: 97 deville hard starting, no codes



pugel
09-13-08, 10:30 AM
97 deville hard starting
no codes (why won't she speak to me and tell me what's wrong?)
148,000 miles
runs perfect otherwise
coolant temp guage looks right (temp sensor OK?)
gas milage great (no change since I've owned it from 95,000 miles)


@65,000 miles previous owner had

throttle body cleaning
new spark plugs & wires / air filter / fuel filter / pcv valve
@90,000 miles previous owner had

throttle body service
fuel injection flush with MOC
I just installed new spark plugs / air filter / fuel filter

Problem:
First start of day takes a lot of cranks and then it barely catches, acts funcky for a second or 2 and then runs fine.
Subsequent starts that day are fine.

What would be the first (cheap) thing I should do?
I was thinking of fuel injector cleaning.

Harry Yarnell
09-13-08, 11:30 AM
Fuel pump's weak.

Ranger
09-13-08, 11:57 AM
Yup, check the fuel pressure, FPR and the relay.

pugel
09-13-08, 01:06 PM
Today it's raining like crazy here so I can't check the fuel pressure until it stops. However, I needed to run some errands so when I started it, it started just fine:confused: Is the wetness & humidity a clue to a problem when it's dry & less humid or just a coincidence?

Ranger
09-13-08, 03:18 PM
Doubtful.

pugel
09-14-08, 11:22 AM
just checked fuel pressure; current values are:
key on (engine not running) = 35 psi
engine running = 40
key off = holds 40 (no leak)

don't have FSM so don't know what psi should be

I have some old notes that I checked it a few years ago and back then it was:
key on (engine not running) = 45 psi
engine running = 50
is this what is should be?

what should I check next or replace first? regulator?

Harry Yarnell
09-14-08, 11:48 AM
45-50 I believe is correct. I had similar low pressure (40#) on a '97 a year ago. It would crank forever and finally reluctantly start. Apparently 40# is enough to keep it running (probably wide injector pulses). It would fire instantly when shot with some starting ether. New pump fixed it.

Ranger
09-14-08, 01:19 PM
I agree with Harry. 35-40 sounds like the pump is weak.

pugel
09-14-08, 01:19 PM
Can I test FPR somehow to make sure the problem is really the fuel pump? I tried disconnecting vaccuum hose to FPR and fuel pressure rose to 48 while idling. I assume this means FPR allows higher pressure at higher rpm (low/no vaccuum). Does this mean FPR is OK? Obviously no change in fuel pressure with engine not running and vaccuum hose disconnected.

Reading other threads, it seems 97 deville needs to drop gas tank (no access panel in trunk) to change fuel pump. Fuel pump costs about $250. Couldn't find "how to replace" thread. Never dropped tank before, should I attempt this? Any "how to" pointers would be really appreciated.

Harry Yarnell
09-14-08, 04:38 PM
Without a lift, it's dangerous. WITH a lift, it's a pain in the ass. Some of the tin shields around the exhaust pipe need to be removed, or at least loosened.There are two straps holding the tank in the car. Four bolts for these straps. The rear bolts should be loosened; the front two removed. This allows the tank to slide down the straps towards the front. The filler and vent hoses need to be loosened; they should pull off as the tank is worked down. Should.
Electrical connector and fuel lines disconnected.
Oh, it sure helps to have the tank empty BEFORE you start this. I'll do this by energizing the fuel pump with an external 12 source to run the pump (if it'll run), and purge the tank into Jerry cans. I once had a pump that you could hear run, but zero pressure. Turns out, the car had been manhandled with a fork lift and they crushed the tank just so as to break off the top of the pump inside the tank. The pump would simply pump gas back into the tank. It was one of those plastic tanks; I punched a hole in the bottom of the tank to drain it.
The actual lowering of the tank can be done with a floor jack. I've done this a number of times, but it's awkward. I've since purchased a hydraulic table from Harbor Freight, and this works great.

Ranger
09-14-08, 09:43 PM
Can I test FPR somehow to make sure the problem is really the fuel pump? I tried disconnecting vaccuum hose to FPR and fuel pressure rose to 48 while idling. I assume this means FPR allows higher pressure at higher rpm (low/no vaccuum). Does this mean FPR is OK? Obviously no change in fuel pressure with engine not running and vaccuum hose disconnected.


