: 97 Deville Concours - Rough Starting



bvaughn503
06-24-12, 01:40 PM
I just replaced the motor an transmission in oregon now i live in colorado an first start off the morning it takes awhile to start like 3 to 5 minutes than it starts ruff than ill turn it off an it will start right up but the lights kinda flicker for a min than that goes away does anyone have an idea what causes it to have a hard first start.

Faded Crest
06-24-12, 02:18 PM
Weak fuel pump, stopped up fuel filter, bad fuel pressure regulator are candidates.

bvaughn503
06-24-12, 02:57 PM
Is there an external fuel filter..

Submariner409
06-24-12, 03:59 PM
Maybe on the left frame rail, just about under the driver's side rear door. Retainer bracket, quick connect and hex fitting. Bleed off fuel pressure at the fuel rail test port or you'll really get a face full of gas. Replacement filters at any large parts chain store.

Google "cadillac forums 1997 deville fuel filter".

Faded Crest
06-24-12, 04:53 PM
^^^ I recently changed a fuel filter on a '92 Fleetwood, bled off the pressure and still got a face full of fuel. :annoyed:

bvaughn503
06-24-12, 06:04 PM
Some one told me the idle air control valve could cause that too watchu think it gets codes 0171 an 0174 ill clean the maf sensor an the check engine light goes off but it still starts the same first start

These dam cadillacs are as bad as women there never satisfied.... I just put in a new tranny an had carroll custom cadillac rebuild my engine an now she dont wanna start i think there worst than women... jus sayin tho

Submariner409
06-24-12, 06:19 PM
The two lean mixture codes point directly at a decent sized vacuum leak, not a fuel filter. Start snooping for a hisssssss at idle in P - remove the engine cover and really snoop.

It's not the MAF itself, either, unless you have an intake duct air leak at or after the MAF. VERY seldom will "cleaning the MAF" do a thing for your problem. (Unlikely, as your MAF is bolted to the throttlebody ???)

bvaughn503
06-24-12, 07:09 PM
Do those codes have anything to do with the hard start in the morning.

Submariner409
06-24-12, 07:36 PM
Sure - Lean fuel mixtures can cause anything from hard starts to lousy idle to a midrange bog to nasty fuel detonation (hot cylinder/carbon chip/plug electrode = preignition).

Just for grins, here's a 10-minute fuel mixture check - cold hard start...............remove the air intake duct at the MAF - your MAF is bolted directly to the throttlebody ??? - and (door open and key ready to go) squirt a moderate shot of starting fluid into the MAF screen. Hop in the car and start it. Quick start ??? The starting fluid (ether-based) is more volatile than lacquer thinner - the engine should start immediately and run well enough for the ECM cold idle enrichment process to override the air/vacuum leak.

IF the engine lights off immediately, rather than a long crank, you have air/vacuum/fuel problems. Your codes point to an air/vacuum leak.

bvaughn503
06-24-12, 08:28 PM
K i looked real hard an i cant find any hissin... could it be the idle air control valve i took it out an it was filthy grimey..

bvaughn503
06-24-12, 09:59 PM
So after reading all the threads i could. i think its the fpr but i cant find were it tells u how to check it to see if its good or not

Submariner409
06-24-12, 10:12 PM
A failed FPR will normally cause excessively RICH mixtures, not the lean codes you have.

I believe that, in your car, the Fuel Pressure Regulator is in the fuel rail, just to the right of the rear part of the rail, looking over the engine from the radiator. A domed thingy with a vacuum line attached to the throttlebody casting by a plastic pipe. To test the FPR, remove the engine cover, start the car and let it idle. Carefully remove the vacuum pipe from the nipple on the FPR - if there's any fuel in the FPR nipple the diaphragm is ruptured. The vacuum line should have decent suction with a fingertip placed over the open end. Cadillac Tech Tips.

bvaughn503
06-24-12, 10:38 PM
K i did like you said it didnt look like there was any gas in the nipple or line but there was no suction in the line either

Ranger
06-24-12, 11:21 PM
That line should have vacuum. Check the other end. Also it would not hurt to clean the TB.

bvaughn503
06-24-12, 11:48 PM
Thanks ill try that now...

bvaughn503
06-25-12, 12:46 AM
The other end was connected pretty good..

