I’ve recently got this car from a friend. The car had been setting for about 9 years. We got it running great. We pumped out the old gas, changed fluids, new fuel pump, filter, spark plugs, etc. The car has 117K miles. We put about a hundred miles on it since we got it running. Then, one day we go out and it doesn’t start. It cranks but no fire. It has spark, but the injectors aren’t opening. I purchased a noid light set and confirmed no electrical current to the injectors. Since there’s no injector relay on this car, the wires run directly to the ECU. We replaced the ecu. Still nothing. The engine was throwing a code for the coolant temp sensor. Replaced that. Still nothing. The fuel pump is running properly it seems. If I crack open a fuel connection and turn the key on, fuel will spray, indicating good fuel pressure. You can’t smell fuel as if it were flooding. Obviously, I smelled it after I opened a fuel line connection at the fuel rail, pre and post fuel rail. I’m baffled. Any ideas? Jag dealers don’t work on these models anymore. Thanks! P.S. It will fire on starting fluid.
I’d ask this question on a jag forum. It is a fairly specialized and very English car, as I’m sure you’re aware now. They are quirky.
There are a bunch of forums out there.
Congrtaulations on your troubleshooting so far.
I’m not in-depth familiar with Jags, but the squarewave being sent form the ECU is probably triggered primarily by a crank position sensor. Since you’ve confirmed that there’s no signal going to the injectors, that’s where I’d look next.
Other variables such as the crank or cam speed, engine temp, etc. are variables to the pulsewidth, but the signal is initiated primarily in response to the crank sensor.
Again, I’m not familiar with the specifics of this engine, but these are the general principles.
Thank you! I have a Haynes repair manual and I did just notice that there’s no engine code for the crank sensor. I guess I’ll try that next. Any website suggestions for those jag forums?
Google. I’m sure there are tons of them.
@Short stuff, the ECU probably grounds the injectors. Most cars are wired up this way.
Have you hooked up a fuel pressure gauge to the rail?
I’m not familiar with this model of Jag, but most injectors are fused; either through an injector-only fuse or in a circuit that encompasses other components.
In case the injector fuse is not clearly marked you need to check all of them.
As db4690 correctly stated, the wires to the ECU do not provide power; they provide a route to ground only through the ECU.
Captain Jaguar’s Cathouse. The best resource you’re ever likely to find on the Internet for your car. Find the correct manual here for your car, I can almost guarantee that it’ll be far far superior to the Haynes manual you’re using.
Thanks to all for your input. We replaced the crank sensor and, ta-dah! it runs great!