As long as there is no leakage from the FPR nipple, the FPR is OK.

pugel
09-15-08, 09:50 PM
I think I read somewhere that newer devilles than mine (99?) have an access panel in the trunk to get to the fuel pump without dropping the tank and all that goes with that. Is that true? If so, has anybody made there own secret access panel? Seems like with my high speed air cutter I could make one in a few minutes as long as I new where to cut and there was some space between the trunk and the tank.

Ranger
09-15-08, 11:00 PM
Yes to both questions. Devilles did not get the access panel till 2000. Someone did cut their own access panel. I think he even may have posted pictures. Wish I could remember who it was, but if you do some searching you may find the post. I think it was only a year or two ago, but I could be wrong. The memory is the second thing to go you know.

stoveguyy
09-19-08, 11:38 PM
i have had bad fpr's with no leaks. poor hot starting. dry fpr. replaced and car started like a champ. the fuel pump fittings are right under the rear seat cushion. i think the clearance from the sheetmetal to the pump is about 1/2". i would not try to cut it with a sawzall.

pugel
09-20-08, 10:22 PM
Can I test FPR somehow to make sure the problem is really the fuel pump? I tried disconnecting vaccuum hose to FPR and fuel pressure rose to 48 while idling. I assume this means FPR allows higher pressure at higher rpm (low/no vaccuum). Does this mean FPR is OK? Obviously no change in fuel pressure with engine not running and vaccuum hose disconnected.


OK, I'm asking my above question again since I'd hate to drop the tank and replace the fuel pump just to find out it's the cheaper and trivial to replace FPR. Can I test the FPR? Can I bypass it on key-on somehow? Can I do anything to prove FPR is good? Should I take $40 gamble and try new FPR?

Ranger
09-20-08, 11:32 PM
No, you cannot bypass it. Just pull the vacuum hose while the engine is at idle and look for fuel seeping from the nipple. If you want to be double sure, add vacuum to the nipple by adding a piece of vacuum hose and applying vacuum with a hand help vacuum pump or your mouth will even do. If it won't hold vacuum or you see fuel when you pull the hose off, it is bad. If there is no fuel and it will hold vacuum, it's good. Simple as that.

pugel
09-21-08, 10:50 AM
Sorry to be so stupid here but I just don't understand how this works. How come when I disconnect the vaccuum hose to the FPR, the fuel pressure is 48 while idling? Doesn't this mean that the pump is capable of 48 and thus OK. And the FPR is reducing it too much? Or am I missing something?

Ranger
09-21-08, 11:28 AM
If your fuel pressure is 48 psi, the pump is fine. There is a diaphragm in the FPR with fuel (under pressure) on the lower side from the fuel rail and vacuum on the top side from the manifold. If the diaphragm ruptures, raw, unmetered fuel gets sucking into the manifold and the engine runs rich. When it is shut down, the fuel pressure in the lines bleeds off into the vacuum hose and manifold so when you restart (hot), it is like trying to start a hot carberated engine with the choke closed.

pugel
11-06-08, 09:37 PM
post mortem...
changed fpr ... no better.
changed fuel pump ... has never run better ... wasn't as bad a job as I thought it would be ... and now my fuel guage works better too
thanks to everyone for the advice

Johnv2
10-23-10, 06:44 PM
post mortem...
changed fpr ... no better.
changed fuel pump ... has never run better ... wasn't as bad a job as I thought it would be ... and now my fuel guage works better too
thanks to everyone for the advice

Was it costly and how long did it take you to finish?

Johnv2
10-23-10, 06:48 PM
[QUOTE=Johnv2;2397336 Did you do the pump yourself how long did it take you to finish?[/QUOTE] cost?

zonie77
10-23-10, 07:39 PM
Having exact same problem. Time to drop a tank.

Submariner409
10-23-10, 08:10 PM
Was it costly and how long did it take you to finish?

Look in www.rockauto.com - the AIRTEX pump module for your car. $175.....................If you have to drop the tank it's no fun. A day up on a lift.

Johnv2
11-15-10, 07:45 AM
my mechanic changed the fpr and the check valve. He claims there is plenty pressure from pump and its ok but I think its time to get a pump. Up here in Canada 600. for a pump alone your lucky.