no start, good spark and injecter pulse
05-05-2007, 07:12 AM
#1
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
no start cranking with key, but runs fine when push started
"Hi,
Great forums here, hope to get some help as well.
I have a `95 Camaro with a 5.7L stick that will not start. It was backfiring after starting for a while, if you`d rev`d it slow it would seem to run
fine, but stab the throttle and it stumbled and backfired, but now it will not start at all. It has good spark on all plugs, injector pulse on all injectors, but will not fire, pop, or anything while cranking (even if you add fuel to through the intake). Here`s the really strange part, about 80% of the time when you release the key from crank, the motor tries to run backwards!! It`ll roll over real slow 2 or three times trying to run backwards, if you release the clutch in gear while it`s doing it, it`ll move backwards in a forward gear. We`ve done a complete tune-up, cap rotor, wires, plugs, changed the optical eye in the distributor, changed the ignition module, changed the coded tumbler and key, removed the aftermarket security system (which didn`t appear to be tied into any ignition wires) all with the same results. A diagnostic scan with the latest Snap-on SOLUS scan tool says nothing is wrong. Am I looking at a bad computer?? Any ideas and or responses would be greatly appreciated.
Thanks."
*edit*
as found out later in this thread, the car runs fine when push started. So it cranks in the right direction but pops off and runs backwards with the key, but runs fine when push started.
Great forums here, hope to get some help as well.
I have a `95 Camaro with a 5.7L stick that will not start. It was backfiring after starting for a while, if you`d rev`d it slow it would seem to run
fine, but stab the throttle and it stumbled and backfired, but now it will not start at all. It has good spark on all plugs, injector pulse on all injectors, but will not fire, pop, or anything while cranking (even if you add fuel to through the intake). Here`s the really strange part, about 80% of the time when you release the key from crank, the motor tries to run backwards!! It`ll roll over real slow 2 or three times trying to run backwards, if you release the clutch in gear while it`s doing it, it`ll move backwards in a forward gear. We`ve done a complete tune-up, cap rotor, wires, plugs, changed the optical eye in the distributor, changed the ignition module, changed the coded tumbler and key, removed the aftermarket security system (which didn`t appear to be tied into any ignition wires) all with the same results. A diagnostic scan with the latest Snap-on SOLUS scan tool says nothing is wrong. Am I looking at a bad computer?? Any ideas and or responses would be greatly appreciated.
Thanks."
*edit*
as found out later in this thread, the car runs fine when push started. So it cranks in the right direction but pops off and runs backwards with the key, but runs fine when push started.
Last edited by Rukee; 06-12-2007 at 04:54 PM.
05-08-2007, 12:22 PM
#3
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
05-08-2007, 01:53 PM
#4
Registered User
Join Date: Oct 1998
Location: Jackstandican
Posts: 3,144
"Hi,
Great forums here, hope to get some help as well.
I have a `95 Camaro with a 5.7L stick that will not start. It was backfiring after starting for a while, if you`d rev`d it slow it would seem to run
fine, but stab the throttle and it stumbled and backfired, but now it will not start at all. It has good spark on all plugs, injector pulse on all injectors, but will not fire, pop, or anything while cranking (even if you add fuel to through the intake). Here`s the really strange part, about 80% of the time when you release the key from crank, the motor tries to run backwards!! It`ll roll over real slow 2 or three times trying to run backwards, if you release the clutch in gear while it`s doing it, it`ll move backwards in a forward gear. We`ve done a complete tune-up, cap rotor, wires, plugs, changed the optical eye in the distributor, changed the ignition module, changed the coded tumbler and key, removed the aftermarket security system (which didn`t appear to be tied into any ignition wires) all with the same results. A diagnostic scan with the latest Snap-on SOLUS scan tool says nothing is wrong. Am I looking at a bad computer?? Any ideas and or responses would be greatly appreciated.
Thanks."
Great forums here, hope to get some help as well.
