full power problem

[janozr1]

ZR1 profesors.......need info for my Z problem
at full power after Im touching 3...4 000 rpm engine loosing power and service engine light come on , if Im leave gas pedal at that moment (rpms going down) and the SES light go out .....At NO FULL POWER car run normally. I check air pump , air leake , fuses...all work fine , can be reason for troubles second fuel pump or what ???
thanks for your comments,
regards,Jano

[A26B]

When the SES light comes on, a code is stored. Pull the code and you will know what the source of the problem is. Otherwise, you're just guessing.

[tccrab]

Agreed.
Pull the codes, that will help narrow down the diagnosis.
Your secondary fuel injectors are not getting the signal to turn on and your engine goes lean when the secondary throttle plates open up.
When the SES (Service Engine Soon) light comes on the computer disables the secondaries, so it becomes a chicken or the egg kind of problem.
There are *many* things which will cause the SES to come on, from bad secondary fuel pump to relays and even ECU problems.
Let us know what the codes are and we'll go from there.

[jonszr1]

I am having the same problem ck codes port throttle selinoid failure replaced it and it still does the same code can anything else cause that code . thnax

[tomtom72]

Off the wall noob thought.

What about the secondary port system MAP sensor? If it goes bad or is not producing a signal won't that affect 2* throttle operation? On a 90 that's the MAP under the ECM bracket.


Tom

[Aurora40]

Originally Posted by tomtom72

What about the secondary port system MAP sensor? If it goes bad or is not producing a signal won't that affect 2* throttle operation? On a 90 that's the MAP under the ECM bracket.

(man, why no "I agree" smilie?)

The car determines if they are opened based on that sensor, I believe. I seem to recall the later year cars had some differences in how the ECM determined if the secondaries opened up, but don't recall exactly.

[janozr1]

OK guys , thanke you all for now, so I just pull codes ,my Z is 94 (paper clip with pin 5+6 together .....first time doing...hope Im right ,
soooooooooooo I got code 61 .... BINGO =D>=D>=D> , now Im curious how much EUROS will I need to eleminate my BINGO nmb.
I forgot to tel you that throubles with full power start some miles later when I filled empty fuel rezervoar so I suspicion second fuel pump
Im waiting for your comments , again
best regards to all, Jano

[janozr1]

Is this possible in my case ???

ZR-1 Stumbles and Dies The ZR-1 has two fuel pumps a primary and a secondary. In this case the primary fuel pump failure is the prime candidate as the root cause.
Both pumps run from start-up until a certain coolant temperature of ~176-degrees F is reached, then the secondary goes off unless the power key is on and the secondary port throttles are enabled.

[Aurora40]

In that case, I believe the car would shut down after the coolant reached temp. The primary pump was the failure.

You can test your secondary pump, though, by pulling the fuse for the primary. Don't drive around a lot like that, but it will tell you if the secondary fuel pump works at all.

[Jagdpanzer]

The primary pump went down on my 94 Z a few weeks ago. It would run fine after initial startup then die after a few minutes running. Tried starting and it would run for a second or two then die again.
Troubleshooting this was driviing me crazy so I broke out the red Corvette service manual and learned Zs have two electric fuel pumps. Both fuel pumps run until 176 degree engine coolant temp is reached then the electronics cut out the 2nd pump until it is needed again to support the secondary fuel injectors. Both pumps also run during startup until engine reaches idle rpm, even if the engine coolant temp has reached 176 degrees.
Went down to my local Pep Boys and picked up a Carter replacement pump for $76. Changed the primary pump out and replaced the fuse which had also blown and this solved the problem.
Cut the old pump up in my lathe afterwards and found it had seized up on the commutator brushes, otherwise it looked fine.