TOP END REFINISHING

[Franke]

The sec vac pump should turn on when the key is placed in the run position unless the switch inside the vac pump senses greater than 12" of vacuum which is not possible with every thing disconnected. There is an inline fuse of 10 amps for the vac pump. Check at the pump to see if wiring is disconnected or the fuse is blown. Check for voltage there.

[Schrade]

Originally Posted by Franke

The sec vac pump should turn on when the key is placed in the run position unless the switch inside the vac pump senses greater than 12" of vacuum which is not possible with every thing disconnected. There is an inline fuse of 10 amps for the vac pump. Check at the pump to see if wiring is disconnected or the fuse is blown. Check for voltage there.

It came to me last night - an hour after sackin' out - layin' there, thinkin' on it!!!

I did NOT plug in the forward 2 connectors on the DIS module.

Let's try it again, the RIGHT way...

[XfireZ51]

Originally Posted by Schrade

It came to me last night - an hour after sackin' out - layin' there, thinkin' on it!!!

I did NOT plug in the forward 2 connectors on the DIS module.

Let's try it again, the RIGHT way...

Minor detail. NOT!

[Schrade]

Still thinkin' on this throttle hesitation here...

If [since] 80% throttle opening comes from ONLY [ < 20%, actually] physical Range Of Motion OF THROTTLE LINKAGE ...



https://lh6.googleusercontent.com/-D.../HPIM7334c.JPG

then EVERY operational parameter has almost 0 tolerance for deviation, from 0% Throttle Opening, to 80% Throttle Opening, when 80% throttle is reached in such a short span.

There HAS TO be some 'buffer' integrated into all parameters' sync'ing properly; otherwise, every 1 year-old LT5 with even minor hardware degradation is gonna' have some problem...

such as 'Off-Idle Sag'

unless the potentiometer in the TPS has some buffer mechanism built-in, such as logarithmic resistance, and not linear (never mind just now that FSM says that the TPS Voltage response is linear..................... )

This make any sense to anyone?

[Paul Workman]

Originally Posted by XfireZ51

Minor detail. NOT!

Yeeeaaaah.... It might cause a "hesitation".....

[Schrade]

O...K...

So plug in the 2 forward DIS module connectors, and turn the key.

No sec vac pump. And why do I have fuel pressure, with both FP fuses pulled?

No, I don't have both FP fuses pulled - #2 FP fuse is in, on the UNDERdash Aux fuse block - the 10 Amp fuse on the end of the block, and the 10 Amp fuse on the OTHER end of Aux fuse block, for 'CRNK-A/B' is pulled OUT.

Switch them, turn the key, and no sec vac pump.





Back to the FSM drawing board...

[Schrade]

2' vac pump diags.

Test the ground at the 2' vac pump fuse (please be bad)

nope



Fine ( MF'er )

Power comin' in?

[Franke]

OK it looks like you have the voltage to the fuse on the orange wire... The blue wire should go to the vac pump. Maybe jumper across the terminals to see if the pump runs?

[Schrade]

Originally Posted by Franke

OK it looks like you have the voltage to the fuse on the orange wire... The blue wire should go to the vac pump. Maybe jumper across the terminals to see if the pump runs?

I thought about that, but the pump ran fine before, and the battery was un-plugged from before wrench 1 turned a bolt.

So test for a good ground, and good power.

Then what I saw comin' IN bothered me.

Isn't 11.77 V reflective of a problem? Cause it sure wouldn't drive the pump...

I went to FSM, and schematic shows 12V from IG Switch, to splice S239 near Cruise Control Module, P side UNDERdash, and from there, to

1) 2' vac pump, through fuse,
2) Power Window Circuit Breaker @ Main Fuse Panel, and
3) A/C Fuse.

My plan was to test for identical 11.77 V @ '2', and '3', and then work back to IG Switch OUTput, and see if it ALSO was out-putting 11.77 V

But the best laid plans of Schrade & men oft go awry. And this job is in regression, with a decay rate seeming exponential in proportion.

The IAC connector gasket fell off. I unbolted the TB to look, and now 1 of the nuts from the TB linkage / cam shield fell off. It's not in the induction port, but now that I thought longer on the IAC gasket, there is the most remote of possibilities that IT found it's way into #2.

[Franke]

I'm thinkin that your dropping about 1/2 volt or so between the battery and the fuse connection through the ign switch and wiring for the vac pump. Possibly a slightly resistive connection but I would make sure that your battery is fully charged since you were doing fuel pump testing and they draw at least 4 amps each I think. Also, since that vac pump ckt is separate from the DIS module I don't see why the pump shouldn't run. In theory if you put 12V on the dk blue lead to the vac pump with the fuse connector off she should run.

Good job finding those 2 parts. There are so many nooks and crannies on these motors that people have lost small animals and ratchets and.... and...