Here is the background :

- It is a 1990 XJS Convertible that, until a few weeks ago, had not been started/driven for about a year.
- I was able to jump start it though and took it for a drive in the country but nearly got stranded because, whenever I accelerated to more than ~60 mph, it would then slowly begin losing power until it was basically just crawling down the road at ~ 5 mph or so. Other than occasionally losing power, the car ran smoothly otherwise.
- This happened a few times but, thankfully, it would improve after I pulled over and let it sit in park for a few minutes with the motor still running. I got it home and pulled it into the garage but a few days later it wouldn't start.
- Originally, the fuel pump wasn't starting during the ignition sequence so I replaced it. However, after still no-start with new fuel pump - I have been basically throwing parts/money at it with reckless abandon... To this point, I have also replaced the fuel filter, both fuel pressure regulators and fuel pump relay and the main efi relay. Still, no start.
- The car has at least 5 gallons of fuel. I have verified spark on the two front-most spark plugs- one from each bank. Have also verified that fuel is at least getting *to* the first fuel pressure regulator. I haven't checked pressure though as I would have to purchase a gauge and do some monkeying around with the gas lines since there doesn't appear to be a test valve.
- Can anyone suggest something else I should consider/investigate ? Does this sound like its possibly a "water in the fuel lines" problem. Or, should I perhaps begin focusing more on the ignition system - e.g. check *all* the spark plugs, the rotor etc.

Thanks, in advance, for any and all help !!!

Neil

 

Lots of "could be" ideas. Let's start with just a couple and go from there.

Spark at the two front plugs is a good sign but, since you have Marelli ignition, you should pull the cap to inspect it and the rotor just on general principles. Even if not related to your no-start issue you'll want to know the condition of the cap and rotor.

Next, pull the fuel filter and empty it into a clean container. Any water (or other crud) should show up.

Have someone crank the engine while you listen for clicking from the injectors...a mechanic's stethoscope is useful here but you can hold a hose or long screwdriver to the injectors and listen.

Crankshaft sensor failures are common on the Marelli cars. If your injectors are not clicking the sensors are a prime suspect.

Cheers
DD

 

Doug, thanks a ton for the ideas. I'm gonna try them out this week and will post back with the results.

 

is the fuel fresh or is it the old fuel from when it was sitting?

 

If it seems to run out of power at 60mph but comes back to life after sitting for a while idling. I would look at the fuel supply. If you have a fuel pressure gauge you can watch what happens to the pressure when your symptoms show up. Not sure of the fuel tank arrangement in your car but the coupes have a sump tank. if there is a problem getting fuel from the main tank into the sump tank your symptoms would happen. Also if you fuel tank is not vented it could happen too.

 

Thanks for all the ideas everyone. Update follows - please excuse the wordiness- I am very much an amateur at this and just want to make sure I am not missing something...

1 ) As suggested, I put a hose on a few of the injectors while my wife cranked the engine. On each I could hear a very quiet ticking ( perhaps 2-3 ticks per second ). Does that likely verify that the injectors are firing well enough to start ? If so, does that eliminate the crankshaft sensors and/or the ecm that controls the injectors ?

2 ) As suggested, I pulled and empty the fuel filter. There doesnt appear to be any crud or water in fuel I dumped from it.

3 ) The fuel in the car is ~5 gallons of fresh mixed with 1-2 gallons of old plus a bottle of gas cleaner treatment.

4 ) I dont have a fuel line gauge so I havent measure the pressure yet but I have verified that fuel *is* getting to the front fuel pressure regulator which is brand new. Wouldnt this likely eliminate any issues with the gas tank and sump tank ? Before I invest in a fuel pressure gauge, is there any other fuel supply check I could do -- assuming my verification of fuel at the pressure regulator ?

5 ) I havent pulled the cap to inspect it and the rotor yet... Mainly because, wow, thats alot of wires to put back correctly - and so its going to be a little time consuming to label each wire etc,.. Thought thats all I can think of to check at this point so I will probably do that next...

Again, thanks for the ideas... and please keep'em coming.

Neil

 

You need to see what the fuel pressure is doing when the problem occurs. If it stays steady then you can rule that out.

As for the distributor if you have a Lucas ignition then you should get inside it and make sure the advance is working. Both centrifugal and vacuum. They will cause overheating and of course lack of power. Not what you are describing though.

 

Recap of the situation and some new information:

1 ) 1990 XJS convertible does not start.
2 ) New fuel pump, filter, pressure regulators and main/EFI relays.
3 ) Pressure immediately after the fuel filter is ~42 psi.
4 ) Fuel is ~5:1 fresh/not-fresh
5 ) Used in-line spark plug tester to verify adequate spark on one plug from each bank.
6 ) Used hose to listen to fuel injectors while cranking and heard very slight, but regular ( ~2-3 per sec ) 'ticks' and so I assume that eliminates the ECM that controls the injectors ?

What should I look at next -- to specifically address 'no-start' condition ?

