LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Trouble Shooting the 396! Come Join!

Old Nov 13, 2006 | 06:33 AM
  #1  
Speed Density's Avatar
Thread Starter
Registered User
 
Joined: Apr 2006
Posts: 242
From: Idaho and Canada
Trouble Shooting the 396! Come Join!

Okey guys,


After having some trouble with my builder, ive decided to take the car home, the project is about 80% done and ive got some work to do.

First off, the car has been started and has idled normal with the setup exatcly the same, or so i think. It has a baseline from alvin.

After installing the new trans and stall tonight, i decide to prep everything and fire it up.

First time, idle okey, then starts to fall and fall and finaly dies. that lasted about 20 seconds.

2nd time, starts idles and dies, about 4 seconds.

At this point im just trying to go over the basics "Fuel, Air, Spark"

I have Fuel, new walbro, and i have a FPR and it was around 38, not sure if thats an acurate or not.

Spark, have new plugs gapped to perfection. Opti is only a year old, could be bad, but not sure.

Air, its breathing.

Something i thought but have played a part in the killing was turning the crank hub manualy to get the conveter bolts in, i heard a pressure release everytime i turned it, not loud or long, but a slight hisss.

So at this point im stuck on what the problem could be.

Any Ideas Guys?

Tony.
Old Nov 13, 2006 | 07:15 AM
  #2  
MEAN LT1's Avatar
Registered User
 
Joined: Aug 2001
Posts: 1,983
From: Jacksonville,fla
Originally Posted by Speed Density
Okey guys,


After having some trouble with my builder, ive decided to take the car home, the project is about 80% done and ive got some work to do.

First off, the car has been started and has idled normal with the setup exatcly the same, or so i think. It has a baseline from alvin.

After installing the new trans and stall tonight, i decide to prep everything and fire it up.

First time, idle okey, then starts to fall and fall and finaly dies. that lasted about 20 seconds.

2nd time, starts idles and dies, about 4 seconds.

At this point im just trying to go over the basics "Fuel, Air, Spark"

I have Fuel, new walbro, and i have a FPR and it was around 38, not sure if thats an acurate or not.

Spark, have new plugs gapped to perfection. Opti is only a year old, could be bad, but not sure.

Air, its breathing.

Something i thought but have played a part in the killing was turning the crank hub manualy to get the conveter bolts in, i heard a pressure release everytime i turned it, not loud or long, but a slight hisss.

So at this point im stuck on what the problem could be.

Any Ideas Guys?

Tony.
Hmm, Everything sounds fine, the hissing sound is compression being released to atmosphere. You say FP is at ~38psi but is it holding steady while the car is running?.
Old Nov 13, 2006 | 09:13 AM
  #3  
Sweetred95ta's Avatar
Registered User
 
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
Yeah, sounds like you're running out of fuel. What does the fuel pressure do as the car is dying?
Old Nov 13, 2006 | 11:29 AM
  #4  
Casey_SS's Avatar
Registered User
 
Joined: Aug 2004
Posts: 107
From: Cedar Park, TX
Any codes? OBDI or II? Any way to get a datalog? If it's OBDI and you're in the Austin area, I have Datamaster and would be willing to help out...

After watching the fuel pressure while it's stalling, I'd check the connections on the MAF and IAC, then try adjusting the throttle body blades to open a bit more at idle. Sounds like you have the basics (fuel & spark) just about covered...once the fuel is verified airflow & electronics are next.
Old Nov 13, 2006 | 01:12 PM
  #5  
SStrokerAce's Avatar
Banned
 
Joined: Oct 2002
Posts: 6,518
Sounds like vacuum leaks to me, with it dying that fast. Make sure everything is either plugged into the intake or the other holes are plugged.

