Falling on it's face - ZR-1 Net Registry Forums

chriskinzel · 07-11-2013

Took the old gal for a ride tonight. Everything started ok running good. Decided to make a run up the canyon and she started not wanting to run past 3k. It did this regardless of what position the power key was in. I changed all injectors 750 miles ago, and both fuel pumps and filter last summer. It seems like a fuel issue, and I have not pulled out my fuel Preasure gauge yet. It seems fine if you keep it under 3k, or less than 1/4 throttle, but what fun is that! Any ideas from the great brotherhood?
Thanks
Chris

SteelBlueZR1 · 07-11-2013

Sorry to hear your troubles. I would pull codes and see if you have any codes. You may have a secondary port low vacuum code, which I think is a code 61. My car behaved the same way when the secondary port solenoid went bad. Would stumble like hell above 3k and make no power. However, come to think of it... the car ran ok with power key off.
Also, definately check the MAP hose and replace it if it is not snug fit, and/or is not the oem design with a hard plastic tube. Jerry's Gaskets has the NOS part.

tf95ZR1 · 07-11-2013

My car ran great up to 4K rpm then "fell on its face"
Vacuum reserve was used up so secondaries closed.
New vacuum pump: problem cured!

Just sayin'

This happened years ago at the Nellis AFB Mile Run,
Gathering West (lets do it again!)
Marc Haibeck happened to be there and diagnosed the
problem literally in 30 seconds. Also, Rick Jesperson
happened to have a spare pump with him!
Picture Marc sitting on my tire on the tarmac changing out my pump.
Priceless!

Pete · 07-11-2013

Yeap, sounds like secondaries are shutting down.

Check vacuum pump if it works and you have a 1990 -1992 get a long piece of vacuum hose and connect one end to vacuum pump the other to the MAP sensor under your ECM if all good look for vacuum leak.

Pete

Paul Workman · 07-11-2013

My pump worked fine till the day I decided to remove the secondaries as part of my FBI porting. If it turns out to be a vacuum pump, I'll give you mine to a good home.

P.

chriskinzel · 07-11-2013

Thanks for all the advice. Sound vacuum related. I will check the pump for operation and leaks. I will also pull codes. Maybe it's time to remove secondary's. If I do yank them, do I need to get a chip from Marc H.? Whatever it is it sounds like some good under hood time with the tools! I will let you know what the outcome is.
Thanks
Chris

chriskinzel · 07-12-2013

Vacuum pump runs fine. After I tuen the key on it runs for about 2 seconds, the shuts off. Pulled codes and I have a 43. I seems to run fine until it gets hot, then it seens to have problems. Ideas>

07-11-2013	#1
chriskinzel Join Date: Nov 2011 Location: Salt Lake City, Utah Posts: 169	Falling on it's face Took the old gal for a ride tonight. Everything started ok running good. Decided to make a run up the canyon and she started not wanting to run past 3k. It did this regardless of what position the power key was in. I changed all injectors 750 miles ago, and both fuel pumps and filter last summer. It seems like a fuel issue, and I have not pulled out my fuel Preasure gauge yet. It seems fine if you keep it under 3k, or less than 1/4 throttle, but what fun is that! Any ideas from the great brotherhood? Thanks Chris __________________ 91 ZR-1 Red on Red #922

07-11-2013	#2
SteelBlueZR1 Join Date: Aug 2011 Location: Evergreen, Co. Posts: 346	Re: Falling on it's face Sorry to hear your troubles. I would pull codes and see if you have any codes. You may have a secondary port low vacuum code, which I think is a code 61. My car behaved the same way when the secondary port solenoid went bad. Would stumble like hell above 3k and make no power. However, come to think of it... the car ran ok with power key off. Also, definately check the MAP hose and replace it if it is not snug fit, and/or is not the oem design with a hard plastic tube. Jerry's Gaskets has the NOS part. __________________ Bert Rankin 1991 ZR1 Steel Blue / Steel Blue #1029 Haibeck chip, slotted rotors, camber brace, C-beam plates, OBX exhaust, Nitto NT555 tires [SIGPIC][/SIGPIC]

07-11-2013	#3
tf95ZR1 Join Date: Aug 2005 Location: Northridge, CA Posts: 1,461	Re: Falling on it's face My car ran great up to 4K rpm then "fell on its face" Vacuum reserve was used up so secondaries closed. New vacuum pump: problem cured! Just sayin' This happened years ago at the Nellis AFB Mile Run, Gathering West (lets do it again!) Marc Haibeck happened to be there and diagnosed the problem literally in 30 seconds. Also, Rick Jesperson happened to have a spare pump with him! Picture Marc sitting on my tire on the tarmac changing out my pump. Priceless! Last edited by tf95ZR1; 07-11-2013 at 01:14 AM. Reason: Wanted 2

07-11-2013	#4
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,679	Re: Falling on it's face Yeap, sounds like secondaries are shutting down. Check vacuum pump if it works and you have a 1990 -1992 get a long piece of vacuum hose and connect one end to vacuum pump the other to the MAP sensor under your ECM if all good look for vacuum leak. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage

07-11-2013	#5
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,493	Re: Falling on it's face My pump worked fine till the day I decided to remove the secondaries as part of my FBI porting. If it turns out to be a vacuum pump, I'll give you mine to a good home. P. __________________ Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry

07-11-2013	#6
chriskinzel Join Date: Nov 2011 Location: Salt Lake City, Utah Posts: 169	Re: Falling on it's face Thanks for all the advice. Sound vacuum related. I will check the pump for operation and leaks. I will also pull codes. Maybe it's time to remove secondary's. If I do yank them, do I need to get a chip from Marc H.? Whatever it is it sounds like some good under hood time with the tools! I will let you know what the outcome is. Thanks Chris __________________ 91 ZR-1 Red on Red #922

07-12-2013	#7
chriskinzel Join Date: Nov 2011 Location: Salt Lake City, Utah Posts: 169	Re: Falling on it's face Vacuum pump runs fine. After I tuen the key on it runs for about 2 seconds, the shuts off. Pulled codes and I have a 43. I seems to run fine until it gets hot, then it seens to have problems. Ideas> __________________ 91 ZR-1 Red on Red #922

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