QuestionQUESTION: Howard, i have 150 pounds of compression spark at the coil an plugs new fuel pump and its working it seams that my fuel injectors are not working it cranks fine i though it may be a the diode pack for the fuel injectors i was driving it one day and it just seen to load up i could get it started after it sat a while it did start but power was not good i got it started again but only made it around the block and got back into my garage it shuttered and stopped and never started again I checked the timing and i am right on the mark. please help battery is at full charge.
ANSWER: Hi Jeff,
To test the injectors you can put a stethoscope on the injectors and listen to them click or get a Noid light from any parts store. (Not expensive) Get the one for either Lucas or Bosch.
If you are referring to the little box on the right inner front fender wall, that is a resistor pack that powers the injectors. The ECU in the trunk grounds the injectors to open them. The Diode pack on the fire wall is for the main and fuel pump relays. (red box)
A new fuel pump does not mean that you have the correct fuel pressure at the fuel rail, to know that, you need to connect a fuel pressure gauge in a "T" with the system. You need 32 to 35 PSI and low 40s with the vacuum off of the pressure regulator.
You have done some of what is necessary to find the problem, (compression, spark/timing) but you still need to know if you have injector pulse and correct fuel pressure.
One more item that is common on the Ser III Jag. Even though the battery is up, connect a second good battery as a jumper as though you had a dead battery and try to start it.
Let me know the results.
Howard
---------- FOLLOW-UP ----------
QUESTION: Howard, thanks again in advance for your advice, i have good fuel pressure and i hooked up 2 good batteries, hook up the noid light Bosch two and no light it looks like no injector pulse no power to injectors. Any thoughts?
ANSWER: Jeff, if the noid light did not pulse you need to test for power on one of the two wires. If you did that (the noid light not flashing is not a test for power to the injector) you need to then use a 12v test light or a volt meter to test that. If you have done that as you say "No power" then you need to test for power at the brown w/slate tracer wires (two) at the resistor pack. (right front inner fender well)
The wires are powered up at their source because you said you have fuel pressure (how much you didn't say) because the fuel pump relay is powered by the same wire.
Howard
---------- FOLLOW-UP ----------
QUESTION: Howard, you are the best there is. For you and others here is what was wrong. STEP 1 listen to someone who knows even if you are like me and have been a wrench all your life and I am 57. It was the fuel pump even though I replaced it just a couple of moths ago. Now Howard it smells like rotten eggs when it is idleing, can I adjust this? Again thanks for your help.Its running great otherwise.
AnswerIf you are sure the timing is correct and the fuel is not stale, I would guess either the CATs are destroyed or the fuel mixture is off. You can adjust mixture at idle with the Allen screw down in the bottom of the hole in the throttle assembly. It is difficult to get to because of the angle required to get to it. I have cut off about a inch of a Allen wrench and I put it in a 1/4 in drive socket and use a universal joint on an extension to get to it. To keep the piece of Allen in the socket I put a small piece of sheet plastic over the end of the Allen as I push it into the socket.
The major factors on mixture on the "L" Jetronic system is the coolant temp sensor and fuel pressure and the airflow meter. The 0-2 sensor effects it but not a lot. If the mixture is rich you could have a leaking injector or a leaking cold start valve also check the fuel pressure regulator vacuum hose for signs of raw fuel.
I hope this helps, let me know.
Howard