Bret
Old Nov 13, 2006 | 01:16 PM
  #6  
MEAN LT1's Avatar
Registered User
 
Joined: Aug 2001
Posts: 1,983
From: Jacksonville,fla
Once th car is started try and give it some gas, It may be in the tune. I know of several combination that didnt want to idle when first being started. May have to give it some timing, or up the idle to compensate for the time being. Whats the iac counts?.
Old Nov 13, 2006 | 01:40 PM
  #7  
Shon Herron's Avatar
Registered User
 
Joined: Jul 1999
Posts: 2,054
From: Six Mile, SC, USA
long shot, last resort but local car would do this, start up, idle then die, fuel pump tested fine, Opti replaced still did it. turned out to be the switch, could hold the switch between on and 'start' and run all day long but something was loose, replaced switch and all was well.

I would think this is not the issue but if nothing else seems to pan out, check there.
Old Nov 13, 2006 | 02:44 PM
  #8  
Speed Density's Avatar
Thread Starter
Registered User
 
Joined: Apr 2006
Posts: 242
From: Idaho and Canada
Its OBDI, and I live in Idaho, thanks for the offer though.

I have TTS (Free Version) ill have to snag up the real deal.

I wasnt able to get a clean reading on the FPS because the reg is on the fire wall :eyes: but will check to see if its steady.

Bret,
Any ideas on a location that i might miss if i look for leaks?

Shon,
What switch my friend?


Tony.
Old Nov 13, 2006 | 03:00 PM
  #9  
Shon Herron's Avatar
Registered User
 
Joined: Jul 1999
Posts: 2,054
From: Six Mile, SC, USA
Ignition switch in the column where the key goes into the hole.
Originally Posted by Speed Density
Shon,
What switch my friend?


Tony.
Old Nov 13, 2006 | 03:04 PM
  #10  
blown383's Avatar
Registered User
 
Joined: Aug 1998
Posts: 1,384
From: Los Angeles, CA
How did you install the new walbro? Sometimes the hose slips off and you lose pressure and it would act exactly how you described.

-B
Old Nov 13, 2006 | 03:23 PM
  #11  
plattted's Avatar
Registered User
 
Joined: Sep 2003
Posts: 372
Idles and dies

Check the vaccum when it does start - should be 16 to 20 lbs.with stock cam and as low as 10 in with hot cammed engine. The map sensor reading in volts will tell you the vaccum, if you do not have a guage and there is a chart equating MAP volts = in of vaccum. Fuel presure adjust, to 43.5 lbs is what many performances prefer . Good Luck, 93Z Ted
Old Nov 13, 2006 | 03:24 PM
  #12  
Speed Density's Avatar
Thread Starter
Registered User
 
Joined: Apr 2006
Posts: 242
From: Idaho and Canada
It was installed at the Shop. So I wouldnt know.

Tony.
Old Nov 13, 2006 | 04:51 PM
  #13  
SStrokerAce's Avatar
Banned
 
Joined: Oct 2002
Posts: 6,518
There are all the ports on the sides of the intake, plus make sure the one below the TB and the EGR/AIR if you deleted them are sealed off, any leaks can cause issues like you described.

Bret
Old Nov 13, 2006 | 05:32 PM
  #14  
Sweetred95ta's Avatar
Registered User
 
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
Now that I think about it, I had a real similar problem when my 'modified' fuel pump bucket didn't stay together. Have you tried filling the tank up and starting it? If it has more than a half a tank (not 1/2 by the gauge, a real 1/2 tank), then you probably don't have anything to worry about. A fuel pressure test will tell if the problem is with the pump or not.
Old Nov 13, 2006 | 06:45 PM
  #15  
Speed Density's Avatar
Thread Starter
Registered User
 
Joined: Apr 2006
Posts: 242
From: Idaho and Canada
Bret,

Its a Victor E, I just did a run around of the intake and sheetmetal elbow and it seems everything is connected and were it should be.

Im going to try and fiddle with the FPR when I get home tonight, considering that it does smell like Fuel.

Sweet,

Its got about 3/4 a tank and its been sitting there for about 5 months. Im thinking about draining it or just adding some fresh 93octane in the car.

Tony.

Thread Tools
Search this Thread

All times are GMT -5. The time now is 08:55 AM.