1996 LT4 Won't Start!
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
Likes: 0
1996 LT4 Won't Start!
Hi All - This is my first post so hope I get it right. I have a '96 LT4 w/26K miles, garage kept. She has always started on the first crank! Never a problem. Performed as new! Went to start her last week and she would crank, but not start. I DID NOT hear the 2 sec. Priming Sound when I turned the key to ON, which was always audible. So, here is where I am; I cranked her for about 10 sec. The oil pressure climbed to the 1st. "tick-mark", but did not start! Given the Oil Pressure Switch and the Fuel Pump Relay are wired in parallel, I expected she would start. Hard to believe both circuits are faulty. No pressure in the fuel rail. Anyway, checked all the fuses - Ok, Ran OBD2 Scanner - No Codes, Inspected the water pump for leaks - No Leaks, Opti was dry, Checked for spark at the coil - Ok, Measured Ignition Control Module plug (Pins A & D to Grd. - each 12vdc, Pin B to Grd, - ~1vac), thinking the Opti & PCM/ECM are ok. Any recommendations you may have are greatly appreciated. Thx.
Pro
Joined: Dec 2017
Posts: 534
Likes: 162
From: Omaha, NE
Hi All - This is my first post so hope I get it right. I have a '96 LT4 w/26K miles, garage kept. She has always started on the first crank! Never a problem. Performed as new! Went to start her last week and she would crank, but not start. I DID NOT hear the 2 sec. Priming Sound when I turned the key to ON, which was always audible. So, here is where I am; I cranked her for about 10 sec. The oil pressure climbed to the 1st. "tick-mark", but did not start! Given the Oil Pressure Switch and the Fuel Pump Relay are wired in parallel, I expected she would start. Hard to believe both circuits are faulty. No pressure in the fuel rail. Anyway, checked all the fuses - Ok, Ran OBD2 Scanner - No Codes, Inspected the water pump for leaks - No Leaks, Opti was dry, Checked for spark at the coil - Ok, Measured Ignition Control Module plug (Pins A & D to Grd. - each 12vdc, Pin B to Grd, - ~1vac), thinking the Opti & PCM/ECM are ok. Any recommendations you may have are greatly appreciated. Thx.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
no, no, no Try the five dollar solution first (or in the case of a corvette the $25 solution). Its probably the fuel pump relay, its located under the right side lower trim panel. Or the fuel pump switch, located at the back of the engine (along with the engine oil pressure sensor). Easy enough; and by corvette standards, inexpensive, and on a 23 year old car should probably be replaced as a matter of course, regardless of mileage. After that, if it still won't start, and you're certain its a fuel issue, then look at the fuel pump. Good luck.
Last edited by mtwoolford; Aug 9, 2019 at 12:10 AM.
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
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I sprayed starter fluid into the intake. Engine didn't sputter! I'm not convinced that the 1.0 vac (Spec. 1-4 vac) measured on Pin B to Grd. of the Ignition Control Module Plug while cranking the engine, is typical. Has anyone else measured this voltage?
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
Likes: 0
no, no, no Try the five dollar solution first (or in the case of a corvette the $25 solution). Its probably the fuel pump relay, its located under the right side lower trim panel. Or the fuel pump switch, located at the back of the engine (along with the engine oil pressure sensor). Easy enough; and by corvette standards, inexpensive, and on a 23 year old car should probably be replaced as a matter of course, regardless of mileage. After that, if it still won't start, and you're certain its a fuel issue, then look at the fuel pump. Good luck.
I'm all about inspect/test the easily accessible areas that make sense and not just exchange parts. Since the oil pressure sensor and relay are wired in parallel, and it wouldn't start, suggesting they are both bad makes no scense. That said, I think I can measure the voltage at the oil pressure sensor? If the voltage is present I'll move to the Fuel Pump Switch, Relay and FP and keep you posted. Thank you.
Thread Starter
Cruising
Joined: Apr 2016
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If the oil pressure sensor & relay are in parallel, it seems likely the pump is bad. Going to check output of oil pressure sensor, it should be there, to further convince myself. Thanks!
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Thread Starter
Cruising
Joined: Apr 2016
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Don, Hoping its not the Opti...have good spark and believe the correct signals on the ignition control module plug, which I believe suggests the Opti & ECM/PCM are ok..However, it is on the list. Thanks.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
May help (?):
https://petrisenterprises.com/blogs/...roubleshooting
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
https://www.corvetteforum.com/forums...-pressure.html
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
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One positive item you have going for you is your opti is vented. None of my optis were vented.
May help (?):
https://petrisenterprises.com/blogs/...roubleshooting
May help (?):
https://petrisenterprises.com/blogs/...roubleshooting
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
Likes: 0
check fuel pressure before replacing the pump:
https://www.corvetteforum.com/forums...-pressure.html
https://www.corvetteforum.com/forums...-pressure.html
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
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Well! I gave her a couple more shots of ether & this time she started...but did not continue to run. Oil pressure was well above 4 psi. No fuel pressure at the rails. So, does that say the ECM/PCM & Opti are Okay? Thinking I need to measure for 12vdc at some point after the Oil Pressure Sensor & FP Relay. Is there any point less intrusive then the Fuel Pump harness on top of the tank? Thx..
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Another link that may help: https://www.corvettebuyers.com/c4vet...cts_launch.htm
Click on upper left corner for complete menu.
Click on upper left corner for complete menu.
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
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Well, you were correct....the ether treatment got her started but wouldn't continue to run. Eliminated everything suggested, for which I was grateful for everyone's help. Checked for 12vdc at the FP plug and had it for 3 sec. after turning the key to ON! Imagine that...I'm assuming I just need a new fuel pump. Any recommendations on a brand? Thx.
Melting Slicks
Joined: Dec 2004
Posts: 2,656
Likes: 635
From: Dallas TX
If I needed a pump in my 96 I would look hard at the options from Racetronix.
https://www.racetronix.biz/storeitems.asp?fscat=4
Should be the FPA-010 kit.
Now if your fuel hanger and sending unit are nasty, I would replace those while I was in there, ~$150 or there abouts.
https://www.racetronix.biz/storeitems.asp?fscat=4
Should be the FPA-010 kit.
Now if your fuel hanger and sending unit are nasty, I would replace those while I was in there, ~$150 or there abouts.
Thread Starter
Cruising
Joined: Apr 2016
Posts: 14
Likes: 0
If I needed a pump in my 96 I would look hard at the options from Racetronix.
https://www.racetronix.biz/storeitems.asp?fscat=4
Should be the FPA-010 kit.
Now if your fuel hanger and sending unit are nasty, I would replace those while I was in there, ~$150 or there abouts.
https://www.racetronix.biz/storeitems.asp?fscat=4
Should be the FPA-010 kit.
Now if your fuel hanger and sending unit are nasty, I would replace those while I was in there, ~$150 or there abouts.
Melting Slicks
Joined: Dec 2004
Posts: 2,656
Likes: 635
From: Dallas TX
Thanks for the recommendation, however the only part that has been upgraded is the headlight gears - all original LT4! So, want to stay with AC Delco "pump". Do you know the Model #? There seems to be at least two (2) types. Confusing? I also want to replace the Fuel Strainer and some pumps include it and others don't. Thx.
Rock Auto lists the EP376 Delco pump as being applicable for the 96. They have them in stock.
They also seem to list an AC Delco sender assembly(hangar, sending unit, etc...) as available if you need that also.
Thread Starter
Cruising
Joined: Apr 2016
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Have ordered the Pump/Strainer EP376, TS17) tank gasket and neck filler..hoping to get it completed this weekend. Thanks for your help! Will let you know the results...