LT1 diognostic help please
Thread Starter
Teching In
Joined: Jun 2006
Posts: 6
Likes: 0
From: Shoreline, WA
LT1 diognostic help please In need if a little LT1 diognostic assistance....
A little background first. Car is a 1994 Z28 M6 (street car). Some folks here might remeber this as Joe Waldron's old car that I bought from him last year. I removed a 3k mile 383 stroker motor from this car to transplant into my 1994 Z28 ITE road racer. After a new optispark and a little tuning this engine runs sweet (390 RWHP / 393 RWTQ).
Anyway, I just completed installing a 58k '95 LT1 and PCM from a wrecking yard into the street car so I can get it back on the road. When I went to start it up for the first time it wouldn't fire. As I kept cranking the engine began to fire but very weak and wouldn't kick over and run. It only fires while holding the key on, although when I let go of the key it will continue to fire for a few more revolutions then stops.
I checked for spark and it's putting out a healthy spark (inspected the optispark before install and it looked fine). Fuel is getting to the rail. every cylinder seems to be firing because I can feel heat in every header tube from each cylinder.
I had removed and replaced the fuel pump when I was pulling parts off this car to put on the racecar. one thought was that there was some problem with the stock fuel pump I put back in the fuel tank, but seeing fuel getting to the injector rail make me think it's all right. I don't have a fuel pressure tester to check the pressure though. I have a Auto X-Ray scanner but it's not showing any trouble codes. I double checked all the wiring harness connectors and everything is hooked up right.
What else should I check? Have I missed anything obvious? Any help would be very much appreciated! TIA
Steve Sampson
A little background first. Car is a 1994 Z28 M6 (street car). Some folks here might remeber this as Joe Waldron's old car that I bought from him last year. I removed a 3k mile 383 stroker motor from this car to transplant into my 1994 Z28 ITE road racer. After a new optispark and a little tuning this engine runs sweet (390 RWHP / 393 RWTQ).
Anyway, I just completed installing a 58k '95 LT1 and PCM from a wrecking yard into the street car so I can get it back on the road. When I went to start it up for the first time it wouldn't fire. As I kept cranking the engine began to fire but very weak and wouldn't kick over and run. It only fires while holding the key on, although when I let go of the key it will continue to fire for a few more revolutions then stops.
I checked for spark and it's putting out a healthy spark (inspected the optispark before install and it looked fine). Fuel is getting to the rail. every cylinder seems to be firing because I can feel heat in every header tube from each cylinder.
I had removed and replaced the fuel pump when I was pulling parts off this car to put on the racecar. one thought was that there was some problem with the stock fuel pump I put back in the fuel tank, but seeing fuel getting to the injector rail make me think it's all right. I don't have a fuel pressure tester to check the pressure though. I have a Auto X-Ray scanner but it's not showing any trouble codes. I double checked all the wiring harness connectors and everything is hooked up right.
What else should I check? Have I missed anything obvious? Any help would be very much appreciated! TIA
Steve Sampson
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
Damn Steve just the other day some one runs into Joe and we start talking about you guys and here you are!
Hard to tell at this point. Do need to check the Fuel pressure and there is always the chance the opti is not lined up correctly(easier to do then many think)
Here is the number 425-922-8944
Hard to tell at this point. Do need to check the Fuel pressure and there is always the chance the opti is not lined up correctly(easier to do then many think)
Here is the number 425-922-8944
Thread Starter
Teching In
Joined: Jun 2006
Posts: 6
Likes: 0
From: Shoreline, WA
Good to hear from your Ellis. Small F-Body world, isn't it?
I picked up a fuel pressure gauge and it's showing between 40 - 43 PSI, so the fuel pump seems to be okay. I also had the thought about the optispark not being lined up properly. it took me a few trys to get it where I thought it was line up right, but maybe not. The more I think about it, when I try to start the engine it kind of acts like the distributer is maybe 90 degrees off or something.
I'll start dismantling the front of the engine and check the optispark alignment. Too damn hot today to do much on it today though. It's friggen 100+ degrees here in Vancouver (WA) today!
Thanks for your input. I'll let you know what I find out about the opti alignment.
Steve
I picked up a fuel pressure gauge and it's showing between 40 - 43 PSI, so the fuel pump seems to be okay. I also had the thought about the optispark not being lined up properly. it took me a few trys to get it where I thought it was line up right, but maybe not. The more I think about it, when I try to start the engine it kind of acts like the distributer is maybe 90 degrees off or something.
I'll start dismantling the front of the engine and check the optispark alignment. Too damn hot today to do much on it today though. It's friggen 100+ degrees here in Vancouver (WA) today!
Thanks for your input. I'll let you know what I find out about the opti alignment.
Steve
Thread Starter
Teching In
Joined: Jun 2006
Posts: 6
Likes: 0
From: Shoreline, WA
Good call Ellis! It WAS a mis-aligned optispark. Damnit! The vented opti is a PITA to align compared to the non-vented.
Is there a way I can know for sure that I get the opti aligned right this time without spending all the time to reassemble everything to see if it runs or not?
Oh well, it really didn't take me that long. I'm starting to get pretty fast at tearing this thing down and reassembling it again.
Steve
Is there a way I can know for sure that I get the opti aligned right this time without spending all the time to reassemble everything to see if it runs or not?
Oh well, it really didn't take me that long. I'm starting to get pretty fast at tearing this thing down and reassembling it again.
Steve
