QuestionQUESTION: Test results:
ALL TESTS IN FAILED MODE
spark test: good
air flap open (key on): 32/40 psi
noid test: passed
POWER TO ONLY 1 SIDE OF INJECTORS!
last evening while testing we had power to BOTH sides.
FOLLOWING TEST WHILE RUNNING:
Put pressure gauge before rail, poured gas into intake, started car and continued to pour fuel to keep running; fuel pressure started at 40 and dropped to 0. Car continued to run as long as fuel was poured.
ALL TESTS
ANSWER: Adam, the injectors are electromagnets which are coils. If you have power on one side you MUST have power on both sides of the injector.
If the fuel pressure drops to <0> while the engine is still turning then you have a failure in the fuel pump system.
Both of these need to be corrected before you can do anything more.
Howard
---------- FOLLOW-UP ----------
QUESTION: What would be the best method for testing fuel pump? (we see correct pressure w/key on ~ flap open)
The power to BOTH sides of injectors has tested intermittently. Any idea how to test what may cause it to change? Could there be a short?
AnswerIf all the injector wires are off, you may see power on only one side but if only one injector wire is off you will show both sides hot because the power is coming from the resistor pack on the right front fender well to the injectors and since the injector is a coil current travels through the other injectors to both sides of the wire.
As for the fuel pump circuit you need to conduct your spray test again watching the pressure gauge as you continue to spray to keep the engine running and if you see the pressure drop to 0 as you said, keep spraying and reach into the air flow meter and open the flap to see if the flap has closed for some reason.
Another method is to conduct your spray test and if the pressure goes to 0 while you are still spraying and the engine is still running then stop and place something thin on edge in the air flow meter that will hold the door open just a little but will not restrict the air flow and will not be sucked into the engine and run the spray test again.
If it still goes to 0 and the engine is still running on spray then you know for sure there is a failure in the fuel pump circuit.
If the pressure does not go down then there is something eliminating manifold vacuum. Which requires a pressure test of the exhaust manifold. Remove one of the two plugs and find a piece of rubber or even a cork and drill a hole through the center and put a piece of pipe in the hole that you can slip a low pressure gauge on to. (most vacuum gauges have a low pressure section for testing carb fuel pumps on)
Run the engine on spray and raise the RPM up and try to keep the spray going and engine running and watch the exhaust pressure. It should not get over 1.5 PSI. If this is the problem it will go to 5 to 7 PSI quickly. (don't run the engine long as the rubber or cork plug will get too hot from the exhaust manifold.)
If you get a reading higher than 1.5 PSI you have a stopped up exhaust system. Melted CAT, or something in the mufflers.
let me know,
Howard
