications also. An actual half tank on mine indicates as 3/4 on the gauge, empty indicates around half.

In your case, are you sure it's not a similar event of indication and not pump blockage?

 

Not any reports of blocked fuel passages. Only a few jet pumps have been replaced.

Might be worth a look to see if any hoses fell off or have decayed. Both pumps are easy to get to under the back seat. At least Ford/Jaguar thought about service! The old drop the tank to replace the pump system was a painful job!!

The fuel pumps are under the black covers. Be careful with the plastic covers so you don't break anything.


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Do the pumps transfer fuel side to side? I thought both pumped fuel to the engine from a common tank, not two separate tanks like older Jags.

 

Well forgetting about the STR for now.

The S-Type and the Lincoln LS share the same tank and pump set up. Yes the transfer pump transfers fuel from the passenger side of the tank to the driver’s side and attempts to keep them even. Does anyone know how it does this? I don't know.

The driver’s side pump feeds the engine. So one of the best indicators of a failed/non-working jet pump is you run out of gas somewhere between 1/2 and 1/4 tank. It looks like the tank will self-level until it is drained below a certain point and then the jet pump is necessary.

Here is a fuel tank picture which might help.

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It's just the STR that uses 2 to pump to the engine (burns more fuel!)

 

I got a bit of spare time and pulled the seat out to have a look at the two sides of the tank and got quite a shock - there is no sign at all of the transfer pipes between the two sides of the tank. Did Jaguar change the system at some point or do I have an orphan car with a non standard fuel system? Images attached (I think)

 

Thanks for the pictures and maybe the S-Type has some different plumbing?

Have you taken the white caps off to check further?
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Roger; The fuel tank was the only recall ever issued for the 2005 S Type and looking at the JEPC I do see variations in the plumbing but the tank looks to be the same? So I think they made some changes after the fuel tank problem came up.

What is the last six digits of your VIN?

Look at the Ford Parts post below. They explain the saddle tank and it operates different than what I had read before. It might explain your problems?

Addressing Ford Saddle Fuel Tank Concerns
Ford has installed saddle type fuel tanks in several car models for more than a decade. These tanks have proven durable and safe, but the operation of the fuel pump and sending units are sometimes misunderstood. Diagnosis and repair of these units is easier when the operation is understood.



Operation


Saddle fuel tanks use two fuel level sending units. During fueling, the tank fills up the primary (fill side) side, then fuel moves through a connecting passage to fill the secondary side. In the fill side, the Fuel Pump (FP) module contains the primary sending unit that reads: half to empty. The secondary side sending unit reads: half to full tank.

The FP module has a jet pump that draws fuel from the secondary side of the tank using the fuel transfer tube. During refueling, all fuel goes into the primary side of tank. Once the primary side of tank is full, fuel moves through connecting passage to fill the secondary side of tank. As the vehicle is run, fuel is pumped from the secondary side of tank first, using FP module jet pump and connecting tube. When secondary side of tank is empty, the FP module draws fuel from the primary side of the tank.

Faults
A fault at the secondary side of tank will cause the gauge to default to the primary side sending unit reading. This results in maximum reading of half tank. This reading will stay the same until fuel level on secondary side is empty and fuel on primary side of tank begins to drop. A fault with the primary side sender will cause the tanks to read empty.



DTCs
Incorrect installations of aftermarket remote start systems have been known to cause Diagnostic Trouble Code (DTC) P0 0460 in the Powertrain Control Module (PCM). This occurs when the correct control modules are not being powered up during a remote start event. If a vehicle is configured where the fuel sender is not wired directly to PCM, then the fuel level reading is sent to the PCM from another module over the network. If the PCM does not see fuel level information because the correct module is not powered up when the engine starts, the DTC will set.

DTC P0 2879 is related to a fuel tank jet pump fault. The PCM sets this code based upon readings from the fuel tank sender units. This DTC will set when PCM detects that the secondary side of the tank still has fuel stored and the primary side fuel level begins to drop.

The secondary side of the tank is the last to be filled and the first to be emptied. If there is fuel left in the secondary side and fuel level in the primary side of the tank begins to drop, the PCM will conclude there is a fault with the jet transfer pump. Under certain driving conditions, such as hard cornering, it is possible for fuel to slosh over from the primary side to the secondary side.

Intermittent Issues
Sulfur contamination may cause intermittent fuel sender malfunctions. Sulfur can build up on the sending unit pivot or center card contacts, which will prevent the sending unit from getting a good ground. Adding fuel system treatment or changing fuel sources can correct this issue after 2-3 tanks of fuel. If the concern persists, diagnose the senders using Ford Workshop Manual procedures.

Replacement Sender

If sender replacement is required, install upgraded sending unit which has been released by Ford. The original sending unit was grounded through frame only. Upgraded sending units have dual contacts and upgraded ground circuit. The upgrade replacement unit has an additional ground wire. Connect additional ground (pink) wire to same location as original blue wire, and then heat shrink the electrical connector in same manner as original. Route the wires and apply zip ties as with original to prevent wiring from contacting float arm.

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I didn't remove the caps, because they are sufficiently tight I decided to make a proper removal tool rather than risking damaging them.


The Ford info you sent is consistent with what I am seeing in the digital outputs from the two senders and quite different from what I was expecting to see, based upon the description of the original Jaguar system.


Very useful Thankyou.


My Vin is


SAJAC03RX5HN09738

 

transfer pump failure can be diagnosed using this diagram. I'll unplug rear ECM and keep checking resistance.
Maybe removing under seat covers would be even easier.
This is how pump system works:
Electrical RH pump pumps fuel to engine and to LH transfer jet pump.
Jet of fuel in LH transfer pump pumps fuel to RH part of tank. Ratio is about 1:3, 1 oz. of "jet fuel" pumps 3 oz. of "delivery fuel".

 

I had more-or-less forgotten this post. I ultimately solved my problem by removing the pumps and cleaning all the filters. See my post 'Tool for removing S-Type Fuel Pumps'. I am interested, though, that you get such impressive transfer efficiency (1:3) from the jet pumps.

 

I'll start with checking resistance and common ground for level sensors.
Thanks for your response.
I also have almost stalling engine about 20 miles after filling gas.
Ground bolt is the only common part for fuel pump and level sensors (see diagram in post 12), not counting rear ECM

 

I want to thank Roger for his great work on this home made tool. It's just plain brilliant!

If you have not read this before it's a great example of a guy who looks at what needs to be done and then just figures it out!!

No need for expensive dealer tools.

https://www.jaguarforums.com/forum/s...-pumps-130587/
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Big channel locks worked fine yesterday (they always do), paid $25 from Home Depot long time ago. Same type top plastic ring is used on many cars. 2 long screwdrivers work fine too.

 

Great way to break the plastic using pliers. The PVC pipe is about $5.
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Clubair!
Thanks for your info in this thread, it helped me check level sensors and understand how transfer pump works.