full power problem

[janozr1]

ZR1 profesors.......need info for my Z problem :pray
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,
:hello: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. :redface:

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.

:cheers:
Tom

[Aurora40]

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.
:iamwithst (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 :blahblah:
Im waiting for your comments , again:hello:
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.

[janozr1]

OK , tomorrow will drive Z first with one than with second fuel pump, I will
remove 10a fuses and see what will be ...
thanks for now,Jano

[janozr1]

Here are results...if I take out fuel pump fuze 1 car die , reply with pump fuze 2 (it is near fuze-pump 1 or somewhere else?????) car work normall so my
conclusion is that second fuel pump dont work...???

[Jagdpanzer]

If you have access to a fuel pressure test gauge you can check the engine fuel rail pressure with the ignition key on and the engine not running. Both pumps should be running in this condition. Rail pressure should be at around 40-45 psi. Now pull the fuse for primary pump and see what happens. If the pressure stays up then the secoundary pump is OK. You can can also check the primary pump out this way to.

[Aurora40]

If your car is cold, coolant temp is close to ambient, and you pull the fuel pump 1 fuse and it won't run, then yeah, it sounds to me like your secondary fuel pump doesn't work.

[janozr1]

No, I cant messure fuel pressure, i dont have tool , but If every pump have own fuse, car run or not when Im put in-out fuses , am I right , so in my case car not run when I remove first pump fuse.......that mean to me ...second pump is bad . Correct or no ???
If Im gonna check and replacement pumps which one is first and second ...lower or higher on the fuel holder.
regards,Jano

[janozr1]

so , last news...
both pumps runs good under 176 F , than secondary pump
go off so reason for that isnt fuel-pump problems , problem is somewhere else
( code 61 ) .....Im waiting for any suggestions

jano

[tomtom72]

Jano,

Both of the pumps are the same part number, identical pumps mechanically. The ECM calls the second pump on line when the conditions say the pump is needed.

In my 90 FSM the listing for DTC # 61 is Secondary port throttle system fault. Usually, by not exclusively, this means the the Secondary Port solenoid switch is/or has failed. OR that the vacuum leak is bigger than the system can tolerate and still work properly(this is most unlikely).

Sorry I do not have a reliable source for DTC's for any other yr ZR-1. I have a 90 so I have a 90 FSM. I would say a quickie way to see if the secondary solenoid will not hold vacuum is to disconnect the vacuum line from the vacuum pump at the line splice over by the right side water tube on the Injector housing. Connect a hand vacuum pump to the end of the line that goes under the plenum by the the tube & alternator ( that's where it is on a 90). Apply vacuum to the line up to about 10 to 12 inches of Hg and see if the vacuum gauge stays or if it drops quickly or drops slowly....that means a leak. If it holds vacuum for at least 2 mins. then there usually are no leaks.

Just as an appendix to all my ramblings: Over at the NetRegistry site, in the maintenance section, under the common issues(?) or How To section there is a very well written explaination of the workings of the secondary port throttle system along with all the vacuum parts needed to make the system work.

:cheers:
Tom

[janozr1]

Tomtom ,
first would like to thank you for great answer , after many readings
on this forum and members answers I learned that is my problem under the plenum as you thinking too , so my suspect is sec. air inlet valve which is I
think clogged because I dont find any vac.leak. (this happened after long hot ride when I stop and take fuel on the gass station ) I never pull off plenum before so Im thinking now how can test- check it =D>=D>=D>
I also learn that sec fuel pump goes out at 176 F to protect my engine.

regards,Jano

[tomtom72]

Jano, Glad to be able to help out, albit in a small way.:thumbsup:

It's been a long time since I went thru the secondary vacuum system, parts and functions. I did mine over when I did my injectors a few yrs ago.

A small, but important point to remember about Electronic Engine Control systems, EEC systems, is that the only way a DTC can be set is if a sensor or a control device that is monitored by and or controlled by the ECM is not functioniong correctly. Usually if the sensors fail they send no data to the ECM and /or do not acknowledge the reference signal or emit a reference signal. The devices that are controlled by the ECM set DTC's if they do not function, either mechanically or electrically and in some devices they also have a reference signal. All that said, I'm a long way from being smart in EEC operation and theory and functionality. Sooooo, I would suspect that if you can do the vacuum test on the secondary control solenoid and it passes the vacuum test then that solenoid & the check valve before it are okay from a vacuum aspect. The control solenoid may have a fault on it's electrical side. That may be an avenue to explore further. The rest of the parts in the secondary control system take their orders (so to speak:redface: ) from that control device. The rest of the system can only respond to the solenoid's commands: the tank, the hose, the actuator diaphrams are all just mechanical parts with no direct connection to the ECM.

In any event please read up over at the NetReg site because my knowledge is far from the whole story. I would say that it is likely you will have to pull the plenum to properly diagnoise and correct the issue.

:cheers:
Tom

PS I'm leaving to go watch F1, be back later!

[Jagdpanzer]

Tomtom ,
first would like to thank you for great answer , after many readings
on this forum and members answers I learned that is my problem under the plenum as you thinking too , so my suspect is sec. air inlet valve which is I think clogged because I dont find any vac.leak. (this happened after long hot ride when I stop and take fuel on the gass station ) I never pull off plenum before so Im thinking now how can test- check it =D>=D>=D>
I also learn that sec fuel pump goes out at 176 F to protect my engine.
regards,Jano

Here is a great post over at the Corvette Action Center ZR-1 forum on LT5 Secondary Port Operation & Vacuum Diagnosis:
http://corvetteactioncenter.com/forums/showthread.php?t=14272

[janozr1]

OK, I done , my plenum is off , now everything seems to me just normall,
no any leaks , inlet valve actuators are well , how can I test inlet soleonid
valve now ???
jano

[janozr1]

BINGO , both sec. actuators are leaking , I disconeted and conect them (bypass) direct to vaccum pump which is running nonstop.
SOOOO , thanke you all for this help via forum, I m proud mechanical now .;)
Last info i need is where is best way to buy them , including with shipping oversea ....Kurt or....

regards,jano:thumbsup:

[gbrtng]

BINGO , both sec. actuators are leaking , I disconeted and conect them (bypass) direct to vaccum pump which is running nonstop.
SOOOO , thanke you all for this help via forum, I m proud mechanical now .;)
Last info i need is where is best way to buy them , including with shipping oversea ....Kurt or....

regards,jano:thumbsup:

Try pushing a diaphram in and hold a finger over the vacuum port
to see if the diaphrams REALLY are leaking. It is highly unlikely that both
actuators are leaking. You might find that a vacuum line is leaking
or the vacuum pump has failed instead. Good luck !

[janozr1]

gbrtng , yes Im sure I check them well , Im just looking where to buy them...