Starts, stutters and stops - sometimes....

I'm scratching my head at this one a little....

1995 SC

I'll go out to the garage, start it up, starts fine, runs well, run around town, several starts at the various various shoping stops, everythings ok.

Every so often, it'll start, stutter around 500rpm or so, I mean it runs really rough and then maybe it'll clear out and it's fine, or it'll stall.

Did it to me the other night, got so bad I had to be flatbedded home. One thing I did notice, the parking spot was ever so slightly "down hill" and I was "nose down".

When we got the car backed out to load on the towtruck, it was "nose up" and it started fine, I didn't want to trust it at the time, so I continued with the tow.

Got it home, it started fine, put it in the garage and went and consulted the manual. I don't have a scanner yet (soon to be remedied), it seemed like a fuel filter was in order.

Changed out the fuel filter, took it out for a spin last night, seemed fine. Picked up some injector cleaner, dumped that in, bombed home on the freeway, ran ok.

Parked it out front, it sat for a while, then the wife and I decided to go out for a bite, started fine, went to eat, ate, tried to start, same thing - stutter around 500rpm, stall. Parking spot was again a little "down hill".

I was able to push it back to get the nose up, it started fine after a little clearout, definitely smells like it's flooding.

Took it home and here I am. What on earth is going on here?

I'm hoping a scanner will be able to give me a bit more info, I know this isn't much to go on at the moment.

Any suggestions?

My first thought is the fuel pump. Next time it won't start, instead of changing the car's orientation, try opening the trunk and hitting the floor (forward left of the spare) firmly with a solid object (I used a small fire extinguisher). In some cases, this will jar the pump into action. If this seems to work, a fuel pump replacement will be needed soon. If it doesn't make any difference, I would take a fuel pressure reading at the rail. Should be at least 40 PSI when starting.

My car does the same thing.If I park uphil,nose up,she starts up with a bang! if I park downhill,she bitches and moans.

This will sound odd.. There is no chance this is a fuel pressure regulator issue? Just with the car nose down and it seeming like its flooding. Not sure how touchy those things are regarding orientation of the car.

Good luck sir. Hope you get it figured out.

My 1995 has done the same thing for a very long time.

I can drive a good distance, about over 50 miles on the highway, then when I get onto back roads and God-forbid a stop light it will do the same stuttering and may stall.

With this range anxiety I could have had an all-electric and not have to pay for Premium.


As for the stop lights, when I do feel the stuttering, I keep plently of room between me and the next guy. Giving it a little gas here and there keeps it from totally stalling. But when it does, I am able to restart the thing immediately.

Most recently and frequently at only a certain location my car will start acting the fool. A new shopping plaza atop a large hill is the site where my car will give me issues, and really it's only there. This leads me to think its and altitude thing but don't know what systems would react with height. I'm wondering if this issue is the same as the issue of parking on an incline. The parking at the plaza is flat but still pretty far up.

I get my groceries then start the car. This last time it stalled twice. Having owned my share of shiddy cars I started it again but gave it some gas right after the start. It wasn't pretty and didn't feel right but it drove and as soon as I got to the bottom of the hill the car smoothed out.

I could place a bet with anyone that it would happen in that location. It just seems weird.

Let me add - when it's running like crap - giving it throttle has NO effect.

It sounds to me like something is broken or messed up with the fuel pickup. I can't imagine what on a module but with an access panel in the trunk, it might be worth a look.

Wouldn't be a bad time to take throttle body off, clean with throttle body cleaner and check all sensors, IAC, MAF and TPS. Relatively easy job if you haven't done it yet.

Sorry, I've been busy....

Fuel pressure gauge says 20psi or so with the igntion on, supposed to be 41-47psi.

Start it up, pressure is about 40psi, shut it down, pressure starts to climb.

I've noticed some odd ignition switch behavior, when I turn on the ingnition, the pump comes on for 2 secs (normal), as I go to turn it off, very slight movement toward off cycles the pump for 2 secs (?), then a little further along it'll do it again (?).

I don't have the fuel shutoff adapters I need for the next step in the manual troubleshooting procedures.

At this juncture, I'm really tempted to just go ahead and replace the fuel pump and fuel regulator so I know they're new and take it from there.

It IS a 17 year old car after all....

