Frank, thanks for the input:

I've got a oil switch here new in the box. I just never installed it....I'll pull the distributor again tomorrow and install it. From what I can tell the switch just drops out the fuel relay if the oil pressure drops too low. I've bypassed the relay for test purposes by connecting a +12v to pin "G" on the ADL(makes the pump run all the time). I change the oil switch tomorrow any how. And i'll adjust the TPS sensor down from .58 to .54.... I'll make a post if either of these things make a difference.

 

I think tomorrow might be your lucky day!


"The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time.
If it sees appreciably more than 0.54 volts, it will assume the engine is flooded and the driver has pressed the accelerator to the floor to clear the flooded condition and restrict the fuel flow as a result (.54 volts during start and at idle from the TPS is very important to both starting and run performance.)"

Good Luck!

p.s. You might want to also take a quick look at that little wire attached to your coolant temperature sensor to make sure it's in good shape and connected.

 

Try disconnecting the knock sensor ( it should be on the passenger side of the engine block, under the motor mount). If the engine wont start then, disconnect the harness to the knock sensor module. GM knock sensors tend to rust internally causing a short. The ecm then senses a continuous knock problem and retards timing. Check your timming while you cranck the engine over, with and without the knock sensor hoocked up and see if there is a difference. Hope this helps.

Will

 

So Far Today:

Readjusted TPS down from .58 to .54 volts....car still will not start.
Unpluged TPS ...car still will not start.
Pulled distributor to install "new" oil pressure switch...car still will not start.
Checked coolant sensor wire and O2 wire (removed excessive oil from O2 wire): wires are attached and are not shorted to any metal objects surrounding them.

Note:I cannot reach the knock sensor wire at this time - will try again later after frustration level is lower.

 

Did you scan your old computer for codes? Were there any? Did you have a CODE 54? That should have been your first step. If you didn't, don't bother trying now because the computer has been disconnected long enough to clear it's memory.

You can try a couple of things:

1) Get the car running with ether or whatever you were using before to keep it running.

2) Disconnect the FUEL PUMP RELAY.

- The engine should continue to run; if it DOES NOT you have a bad oil pressure switch.

* You can also try disconnecting the SET TIMING CONNECTOR wire (tan w/black) and see if the vehicle will start while it is unplugged.

Have you tried swapping out the fuel pump relay? You can switch it with one of your other relays for testing purposes. The fan relay, MAF burnoff relay, etc. are all the same.

Also try unplugging the MAF and try starting the vehicle with it unplugged.

Also, while the car is running while spraying the throttle body, is the SERVICE ENGINE SOON light on?

Does the SERVICE ENGINE SOON light come on and stay on steady with KEY ON, ENGINE OFF?

 

Oh Man! I feel for you.

Listen, did you perchance install a fuel pump or change the wiring on it?

The reason I ask is that the first time I ever changed the fuel pump, I had the wires reversed and the car cranked but wouldn't start.

Anyway, best of luck - methinks you need TJ WONG to da rescue.

Hang in there and have a cooler full of wobbly pops on hand for the stress breaks!

 

FrankCandid:

As far as I know the is the original fuel pump in the car (car has just over 237,000 miles on it -- I like to dive it! ). I did not disconnect the pump's wires when I had it out. I have 40+ psi on a fuel rail pressure gage so it seems like its pumping OK. I also ran the pump (manually by jumping pin "G") to check if gas is going full circle out of the return line....lines are good.

 

Since you've adjusted the TPS voltage and changed the oil pressure switch and done ALL that other stuff, I can only offer you my last 2 cents so here it is:

Since it is the original fuel pump, and since it is easy to yank it out, you might want to yank it out one more time and take a good look at the wiring to make sure any wiring is free from bubbling/melting/corrosion - many times bad wiring there can lead to misdiagnosis.

Maybe try a more in depth testing of the fuel pump and pressure as suggested in the following link:

http://www.aa1car.com/library/2003/us60324.htm

Aside from that, and as frustrating as it is, maybe take a look at the C&P L98 start sequence I posted and go through the steps one by one with a scan tool to see if each requirement is happening when it is supposed to.