Submariner409
06-25-12, 10:48 AM
Go back to the disconnected FPR vacuum line - with the engine idling have an assistant increase engine speed to 1500, then 2000 - up and down several times - does vacuum in the lne vary ? That line sends a manifold vacuum "signal" to the FPR to control the amount of fuel bypassed back to the tank - the vacuum varies with throttle opening. If you wanted to, you could hook up a run of the mill vacuum gauge to the line and watch that.

bvaughn503
06-25-12, 11:01 AM
First thing you guys are awesome preciate all the help... so i went out this mornin wont start again so i check fuel pressire an it barely dribbled out yesterday after it was started it had a lot of pressure

Submariner409
06-25-12, 11:19 AM
The fuel pump should run for 2 - 3 seconds at key:ON, then, if you sit for a few seconds before turning the key to START, the pump will wait until you turn the key - it will not run all the time with the key ON - only when the engine is cranked or the key is in RUN - engine running.

So............next cold start, try this: Turn the key:ON for 5 seconds, turn it OFF for 10. Do this twice more and try the cold start. What happens ???

(Where I'm going is to have you fully prime the fuel system after the engine has been OFF for quite some time. The FPR and system should hold fuel pressure for a long time - overnight, in fact.)

Next step is to rent a fuel pressure test kit from a large auto parts store. Hooked up to the fuel rail test port it should show 40+ psi at Key:ON and 41 - 47 psi running at idle. Pressure should change a bit with throttle opening. If that's not the case it's FPR, fuel filter, or fuel pump module replacement time.

bvaughn503
06-25-12, 11:34 AM
So i never did start it yet... i did like you said with the key and nothing i checked the fuelrail an it dribble out again to a stop. Should i get her started an check the fuel pressure now

Submariner409
06-25-12, 11:37 AM
So i never did start it yet... i did like you said with the key and nothing i checked the fuelrail an it dribble out again to a stop. Should i get her started an check the fuel pressure now

Yes - should be 41 - 47 psi running - this is pointing at either fuel filter or pump module. Pictures in my albums. Tutorials in Cadillac Tech Tips.

bvaughn503
06-25-12, 12:22 PM
Its holdin at 35 psi

bvaughn503
06-25-12, 12:24 PM
The mechanic i took it to thinks its a fuel filter wats the techs think...

Submariner409
06-25-12, 12:35 PM
Its holdin at 35 psi

That's easily 6 psi too low, and low fuel pressure is the cause of a lot of driveability problems. You're getting closer to a fuel tank drop and pump module replacement - if the filter doesn't do the job - cross your fingers.

Look at your car, fuel systems, in www.rockauto.com to see what the pump module looks like. My advice, if it is necessary to replace the pump, is to replace the entire module because the fuel level sensor and tank pressure sensor would then be new also.........for not much money over the pump alone.

bvaughn503
06-25-12, 12:39 PM
I thought a pump works or it doesnt is that true or no...

Faded Crest
06-25-12, 12:56 PM
I have heard some horror stories about the cheaper fuel pump assemblies. Make sure you get a quality part... Good ones are around $300. This is not a job you want to do twice. It's no fun getting that tank down. You have to drop the exhaust from the hangers and remove the heat shields to make enough room for the tank to come down.

bvaughn503
06-25-12, 01:05 PM
Thanks to everyone so far for there advice its much appreciated its to good to be true u cant even pay a mechanic to talk to you let alone teach u some shit... thanks again im gonna change fuel filter than see were the pressures at

Ranger
06-25-12, 01:14 PM
So i never did start it yet... i did like you said with the key and nothing i checked the fuelrail an it dribble out again to a stop. Should i get her started an check the fuel pressure now
Wait a minute. Are you saying that fuel dribbles out of the FPR when the vacuum hose is pulled? There should be NO fuel present.


I thought a pump works or it doesnt is that true or no...

No. They can work, but not put out enough pressure. I have even seen some intermittently fail and them come back to life.

drewsdeville
06-25-12, 01:23 PM
Wait a minute. Are you saying that fuel dribbles out of the FPR when the vacuum hose is pulled? There should be NO fuel present.


No. They can work, but not put out enough flow.