Are you measuring FP with the vacuum line removed from the regulator? (you should be - remove and plug the line)

I had similar symptoms. Kept getting worse until it would no longer start. Rebuilt the fuel plump and it started right up but idled very roughly. Turns out the crud in my gas tank that caused the pump to fail also caused the #5 fuel injector to fail. Swapped it out and she now purrs like a kitten.

AKC wrote:

Sorry, I've been busy....

Fuel pressure gauge says 20psi or so with the igntion on, supposed to be 41-47psi.

Start it up, pressure is about 40psi, shut it down, pressure starts to climb.

I've noticed some odd ignition switch behavior, when I turn on the ingnition, the pump comes on for 2 secs (normal), as I go to turn it off, very slight movement toward off cycles the pump for 2 secs (?), then a little further along it'll do it again (?).

I don't have the fuel shutoff adapters I need for the next step in the manual troubleshooting procedures.

At this juncture, I'm really tempted to just go ahead and replace the fuel pump and fuel regulator so I know they're new and take it from there.

It IS a 17 year old car after all....

...you likely have a bad ig switch. KO turns the fuel pump on for a couple sec. If you have a make/break it may cycle the pump.

deekster_caddy wrote:

Are you measuring FP with the vacuum line removed from the regulator? (you should be - remove and plug the line)

I seem to have missed that little bit, wait - it's not in the manual. Why would I want to disconnect the vacuum? It wouldn't be there with just the ign on, and the FP check with the car running was just a sanity check.

AKC wrote:

deekster_caddy wrote:

Are you measuring FP with the vacuum line removed from the regulator? (you should be - remove and plug the line)

I seem to have missed that little bit, wait - it's not in the manual. Why would I want to disconnect the vacuum? It wouldn't be there with just the ign on, and the FP check with the car running was just a sanity check.

The fuel pressure regulator adjusts fuel pressure according to engine load. Applying vacuum should reduce fuel pressure, removing vacuum should increase it. According to my FSM, applying 12-14" of vacuum should reduce fuel pressure 3-10 psi.

I understand, and believe me, I have no intention of seeming snarky here.

The FSM Fuel Pressure Test is initially a "IGN On" test only to look for correct fuel pressure prior to engine start. Vacuum doesn't enter into it.

I'm reading 20psi low, no matter how many times the pump comes on, it only gets up to about 20psi. That's too low.

I'm going to go ahead and replace the FPR and the Fuel Pump as stated previously and take it from there.

And per others suggestion, some cleaning here and there won't hurt.

Thanks for all the input so far, you guys DO help.

Just realizing you are talking about a '95. The procedure for checking fuel pressure with the vac line removed is for Series II engines, I'm not completely sure it applies to the Series I engines, but I suspect it does.

Sorry if this adds any confusion. I just noticed your signature stating that it's a '95.

Addendum - Still waiting on parts, meanwhile - another clue; It seems to only do this after sitting at idle for a while. If I drive and stop, drive and stop, it starts just fine. If I drive, sit somewhere at idle for a period of time, then shut it off, it may or may not start smoothly. So it would seem that temperature is playing a part in this. Could it be vapor locking?

do you have a shorty intake with K&N filter?

No, but I did replace the stock element with a K&N filter, I do that for all my cars I've had.

My 98 has been parked since Nvember, since the good weather hit a few weeks back the same stumble and rough idle have plaqued me and i dont feel confident driving any distance, but managed to use about 3-4 gallons (parked it full in november) topped it off theother day and seems to be running smoother - i added a small drygas and it must have just been moisture somewhere in the system messing with the computer. running like a champ now...i assume you tried drygas?

Thanks for that, I suppose it would be something worth looking at, although it's parked in a garage most of the time and I'm in California where we haven't had a lot of moisture lately.

I did get my scanner the other day, this is the first chance I've had to hook it up and this is what I got;

NO CODES!!!?