Again, good luck!

 

If your car runs with an auxiliary fuel source, ie: ether sprayed into the throttle body, then you either have a fuel pressure problem (ie: fuel pump/fuel lines), fuel volume problem (ie: fuel pump/fuel lines) or a fuel delivery problem (ie: injectors/fuel pump/fuel lines).

How much volume is flowing to the fuel rail? Have you pulled the intake and return lines off the rail and tested volume yet?

 

How much volume is flowing to the fuel rail? Have you pulled the intake and return lines off the rail and tested volume yet? [/QUOTE]

Correct me if i am wrong here guys....He has video of the 40+ lbs of pressure on the fuel rail so what the heck does volume have to do with it?? Wouldn't the volume be limited by the size of the fuel line, fuel rail inside diameter ?? The pump is just going to pump so much pressure inside
the lines and reach it's pressure on the regulator and thats it. Unless he puts some 1 1/2 water pipes on it for fuel lines then the volume is going to increase.
He's not getting spray in the cylinders by the injectors thats why it runs on the starter fluid.
I still think it's the injectors
I do realize that if the injectors were firing the volume would make a big difference. And on a performance
engine it would need a higher lph pump because the fuel would be used up at a faster rate.

 

After re-reading my thread many, many times I'm back to looking more intently at Hooked On Vetts post:

"I'm guessing the ECM is not pulling the injector coils to ground due to a bad ground (high resistance) or the ECM is bad."

I've swapped out the ECM already (turned out--original was not bad or "new" ECM has the same problem internally- but I doubt it).

Over the last week I have ohm'ed both banks of injector wires several times(with the injectors and ECM unplugged) - there apears to be no resistance to ground (infinity). Wires in injector loop are good!

Today - I removed the INJ 1&2 fuses in the fuse block and hooked up the Actron 3 tester with one leg to the 12v feed for the injector bank (1 then 2) and the other on lead to the injector drive (D15 then D16) socket on the ECM connector and was able to trigger each of the injector banks individually. Injectors seem good!

If there is a problem it must be ground related issue at the ECM connector or within the ECM unit. Will install make-shift ground wire for test purposes in a little while.

 

I must say you're one patient and persistent person. Most people would have given up.

You need to be carefull when you swap things out. Installing different parts can cause other problems and change the symptom.

One thing to note when you hold the throttle body open and spray the ether in, the TPS will most likely be over 2.5 volts so the ECM will not pulse the injectors due to clear flood mode. That could be why the engine only runs as long as you spray in the ether.

From your latest post, you said the spark is not consistent.
You changed out the complete distributor.

How about trying this? On the side of the distributor cap are push on conectors for the 12 volts for the coil and the tach. connector.

The color of the tach connector wire is white. Pull off that connector, leave it hang and try and start the engine.

Also note on the 89 on startup, the ECM does not pulse the injectors
until the engine has made two revolutions. You can see that on your injector tester. So when you try and start the car give it a good cranking.

 

I've checked the ground from the engine block to the battery and all the ground pins on the ECM to the engine block. All grounds are good...all the way to the ECM.

I'm going to check the ECM harness for the proper voltages on C14,D2, B1, B2, C16 and A6 next. Since these are solid state switches that close the ground - maybe the voltage is weak or missing.

Hooked on Vetts:

I've been extrealy careful swaping things out. I'm 100% certain that I have not complicated the problem from swapology. What ever the problem is it is consistant (car still runs... only on ether though).

The spark did seem less consistant at one point...I found that the stupid Mallory coil was bound up on the hood gasket so because of this the distributor coil was not seated all the way. I corrected the problem and cut off part of the coil cover. After this the spark was consistant again.

I did change out the entire base of the distriutor though since the reluctor for the pick-up coil is bonded to the shaft.

Again -- after all this the problem remains the same...engine will run, but only on ether. Oh and about the ether spraying. I mostly just have been spraying the ether into the throttle body(with it open) and then letting TB spring back shut before I crank it(blades are shut during cranking).

