90 - Running out of breath at 5000 - No Codes

[scottfab]

SECONDARY PORT THROTTLE VALVE SYSTEM error
But of course you know that.

Try seeing of the actuators pull in
http://www.zr1specialist.com/HAT%20W...0Operation.pdf

If they do maybe your secondary fuel pump is tits up.
You could be running out of fuel but no code is set if it's not
lean enough to trip the code.

[dondon]

Originally Posted by scottfab

SECONDARY PORT THROTTLE VALVE SYSTEM error
But of course you know that.

Try seeing of the actuators pull in
http://www.zr1specialist.com/HAT%20W...0Operation.pdf

If they do maybe your secondary fuel pump is tits up.
You could be running out of fuel but no code is set if it's not
lean enough to trip the code.

Thanks for your help with this problem. I have performed the check by shorting pin C17... unfortunately everything worked as it should, so now to keep checking till I find something.

I don't have equipment to check the fuel pump... so I'll have to take it in sometime this week. Thanks for the input.

[scottfab]

Originally Posted by dondon

Thanks for your help with this problem. I have performed the check by shorting pin C17... unfortunately everything worked as it should, so now to keep checking till I find something.

I don't have equipment to check the fuel pump... so I'll have to take it in sometime this week. Thanks for the input.

Open the hood.
Engine off but ign key on.
Does the vacuum pump under the passenger side head light run?
Does it keep running without shutting off?

[dondon]

Originally Posted by scottfab

Open the hood.
Engine off but ign key on.
Does the vacuum pump under the passenger side head light run?
Does it keep running without shutting off?

It runs for a moment then stops.

FYI - the shorting of C17. While the actuators are moving, the pump runs, then shuts off again. Actuators stay open for as long as I'm patient enough to short the circuit.

[scottfab]

Originally Posted by dondon

It runs for a moment then stops.

FYI - the shorting of C17. While the actuators are moving, the pump runs, then shuts off again. Actuators stay open for as long as I'm patient enough to short the circuit.

Sure sounds like secondaries are fine. Look to fuel pump #2 failure.
The only thing that puzzles me is that I'd expect a lean code to be set.

[Paul Workman]

Originally Posted by dondon

Thanks for your help with this problem. I have performed the check by shorting pin C17... unfortunately everything worked as it should, so now to keep checking till I find something.

I don't have equipment to check the fuel pump... so I'll have to take it in sometime this week. Thanks for the input.

A lot of preliminary stuff can be done at home. (Besides, I don't know 'bout your situation, but there isn't any dealership I'd take an LT5 to for anything!)

As for checking the fuel pumps, all you need is a fuel pressure gauge that you can rent free from AutoZone** and a Volt Ohm Meter from Radio Shack or the like.

You can start by measuring current draw to the pumps. There is a fuel pump test connector jutting out of the same wire loom as the diagnostic connector, located near the top of the power brake booster, next to the firewall.

With the key off, and the VOM configured to read Amperes (most set up to read 10A) put the red lead to the positive terminal of the battery and the black lead to the little red pigtail. Each pump draws between 4-5A. So,if both pumps are running normally, you'll measure between 8 and 10 amperes, you'll hear the pumps running, and with a fuel pressure gauge connected to the Schrader valve, fuel pressure should be about 52 pounds, give or take a pound or so.

Configuring the meter to read amperes...



The red test connector connected (via a yellow jumper with alligator clips on each end - alligator clip leads available from Radio Shack) to the black lead of the meter.



With the red lead connected to the positive post of the battery, the current draw is normally 8-10 amperes if BOTH pumps are running. If only 1/2 that current is present, then one of the pumps is either kaput or there is a connection issue (possibly).



Then you can check the fuel pressure under driving conditions, by taping the pressure gauge to the windshield and monitoring the pressure at normal load and at WOT.



Pressure should be in the mid 40s in normal driving loads, and "pop" up to 52 (give or take) at WOT.

If the fuel pressure is low, especially at WOT, it could mean a problem with a pump, OR the fuel filter. (The filter is next to the frame rail behind the right front tire, and under a heat shield.)

Since the secondaries tested OK, you might want to know what the resistance is across the injectors when they're HOT. They should read between 12-14 ohms (hot). If they read 10 ohms or less, it indicates problems likely. A reading of 8 ohms or less and the injector is definitely in need of replacement; not only to run better, but to prevent the possibility of a burnt valve (ask me how I know...). (The procedure is well laid out in the FSM.)

And, of course, the easy thing to do is change plugs.

[scottfab]

absolutely phenomenal wright up Clear easy to understand and easy to read

Originally Posted by Paul Workman

A lot of preliminary stuff can be done at home. (Besides, I don't know 'bout your situation, but there isn't any dealership I'd take an LT5 to for anything!)

As for checking the fuel pumps, all you need is a fuel pressure gauge that you can rent free from AutoZone** and a Volt Ohm Meter from Radio Shack or the like.

You can start by measuring current draw to the pumps. There is a fuel pump test connector jutting out of the same wire loom as the diagnostic connector, located near the top of the power brake booster, next to the firewall.

With the key off, and the VOM configured to read Amperes (most set up to read 10A) put the red lead to the positive terminal of the battery and the black lead to the little red pigtail. Each pump draws between 4-5A. So,if both pumps are running normally, you'll measure between 8 and 10 amperes, you'll hear the pumps running, and with a fuel pressure gauge connected to the Schrader valve, fuel pressure should be about 52 pounds, give or take a pound or so.

Configuring the meter to read amperes...



The red test connector connected (via a yellow jumper with alligator clips on each end - alligator clip leads available from Radio Shack) to the black lead of the meter.



With the red lead connected to the positive post of the battery, the current draw is normally 8-10 amperes if BOTH pumps are running. If only 1/2 that current is present, then one of the pumps is either kaput or there is a connection issue (possibly).



Then you can check the fuel pressure under driving conditions, by taping the pressure gauge to the windshield and monitoring the pressure at normal load and at WOT.



Pressure should be in the mid 40s in normal driving loads, and "pop" up to 52 (give or take) at WOT.

If the fuel pressure is low, especially at WOT, it could mean a problem with a pump, OR the fuel filter. (The filter is next to the frame rail behind the right front tire, and under a heat shield.)

Since the secondaries tested OK, you might want to know what the resistance is across the injectors when they're HOT. They should read between 12-14 ohms (hot). If they read 10 ohms or less, it indicates problems likely. A reading of 8 ohms or less and the injector is definitely in need of replacement; not only to run better, but to prevent the possibility of a burnt valve (ask me how I know...). (The procedure is well laid out in the FSM.)

And, of course, the easy thing to do is change plugs.