Fixed :lildevil:

bvaughn503
06-25-12, 01:32 PM
Fuel dribbles out were u put the tester at the end of the fuel rail but after i got her started i took it to check fuel pressure an it would spray plus it would stay at 35 psi while running even if we revved it up it stayed at 35 psi

bvaughn503
06-25-12, 01:34 PM
I checked a few times now no fuel in fpr vacuum line an it has suction.

drewsdeville
06-25-12, 01:44 PM
Fuel dribbles out were u put the tester at the end of the fuel rail but after i got her started i took it to check fuel pressure an it would spray plus it would stay at 35 psi while running even if we revved it up it stayed at 35 psi

Just to confirm, because you never know, fuel isn't "spraying" with the tester attached, is it?

bvaughn503
06-25-12, 01:48 PM
No i just pushed on it with my finger to see if it had any pressure after i drove it than we put a tester on it an started it

Submariner409
06-25-12, 01:51 PM
Bottom line: 35 psi, running, is low fuel pressure. The spec on your car is 41 - 47 psi, running at idle.

Again..............your first suspect is the fuel pressure regulator, a 15 minute change job for $55 parts cost. If that doesn't get the pressure to above 41 psi, running, it's fuel filter and/or pump assembly time. Pump is $200 plus 4 hours shop labor.

Read Post #19 again - the part about priming the fuel system at cold start.

bvaughn503
06-25-12, 02:28 PM
Ok ima get the regulator an check it

bvaughn503
06-25-12, 02:29 PM
So i shouldnt pay the shop 60 yet to switch out the filter try the regulator first.

Faded Crest
06-25-12, 02:32 PM
$60 to change the fuel filter? Yikes! I would try the FPR first. Bad fuel filter is always one of the favorite suggestions as to what's wrong with fuel pressure, but that rarely winds up being the problem. Usually FPR or fuel pump itself.

drewsdeville
06-25-12, 02:33 PM
At the same time, after 15 years and probably more than 150k miles, it's probably due anyway and definitely won't hurt.

I, for one, have cured more than a handful of fuel pressure problems with a filter replacement. As cheap as they are, I'd personally start with the filter. However, I'd get it done somewhere else. $60 is outrageous.

Besides, if they are going to charge $60 for a filter replacement, a FPR replacement could be $150. That's a lot of money to just "try" something that may not need replacement.

Faded Crest
06-25-12, 02:33 PM
Certainly wouldn't hurt. But $60 for a 10 minute job?!!!

bvaughn503
06-25-12, 02:35 PM
Im in bfe so everythings more i would do it myself but it takes a special tool dont it

Faded Crest
06-25-12, 02:40 PM
Fuel disconnect tool is around $10 at any parts store. It is a royal pain in the butt if you don't have a lift, just hate to see you pay that much. BTW, if you do decide to get the tool, get a metal one only! Over-the-counter plastic quick disconnect tools suck.

bvaughn503
06-25-12, 02:41 PM
K so im just gonna do both the filter an fpr if that dont do it its gotta be the fuel pump assembly right...

bvaughn503
06-25-12, 02:42 PM
Awesome thanks again

bvaughn503
06-25-12, 03:07 PM
If i do both filter an fpr an that dont fix it does that mean its the pump assembly

Faded Crest
06-25-12, 03:17 PM
^^^ That would be my assumption.

Ranger
06-25-12, 03:20 PM
If the FPR does not leak fuel from the nipple (at idle) I think you are wasting money changing it.

bvaughn503
06-27-12, 05:21 PM
So thanks to all your guys help. I figured out i just needed a fuel filter its started great the last to mornings thanks again

Faded Crest
06-27-12, 05:36 PM
Cool! You were lucky. The cheapest thing it could have been!

bvaughn503
07-07-12, 07:06 PM
Now in the morning it kinda doesnt want to start an itll blow a lil smoke i was drivin down the road an it started smokin a lil bit too any ideas... no codes yet.

bvaughn503
07-07-12, 07:11 PM
Oh i forgot to mention that before wen i was tryin to figure out the cold start promblem i took out the idle air control valve to clean it and i pulled it out and pushed it back in wen i was cleaning it... i read later on not to do that because it can ruin the threads could that possibly be the problem cause it never smoked before

Ranger
07-07-12, 10:17 PM
No, that won't cause smoke. It simply controls the idle intake air.

bvaughn503
07-08-12, 12:13 AM
I had carroll custom cadillac rebuild the engine bout 5 months ago.. its not anything internal is it

Ranger
07-08-12, 11:43 AM
:noidea: I wouldn't think so. Might check with them. I would guess it should still be under warranty?