Good note on the strart up revolutions though....this makes sense...and i can see it in the video too! I've been cranking the crap out of this thing!

I'll try taking off the tach wire in a little bit....for now i got to go take care of some non-car issues.

 

Hooked on Vetts:

OK I left the tach wire off the distributor...cranked the crap out of it and nothin'....same ol' same ol'.

However on the bright side I checked the ECM harness for the proper voltages on C14,D2, B1, B2, C16 and A6 -- thinking that these are solid state switches that close the ground/ grounds - maybe the voltage is weak or missing. Some of these voltages are switched and atleast one comes from the ECM. All the voltages checked out OK with the except pin D2(solid black wire). Pin D2 is the 5v return (i guess it should be feed from the +5 volt reference generated from the ECM off of pin C14.... i don't know...but i need to find out). Note: 5 volt ref. voltage on pin C14 is generated from the ECM (ECM had to be plugged in to get voltage). I got missing voltage...or so it would seem.

Does anybody know where the last place the wire for pin D2 might come from? Which sensor?

 

There is also a possibility that your O2 sensor or MAP/MAF sensor is sending the wrong information to the ECM. ( ie too weak or to strong a signal, but not enough to trigger a fault code.) This will cause the ECM to send a shorter pulse to the injectors (20% duty cycle or less), or a pulse width of too long a duration (50% duty cycle or more), which would cause a too lean or too rich condition. Most likely the MAF sensor would be at fault because when your cranking, the ECM works in open loop mode (without input from O2 sensor). Also check the wire harness to these sensors for shorts to ground or opens. Remember pre 91 corvettes have the crappier insulation for the wiring harnesses. Don't forget to also check the Knock sensor (disconnect sensor and crank her over and see what happens). Hope this helps.

Will

 

Thanks Trackman44: That's good stuff. Right now I'm just looking at the D2 and C14 loop....I'll look at the stuff you mentioned after i check this out.

It looks like the +5 is a complete loop from D2 to C14. looking at the circuit diagram.....the only sensor in the loop are the TP sensor and the Manifold Air Temperature sensor. Well we know that the TPS sensor has power (+5) .....I checked it and adjusted it already several times.

I may have a manifold air temerature sensor tester here - somewhere.....

 

Never mind D2 is a ECM ground.

 

If the injectors are really being pulsed when you crank the engine, I'd assume the engine would be flooded from all the cranking you've been doing.

If you pull a easy to get to plug like #3, can you smell any gas fumes?

If the cylinder is flooded with gas, with the plug removed crank the engine. Any gas should be pushed out the spark plug hole. At least that will tell you the injectors are working.

If no gas comes out of the cylinder, with the ignition off. can your actron tester pulse that one injector for that cylinder and see if you smell any gas?

 

holy crap I finally got my car started and running like a champ and all it needed was a new battery and my fuel pump relay was bad.

 

Hey, I've recently become a member of this forum. I recently bought a 91 C4 from a friend of mine. It wasn't running...still not running, but I see your dilemna and I start thinking twice about keeping the car. I didn't think it would be this hard to get the car back on the road. I keep checking this thread, in hopes that you will get this beast fired up, but instead I get discouraged. I bought it from a friend whom said it was the starter that was going bad. The car has been sitting for 3 years. It's my neighbor whom sold it to me. I've seen it parked in his driveway since day one. I actualy drove the car when it was well and I want that same crazy power for myself now! We first tried to start it about 2 months ago and the starter would crank the engine and stop at a spot that seemed like internal binding. When it hit this spot the starter would click and we would have to crank the engine by hand until it got past that spot and give it another go. It still would not start! I just took the starter out a couple of days ago and took it to Auto Zone, which said the starter seemed fine. Now the engine will not turn at all!! Partially seized! I'm about to dump the car as I'm a novice mechanic and just continue with frustrating finds. Good luck to you and if you have any advise I would greatly appreciate it. Thanks in advance.