And here's part of a data scan I ran (I got the 9185);
Vehicle Data List

CODES PRESENT NO
2ND GEAR SW OFF
3RD GEAR SW OFF
4TH GEAR SW OFF
AC CLUTCH OFF
AC HEAD PRES NORM
AC REQUEST OFF
BATTERY(V) 14.3
LT FUEL TRIM 136
LT FUEL TR CL 16
BOOST(%) 100.0
CC BRAKE SW ON
CC ON/OFF SW OFF
CC RES/ACC SW OFF
CC SERVO(%) 0
CC SET(MPH) 0
CC SET/CST SW OFF
CC SRVO REQ(%) 0
EVAP DUTY(%) 15
EVAP SOLENOID ON
MIL OFF
COOLANT(øF) 204
EGR REQ(%) 0
EGR VLVPOS(%) 0
EGR VLVPOS(V) 0.7
KS COUNTER 250
EXHAUST 02 RICH
FUEL CUTOFF NO
IAC POSITION 47
IDLE REQ RPM 750
INJ PW(mS) 3.1
ST FUEL TRIM 131
KNOCK RET(ø) 0
LOOP STATUS CLSD
MAF(gr/S) 5
IAT(øF) 119
O2S(mV) 253
O2S CROSSCNTS 1
PNP SWITCH P/N
PROM ID 4404
RUN TIME 03:25
SPARK ADV(ø) 16
TCC APPLIED NO
TCC BRAKE SW OFF
TCC DUTY CYC(%) 0
TCC SLIP RPM 255
TCC SOLENOID OFF
THROTTLE(%) 0
TPS SENSOR(V) 0.43
TRANS TMP(øF) 168
VEHSPEED(MPH) 0
Frame:-5 Time:-6.3

This was just sitting in the garage after we got back from the wife's PT appt., it was good and warmed up, I did have it on and off a few times. It almost did it's rough running act once, but it cleared out and smoothed up.

I'm still learning this car, so I'm not sure what some of this data is telling me other than it's rich. (duh, I could smell that) and I'm curious about the EGR data.

I'd like to try to do a data capture when it's running like crap to see if there's any difference, I think I can get it to do it, just have to make sure the wife's not with me. (She's disabled and doesn't suffer vehicular crises well)

If I let it cool off long enough, it starts up ok.

Sorry, this was kinda long winded....

Hi AKC,
I have a '95 and my babygurl actually just started doing the same thing this past Sunday. I stall out on turns and stops, and have engine knocking too. (We got the same color Riv!)

Highway driving is fine - no issues. I thought it was a bad tank of gas because this started happening -right- after the last time I filled her up. Used the fuel injector, same as you. If I stop and put her in park or neutral, we get through OK, but her whine is not the same. Are you having the noise issue as well?

But city driving is killing me. I scanned her and it came up code 171, which I suppose could be a number of things. The O2 sensor, fuel pump/sensor. I'm getting the throttle cleaned right now which I hope will help.

Am I blind/did I miss the post where you put your mileage?

No, you're not blind, I don't think I've ever listed the mileage.

About 146,000. Definitely time to go through things and clean.

Haven't noticed any noise issues.

Just came across this post....my car is currently parked around the corner up the street, because it refuses to start and come home.

With the car not on flat level surface: I've noticed everytime so far, my car has NOT started, it was because it was slightly leaning to one side. Right now it's on the side of the road against the sidewalk. the crown in the road is putting the passenger side lower than the driver's side. Last time, this time happened the driver's side was slightly lower.

Temperature effects: Today was a warm day, the other day was warm as well. Both times this happened. Car runs and drives around town with only one issue...push on the gas and there is resistance somewhere. You can hear it in the exhaust and the car goes about 10-15 mph, before suddenly power is restored and she takes off like a rocket. I watched it struggle up to 2000 RPMs and then shoot through to 3000 in a second. (That was today)
I also noticed once I let her cool down, she starts right up.

Mine is a '95 S/C series 1 3800 with 98,000 miles. I'm losing my mind trying to figure this out. Being my first S/C car and only being a week into ownership, I know NOTHING about this engine and how it functions.

If it's a fuel pump issue, I'll beat the hell out of the trunk to get it to work, but how much are fuel pumps for these cars? My old Z24 was $300...I'd rather not go that route unless I absolutely have to.

If it's a fuel regulator issue...where is it located so I can swap it out?
Would a clogged catalytic converter do this? If so, how can I tell if it's the issue without dropping the exhaust?

There IS a check engine light. However finding someone other than a dealer to scan the car is impossible!!!

AKC wrote:

No, you're not blind, I don't think I've ever listed the mileage.

About 146,000. Definitely time to go through things and clean.

Haven't noticed any noise issues.

Cleaning the throttle did seem to help out. I drove her briefly this morning with no issues. I would still like to replace my fuel pump but this mechanic refused to do it because he didn't think it was worth it for my car (we are at 205,000 miles). UGH.

@ Danny -- I've had my fuel pump replaced once before but forgot how much it was. You could always check out
http://www.moradpartscompany.com/ and see what they have/put in a parts request, if you think you can handle the install.