Getting frustrated
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Yes the VATs has been gone for years. It has run OK in the past and had fired right up and ran smoothly. Its like someone has thrown a switch. I am getting an RPM signal while cranking.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Hang your voltmeter across the battery or main computer +12 feed is better actually, and it better not go below 11 volts at any time, especially during cranking....
Too many bad/sad stories over them optima battinators......better off with a Walmart deep cycle marine battery....
Too many bad/sad stories over them optima battinators......better off with a Walmart deep cycle marine battery....
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
So I hit it with a shot of ether and it fires and runs for a few seconds until the ether is consumed. So no injector pulse to feed it fuel. Cam sensor? I'm not sure where it gets the signal for the injector pulse.
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
I'm guessing you have a returnless system-
Try hitting the ignition -turn the key several times to build up pressure in the line-if it starters/runs you have a bad regulator - or a pressure leaking down.
Starts and quits- See if you can continuously power the pump while you try to start- if it starts/runs you have a cam sensor or something not telling the pump to turn on as it doesn't 'see' the engine running.
Good luck!!!
Burning Brakes
Joined: Jan 2003
Posts: 961
Likes: 275
From: Frederick MD
If he has spark but no injector pulse I would be looking real close at the ECM grounds and power. I haven’t worked on an Ls3 computer (all LS1 stuff) but I know most of those are switched ground by a driver in the PCM. Make sure your hots can carry a load. Voltage doesn’t guarantee it can carry current. Gotta put a load on it. Typical injectors pull anywhere from 1-2 amps when firing. That’s a 10-20 amp circuit when it’s running on all 8.
If this PCM switches the hot to the injector then reverse the idea.
I don’t want to scare you but particularly if the grounds are what gets switched to activate the injector solenoid and you have an PCM ground that can’t carry the needed current it is known to burn out the drivers in the PCM. Make sure you can carry current.
If this PCM switches the hot to the injector then reverse the idea.
I don’t want to scare you but particularly if the grounds are what gets switched to activate the injector solenoid and you have an PCM ground that can’t carry the needed current it is known to burn out the drivers in the PCM. Make sure you can carry current.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Yes I do have 12v at each injector. I am using an aftermarket PSI wiring harness. It has been working fine up until now. The only fuses are at the terminal block on the PSI harness. And I have checked multiple times voltage across fuses and while cranking. Getting power across all of them.
Let me check again voltage drop.
Ok with the POwer Probe it measures min voltage and holds it in memory. It went down to 4.8. while cranking for about 5 seconds I see on the screen it drops to about 8 then gradually comes up to 10.3 while cranking. I'm going to be real embarrased if it is a bad battery with a dead cell or something. It shows key off 12.4 volts and key on it goes to 11.9. Its not tha told but it has been drained a few times down to nothing. Its an Optima which I'm not real fond of
Let me check again voltage drop.
Ok with the POwer Probe it measures min voltage and holds it in memory. It went down to 4.8. while cranking for about 5 seconds I see on the screen it drops to about 8 then gradually comes up to 10.3 while cranking. I'm going to be real embarrased if it is a bad battery with a dead cell or something. It shows key off 12.4 volts and key on it goes to 11.9. Its not tha told but it has been drained a few times down to nothing. Its an Optima which I'm not real fond of
Well you have correct low voltage on start. I went through this with my camaro slow start and failed starts progressing worse to find my battery was marginal and not even bad. New battery cured it. EFI does not like slow cranking. I can only guess the computer gets stupid on slow cranking and definitely with low voltage. Hobo Fake battery tester is only 20 bucks and works great for me.
I have to add the new replacement batteries - at least from Eveready - have deeper bolt holes in the posts and my stock terminal bolts did not reach. But every auto parts store sells the longer battery bolts now.
I'm saving my comments about the computer until the low cranking voltage is corrected.
Hope this can help.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I,m pulling off all the grounds again and will buff any corrosion off and redo them so they are all spotless. If that does not do it I’ll have to get a new battery and give it a try.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Cleaned off all grounds and buffed the frame connections to bare metal. Made sure all grounds were bare metal to ground terminals. Full battery charge and hit it with a whiff of ether. Fired right up and ran until ether ran out. About 3 seconds. I did notice that the injector pulse is there now. The noid light was blinking. Tried again to hit it with ether and now it just cranks again. Still getting injector pulse though. This is driving me crazy.
PSI just says check grounds. Yea I know that.
PSI just says check grounds. Yea I know that.
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
So now you've got to isolate the condition that causes it to run on ether, but then the engine dies when the ether runs out. So it ran on ether, but where was the fuel in all of this? If there was fuel, it should've kept going after the ether shot, right? But it didn't. That's a clue for sure.
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
You might not be getting the correct spray pattern-not enough fuel- dirty injectors- low pressure-
Jump the pump to run it and see what happens when you crank it.-if no luck- pull and injector and look it over.
Your half way there !!!
Richard
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Cleaned off all grounds and buffed the frame connections to bare metal. Made sure all grounds were bare metal to ground terminals. Full battery charge and hit it with a whiff of ether. Fired right up and ran until ether ran out. About 3 seconds. I did notice that the injector pulse is there now. The noid light was blinking. Tried again to hit it with ether and now it just cranks again. Still getting injector pulse though. This is driving me crazy.
PSI just says check grounds. Yea I know that.
PSI just says check grounds. Yea I know that.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
All good ideas here. Thanks for hanging in here with me. I’ll keep at it. I have to take a few days off though. I am busy until next week. My daughter is getting married this Friday so lots to do so the car will be put on hold for a few days. I’ll get back to it next week. The fuel pressure is a little low but I think I have a crappy FP gauge also. Just a real cheapo small one. New fuel pump and regulator that both have worked no problem when installed. The battery is the next culprit I am leaning towards. It is only 3 years old but has been totally discharged a few times. It’s an Optima which I am not real fond of anyway. Hate to spend a hundred bucks if it is not the issue but it is cheap compared to my sanity.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I have 5 batteries, 3 car and 2 boat and all are post style.
Yea we have a wally world about 5 minutes away. I'll just go buy one.
Yea we have a wally world about 5 minutes away. I'll just go buy one.