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Discussion Starter · #1 · (Edited by Moderator)
So, I have a 1993 DeVille Sedan with the 4.9L... I have been having issues for ~3 weeks now...
I bought the car in mid to late June
(In trade for a TRASHED 95 Pontiac Firebird convertible with no title)...
The story was that he bought it, replaced the radiator, thermostat and such, then the water pump started failing, he kept driving it until the serp. belt was being thrown...

I got it home, changed the pump, drove it a bit, then that's when the problems started... I've changed fuel pumps, fuel strainers, fuel filters, then FINALLY seemed to get fuel pressure back at the rail, tried to take it around the block, and didn't get 100 feet...

There are vaccum lines dry rotted everywhere here, and I think that's now my current problem
Would the vaccum lines from the throttle body to the tank pressure control valve and such, cause a no start condition?
If I dump some fuel down her throat, hold er WOT and crank, she will eventually run for a while, sometimes, sometimes just burns what you dump in er and shuts off, it's like one second we have fuel, the next we don't???

Will provide some pictures soon

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Discussion Starter · #2 · (Edited by Moderator)
I dumped some fuel in her throat, she started, idled until she got warm, then idle was stuttering, then it just completely shut off, and every time I try to pull codes from the obd1, the information center flashes unusually, and doesn't display any check eng or serv eng indicators, the only indicator lamp on the dash is the charging indicator when the ign is ON but eng is not running

When the engine got warm and shut off, no amount of fuel I dump down her throat will get her to fire up and stay running besides the fuel I put in

And it DOES have fuel pressure to the rail after It shut off, so it's not fuel delivery from the rear of the car
 

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2005 Deville base
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608 Posts
Fix the rotted rubber (vacuum leaks) and see what that does. Keep in mind, if a couple of lines are cracked and rotten, most likely, all of them are.
 

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2001 Deville
04 Deville
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how's the ignition system? have you checked the timing? there was problems with the distributor gears but not sure if it applys to the 93 4.9. you may want to see if any of your local garages still have their old Snap-On scanners collecting dust in the back room and will let you use it. at least then you can see some data
 

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Discussion Starter · #7 ·
See what it does.
It was the vaccum line to the fuel pressure regulator, the elbow was cracked and had electrical tape around it... Runs fine now, starts beautifully...

Although, I did have to steal the elbow from the egr valve. As I cannot cap off that valve completely (engine doesn't run) I left it disconnected, I can hear the vaccum leak it created as well...

What are the consequences of running with no egr?
 

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Discussion Starter · #8 ·
how's the ignition system? have you checked the timing? there was problems with the distributor gears but not sure if it applys to the 93 4.9. you may want to see if any of your local garages still have their old Snap-On scanners collecting dust in the back room and will let you use it. at least then you can see some data
Theres no DLC, all the codes are pulled from the digital information center when put into diagnostic mode
 

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It was the vaccum line to the fuel pressure regulator, the elbow was cracked and had electrical tape around it... Runs fine now, starts beautifully...

Although, I did have to steal the elbow from the egr valve. As I cannot cap off that valve completely (engine doesn't run) I left it disconnected, I can hear the vaccum leak it created as well...

What are the consequences of running with no egr?
I'm glad that helped.
I recommend replacing all the lines, not robbing from one place to put in another place. The system was designed to have it all in place and will run so much better with everything operating correctly.
Keep us posted.
 

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Discussion Starter · #11 ·
I'm glad that helped.
I recommend replacing all the lines, not robbing from one place to put in another place. The system was designed to have it all in place and will run so much better with everything operating correctly.
Keep us posted.
Yeah I can't get the vaccum line I have on hand over the fitting on the throttle body as I have a smaller diameter line so I will need to go get elbows...

I took it to go run an errand and It died at idle twice, but other than that she pulled through
 

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2010 DTS
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What are the consequences of running with no egr?
What are the symptoms of a failing EGR valve?
  • Your engine has a rough idle. ...
  • Your car has poor performance. ...
  • You have increased fuel consumption. ...
  • Your car frequently stalls when idling. ...
  • You can smell fuel. ...
  • Your engine management light stays on. ...
  • Your car produces more emissions. ...
  • You hear knocking noises coming from the engine.
 

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70 Deville 78 Seville 92 Deville 03 Deville
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I use my code scanner on lesser cars but never used it on my Caddys. The built in unit seems to do anything I needed. I heard there is an OBD plug behind the ash tray but I never looked.

Those cracked vacuum lines look terrible and must be the problem. You might want to look at all the threads here about ISC and gas tank baffle issues. If you are having problems with less than a half tank of gas it could be the tank baffles.
 

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'93 SedanDeville 60 Special
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I have a 1993 sedan Deville 60 special and use the DLC port which is facing the floor, kick panel below the ashtray
all the time with a couple of OBD-I scanners

Really very useful is debugging problems and see what sensors like EGR is affecting how the engine functions

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2001 Deville
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yes the built in diagnostic system is great but it doesn't show live data so having a scanner that does more than read codes will get you to the source of your problem
 

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Again, get what you need and replace all the vacuum lines. Don't mouse it together. It's a Caddy, don't cheap out or you'll pay for it later.
 
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