Hallo, i bought my first jaguar some week ago, an xj40 from 1989 and already on my way home i had a problem, the car hade like a hiccup when driving, mostly when driving a little harder and uphill, but downhill and calm driving it was better for the most, but even in the city when driving the car died then just to start straight away..?

I'm guessing it's some kind of fuel starvation? The car starts fine and runs fine att first but it don't take long until i gets sensitive and i cant drive past any cars because the hiccup and so on.

My first taught was the fuelpump because it has such a loud sound, clearly more than normal, so i changed it but i sounds the same, changed the fuelfilter aswell but still nothing better.

Then my taught was the gastank so i removed it to look inside and maybe remove some dirt from inside but it was not so bad inside at all? The "sumptank" seems to be inside the whole tank and not removable, but as far as i can see its pretty clean inside, saw an old gasket ring inside just laying thats it.
have blown in the hoses to se if any was clogged but they seem fine.
Now i'm out of ideas so i'm turning me to you guys, hope you have any ideas of what maybe this can be, feel like i cant really make the use of my new jaguar when its not running as smooth as it's suppose :-)



Best regards!

 

Hi Simon,

Welcome to the Jaguar Forums! It's great to have you with us.

There are many possible causes of or contributors to a hiccup under load. Fouled spark plugs, clogged fuel filter, failing Crankshaft Position Sensor (CPS), air intake leak, failing Fuel Pressure Regulator (FPR), cracked or worn distributor cap & rotor, broken spark plug wires, a problem with the evaporative emissions system, using fuel with a lower-than-specified octane rating, clogged air filter, oil-contaminated Throttle Position Sensor (TPS), failing Coolant Temperature Sensor (CTS), stuck open thermostat, failing ignition coil or ignition amplifier, etc.

A place to start your diagnosis is to check the Vehicle Condition Monitor for any stored Diagnostic Trouble Codes. To do so, turn the key to position II (ON or RUN), but do not start the engine. Press and release the VCM button on the trip computer to the right of the steering wheel. Watch the small odometer window below the speedometer for a message. DTCs appear in the form of Fuel Fail or FF and a numeral, such as Fuel Fault 5 or FF7. Let us know if you get a message and post it here exactly as it appears and we will try to help.

Unless you know the service history of your car, it probably needs a good tune-up. On an XJ40, a tune-up includes the following:

New Champion RC9YC spark plugs properly gapped at 0.035" (results vary with other brands, even very expensive brands, so just use the correct Champions)
New spark plug wires
New distributor cap and rotor (inspect the distributor shaft for signs of arcing)
New fuel filter
New air filter
Remove the Throttle Body (TB) and clean it
While you have the TB off, drill drain holes in the TPS plastic case and flush all the oily gunk out of it with zero-residue electronic cleaner spray
Clean all the oily gunk out of the air intake and crankcase breather plumbing
Adjust the throttle cable to eliminate most of the slack
Clean all the ground points in the engine bay including both ends of the engine ground strap
Check the wiring at the ignition coil for any burning or other damage
Check the Fuel Pressure Regulator by pulling the vacuum hose off and checking for wet fuel, and consider replacing the FPR preemptively
Consider replacing the Crankshaft Position Sensor preemptively
Consider replacing the Coolant Temperature Sensor preemptively

Check the transmission fluid while hot (after a drive of at least 20 minutes): park on a level surface, with your foot on the brake move the gear selector lever through all the gear positions, pausing at each position for at least 3 seconds (PRND21), then back to Park, and with engine still running, check the transmission fluid. It should be exactly at the HOT full line. Stalling while slowing to stop or make a turn has been associated with low transmission fluid.

Cheers,

Don

 

thank Your for the reply, i Will test this and reply! But i’m wondering why does my fuelpump buzz so loud? Thats why i think its i fuel related problem, loud buzzing and slurping sound and the car runa perfect exept from the hiccups, you can even hear the pump from inside the car when drivning

 

I wonder if what you are hearing is what we call the "helicopter sound" ? This is a repetitive sound that can be heard in the passenger cabin but not in the engine bay or near the fuel pump. It results from hardening of the rubber fuel line that feeds the inlet of the fuel rail. You will see a small disc-shaped pulsation damper on this rubber line. Replacing the fuel hose with its integral damper was the solution in the past, but the hose is probably no longer available.

I can't explain the slurping sound unless it is water collected under your air conditioning evaporator due to clogged drains. The drain tubes run along the sides of the transmission tunnel and you can see them if you pull back the carpet near the center console under the fascia/dash. Foam rubber weatherstrip/insulation in the climate control unit deteriorates over time, and the crumbs of rubber clog up the drain tubes where they connect to the drip tray beneath the A/C evaporator. Have you noticed any water in either front footwell?

Cheers,

Don

 

Hmm okey, don’t really think any of that is the cause of this, i can clearly hear the buzzing from the fuelpump at the rear, the sound of like if was airmixed fuel going through it, if that explains it well enough. Thats why my taughts was around the gastank, fuelfilter and pump but it does’nt seem to clear it.

 

Okey I'm gonna do a recap now because I still haven't fixed this.

I have cleaned the whole fueltank and it flows good, the filter and pump is new and the fault was still there.

​​​​​​I have now changed sparkplugs, wires, coil, distributor cap and rotor. Still the same.
Also had the intake out of the car and changed oil filter and oil then a new gasket for it. Then had apart all the things on the intake like the iacv and the throttlebody and cleand it all.

​​​​​​I have also cleaned all connections I could found but after all this I still have the same fault? The only thing all this has done is added another problem, after I had the intake apart and all that I have a rhough idle, not smooth anytime but it was like that before also, but now when the car getting hotter I suppose it gets worse, the whole engine starts swaying, I guess this may have to do with the iacv? I've tried configuring it but it has done no good, could it be that I broke it when cleaning? I may have pressed in the motor for pin or what it's called don't know how sensitive this is? When the engine starts having the roughest idle the engine light comes on but I get no fault code.

I first thought of maybe a vacuum leak but have gone through everything and every hose and every connection are good what I can see.

Anyone have any ide, starting to get real tired on this haha..


Edit. I can add that after I did all this and went for a testdrive it went flawless for 1-2 miles then it came back again. If I stop the car and turn it off the start it right away it can be better for a littel while but not long and not always

 

You can't see the fault code when the engine is running. Turn off the car, switch the ignition back on but don't crank, THEN press the VCM button to see the fault code.

On another note, does the temp gauge sit at "N" when the car is warmed up.?

The IACV has to be reset after removal and cleaning. The procedure is here:

Jag-lovers' Ebooks

Larry

 

I have checked the vcm just like that still no code, and also reseted the iacv like that, still the same. The temp gauge is is standing like normal

 

Well, how is your temp sensor and wiring to that sensor? It can get pretty crispy.

Very odd to have a check engine light illuminated and no fault code.

Try tightening the female pins on the mass air-flow connector and make sure not to use any dielectric grease in any sensor connectors.

Larry

 

After all I changed the fuel pressure regulator and the pump got quiet so but that was the case. But now I have other problems but have a new pos about that :