94 with the stutterin' stumbles

[D.O.Dug]

Hi Y'all

So here's the deal... driving up a moderate grade about 1/4 mile long...accellerating but not hard... SPUT....SPUT... STUMBLE..! Off the gas thinking "WTF?" then all is cool... smooth going up the rest of the hill. 5 more miles home with no problems. No warning lites, shifts are smooth, idles & starts fine - full tank - new f/filter.

I'm thinking poss. fuel pump? Would this show a code if it were the pump? (haven't had time to check). or is it just "the ghost in the machine"? :confused

 

[Key West Jack]

run a pressure test

 

[Florida Guy]

My money is on a clogged fuel filter.

 

[John Robinson]

If this started after you filled the tank then I would suspect water in the gas. Just for fun put a couple of cans of dry gas in and see what happens.

 

[D.O.Dug]

Thanx, guys. F. filter is 2 wks old so I doubt that's the culprit. I'll run a bottle of Techron thru it next & check for any codes - stay tuned.

 

[Key West Jack]

Try running Seafoam per the instructions. Do a search it is the only quick fix that most believe has some merit.

 

[B17Crew]

Thanx, guys. F. filter is 2 wks old so I doubt that's the culprit. I'll run a bottle of Techron thru it next & check for any codes - stay tuned.

Short write-up on injector cleaner, 85’s-96’s.

Fuel Injection Service.
Chris Petris, Corvette Clinic.

“I recommend annual injector cleaning on all ’85-’88 cars. These cars use either Bosch or Lucas injectors. The injectors sit deeper in the intake manifold than ’89-and-up injectors, so they build up deposits more frequently. You can purchase 3M injector cleaner that is for one-time usage. Remove the fuel pump fuse and fuel cap. Follow the instructions on the hose and hook it to the can. Install the injector cleaner on the fuel rail on the right side below the vacuum fittings at the pressure port. Follow the instructions on the can to use.

Multec injectors were present on all ’89-’96 Corvettes. These are self-cleaning disc injectors. The injector windings are cooled with fuel, so a harsh injector cleaner will damage the windings and short out the injector.”

B17Crew

 

[D.O.Dug]

Thanx, key west but I'm with B17 on this one. Techron is the only thing I use with later-model fuel injectors for one simple reason - it works! I'm thinking it may be a fuel delivery issue, though. Did it again yesterday - going up an overpass onto the frwy. - stumbled a few times, then smoothed out. OK the next 25 miles home. It acts like what us geezers used to experience in the days of carburators - "vapor lock" - caused by the fuel line passing too close to the exhaust maniforld & the fuel boiling in the fuel line, making the engine stumble (or not start when it got too hot). I'll keep a eye on it - if it's fuel crud, it'll go away - if not, it'll get worse. Hard to fix it when it won't stay broke!

 

[Key West Jack]

Thanx, key west but I'm with B17 on this one. Techron is the only thing I use with later-model fuel injectors for one simple reason - it works! I'm thinking it may be a fuel delivery issue, though. Did it again yesterday - going up an overpass onto the frwy. - stumbled a few times, then smoothed out. OK the next 25 miles home. It acts like what us geezers used to experience in the days of carburators - "vapor lock" - caused by the fuel line passing too close to the exhaust maniforld & the fuel boiling in the fuel line, making the engine stumble (or not start when it got too hot). I'll keep a eye on it - if it's fuel crud, it'll go away - if not, it'll get worse. Hard to fix it when it won't stay broke!

I hate it when somthing lingers. I comes back to remind you that you STILL have a pain in the ass. Kinda like an exwife. otfl

 

[D.O.Dug]

.....you got one of those too, huh? Thing is, you can always SELL the 'Vette....

 

[vetwanna]

Don't sell the Vette, it's the one thing that really gets on the ex's nerves. Preliminary studies indicate it may even shorten their life expectencies!

 

[nickyg]

Hi Y'all

So here's the deal... driving up a moderate grade about 1/4 mile long...accellerating but not hard... SPUT....SPUT... STUMBLE..! Off the gas thinking "WTF?" then all is cool... smooth going up the rest of the hill. 5 more miles home with no problems. No warning lites, shifts are smooth, idles & starts fine - full tank - new f/filter.

I'm thinking poss. fuel pump? Would this show a code if it were the pump? (haven't had time to check). or is it just "the ghost in the machine"? :confused

Mine does the exact same thing along with a surging idle after it gets hot. Been working on this one for a while. I'll be monitoring this post to see if some one comes up with anything different to try to narrow down this problem. It seems this happens a lot. I've read a lot of posts concerning this same issue with suggestions from vacume leak, bad plugs and wires, impending opti failure, bad ECM, EGR clogging, etc, etc. Could be a combination of of these issues or just one.

 

[D.O.Dug]

Well, no codes found. Hasn't done it for the last 75 miles...hmmmmmm :confused

Seems to be evident when the weather is warmer. Got some hot temps due here next week - we'll see :eyerole

 

[nickyg]

Well, just removed the IAC and cleaned it up and the orafic it goes into and did a reset. There was some build up, but not a lot. Seems to be idling smoother. Got to take a long trip tomorrow. Let's see what happens.

 

[KANE]

Hi Y'all

So here's the deal... driving up a moderate grade about 1/4 mile long...accellerating but not hard... SPUT....SPUT... STUMBLE..! Off the gas thinking "WTF?" then all is cool... smooth going up the rest of the hill. 5 more miles home with no problems. No warning lites, shifts are smooth, idles & starts fine - full tank - new f/filter.

I'm thinking poss. fuel pump? Would this show a code if it were the pump? (haven't had time to check). or is it just "the ghost in the machine"? :confused

Could be Opti-Spark too. My 1994 Formula ran like garbage because of its Opti-Spark. There was some condensation inside the unit and it scattered the signal- hence it seemed to sputter and miss.

If you've changed the thermostat recently and coolant dripped down across the distributor- chances are it is the Opti-Spark unit.

 

[Key West Jack]

otflotflotflotflotflotfl

Don't sell the Vette, it's the one thing that really gets on the ex's nerves. Preliminary studies indicate it may even shorten their life expectencies!

otfl

 

[D.O.Dug]

Don't think it's the Opti - was replaced about 10k ago & when I did the TB bypass, I kept the w/pump dry. We'll see what happens NEXT.....

 

[Radar]

My money is on the fuel pump or the opti-spark.

Radar

 

[D.O.Dug]

The gremlin still lives............it sure ACTS like a fuel delivery problem, but I can only get it to act up when: ambient temp is 85+ deg. - going up a grade & in OD - cuts out once,twice - may down-shift onto drive, may not - then all is cool.

I've tried nailing the gas to see if car will die out right after this happens, but it accellerates normally.

No codes.

Is there a way to check my fuel press. that would indicate a impending pump failure?
:confused :confused :confused

TIA for your input.