Something weird going on

[cudabob496]

yes, will be grounding box to battery today

[cudabob496]

ok, box powered from and grounded to battery,
same problem.

turn key, starts, runs for a few seconds, then quits.

seems to run a second or two after releasing key, so don't think
the key circuitry is the issus.

Gonna review all this with MSD on monday, and get ready to buy a new 6AL box.

[dodj]

ok, box powered from and grounded to battery,
same problem.

turn key, starts, runs for a few seconds, then quits.

seems to run a second or two after releasing key, so don't think
the key circuitry is the issus.

Gonna review all this with MSD on monday, and get ready to buy a new 6AL box.

Is it possible you are running out of fuel?  It kind of makes me think of a contaminated fuel filter. I didn't read all the preceeding 15 pages...so don't know if that was 100% ruled out already.

[734406pk]

You can connect a timing light to the coil wire, start the engine and turn on the timing light. If the light stops flashing and the engine stalls, you know that you are losing spark. If the light flashes steadily and the engine stalls anyway, the problem is elsewhere. If you don't have anyone to start the car, you can use tape to hold the timing light button on. 

[cudabob496]

Is it possible you are running out of fuel?  It kind of makes me think of a contaminated fuel filter. I didn't read all the preceeding 15 pages...so don't know if that was 100% ruled out already.

thanks, yes, at least 5 psi, and squirters working, but will recheck sight levels to verify.
but this issue of starting right away, then quitting, was happening from the beginning.
Then I discovered my variable timing system was screwy, so took that out of circuit..

[cudabob496]

You can connect a timing light to the coil wire, start the engine and turn on the timing light. If the light stops flashing and the engine stalls, you know that you are losing spark. If the light flashes steadily and the engine stalls anyway, the problem is elsewhere. If you don't have anyone to start the car, you can use tape to hold the timing light button on. 

good idea, will try it

[cudabob496]

while having timing light in my face, discovered can keep engine running above 1000 rpm.
if rpm dips below 1000 rpm, engine dies immediately.
the mystery continues!

[734406pk]

while having timing light in my face, discovered can keep engine running above 1000 rpm.
if rpm dips below 1000 rpm, engine dies immediately.
the mystery continues!

Question: (The engine dies below 1000 rpm.) Are you losing spark below 1000 rpm? (Indicated by the timing light flashing)

[cudabob496]

Question: (The engine dies below 1000 rpm.) Are you losing spark below 1000 rpm? (Indicated by the timing light flashing)

It seems to occur at almost the same time. I can't say that the spark loss
causes it to die at 1000, but can't say its not the carb either. Gonna discuss
with MSD tomorrow. Maybe there's a circuit board they can replace, or do some other
testing that they have not done yet. Its so instantaneous, that its hard to believe
its the carb, and the Holley tech agrees with that. Maybe the rev limiter circuit board
has gone nuts!

[Strawdawg]

just for the hell of it, what are the AF's doing immediately before it dies?

[cudabob496]

just for the hell of it, what are the AF's doing immediately before it dies?

up around 14.5 to 16.

Carb has been completely rebuilt, but have not had opportunity to dial it in.

Holley said that what i see happening could not be a carb issue, but who knows for sure.

Here's what Holley said 3 months ago, after I replaced metering blocks.
"Sounds like car is getting to much fuel. Check for busted power valve. And make sure float level is not to high. If pv is good and everything else checks good. Start looking for vacuum leak."

[cudabob496]

was reviewing thread. Stalling below 1000 rpm started really occurring after replacing both
metering blocks.

[734406pk]

was reviewing thread. Stalling below 1000 rpm started really occurring after replacing both
metering blocks.

Several pages back in this post, it was noted that your AFR went way lean before stalling. This evidence would indicate a lack of fuel for some reason. If you had spark loss, the un-burned fuel would drive the AFR rich, not lean. Can you keep the engine running if you lightly actuate the acellerator pump to overcome the suspect lean condition? If so, the idle circuit in the carb is not delivering fuel for combustion at low rpm. 

[cudabob496]

today, I kept it running for about 30 secs, by pumping accellerator, and keeping rpm above 1000rpm.
I think it would have kept running if I kept the rpm up about 2000 to 2500.
Kinda like there is no idle circuit.
Check primary bowl just now, and gas comes out when shake car.

Maybe the two metering blocks I put in there were not correct, even
though Holley told me they were. Primary metering block has a vacuum
tube sticking out the side, and that is plugged. A lower vacuum tube
below the primary bowl is hooked to a vacuum gauge. Back of carb has tube that
goes to PCV valve.

you got a ZX1100? crazy!

had a 74 H2750, a 73 Z1, and a 2002 ZX7R

[Strawdawg]

That's way too lean for an engine such as yours to idle properly.

Ether it is not getting fuel on the idle circuit, or it has a major air leak.

Given that you changed the metering blocks, I would guess lack of fuel.  Make sure the blocks are identical to the ones you replaced and that all the passages are open to air being blown thru them.  Also check that the gaskets are uncovering the various holes-particularly the idle fuel passages.  I have seen gasket problems in the past.