Victor here...Again... My '89 XJS/5.3 runs for about a minute or two and then won't start until the next day. I've changed out the rotor, cap, cleaned and re-gaped the plugs, replaced the pickup coil and cleaned out the throttle bodys. When it does start up a large amount of white smoke comes out of both banks...and I mean a lot. It gets up to around 2500rpm sputters/falters begins to run erractly, then just dies. After that nothing. Come back after work the next day and the same thing. Checked out the ECU and gone from four to six "clicks" both ways and nothing changes. What to do next...I'm really at a loss for what to do. Any help from anyone out there would be great.

Submitted by Anonymous (not verified) on Mon, 08/14/2017 - 22:46

Did you ever find the source to this issue? I have this exact problem to a T on my 88'! Runs and smokes and if I give it gas maybe gets up to 3k rpm and sounds like the engine is drowning. I replaced everything in the Vee. Vacuum is a bit low. I have a pretty decent trans leak... wondering if the modulator is to blame or a failing fuel pump or a clogged cat.

Submitted by vgardino@comcast.net on Tue, 11/12/2013 - 20:53

I will try changing out the modular valve tomorrow. I've changed out the fuel filer and tried just grounding the orange wire at the fuel relay post. Wire change made no differance...but after I repalaced the filter the "A" bank began to clear up. Don't ask me why, haven't got a clue. It did run for about three to four minutes before faltering. White smoke is dry to the touch and doesn't have that glycol scent to it. So I don't believe its cooant...AKA;...a blown head gasket. One would think that unburned fuel would be black. So maybe it is tranny oil and its shutting the engine down via the oxygen sensor. I will keep all posted. Thanks, Victor

Submitted by BillCorn4895@c… on Tue, 11/12/2013 - 01:31

As Doug suggested "Could be a leaking transmission vacuum modulator which allows trans fluid to literally be sucked into the engine via the vacuum hose. Burning ATF gives of nearly-white smoke." I saw a demo of this on one of the car shows on Velocity TV a few days ago. That car was a '54 Cadillac, and it didn't shut down, but of course it has no O2 sensor or computer. If the trans fluid is burning with the fuel, when the oxygen sensor detects it, it could potentially cause the shut down. It only takes a couple of drops to make lots of smoke. You won't even notice the level change on the stick. It was an easy check too. They just pulled the vacuum hose off the vacuum modulator on the side of the transmission and fluid leaked out. Cheap part too, $10.99 at Advance Auto, exact fit.

Submitted by vgardino@comcast.net on Mon, 11/11/2013 - 18:08

To all...Victor here. Thanks a lot. I'm going to replace the fuel filter later tonight or tomorrow. Depends on how much time I have later in the evening. The ignition is Lucas, which I prefer. The white smoke is not coolant as it does not even have a antifreeze smell. It is just exhaust... I mean it doesn't even smell like unburned fuel. Could the injectors be opening and closing at the wrong time??? If so, is that a problem with the ECU that can be easily remedied??? I even changed out the injector amp. and it did the very exact same thing. So I out my original back in. Thanks for the help and I'll keep all posted. I love this car!!!

Submitted by stevejag@sbcgl… on Mon, 11/11/2013 - 10:28

Doug is the man as usual........ agree with all counts.

If nothing pans out with items Doug suggested, there is a possibility that the cause of the white smoke, whatever it turns out to be, may have contaminated the catalytic converters. It is possible for that to happen and result in a car that will run, but the longer it runs, the less it can breath, then it just stalls. After cooling to ambient temp, it will then repeat. You might need some professional assistance if that turns out to be the case.

Good luck!

Submitted by dougdwyer1@com… on Mon, 11/11/2013 - 09:41

White smoke:

Could be coolant burning, which means leaky head gaskets or other problem allowing coolant into the combustion chambers.

Could be a leaking transmission vacuum modulator which allows trans fluid to literally be sucked ito the engine via the vacuum hose. Burning ATF gives of nearly-white smoke.

Could be a totally harmless accumulation of condensation in the mufflers....which would likely burn off in 10-15 minutes if you could keep the engine running that long.

Engine dies:

The "could be"list is long.

After it dies and subsequently refuse to start have you checked for spark? That would be a good first step, although.....

My gut feeling is that you have a fuel starvation issue which can be approached various ways. I'd begin by bypassing (the known-to-be problematic) fuel pump control circuit and seeing if anything changes. Ground the orange wire at the fuel pump relay. This allows the pump to run simply by turning the key "on".

If no change in engine behavior there are still other fuel system angles to pursue. However, if the engine now stays running after 2 minutes, you've hit pay dirt. You have a problem with the fuel pump control circuit inside the ECU

Also, have you changed the fuel filter? If not, I'd remove the filter and empty the contents into a clean jar. What you see might dictate your next steps.

Last, it might be helpful to know if you have Marelli ignition. Early 89s didn't; later 89s did. The crank position sensors used on the Marelli-equipped cars can cause both "no spark" and "no injector pulse" conditions

Cheers
DD