full power problem - ZR-1 Net Registry Forums

janozr1 · 08-01-2007

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 · 08-01-2007

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 · 08-01-2007

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 · 08-01-2007

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 · 08-02-2007

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 · 08-02-2007

Quote:

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 · 08-02-2007

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 · 08-02-2007

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 · 08-02-2007

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 · 08-02-2007

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.

08-01-2007	#1
janozr1 Join Date: Jul 2005 Location: SLOVENIA,EU Posts: 126	full power problem 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

08-01-2007	#2
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,394	Re: full power problem 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. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

08-01-2007	#3
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,654	Re: full power problem 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. __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

08-01-2007	#4
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: full power problem 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

08-02-2007	#5
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: full power problem 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 __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-02-2007	#7
janozr1 Join Date: Jul 2005 Location: SLOVENIA,EU Posts: 126	Re: full power problem 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

08-02-2007	#8
janozr1 Join Date: Jul 2005 Location: SLOVENIA,EU Posts: 126	Re: full power problem 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.

08-02-2007	#9
Aurora40 Join Date: May 2005 Location: Leesburg, VA Posts: 2,713	Re: full power problem 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. __________________ Bob Saveland Former owner of #2517 [IMG]http://a.random-image.net/aurora40/vette.jpg[/img]

08-02-2007	#10
Jagdpanzer Join Date: Apr 2007 Location: Northern VA Posts: 2,661	Re: full power problem 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.