Hi Gang,
Recently while driving the 1985 Series 3 4.2l the engine died as a result of the fuel pump ceasing to run. I confirmed that the pump was not working (pumping fuel) by applying 12v and not having the pump work. I replaced it with a good used pump that I had as a spare from a parts car. After two days that pump stopped running as well.
So, is this a coincidence? The fuel tanks were nearly empty when the two pumps died. I have noticed that the voltmeter on the dash would jump up to 16-18v momentarily then come back down to 12v~ and stabilize.
Could the low fuel burn out the pumps by not cooling them, or debris in the tanks clogging the pumps? Could that jump in voltage has caused the pumps to burn out?
Any ideas or thoughts on the fuel pumps burning out?

 

I think it's debris. You fuel tanks may be rusting from modern ethanol fuel. Fairly common and covered on the board many times before. Install a pre-filter between pump and tank. I have one on my SBC 500HP coupe and my 30 year old fuel pump is quiet and still going strong.

Search this forum for the term prefilter or pre filter

 

I agree that rust/debris is the most likely culprit. The Bosch pumps are robust but they have no tolerance for this ! The pre-filter are a good idea.

But first.....

Remove you're existing fuel filter and empty the contents into a clean jar. What you see will dictate your next steps.

Even though is it wildly popular to blame E10 for any and all fuel woes I disagree that E10 gasoline should sumarily be singled out as the cause of tank rust/tank debris. Heck, in my neck of the woods E10 has been standard issue for 20+ years and there by no stretch of the imagine has tank rust a predominant issue.

Anyway, tanks have been rusting ....especially in storage conditions.... long before E10 became commonplace. Thus the age old advice to keep tank full during storage.

Cheers
DD

 

Consider this...And the comments.
https://www.hagerty.com/articles-vid...ethanol-in-gas

Seem to me in lab conditions e10 is fine, however the real world empirical evidence is overwhelming that it causes damage. I work at many new car dealerships, some of them test the fuel when a new car comes in with fuel system damage. Consistently they find excessive water in the fuel when fuel system damage occurred. My own Jag tank came apart and clogged the pre-filter shortly after e10 become widely used where I live.

Certainly true fuel tanks have been rusting for years but I believe ethanol exacerbates the issue.

 

i have had two inline pumps fail recently,they are hi-quality from reputable manufacturers.

decided to take them apart, most inline pumps use permenent magnet motors, found 1st pump that was around 15yrs old, had the magnets Epoxied to the case, seems as tho the ethenol softened up the Epoxy, and the magnets came loose, sticking to the armature, making terrable noise!

OK took the second pump apart only around 1-2 yrs old ,same thing magnets flopping around,Epoxy dont seem to like ethenol E10, 1st pump used only gasoline old collector car ,sits for months.

any ideas?

 

.

 

Why do you jump right to E10 as the likely cause? How can you tell? How does one differentiate an E10-realted epoxy failure from....some other cause?

E10 is nothing new. The owners manuals for my 1985 and 1988 Jags mention that using it is OK. Usage has become increasingly more widespread over the years. It's not new science.....

So.....

Any reputable fuel pump manufacturer is very familiar with E10 these days and surely uses materials that are fully E10 compatible....at least on the 2 year old pump. (The 15 year old pump.....maybe, maybe not)

Cheers
DD

 

Installed new pump, and something odd happened. The XJ6 started right up revved up to about 2000 rpms and engine died. Started it up again, engine revved to around 2000 rpms and it died again.
Removed fuel filter and drained it out. The fluid/fuel that came out the inlet end (from fuel pump) came out looking like coffee colored. Hardly any fuel came out the outlet side (going to the engine). Sprayed inside the filter with carb cleaner and hardly anything came out the outlet end. So it seems as if the fuel filter didn't allow much fuel at all to the engine.
I'll change the filter and see what happens next.
Thanks

 

New fuel filter installed. Same result with high idle then engine dying. If I give it gas by pressing the gas pedal it'll run rough, but stay running a bit longer.
I'm dumbfounded as to why did replacing a fuel pump turn into an idling nightmare.
Any ideas as to what is at fault here?

