So today here in Guam. I pulled the distributor. Brought the engine around to TDC. I did this bye moving plug in #1 and placing my finger on the plug hole. I got the whoosh and found the distributor was in wrong. So I pulled the distributor and placed it in the engine so the rotor was on number 1 when at TDC combustion stroke. Yes, I pulled the valve cover to make sure what stoke I was on. I have spark. Is there a way without noids to see if my injectors are firing. A volt meter at the connector?

Thank you

 

try it with starting fluid....injectors or no, it should fire at least......good luck
if it doesn't fire, look to spark....

 

That's a great idea. Thank you

 

The fuel injectors have two wires going to each one. With the key in the Start or run positions all the injectors will have 12 Vdc at each one of them. The computer "pulls" to ground the injectors when they are told to "inject" fuel which completes the circuit. The NOID lights sure make testing the injectors easy.

The injectors also do something called "Batch Fire" where all the injectors on one side will inject and then the other side and so on. Each injector fires twice per revolution I believe.

Advance Auto might have the NOID sets to rent. I bought a set and keep them on the shelf, this means my injectors will work forever according to Murphy's Laws. EBAY sells the NOID kits for $22 with free shipping. In this modern day and age they are useful to have in the tool box.

Be very careful using Starting Fluid in your Corvette. That material is a bit rough on the parts so use it sparingly, do not try to keep the engine running using the Ether. Keep it for your lawn mower instead.

Whenever working around fuel or fuel related parts I have a large Fire extinguisher handy just in case.

Keep all the electrical connections clean, I use DeOxIt on my connectors to ensure a good lasting clean connection. On my C4 there was a broken tab holding the power on to the distributor, when I hit a pot hole the car would miss due to a momentary power disruption. Easy problem to solve.

There are a few wires going to the distributor, be sure they are all connected and secured.

The oil pressure sending unit and the oil pressure switch are mounted behind the intake manifold are part of engine protection scheme. The engine needs to see oil pressure at the switch when cranking to turn on the fuel "On". My 1988 C4 is like that. My C4 it will not start with the oil switch "open" showing no pressure inside the engine. It was somebodies idea of protecting the engine from damage. No oil pressure no fuel, simple. Not all cars have this system from what people have told me or some folks claim it has no effect on the running of their Corvette. If your car has this equipment it must be connected properly for it to work. The oil switch and pressure sender are both mounted near each other but are separate units on a tee.

Hope that this helps you a bit!
Chris

 

Chris,

Thank you for such a well thought out post. This is really great.I am going to check the voltage on the injectors today and the fuses. I thought of that last night, doh. The noids are out because there ain't no auto zone or advanced auto stores on Guam, where I live. Shipping will take up to two weeks and it ain't free.

I am aware of the oil pressure and sending unit. When I crank the car it says 8/9 PSI. So I have enough pressure to run the car. Whet is bother me is it did run. Ran like **** but it ran. So frustrating. I had the same discussion with someone a month ago. I looked it up in the FSM. I think that the oil pressure sends a signal to the fuel pump relay. If the relay fails and you have power to the relay. The FSM says " As a back up to the FPR, The fuel pump can also be turned on by the oil pressure switch. The switch closes if the car has 4 or more psi. I always thought it was a back up in case you loose oil pressure. My external oil cooler line fell off and the oil pressure went to zero and the car shut off, YIPPIE!!.

Being it did run. I have to think we either disconnected something or burned out something. Oh and with respect to start fluid. Yes, it can be bad for the motor.But, It will tell if it can run. Just once.

Thanks again.
Joe

 

You could use a tail light bulb to test for pulse at the injectors.

 

Great idea thank you.
I just checked the fuses. The injector fuses have power. The Fuel pump fuse does not.. So now I am going to use the FSM to trace the wire. And hopefully get fuel in the car. I have fuel pressure when I turn the car on. The fuel pressure gauge says so, 40 psi. But I guess in run the car goes through the fuse. I hope the FSM can help.

Thank you all

 

if you have fuel pressure, the fuse works.....look elsewhere.....

 

So I take out my test lamp. And test the fuel pump fuse. It is not getting any power. The ALCL, Red and Orange wires also not getting any power. The oil pressure switch is getting power. According to the wiring diagram page 838 of the FSM. The oil pressure switch and the ALCL are hot all the time from the same fusible link. Remember I bought this car used and the former owners did some wiring. Does anyone know where that fusible link is located. I traced the wires and it looks like it maybe in the car? I could not get under the car . It was pouring outside and the rain was coming into the garage and floor was getting wet. So I just did not want to work in a puddle. The car did run for me a once or twice. So I must have burned out the link. I am thinking of running a fused wire from the battery to the ALCL. I can't see the car until next week. The auto hobby shop is closed until Friday.

Thank you

 

I think the pulse width to the fuel injector is so short that an incandescent tail light bulb won't have enough time to cause it to flash.

You can make your own NOID light; Use an LED, wired in series with a 1K resistor. The LED will respond much more quickly to a pulse. If the LED doesn't flash, try reversing the position of your LED/resistor in the f.i. connector (reverse the polarity) It doesn't matter which side of the LED gets the resistor.

 

Hey guys thank you. That is a good thing to know

 

12v to pin "G" on your aldl should start fuel pump.....

 

do you have a ground wire or the rear bolt of the thermostat housing? off the top of my head, i'm thinking that's the ground for the fuel pump relay.

also, do you have a couple ground wires coming off the rear of the LH cylinder head? just asking....

 

Being I can't get to the car until Friday. But I will check. Funny as you say that I know exactly what you are talking about.

thank you

 

Checking the fuel pump fuse *usually* requires two people... One to check the fuse and one to turn the key on and off.
On my 95 there is a 2 second pulse of 12 volts through the fuse to the pump to prime the injectors. Then the relay turns off
until the key is turned off and then on again.. Once the engine starts, the oil preasure switch sends voltage to the fuel pump.
Don

 

Don,

Oh, I thought that the FP went on for 2 seconds and then when the car is on the FP would have power for as long as the key is on. Okay so I do get fuel pressure. Therefore the fuse is working, correct?
But the ALCL is not getting an power at terminals A and E. And I think A has something to do with the FP. What does not make sense to me is the oil pressure switch is getting power. The ALCL and oil pressure switch are on the same fusible link, according to the FSM page 838.
Thank you for the help. It makes sense.
Now I have to find the link or run a fused wire to the ALCL terminals A and E and see if the car will run.
Thank you again
Joe

 

Yes, there are two paths that supply power to the fuel pump. The fuel pump relay supplies power before the oil pressure switch takes over.
Don

 

Don,

Thanks for the help. Have a great day.

Joe

 

If you don't have a second person to help you out, you can always setup a camera on a tripod and video record the meters. Also gives you a chance to review the results too.

 

Yes, if you have fuel pressure, your fuel pump fuse is good. It's a bit confusing, because the fuse is after the fuel pump relay, so there is no power to the fuse unless either the relay or the oil pressure switch is activated.