This is a continuation of my earlier thread. My 88 xjs will start and run good for 15-20 seconds then it sputters and dies. I've replaced the filter and pump. I hooked up a timing light to the coil wire and it stays on while it's running but starts flickering right when it dies. However, I don't think it's ignition because I can sort of keep it running with starting fluid. It acts like a fuel problem because it sputters and gradually dies rather than just shutting off.

The car has been sitting for several years. I had the tank renewed, flushed all the lines, and had all the injectors cleaned. I've probably started it 10 times since and it ran for as long as I wanted it to. Now this problem.

Marvin

 

Bridge the fuel pump relay socket so that the fuel pump runs whenever the ign is ON. That will eliminate the ECU from the equation, although you should have a 16CU unit, and they were not known for fuel pump circuit issues like the previous version, BUT. If bridging is too hard, locate the ORANGE wire exiting the fuel pump socket, splice that wire and earth the splice, that also removes the ECU from pump control.

The tank renew/refurbish can sometimes reek havoc, as peel off and other nasty stuff can block the outlet from the main tank to the sump tank, and also the filter inside the sump tank can clog. I fit a 1/2" plastic filter in that supply hose from the main to sump tank when I get these down here, and that is RARE. That will not sort the stuff in the main tank, but at least it does some help??.

Overfueling comes to mind, MAYBE, but 15 - 20 seconds, maybe not.

When its running, is it on all 12?????. The HE is one mean mother if you start and run for a short periods, too many times, as it fouls spark plugs, and they will NOT burn clean themselves. IF any of ours are started for whatever reason, they are not shut down until the thermo fans have done one cycle, no more spark plug issues.

Maybe more, but that is something to occupy you for a minute or 3.

 

Jumping the pump relay didn't help. Even without the jumper the pump will stay running until a couple of seconds after it dies. When it starts it is smooth and revs easily so it seems like it's running on all 12. After it quits it will start right back up.

I read in the manual that the ECM enriches the fuel for cranking (by increasing the injector pulse time) and for several seconds after that. I put a stethescope on the injectors and can hear them clicking until the end but I'm wondering if the ECM is shortening the pulse too much after it starts.

I'm thinking about removing a fuel line, run it to a gas can, and turn on the pump to see if the flow drops off after a few seconds. That might eliminate the possiblity of a plugged tank.

 

Since it is a simple car lets keep it simple.

I would fit a NEW fuel filter, simple/cheap/easy, and eliminates that as an issue. I say this based on your original post where "it ran as long as I wanted, until now", which with a filter plugging up gradually would give this sympton.

Also the plastic filter inside the sump tank may be in need of a good clean.

I agree with the flow test, bridge the relay and place the hose into a gallon container, and it should fill that rather quickly. Also you can get an "idea" of the pressure being delivered, NOT exact or scientific I know, but pressure is visible to a degree.

Then my mind points to the pump itself.

 

I'm leaning towards pump volume as well. If the injectors were shutting down, fuel would be remaining in the rail and there woupd be no need for the pump to run AFTER shutdown, since the rail would already be pressurized with unused fuel. Since the pump runs on after the car shuts down, that tells me the fuel pressure in the rail was too low and that was when the pump was "catching up". Anyone around you could borrow a known good pump from?

 

I agree KINDA.

The pump "run on" after stall is "normal". I looked into this waaaaay back with mine.

If you pull the coil lead with the engine running (NOT if you got a pacemaker), the engine will stop, and if your listener in the boot is reliable, he/she will hear the pump whir for about 1 second.

HOWEVER, if the inertia switch is manually triggered, for example, the pump will stop, NOW, which again is "normal", power to the pump has been shut off, and obviously NO pump run on is heard. Restart "may" be spluttery as the rail will be somewhat drained of fuel.

BUT.
Since restart is apparently "instant" I am still thinking fuel supply issues from blockage and/or a dying pump in the area of actually pumping, it is whirring, but maybe doing little else, and enough fuel is there to actually "fire" the engine for a few seconds, and has got worse with use very quickly. The car has sat for some time, possibly with fuel in the tank/s.

 

Second thought.

The bridge is sorting the pump, OK, but the ECU triggering the injectors is still reliant on the signal from the ignition AB14 amp. That signal is via that dumb "shielded wire", and maybe, just maybe, it is not in good condition, most are not, and the ECU sees NO ignition pulse so shuts off the injectors.

Also, the signal from the CTS (coolant temp sensor) is another "kill engine" cause, either the sensor itself or the plug/wires attached to it.

 

As I mentioned at the beginning the pump and filter are new. One thing I forgot to mention is that the problem didn't start until after I had trailered it to a fame shop because one of the front crossmember mounts is bent. The shop couldn't fix it because they didn't have the clamps to hold it on their rack. So I'm wondering if they knocked something loose or it shook loose during transport.

I'm going to double check the wiring. Also using a stethesope I can hear the injectors clicking until it dies so I think they are not being cut off.

 

Mmmm, fresh info, just like fresh coffee.

I would look at the MAIN engine earth strap fiasco that loops the LH engine mount, maybe, just maybe it is not as it should be. If in doubt run a NEW earth strap direct from the sump bolt to the chassis, eliminating that double nonsense.

I am clutching at straws here as there are just soooooo many possiblities.

Having not read any previous postings, if there are any, try resetting the enertia switch, I seriously doubt it is the issue, but 10 more seconds is not going to hurt. It has been trucked, and who knows what at the crash shop??.

 

Did you ever feel like an idiot and then realize you are one? Well, I are one. My kitty just needed some milk (aka gasoline). It was almost completely empty. Apparently there was enough in the surge tank to start it but not enough to keep it running. After shutting it off there must have been enough gas in the return to put more in the surge tank.

I thought there was plenty of gas because 1) There was always gas under pressure in the supply line and 2) I had put in about 4 gallons after replacing the tank. However, after I found out it was empty I remembered that when I 1st put gas in it one of the tank fittings was leaking so I had to drain it back out. I guess I didn't put it back in.

Anyway thanks for all the advice. At least I know a little more about the XJS fuel system. Aside from a slight idle miss it now purrs again.

Thanks Again,
Marvin

 

HOO BLOODY RAH.

Fair dinkum, YOU ARE NOT SILLY, been there looooooooooong time ago.

Now I can get back to the Rover AND drinking, in whatever order I choose.

HAVE A SWIG, you definately need it.

 

I was going to post a similar question soon, but I first I will check my fuel supply. I did this a few weeks ago too, so don't feel bad. Mine was a Ford Fiesta I was asked to sell. One cannot fill the tank with a soft funnel. It has some sort of a butterfly opening that only the metal spout of a gas pump will open. The dealer actually said owners have towed them to a gas pump. I made a funnel from a curtain rod. I'll be back with my question about the 1994 XJS 2 X 2 I purchased and will be towing home Thursday. I am glad you guys are here because I am an old woman that knows little about this car other than it was love at first sight. Cheers,,,

 

Carole,

Welcome to the Forums.

When the dust settles a tad, please do an Intro in the New Members Area.

Good luck with the new toy.
They are NOT complicated, just seems that way by over thinking things too much.

You have not mentioned V12 or 6cyl, and that will make a difference to assistance.