 

So the engine is starving for fuel. Maybe the failed pump was a coincidence, or else the new pump is strong enough to pull out even more debris and possibly water along with it. How long since the tanks were flushed and cleaned? Putting E10 aside, just bad fuel can cause havoc. Have you refueled somewhere different to your usual place/s recently?

As an aside: My late father was a British Army trained mechanic in his early days and he had 2 rules on this topic 1.) never buy fuel from an old station with old tanks, or from one situated at the bottom of a hill due to possible water ingress, and 2.) the older the car, the more you keep the tank topped up to avoid sucking up crud from the bottom!

 

Just for the heck of it......

Check the ducting from the air flow meter to the throttle body for condition and tightness. If it leaks, you can get symptoms as you describe. Nothing to do with the fuel pump, obviously....but it only take a minute to check



The tanks have crud, obviously, and need cleaning.

Some remove the tanks for a professional clean-out.

A pal of mine flushed his with a garden hose (!) to get the excess crud out. The he installed the pre-filters. The first two filter clogged in a couple days. The next pair in 4-5 days. The next pair after a month or so. The next went several months. After that, smooth sailing. Cost him about $150 in filter but it was easier than dropping the tanks.

Cheers
DD

 

So far so good around here on the fueling issue for my cars. Several factors, I think.
1. some decades ago, Ca mandated gas station tanks pass a leak test. Many failed.
Tanks removed. Some replaced with newer tech and some merely removed the tanks and closed up. Result is reasonably clean gas is sold.


2. The mostly dry climate means less water leaking into tanks.


3. CA SMOG requires vapor proof tanks. No water enters!!


4. CA requires it's own fuel blend. Less corrosive as a side benefit?


5. Ethanol laced fuel works just fine in regularly used cars. Might not fare a s well in seasonal engines. I've seen what it might have don e to carbs of small engines. it ain't pretty.


6. Pot metals as used on older systems,. carbs, pumps, etc may not fare as well in an E10 or better environment than better stuff.


7. Some fuels have better corrosion inhibitors?? I don't know.


Carl

 

One more:


The generous sized drain plug of the Salons invites a good flushing as
Doug's pal did with great success.


Other critter's drain plugs far more puny if the exist at all.


The prepump filter makes so much sense.


Carl

 

I sorted out the start-run-die illness on the XJ6!
Ended up being an intermittent fuel pump relay fault. Clicked open when starting engine then would close after it started.
Here's what I did to figure it out:
I checked the fittings for the air flow meter and made sure the flap operated the fuel pump, checked out tight and fitted properly, flap operated.
Started Jaguar, and illness persisted.
Drained the new fuel filter and fuel was clear and flow through it was good. Started it after the fuel filter check and run then die was still there.
I bench tested the fuel pump relay and it "clicked" open. Started it again and engine began to sputter, so I went to the fuel pump and it was NOT spinning/operating. Grabbed my meter and no 12v! If it starts and runs for a minute then the pump had to operate at some point. Relay opened when it started then closed the circuit. Replace the fuel pump relay with a spare.
The 4.2 started and ran without hesitation. Let it get to operating temp and it ran great!
Sorted, job done.

 

Good work!


Cheers
DD

 

Old post but I wanted to bump because I absolutely love it when a person follows through with the solution to the mystery!!

Like having the answer key to a test...

Happy Holidays all

 

Someone should kindly show me where to locate the fuel pump relay (possibly with picture or diagram)

 

On the firewall you'll see the red diode pack, the large metal starter relay, and two other relays.

Of the two other relays look for the one that has white/green wires. That's the fuel pump relay

Cheers
DD

 

any rust or gunk is going to collect at the lowest point of the tank

drain the tanks, removing the mesh/screen bungs, remove the sender-float assembly, use a water pressure machine, stick through the filler cap and clean it hard. Then do it through the sender hole, then up through the bung hole, then one las time through the filler cap.

allow to drain and dry overnight. You might use a hair dryer or blower sticking it through the sender hole. Reassemble with new seals where needed and fill tanks. adding 1 bottle of STP Fuel treatment to remove any remaining water.

Check for leaks !