• If you're looking for help and want to draw people in who can assist you, use a descriptive subject title when posting your message. In other words, "2008 LaCrosse" isn't going to indicate to anybody that you need help. However, "Need help with my 2008 LaCrosse" will. Be as descriptive as you can. Please use common sense...

Car randomly sputtering and dying

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
1996 RMW.

Okay, so here's something that neither my mechanics, nor I can figure out. My car will run B E A U T I F U L L Y. For like a day or two, let's say about 50 miles roughly. In this time, I can drive fast, I can bog the engine down with the cruise control as I go up hill, I can kick her down into passing gear, and I can do literally everything that a perfectly running car can do. Well, after this rough distance, the car will cough, sputter, then just die, and won't start for DAYS. When it does start, it'll repeat the cycle all over again. It's acting like it's starving for fuel. I have replaced the fuel filter with a Wix one (at the recomendation of the Oreilly's guy who restores old GM cars). The fuel pump kicks on fine, and stays on like it should. I originally thought it was bad gas from a notorious gas station where I live, so I dumped 2 cans of sea foam in the tank. But whenever a mechanic looks at it, it'll run fine for them. I don't get it, maybe you guys do?

Oh the last time it died on me, it threw an oil pressure light, and change oil now light.

It's worth mentioning that I JUST replaced the OPSU like three weeks ago, and I just changed the oil two days ago.
 

HotZ28

Full Member
7,062
326
83
Buick Ownership
1996 Roadmaster Limited Collectors Edition 58k - 1996 PAU
Have you tried cleaning the MAF, or replacing it? How about the CKPS. coil, or the ICM, which is mounted on the drivers side head. A lot of unknowns here. Any codes?
______________________________
 
Last edited:

century61

Full Member
88
5
8
Indiana
Buick Ownership
2008 Buick Lucerne 3.8 liter
Dont forget the fuel pressure regulator. Unhook the vacuum line from it and see if there is any gas in the line or appears wet. If it is then replace it.

If you have a OBDII scanner check the coolant temp sensor
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
I gave up and took it to a licensed mechanic for a diagnostic. Turns out that the car was tuned for premium gas (I was told when I bought the car that It was okay to run regular pump gas through it) and it clogged the injectors and screwed the lines up. I was told I was lucky there wasn't more extensive damage done to the internal portions of the car. So for an entire fuel delivery system replacement (Pump, lines, filter, injectors) it was less than $500, so I'm gonna have them do that, and that includes replacing the parts to the setup they're at now (guess it had aftermarket injectors and a racing fuel pump?) and doing a flush of the tank.

But yeah, lines, injectors, fuel filter (even the new one I just bought), and the pump were shot, and the tank needs to be pressure washed out.

So hopefully this thread helps someone else in the future!
 

century61

Full Member
88
5
8
Indiana
Buick Ownership
2008 Buick Lucerne 3.8 liter
That does not sound right to me. The only difference that I am aware of between premium and reg. is the octane. Are you sure that you didnt cause this with the seafoam? Perhaps loosening up a lot of stuff and sending it on to the fuel pump and injectors?

Im not a mechanic (DIY) but the explanation perhaps was just being nice and that even though its tuned for premium it might have been the seafoam that caused the need for cleaning and such.

JMHO
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
My thought process is that the bad gas initially started it- gumming up the filter and clogging it first.

Then after whatever probable sludge is in the bottom of the tank (car is 22 years old, and has nearly a quarter MILLION miles on it) got loosened up the rest of the way with the two cans of sea foam (cause it was probably too little- too late for it to be able to actually help), then the lines were probably blown out by the chunks of crap, the new filter may have let some slip past, and clogged my injectors.

That's my honest thought process, and I mean, while this thing was hopped up for drag racing by POs, I'm only wanting a reliable daily driver (maybe with a bit of power lol).

Honestly, I hope whatever the mechanic is doing fixes it. Cause I know that I'm going to be replacing everything short of the block before all is said and done- I just want the major repairs to be as spaced out as possible lmao
______________________________
 

1992RML

Member
50
5
8
Buick Ownership
1992 Buick Roadmaster Limited
I am reading page 245 of the 1992 Roadmaster Owners manual and it states under the Fuel Paragraph. "Use Regular Unleaded Gasoline Rated at 87 Octane or Higher" Maybe 1994-96 RM's run on Premium , but I believe it runs on Unleaded Regular also. The Mechanic is wrong on the Premium Gas Issue, But if the mechanic solves the problem , all's well that ends well, and new parts will never hurt then its a Win Win . I would have the gas tank flushed/cleaned/replaced also . Is their not a fuel strainer in the tank ?
 