A. crankshaft position sensor
B. cap,rotor,points
C. ??

Thanks in advance for any help/ideas offered.

I hate to give up and take it to a shop-- but, its not looking at this point is it ?

Neil

 

Well, after doing a little more research online and in these forums - it seems the crankshaft position sensor could still be the culprit and, from what i can tell, is the next most likely problem. So, I ordered one and will post back once i am able to get it swapped out...

 

Just remember there are 2 of them on you car.

 

have you verified spark? also, you need to check the fuel pressure at the rail.

also, you should eliminate the old gas completely.

 

mrtalkradio,... thank you, I did learn that there are 2 positions sensors but I am only replacing the one in the front ( the tdc sensor ) for now... If you have any knowledge as to which one is more likely the culprit in a no-start condition, I would love to hear it. Also, do you happen to know where that cable/sensor is located ? I did a quick search ( from above ) last night but couldn't locate it -- unfortunately, I dont have much experience with this sort of thing.

M90Power,.. Right, I only checked the pressure immediately after the fuel filter... I couldn't find any point on the rail to ( easily ) insert the gauge. So, I will take a look at that issue again if the CPS replacement doesn't work. And, yes, I have verified spark from plugs on both banks.

 

have you tried starter fluid. doesnt take much at all.

 

Yes, have tried starter fluid ( both a little and a lot ) to no avail...

 

The front sensor is easily visible from below, essentially just under the crankshaft balancer. The wiring harness sorta snakes upward to the left of the water pump area and connects to the main harness inside the "vee"....(sort of) near the oil filler cap.

The sensor itself is easy to replace...two minutes. Routing the wiring harness and getting your fingers on the connector is tricky, though

Cheers
DD

 

If you tried starting fluid and it didn't even cough then are you really certain you have spark?

 

I used an inline spark plug tester that flashes when there is adequate spark. I tested a plug on each bank and both looked good. No, there was no 'cough' or anything different when I sprayed fluid into the intakes.

 

Ok, I installed new TDC sensor and drained gas and refilled with new gas -- but no improvement.

Here is re-cap for the situation :

1 ) 1990 XJS convertible does not start.
2 ) New fuel pump, filter, pressure regulators, main/EFI relays and TDC sensor.
3 ) Pressure immediately after the fuel filter is ~42 psi.
4 ) Old fuel replaced and refreshed with fresh fuel.
5 ) Used in-line spark plug tester to verify adequate spark on one plug from each bank.
6 ) Used hose to listen to fuel injectors while cranking and heard very slight, but regular ( ~2-3 per sec ) 'ticks' and so I assume that eliminates the ECM that controls the injectors ?

Any ideas for what to try next ?

I am not confident that what I heard on the injectors ( item 6 above ) means anything and so wonder if there are not some other ways to test that the injectors are pulsing... ?

Also, I tested fuel pressure right after the fuel filter ( in the trunk ( or boot, is it ? ) ) because i couldn't find any easy place to test on the fuel rail. What are the odds that there is something wrong between the fuel filter and the rail ?

 

Funny thing was I was just going to post a recomendation up to jag-lovers on the CTS (CPS) thing - my 90 dumped me at a major intersection and would not start after - towed home - new fuel pump - battery etc - then read about the CTS. In my case it was the CTS but not the device itself but rather the connector from the CTS lead to the Marelli - since you have replaced the CTS you will know where the connector is (if you stand on the driver's side and stare down at the AC compressor then just in front of that is the connector - a yellowish square thing). Pull that apart and inspect the connector's copper tabs (male and female). I bet they are corroded. You need to clean them up to a bright copper condition. Actually before you do the clean up - pull one of the ignition coil leads and place its end near a ground point - get someone to start it while you watch the coil lead - there should be a spark but note its strength. Now do the clean up of the connector and repeat the spark test thing and I bet you will be impressed by the spark now.

Anyway I have done the clean up twice now in the last two years but last on Monday (9th) the Jag dumped me a major intersection again and though I tried to clean the connector right in the middle of traffic I had no luck and the cops made me tow it home. I left it in the garage until the 13th knowing full well it was the connector. Gave it the spark test first to confirm suspicions and this time there was no spark at all! (other times I would get a very weak spark). Sure enough on inspection the connector's copper was corroded again and in fact one of the female tabs was completely gone. So I simply cut off the connectors, bared a bit the sensors' two wires on each side and soldered in jumper wires between the two side and heat wrapped the joints (if you want to do it this way make sure you connect blue to blue since the cable is a shielded cable with the signal on blue and the shield and its associated wire (not blue) leads back to the Marelli's ICM ground which is a high quality signal ground and not the grungy car ground).

I hope this helps - The one thing noticed is that the corrosion thing happens during the summer down here in Florida where every day is very hot and very humid and also being near salt helps in the corrosion. From the looks of my corrosion there is some kind of electrolosis going on. Of course in NC where it is often hotter and more humid than coastal FL you will be subject to the same effect.

 

Folks:

just to clarify - whereever I say CTS I mean CPS (crankshaft position sensor).