Problems with 92' LT 1 Corvette engine

[night_rider_692004]

Hello!



Perhaps there are some enthusiasts which have the same engine=>
I installed a 92'Corvette engine in my 69' Camaro.
Now I have the problem that the engine won't run so smooth like before.
A few weeks ago it fast the first time that the engine had some misfire and a bad throttle response. If it will be a carburated engine my tipp is that there is not enough fuel, not a ignition problem.
Then the problem gone. Why ? This day it was the same again. During driving the described problems started again. It's possible to drive home with 2000 rpm, but not depress the pedal to fast => than the engine will go down in rpm.(It's like too much air for too less fuel)
There's no failure on the engine check light.
I reroute the fuel lines last winter and the line between tank and pump is now four times longer or could there be a leak?
But why the engine runs normal all the time this summer?
Or could this be the not trouble free ignition system? (The engine has 40000 miles)
HELP!

[alocker]

Sounds like a fuel issue. When high pressure fuel pumps go bad, they sometimes act this way intermittently. You need to get a fuel pressure gauge and tape it to the window and go for a test drive. I believe the pressure sould be around 45 PSI at idle and should go up 3-5 PSI when you give it gas.

If fuel pressure is ok, next would be ignition. It could be the coil or the optispark on its way out.

[ProTouring442]

Didn't the earlier LT1s have some sort of problem with the Optispark? Wasn't properly vented or some such? Just a thought anyway.

Shiny Side Up!
Bill
'72 442 "Inamorata"

[68sixspeed]

'92 optisparks can have issues with age, and especially if they get water on the pickup. There was a kit we put on a '92 that helped, because othewise the car would run bad if it got wet or even after an under-hood washing. I think this month's Vette magazine has an article on the opti-spark replacement stuff from MSD. Also, I remember the '92 vette was fussy on fuel-- if it sat for a few weeks, it would run rough until it got some fresh gas through it.

[Lowend]

The LT1 is known for devloping vaccum leaks around the rear intake manifold gasket.

[WS6]

It should not be the optispark if it's intermitten like you've described. It could be the Ignition control module though. However, I would look at fuel first it is usually straight forward either you have it or you don't. The injectors are very reliable. Has this engine sat for extended periods of time without having the fuel run through the injectors? If so I would have them removed and cleaned by a professional shop. That's just good maintainence that ensures excellent running and power.

[night_rider_692004]

Hello!

I told you that I rerouted the fuel line between tank and pump. I think about the loop of the hose which has the highest point, because tank and pump have the same level. So my thoughts are that there's air on the inlet side in the hose and the pump isn't always able to suck the air out. This would be a good theory why the engine is sometimes running and sometimes it's not ok. Yesterday the problem began during a sharp turn and i know that the tank has a problem with moving fuel => sucking air. Normally if this effect is heavy the engine stops running for a short, short moment because of no or too less fuel.
The first time the problem began was with only less fuel in the tank.

Yesterday evening I had a test drive. The problem is still there: With depressing the loud pedal fast the engine had a bad response, with depressing slow increasing RPM is not a problem. So I still thinking about fuel management.

So "killing" this loop will be my first step

[Rybar]

Sounds like an Opti problem to me. Try swapping out the opti for a new one and see if that helps.

[WS6]

I think you're on to something with the fuel line night rider. It should not be that way even if it doesn't solve your problem.