Last edited:

century61

Full Member
88
5
8
Indiana
Buick Ownership
2008 Buick Lucerne 3.8 liter
I am reading page 245 of the 1992 Roadmaster Owners manual and it states under the Fuel Paragraph. "Use Regular Unleaded Gasoline Rated at 87 Octane or Higher" Maybe 1994-96 RM's run on Premium , but I believe it runs on Unleaded Regular also. The Mechanic is wrong on the Premium Gas Issue, But if the mechanic solves the problem , all's well that ends well, and new parts will never hurt then its a Win Win . I would have the gas tank flushed/cleaned/replaced also . Is their not a fuel strainer in the tank ?
I am reading page 245 of the 1992 Roadmaster Owners manual and it states under the Fuel Paragraph. "Use Regular Unleaded Gasoline Rated at 87 Octane or Higher" Maybe 1994-96 RM's run on Premium , but I believe it runs on Unleaded Regular also. The Mechanic is wrong on the Premium Gas Issue, But if the mechanic solves the problem , all's well that ends well, and new parts will never hurt then its a Win Win . I would have the gas tank flushed/cleaned/replaced also . Is their not a fuel strainer in the tank ?
I would think the fuel strainer is built into the fuel pump. I could be wrong though. The fuel filter though should be just upstream from the tank. Did they replace the filter?
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
I personally replaced the fuel filter myself, but they replaced the entirety of the fuel assembly. (Injectors, rubber lines, steel lines, pump, and cleaned the tank)


Drove it 4 hours and it did the same f$%king thing again. I'm seriously getting fed up with this car extremely quickly.

If it ain't one thing wrong with it that I can't fix, it's something worse.

And I havent even BEGUN to look into the misfire yet.
 

Steveyo

Member
79
22
8
Buick Ownership
2019 Buick Encore
Not sure what is meant by bad gas, but the running perfectly for many miles and then dying repetitions sounds like the experience I had driving a Government sedan many years ago. The car was finally towed, investigated, and discovered to have water in the gas, which happens on rare occasions. Does the "sea foam" product somehow get rid of water droplets in gasoline? @Rebmob_77----are you sure the mechanic fully drained and cleaned the gas tank?
______________________________
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
Not sure what is meant by bad gas, but the running perfectly for many miles and then dying repetitions sounds like the experience I had driving a Government sedan many years ago. The car was finally towed, investigated, and discovered to have water in the gas, which happens on rare occasions. Does the "sea foam" product somehow get rid of water droplets in gasoline? @Rebmob_77----are you sure the mechanic fully drained and cleaned the gas tank?
Yes, seafoam gets rid of water, cleans sludge, and the whole nine. Yes, I'm certain my mechanic did, he's an honest man, and not only that but I went from having a full tank of gas when it was towed in to getting charged $5 for gas to get it to the gas station

now unless both the Mcclure's in town, and the Speedway on the other side of town both have bad gas, I'm at a loss
 

century61

Full Member
88
5
8
Indiana
Buick Ownership
2008 Buick Lucerne 3.8 liter
Do this: Find the gas pressure regulator and take the vacuum line off it. Does it look wet? Like it has gas in it? If it does thats your problem. Replace it. Did you check the coolant sensor?

I would put a scanner on it ( this is mine ---> https://www.amazon.com/gp/product/B072VGJ7S8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ) do a bit of investigating when its running poorly. Check the fuel trims and read up a bit on them. You should be able to track this down. To me it sounds like after it warms up it is getting the fuel mixture wrong. Should be able to find that. I would not give up.
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
I'll be sure to say something to my mechanic when he gets in on monday (got stranded 40 miles from home... NOT a cheap tow bill for a nearly 3 ton hunk of steel!- they had to bust out the heavy duty rolloff)
 

Zeroboostbuick

Well-known member
1,316
355
83
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
It's not ideal to use 91+ octane if the engine was made for 87.

Does your engine have that messed up Optispark system ???? sure sounds like some other people who had problems with the optispark.
______________________________
 

Rebmob_7577

New member
24
3
3
Buick Ownership
Roadmaster Estate (1996)
It's got an OptiSpark. I'm praying that it isn't that, however. If it's the OptiSpark, I'm probably gonna have to stick it in the barn and leave it to rot away and find some cheap car to DD. I can't throw much more money at this car right now.
 

BigBoyDale

Member
42
1
8
Buick Ownership
1995 Buick Roadmaster Estate Wagon
Mine did the same thing..would almost die. Then would run right, even ran about a hundred miles no problem..Then it died again. Fuel pump. Changed filter, pump, strainer and fixed it. When it dies, check fuel pressure..bet it's low.

edit..see you have done that...I'm outta ideas. Wait...Have you changed the throttle position sensor. It's easy to get to and I had a Z that one was failing on and it would run great for a few miles and then start limping wanting to cut off. Cheap and easy to change.
 
Last edited:

Hertz2fly

Buick Newbie
6
1
1
Buick Ownership
Buick
Hello all,
New to the forum. I've got 3 RMW's and had this problem before- it would strand me on the side of the interstate about 35 miles North of town-twice.Would lose power at 70 mph and after some 30 minutes rest would barely run and stumbled badly.Hauled to the shop and it ran just fine for days.
Turned out to be a bad alternator. Did it again- the replacement alternator was bad...
 

G-394875

Hello all,
New to the forum. I've got 3 RMW's and had this problem before- it would strand me on the side of the interstate about 35 miles North of town-twice.Would lose power at 70 mph and after some 30 minutes rest would barely run and stumbled badly.Hauled to the shop and it ran just fine for days.
Turned out to be a bad alternator. Did it again- the replacement alternator was bad...
I’ll email my mechanic and let him know because he’s had the thing on a lift for a WEEK and can’t figure it out.
 
Top