I recently got a 1986 C4 Corvette put a new fuel pump in and drove it home then it started with a crank but no start issue. Since then I have checked the fuel pressure its 42 at the rail and no drop in pressure. I put in a new fuel pump relay also. I checked Injectors with Multimeter and there within OHM Specs also with a Noid lite no Pulsing. Used Jumper wire to check codes only stored code is 46 VATS Anti theft Fault so I got vats bypass and no change in condition. So through Manual,Forum,and YouTube I decided to try the ICM since dont have spark when I use my Inline Spark Tester. My ignition coil is at almost Zero Ohms resistance. Im getting oil pressure when i crank it over. I have good ground and get battery voltage through the fuse panel. The car acts like it wants to start and every so often it would start I could drive it around then park it shut it off sometimes would start back up and sometimes it wouldn't Now for past week it wont start at all. If anyone has any ideas I dont know if ECM is my next step I dont know anyone who has one to try there's.

 

Replaced ICM got spark at all wires now. Still no injector pulse with Noid lite anybody got anything im missing.

 

It sure if you have a service manual but just think of what controls the injectors firing.

ECM? Maybe. Did you check all of your fuses?

is injector pulse related to the pick up coil signal? If the plugs are firing the dizzy and related components are probably fine.

there’s a lot of info on here. Maybe a search for injector pulse may bring up useful info

good luck.

 

There’s two fuses in the fuse box that control the injectors, worth checking them. Also making sure you have enough pressure at fuel rail.

 

http://www.corvettebuyers.com/c4vettes/l98.htm

Did you ohm out injectors?

What about your vats/ anti theft? All in order for that?

 

Pickup coil is within ohm specs. Injectors are within specs. I get engine code 46 which is Vats fault but I bypassed the Vats with resistor. Havent tried ECM there not cheap.

 

Some things I did to get mine started.

i replaced the ECM and the PROM, took out the injectors and used a small battery to quickly power them one at a while sprayed injector cleaner into them. Replaced many of the vacuum lines (this played a huge role in getting the car running). Also test the ohms on the injectors and the voltages of the Throttle position sensor and idle air control valve.

you could hit up harbor freight for a vacuum line tester for cheap and pull some lines and see if they hold a vacuum.

One BIG issue I had earlier this year was that I had the rubber boot around the filler neck of the tank removed. I had the cover over the filler and the cap on, but somehow the tank still allowed a serious amount of rain water in! I’d say nearly half was water. I sucked out some of the tanks contents and let it sit in a tube for a while and eventually it separated.

when I first got the car it also had really bad fuel. I’d had maybe a few gallons of questionable fuel that I tried to offset with many more gallons of good fuel. That didn’t work. Check the fuel and if there’s separation, drain the tank completely, remove the fuel sending unit and use a harbor freight $10 fuel can fuel pump to suck almost all of it out and soak the rest up in rags to later burn or something.

 

Through trial and error testing and retesting I got it running. I did figure out something that I havent seen mentioned is that a VATS bypass resistor only bypasses starter relay part of VATS it does nothing to help with the Injector Pulse Signal from VATS. Took dash apart to check VATS module if I crank the car with one hand and Tap the Module with the other hand it will start right up.