L03 hesitation

Here is a problem with my 91 OCC that I have been chasing since I got it earlier this year. From a dead stop, if you hit the gas it will have a moment of hesitation before it actually goes. It seems to only happen from a stop. Here is what has been done in the past few hundred miles: plugs, wire (delco), cap, rotor, reman distributer (bad bearings on old one), and last week a new delco fuel pump. It developed a problem with trying to stall and rough idle, new pump took care of it. I replaced the filter and the sock on the pump, also soldered the connections on the sending unit. Engines idles good now, but still has the hesitation. No CELs either and the car has 111k on it. Where do I start?

vaccum lines maybe?..

WagonLover wrote:

vaccum lines maybe?..

Hmm, now that you mention it I could have a leak. When you lay into it, the vents will change from the defroster to the upper dash vents (or the other way around, can't remember). This has manual climate control.

Engine is blown sell it to me.

It's missing 45 cubes!

Is the hesitation worse when your AC is on?I remember that either JET Performance or TCI
use to sell this electronic gadget that plugged into the throttle position sensor.It was
advertised specifically to eliminate the hesitation that is common to all TBI V-8s and thats
all I can tell you.The hesitation was supposedly more common in the 305 than the 350s.
Almost ordered one but my car only hesitated when it was cold.One more thing my car
will stumble badly if the timing is the least bit retarded.Probably should have said that first.
Check The Timing
Jim Gordon

buickestate wrote:

It's missing 45 cubes!

I was figuring Nick be in here with that one.....or it needs an LT1.

Have you driven another L03? Mine doesn't have instant throttle response from a dead stop. In fact until you are in the 2000 RPM range it doesn't jump at all. I have had 3 of them and my 91 Olds (both of them) feel peppier than my 92 CHevy (with less miles even).

The Chevy sounds like yours from what you said. I never chased down all the Vac lines but that may be a good start.

buickestate wrote:

It's missing 45 cubes!

If only I could just give it those missing cubes.

Flasheroo wrote:

Is the hesitation worse when your AC is on?I remember that either JET Performance or TCI
use to sell this electronic gadget that plugged into the throttle position sensor.It was
advertised specifically to eliminate the hesitation that is common to all TBI V-8s and thats
all I can tell you.The hesitation was supposedly more common in the 305 than the 350s.
Almost ordered one but my car only hesitated when it was cold.One more thing my car
will stumble badly if the timing is the least bit retarded.Probably should have said that first.
Check The Timing
Jim Gordon

Never tried it with the AC on, I'll have to give that a try. As far as timing, I couldn't find my timing light when I put the new distributor in, so I just put it in the same as the old one was. Seemed to run ok at the time.

Sprocket wrote:

buickestate wrote:

It's missing 45 cubes!

I was figuring Nick be in here with that one.....or it needs an LT1.

Have you driven another L03? Mine doesn't have instant throttle response from a dead stop. In fact until you are in the 2000 RPM range it doesn't jump at all. I have had 3 of them and my 91 Olds (both of them) feel peppier than my 92 CHevy (with less miles even).

The Chevy sounds like yours from what you said. I never chased down all the Vac lines but that may be a good start.

This is my first L03, but not my first 305. My old truck has a 305 (carb'd) and I had a monte carlo with a carb'd 305. The power didn't seem too bad when I first got the car, but now I am really seeing the difference. I guess I am just spoiled because all my other B-bodies are LT1 cars. I do have a lead foot, so I guess I see the difference more than others might

Cadet57 wrote:

Engine is blown sell it to me.

Dangerous words around a guy that admits to owning way too many cars!

I cured that on my first 91 RMW with the LO3, it got a lot peppier and lauched better too!

95BRMW wrote:

WagonLover wrote:

vaccum lines maybe?..

Hmm, now that you mention it I could have a leak. When you lay into it, the vents will change from the defroster to the upper dash vents (or the other way around, can't remember). This has manual climate control.

There is a check valve in the line on the front of the TBI unit. Could be inop.