Hello everyone, here is the problem! Bought the car as is, long story short. I have been doing mechanical work for 40 years and always wanted one of these. I now have spark, fuel pump runs like it should. Have 45lbs pressure at pump and 36psi at return to tank on fuel rail. If I give it a shot of either starts right up then off. I used a noid light on injectors and it lights up. Listened to injector tics when started with either. It is like the injectors are not putting fuel into cylinders.I Truly believe it can't be to serious what am I missing? This thing sounds great when it runs! Could it be the ECU? The Haynes manual is very confusing. Sensor? Thanks up front for any help.

 

Welcome to the forum r3ml,

I've moved your post from General Tech Help section to the XJS section where the resident experts should be able to help you.

Hope it's something a lot simpler than the ECU.

Graham

 

As far as injectors go I don't think it gets any better than a blinking noid light and a clicking sound. That let's the ECU off the hook as I see it. I can't easily envision all the injectors being plugged solid or mechanically defective and, shoot, it oughta at least start even if only half of 'em are working.

I'm wondering about your fuel pressure and how you measured it. The pump should produce 75+psi "deadhead" pressure and regulated pressure @ the rail should be 35-40 psi (I think 36 psi is the spec....can't quite remember). Without a bit of mulling I'm not sure how to interpret 36 psi on the *return* line. Seems high to me, for a return line.

Where exactly did you take your reading?

It should be taken at the hose attched to the left side of the fuel rail. You'll have to cut the hose , splice-in a "tee" for your pressure gauge, and then replace the hose afterwards....which is easy to do and, if original, is long overdue for replacing anyway, as are all the others.

Others will chime in.

Cheers
DD

 

I took the return side pressure reading at the hose before the vacuum regulator on the drivers side where the rail enters into the regulator .It then comes out this and into the fuel cooler. Just to let you know the car has been stored for a year. Also fresh gas And A Big THANKS for getting this where it needs to be

 

Ok, I got it. Sounds like you are taking the reading at the right place and your 36 psie result sounds about right.

I thought you had 35 psi going into into the fuel cooler.






Stale gas? Just a thought. A year isn't really all that long. The gas should still be good enough to at least start the engine. I've started engines with 2-3 year old gas.

Cheers
DD

 

I'm with Doug & Co.

The CTS (coolant temp sensor) on the rear section of the LH thermostat housing is a known no-start issue. Either the sensor itself, and/or the wiring itself. Such as, with the engine running correctly, simply unplugging that sensor will stop the engine with conviction.

I am asking the next, coz I have to. You have fuel pressure, GOOD, but do you have "fuel flow". The flow from the inlet hose, RH front of the rail, should fill a litre container in a few seconds, unplugged from the rail obviously.

The fact its running on ether, is a fuel issue.

 

Thanks for the info on the cts I'll check it today and get back with you. As far as fuel flow I found that out the hard way. While watching an checking pressure at the pump a couple of times I ended up over filling a gal. gas can! LOL I truly do appreciate all the help, if you could see the shape of this car, it has no rust! original paint an near perfect interior! I will put up pictures of me jumping for joy when I get it running for all to see.

 

Grant and Doug, can't thank you enough!!!!! I pulled the wires off the cooling sensor checked voltage got 5 volts, Cool! ECU is working. I then proceeded to put OHM meter on sensor it read OPEN no continuity. Tried to get one today but had to order it. Needless to say couldn't wait so I took a sensor I had in the garage that went to a Saturn which is basically same voltage use for the PCM. Low and behold cranked it a couple of times and BOOM she started to run!!!!!!!!! Ran it about 15 min. she really stank out the exhaust guess I didn't all the old gas out. Shut her off restart good. Did this a couple of times need to do some additional work, cap rotor, plugs wires. FIGURED I would try 1 HR. later WELL no restart, Check my jury rigged sensor it was DEAD. So I'm going to wait for the new one to come in. YOU GUYS WERE REALLY A BIG HELP!!!!!!!!! THANK YOU SO MUCH! I will keep you posted as the rest of the car is all minor repair I HOPE! LOL

 

I'm not sure if I added to the post or write anew one. so here is what happened, I bought the new coolant sensor put it in no start! So I dug deeper and found after installing it that it had failed, open, when I tried to start the car. DUG even deeper now!! Found the air temp sensor is also no good. I checked the voltage for both, I get four volts. Is this correct? I was looking at the prints and see that these two sensors along with the Manifold pressure sensor share a common wire off two wires from the pressure sensor. I'm thinking a possible short maybe in the pressure sensor but where is this located? Once again the manual says on the wing valance for a 1984 XJS v12 What would it look like? With the air temp sensor disconnected and the temp sensor disconnected the car starts but is VERY erratic in idle.

 

I'm not sure if I added to the post or write anew one. so here is what happened, I bought the new coolant sensor put it in no start! So I dug deeper and found after installing it that it had failed, open, when I tried to start the car. DUG even deeper now!! Found the air temp sensor is also no good. I checked the voltage for both, I get four volts. Is this correct? I was looking at the prints and see that these two sensors along with the Manifold pressure sensor share a common wire off two wires from the pressure sensor. I'm thinking a possible short maybe in the pressure sensor but where is this located? Once again the manual says on the wing valance for a 1984 XJS v12 What would it look like? With the air temp sensor disconnected and the temp sensor disconnected the car starts but is VERY erratic in idle.

 

Answered that in your "private message".

I wont take up server space by repeating it just yet??.