I have a `95 Camaro with a 5.7L stick that will not start. It was backfiring after starting for a while, if you`d rev`d it slow it would seem to run
fine, but stab the throttle and it stumbled and backfired, but now it will not start at all. It has good spark on all plugs, injector pulse on all injectors, but will not fire, pop, or anything while cranking (even if you add fuel to through the intake). Here`s the really strange part, about 80% of the time when you release the key from crank, the motor tries to run backwards!! It`ll roll over real slow 2 or three times trying to run backwards, if you release the clutch in gear while it`s doing it, it`ll move backwards in a forward gear. We`ve done a complete tune-up, cap rotor, wires, plugs, changed the optical eye in the distributor, changed the ignition module, changed the coded tumbler and key, removed the aftermarket security system (which didn`t appear to be tied into any ignition wires) all with the same results. A diagnostic scan with the latest Snap-on SOLUS scan tool says nothing is wrong. Am I looking at a bad computer?? Any ideas and or responses would be greatly appreciated.
Thanks."
05-08-2007, 02:03 PM
#5
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
Absolutely not. The engine wasn`t removed nor was anything rewired, it was running fine. The motor turns over the correct direction, only when you release the key from crank position does it try to go backwards.....I said it was really strange.
05-08-2007, 02:53 PM
#6
Registered User
Join Date: Oct 1998
Location: Jackstandican
Posts: 3,144
Did you do the tune up before or after this happened? Whatever the case may be it sounds ignition related.
05-08-2007, 04:29 PM
#7
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
Tune-up was done after it wouldn`t start. While doing the tune-up the rotor screws and two cap screws snapped so the distributer was replaced with a used one, original optical sensor was installed with the tune-up. Optical sensor was then replaced with the used one after the tune-up was done and it wouldn`t start with the original optical sensor. While doing the optical sensor, nothing was out of line or rubbing inside the cap.
05-08-2007, 07:09 PM
#10
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
It was running just fine, then it wouldn`t start for a while, then it would start and run good with a light throttle but would buck and backfire hard if you were too quick with the throttle, then it wouldn`t start at all. After it wouldn`t start at all is when the tune-up, used optical sensor and ignition module replaced. Got a busy day but I`ll try to check compression on a few cylinders tomorrow.
05-08-2007, 08:28 PM
#11
Guest
Join Date: Sep 2004
Posts: 0
If you have compression and spark and you are adding fuel manually so you know it's getting in and it still does not fire the only thing left is the spark is happening at the wrong time.
So since I don't know if this has been asked/done I will ask. First has compression been done (at least on a back cylinder ) to preclude a broken cam???????
Has valve timing been checked for a slipped timing chain??????
So since I don't know if this has been asked/done I will ask. First has compression been done (at least on a back cylinder ) to preclude a broken cam???????
Has valve timing been checked for a slipped timing chain??????
05-15-2007, 09:38 AM
#12
Registered User
Thread Starter
Join Date: May 2007
Posts: 68
Compression on cyl # 7 is 125psi while cranking, and bounced up to 145psi when the motor again tried to fire and rolled over backwards when the key was released from crank. Just picked up a used computer and the same results. Any ideas??
05-16-2007, 05:44 AM
#14
Guest
Join Date: Sep 2004
Posts: 0
There are a few things you must do when checking compression. First and foremost is pull the fuse(s) for the injectors. If fuel is squirting in the cylinders while you are testing the compression, it can reduce the compression reading.
Second, the throttle butterflys must be wide open.
Last, since you are partly there already, it's a good idea to watch the valve movement along with the piston to check for proper valve timing.
Second, the throttle butterflys must be wide open.
Last, since you are partly there already, it's a good idea to watch the valve movement along with the piston to check for proper valve timing.
Last edited by Guest47904; 05-16-2007 at 05:50 AM.
05-16-2007, 05:51 AM
#15
Registered User
Join Date: Jun 2004
Posts: 411
There are a few things you must do when checking compression. First and foremost is pull the fuse(s) for the injectors. If fuel is squirting in the cylinders while you are testing the compression, it can reduce the compression reading.
Second, the throttle butterflys must be wide open.
Second, the throttle butterflys must be wide open.
But of course if all 8 cylinders have like 80psi then you have a big problem.
How many miles on this thing??
Is it possible that the timing chain has jumped? or that you installed the opti of of time??