QuestionQUESTION: Hi Howard, I stored this Jag for 6 or 7 years and am now trying to bring it back to life. It used to run fine. Seems to have no spark to the plugs. Got 13 volts at the positive coil term to ground but nothing positive to negative coil terminals. What do ya think? Thx, Jim
ANSWER: Hi Jim,
The ignition unit (mounted on the front of the intake manifold)receives a signal from the distributor pick-up. Then the trigger signal is sent to the ECU (in the trunk) via a white w/black tracer wire that runs along the top of the coolant rail on the intake manifold with a bullet connector at about 3/4 the distance towards the rear. You should check the pick-up coil in the distributor for resistance (2.2 to 4.8 ohms) and that if you wiggle the inside and outside wire it maintains the same resistance. The pick-up wire is noted for breaking inside the insulation. The control unit mounted on the front of the manifold has a GM control unit inside and when the unit fails, it is often the GM unit inside (which can be matched up at most auto parts stores.)
Also be aware that even though you may have correct voltage available and the starter may spin fast, if you do not have a "Deep charged battery" (Diesel or Marine battery) you can get a no start condition. To test this you can just take an additional good battery and connect it up like a jumper battery and if that makes the car start, then you must put a "Deep Charge" battery in place of what ever you have.
Howard
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QUESTION: Hi Again, Hooked up a jumper battery and it did turn faster but didn't start. Previously checking spark with my timing light. This time with a spare plug. Not the ZAP I hoped for but I have spark. Pulled a plug and it looked dry. Living in AZ, not uncommon for gummed up systems due to storage. Any advice on checking the fuel system? Would a "Quick Start" spray be an alternative? Thanks again, Jim
AnswerThe injection system is the Bosch "L" Jetronic system and leaving it for any length of time can cause problems.
I have a procedure I use for cars that sat for a time. If the tanks have a lot of fuel I drain both tanks and put fresh high test fuel in and remove the air filter and turn the key on and open the airflow meter flap and listen to the fuel run through the rail for several sec to a minute. Then open the gas cap on the tank you have it set to and have someone hold the flap open so the pump will run and check to see that the fuel is returning to the correct tank. Then switch tanks and confirm that the fuel returns to that tank. This is a rough test of the fuel supply system. This also mixes the new fresh gas in the stale gas left in the lines and system. (except the injectors)
Reinstall the air filter and have someone try to start the engine while you spray a little starting fluid into the front air horn. Most Jags I did this to ran ok on the remaining stale and fresh gas mix. And would restart ok while still warm but sometimes not want to restart cold. Keep in mind that the cold start valve (injector) is not activeated nor controlled by the ECU. It is controlled by the "Thermal time switch" in the coolant rail. (the large switch with individual wires) Usually after a tank of fresh gas is run through and a test of the cold start valve system it should operate ok.
Howard
