It's been a little while since I posted, but basically I very recently bought an 87 coupe without even hearing it run. Owner said there had been a fire in the trunk from a rusted out fuel pump, and that he had replaced the pump, and had it running, but not well and that when he went to blow some mouse nests out of the V it just stopped. When I was looking at it I found the dist cap was cracked and the pieces sort of separated. Anyway, bottom line is that I took a gamble, gave him $1500 bucks since the body was quite nice and rust free. The fire in the trunk did not damage paint or anything, just some wires are a little funky looking. I was hoping a new dist cap would fix it.

So I try to get it started after getting it flat-bedded home. Will not fire although I have good spark after installing a new dist. cap. After researching, I checked for ground on ECU pin 1(good) checked 12V on 22(good) amp signal on pin 18 (BAD). Found the tiny shielded white wire was terrible. Repaired the white wire and shielding and I am running on the right bank. I have spark on the left, but apparently no fuel. The engine wiring on the car is pretty bad. There is extinguisher powder in the V from some previous event. Anyway, at least I heard it run and know it doesn't have any nasty engine noises from dropped seats or anything. I plan on replacing all the engine harnesses before trying to run the roads, but does anyone think they know why I may be running on right bank only?

Thanks, sorry for being long winded, but thought a little background would help.

Bill.

 

To fire the injectors, the ECU switches them to ground. You will need to go through ALL of the wiring, it is almost guaranteed to be bad wiring. If it is firing on one bank and has spark then the injectors on the other bank are NOT firing. The fuel rail is common to both.

Pull all of the connectors from the injectors on the side that is not running, you will need a multimeter, put it on Ohms and check both pins in the plug for a short to ground. If this is good then turn the ignition on (don't start it) and check for 12 volts on one pin of the connector. One pin will have 12 volts the other 0 volts.

 

Thanks a lot for the reply. I think I'm going to just pull the whole injector harness out and make a new one. This will allow me to do the plugs at the same time. If I still have a problem after that, it must be an ECU problem?

Do you agree?

Also, I started it again and put my hand over the exhaust pipes while the motor was running. The right side seemed pretty regular, but the left side was very irregular. I think I may be running on 9 cylinders, supporting your wiring theory.

I need to find those injector connectors. I'll search for those connectors, but if you have a source I would appreciate the convenience of your info.

Thanks,

Bill

 

You can get the connectors at NAPA (and probably some other places). I rebuilt my harness, it's a pretty straightforward process. If you have not yet looked at Kirby Palms book, he has some part #'s for the connectors.

What seems to be hard to find (or too damn expensive if you do) is the boots that slide over the connectors. If you just want to get it running and are not a purist about such things, you can just not put any boots on.

Consider cross linked polyethylene wire for the harness, and (unless you want to rebuild the harness again a few years down the road) don't run it in the V. Tie wrap it to the fuel rail, it's cooler up there and should last a lot longer.

Have fun with it!

John
1987 XJ-S V12
63,000 miles

 

Thanks,

I ordered 12 connectors - Fuel Injector Connector

I was going to order these boots. 880810-1 TE Connectivity / AMP Brand | Connector Accessories 880810 1 | Onlinecomponents.com

They were from a link in a "fuel injection harness rehab" thread.

Can anyone confirm that these fit correctly before I order them?

Thanks.

 

Without digging up old notes those boots look the the exact ones I've always used....and from the same vendor.

Should be OK

Cheers
DD

 

Thanks,

On another note, I have the injector harness out and I'm in the process of cleaning out the V. I ohmed out the injector harness and it was actually OK. It's rough, but technically it's OK. I was actually hoping to find issues to explain why I was running so rough. I'm doing plugs and wires while I'm in there, and I'm doing the other harnesses as well.

On that note, one harness that goes to the AC compressor, water rail temp sensor on the A side, Ignition Amp, oil pressure sensor, primary coil wire, and kick down wires on it................also has a wire that disappears behind the motor and heads down towards the transmission. It would appear to be a huge PITA to undo and replace. It is preventing me from removing that harness.

Does anyone know what that wire is for. It's either kick down or temp sensor I think, but would like confirmation.

Thanks.

 

Kickdown, I reckon. I can't think of any sensor down in that region.

Cheers
DD

 

I think Doug's right.

To test it, have an assistant (with the engine off of course but the ignition on) listen below the center of the car while you close the microswitch that is on the throttle cable. You should hear a "click" as the kickdown solenoid on the transmission engages. Actually, if you are in a quiet environment, you can hear it click yourself.

Regards,

John
1987 XJ-S V12
63,000 miles

When I redid my harnesses, I just cut it at a convenient place in the engine compartment...and labeled it...then I just soldered it into the new harness and put some shrink wrap around it.

 

Vacuum hoses, fuel hoses, wiring repairs, lube distributor, plugs, wires, dist cap? Adjust throttle linkages, reseal cruise control bellows, clean and set throttles to .002" ?

The whole nine yards?

Maybe even throw on a set of cam cover gaskets?

That's the way to do it. Do it all, do it right, do it once. You'll be good to go for years to come.

Cheers
DD

 

Definitely kickdown solenoid. You can unplug it from the spade terminal on the box (US Driver's side 4 inches behind the selector cable arm) and it comes out with the engine. You may be able to pull it through after it has been unplugged, but it may catch on the foam sound padding on top of the gearbox. Mind you, this may have disintegrated long ago!

The important thing is to put it back in place BEFORE the engine goes back in!
Greg

 

Thanks everyone. I think I could unplug it, but there is a little bolt and wire hold down that I can't reach without removing the exhaust pipe. I don't want it that bad. I think I will do a nice solder splice and leave it and replace everything else.

Do injectors plug up? If I'm still running rough after this work I think I'll pop the rail and injectors off and physically watch and see which ones are not fueling. Does this make sense? Thanks.

 

Yes, they can clog up.

What you've described a way to find out if you have a grossly misbehaving injector.... outright dead or badly plugged....which could cause a fairly severe roughness.

But if they all spray you might still have still a problem, as your eye probably won't pick up a subtle flow rate problem or spray pattern problem....which you'd need to know if you're fighting a less severe roughness.

Cheers
DD

 

Having my injectors cleaned on my running XJS made a big difference to the overall running and performance.

As you are going to redo the fuel lines from the injector rail, you "may as well" pull the injectors and get them cleaned.

 

So how does one clean injectors if they are not working correctly? They're not something I've dealt with before.

Regards,

Bill.

 

You can clean them yourself if they are not totally gummed up.

Use one of your old connectors, a 9 volt battery and a switch. This will activate the injector.

A syringe and carburetor cleaner and an appropriate hose from the syringe to the injector.

Pressurize the injector with the syringe then turn the switch on and off a few times with the injector pointed into a container. Works great for dirty injectors if the injectors are completely stuck they may need professional cleaning.

 

10-4

Thanks.