I'm on it! filed both the tanks and infused the gas with Lucas fuel injection cleaner. Definitely has helped the engine smooth out in idle but i'll have to run the other tests since the rough idle shows its ugly head after roughly..... 30-40 minuets of strenuous drive (50-60mph) I just recently Replaced the AFM and rewired it aswell.

I'm gunna hunt for my Flip and try to take some more videos. Gas gauges definitely either faulted or were reinstalled incorrectly.

Thanks, Dough, bbarcher

 

Found this page that shows the injectors and the little screen filters they have:

Jaguar Series III Injector Replacement

You can see the injectors have seals around them that can allow vacuum leaks if they are old and brittle. An example of his professional injector cleaning report is also posted.

 

I just put inline fuel filters on the pre-pump side of the fuel system. The NAPA part # is 3842. They are about $10. I hope to filter out any sediment that remains in the tank(s). Good insurance for a $250 pump.

 

Ok, so my dyslexia is acting up today...the NAPA part # is 3248.

 

Also, I do have a question for those that have added the pre-pump filter. Do you still use the big filter post-pump or do you reduce it to something smaller/cheaper?

 

fuel pumps can overheat? my dad has been in the auto repair business for over 30 years and has never encountered that kind of problem...

 

sneal46, the same big "post-pump" filter should still be used. It takes care of the really small particles that could threaten to clog the injectors. The pre-pump filters do not filter out the really tiny stuff.

Of course there is still a possibility for rust to form in the line between the big filter and the engine, and several people have had clogging due to this rust that gets into the fuel after the filter.

 

This may be "over filtering" the system, but what about a filter on the line that goes into the back of the rail? Something small of course. I wonder if the pump can push the proper psi through all those filters.

 

This thread got me thinking the same thing. You could install a filter under the hood right before the rail. As long as it was not clogged, it wouldn't impede the flow. A lot of cars have fuel filters under the hood or closer to the front of the car at least. I suppose one could move the main filter up under the hood, instead of in the trunk. But I can't say I have seen that done on a Jag. I wouldn't see any problem with it as long as it was safely mounted and the hoses safely secured.

 

Giving another update: after cleaning out the tanks and treating them I ordered replacement; gaskets for the fuel tops, Fuel pump, fuel level senders , pressure regulator. after installing each the problem persisted, my father suggested cleaning out both the previous pump and the new one at his shop. So we did, cleaning it with a special cleaner and then blasting each out with highly compressed air. after testing each operated normally under extended use, on several tests with no deviation.

Afterward my father and cousin suggested that we build a inline filter and shut off valve after the fuel T switch and before the pump to prevent any sort of future fuel related problems.

The part (the inline housing and filter) were purchased from nappa; part number 4100.

My thanks go To Doug for suggesting installing filters ahead of the pump. My 1986 XJ6 now runs again, now much smoother then ever.

(As a note Its hard to decided weather the pump was simply failing , or overheating. my initial thoughts leaned towards overheating because of the intermittent nature of the issue, but all linked by failure after use of over 30 minuets and checking the pump physically/directly after failure showed that it was hot, scolding hot in fact. After thought on the subject I can't come to any certain conclusion as to weather the pump was simply failing due to debris at seemingly random times, or that debris was chocking the pump and causing it to over work/overheat.)

I can't seem to find my flip (camera) but when I do, I'll be making a tutorial on how to get to the gas tanks since ive since removed them 3 times in total.

Thanks everyone, I appreciate the help

 

After only a few days of driving , the symptoms have returned. I'm at a loss for words.... guess I'm back to square one.

1986 - XJ6

New fuel filters, New fuel pump, Tanks have been cleaned.

Symptoms: after being driven from roughly....30-60 minuets the engine begins to hesitate when given gas, sputters when given gas before dying ussually at a idle or when accelerating from a idle.

 

Can you provide a full description of the symptoms? Is the pump still getting super hot? What about the wiring to the pump? Is it hot? Can you check the voltage at the pump terminals by connecting a volt meter to the terminals when the problem is occurring? Low voltage due to a wiring problem needs to be corrected. You should have less than half a volt difference between the voltage across battery terminals and the voltage at the pump. Example: if battery is 13.5, fuel pump should be no less than 13.0 (ideally it would 13.5).

At this point I would suggest repeating the last step that seemed to help, the cleaning of the pump. See if any more debris is left in there. If you have another pump that is possibly good, clean it and swap it in. Pay close attention to the quality of the electrical connections at the pump, if loose, overheating will occur.

It may be time to pull the injectors and backflush them or have them professionally cleaned. If you ever do try to backflush them, you need to connect power to them, and a resistor must be used in line with the power wire or you risk burning out the windings in the injectors. The car has a little resistor box for this.

Also, I read about someone who encountered loose connections at some of their injectors causing driveability problems, although that would not cause pump overheating, more likely to act like a misfire since it would probably not happen to every single injector.

 

I started another investigation, starting back in the engine bay, checking for electrical faults, cooling faults, fuel faults, and finally vacuum faults. Low and behold I founds this.



Nasty vacuum leak after the elbow near the butterfly valve. Will be replacing in the morning.

 

That will do it every time.

 

Looking at that gap there will be a massive effect on engine running. I remember taking off my "elbow" and inspecting the large diameter, but short pipe connecting it to the inlet manifold, but it was always OK.I suppose it hardens up over the years, and the vibration does for it.

 

Just out of curiosity, is that rubber elbow replacable?

 

I looked around on Coventrywest, didn't see it. but that doesnt mean it isnt there hiding. or on another website like jagbits or motorcars. I picked up some marine tubing that fits in place between the elbow and opening to the butterfly valve.

 

Yes, the duct is available new. I think any of the usualy Jag suppliers have 'em or can get 'em


Cheers
DD

 

Here ya go:

Air Box Hose

WorldPAC part # W0133-1637064

Super expensive for what it is though, depending on brand, the prices range from $8-20.

The ones on my car were hard, luckily I found some junkyard ones that were still pliable. The airflow meter will not swing open far enough with that huge leak, and major underfueling is the result. Let us know how it runs with this fixed.

 

I think our OP's car will now start running OK. Keep your fingers crossed !