ED77KATR

My 1991 sat all winter in the garage. i took it out yesterday Fri 15th and filled the gas tank [was near empty] with sunoco 93 Then drove it about 100 miles up to philadelphia. Ran perfect,,,then after sitting 10 minutes I restarted it and it ran like crap. missing a bit and bogging [stumbling] and backfiring a bit and i crawled in it a few miles. I parked it...ate dinner then after sitting a hour it started and ran fine. This morning it started fine ran fine,i drove it 10 miles to my sons house. parked it 10 minutes then it ran like crap again. i drove it like this 5 miles. Parked it. Did my business in philly. then after sitting 3 hours It started fine and i drove it 95 miles home to jersey shore running fine. Parked it 10 minutes in front of house, then as i restarted it to park it in garage it ran like crap again! Any Ideas? ALSO WHERE IS THE FUEL FILTER LOCATED? its never been replaced as long as i owned it[4 years]. I do put Stabil in gas and run it a bit if i plan on parking it more than 2 months. Thanks Ed

ED77KATR

Forgot one more thing. The car has always been cared for. It is all original. Always use AC Delco parts or factory stuff [no chinese crap] Car has 62000 miles on it. never hit. Engine stock. thanks again Ed

CorvetteMike2024

Have you checked for codes yet?

Corvette Mike

Thomas6614

Bad injectors are seemingly becoming an epidemic all of a sudden for 89-91 Vettes on this Forum.

I just replaced mine with all new Bosch III's from Jon @ FIC Injector.

I wasted time and $$ on listening to shops/dealers with an ECM and O2 replacement before checking ohm resistance on the injectors and verifying the dealer was full of it...

They should all be within a range of 16-17...if you have 1 or 2 way out of whack in comparison to the others...that is your problem.

ED77KATR

Is there a way to check for codes without a scanner? Where is the Fuel Filter located? Thanks Ed

gw962

Use a paperclip to jumper the two top right slots on the ALDL. This will be under the dash on the drivers side, just right of the steering column.

The fuel filter is on the passenger side frame rail, next to your pre-cat.

ED77KATR

Thank you everyone for sane advice. A friend told me Autozone will scan for the codes free. Then sell ya the part you need. Has anyone dealt with them? Thanks Ed

gw962

AutoZone probably won't have a scanner for your OBD I. The paperclip will be your best friend on these cars, if you use it.

ED77KATR

Got a paperclip in my hand now, I will keep ya posted Thanks Ed

ED77KATR

Once i stick the paper clip in What do i do? I cant stop thinking of the "Sienfeld" episode where Kramer puts a paperclip into a wall socket barehanded. LOL...... Seriously, will it cause the lights to send out a code? or bypass something? if a blinking light goes off can i count the blinks and figure out the code? Thanks Ed

MaSTeRofDZaSTeR2

Fuel filter's located in the fuel feed line attached to the frame rail at the rear of the vehicle... Threaded fitting type fuel filter. If you haven't changed it in that long, Id definitely change it anyway for future case even if it isnt the prob. 93-96 dont have service intervals but I change my 90 ff(not unlike your 91) atleast once a year. Ive seen an engine go for that alone on a 305 from backclogs in the **** fuel taken at some of these gas stations. I would definitely test the fuel pressure for the bogging and all....injectors(Im currently having a similar prob on my 90 to fill the statistic) maybe fuel pump. If you said its running rough, I noticed since you have a 91, I had a problem that few talked about on this forum with the TPS on the L98 throttle body. Bad Throttle Position Sensor would make my idle run rough sporatically at times. It was to the point the car ran like a cylinder was misfiring sometimes. I replaced it and all was well again. Just a side note if all else fails.

ED77KATR

Its been 4 months now, the damn car still acts up!!! Heres a update on what ive done since. 2 mechanics considered "Good" around here both gave up on it. Couldnt find any codes. So I took it[on the ferry to Delaware] to a great friend who has a repair shop in August[been there since]. He & I grew up together are great lifetime friends. We agreed to let him drive it and gradually figure it out. [He has a modern fully equiped repair shop with a good reputation].The only parts i replaced were the tempature control sensor...fuel filter....new distributor...new spark plugs....new gas. On the scanner nothing shows??? Fuel presure good too,at all times. He took the original exhaust apart ..checked it for blockages,[it was in perfect cond.] then put it back together using neversieze. Could it be the main computer??? Do they go bad? If so how much is a new one VS a good used one? Any feedback here is appriciated Thanks Ed

89 Bob L

The computers usually don't go bad. I would continue with attempting simple repairs before spending money on replacement of major parts. First, I would replace the fuel filter again. 88-92 had minor problems with the fuel tanks rusting. The filter may be clogged again. If that doesn't help, check the throttle body for carbon build-up. The rebuild kits are cheap ($15.00). Check the throttle position sensor. You can also check the fuel injectors, 15.4 is average. If there are any major variations it is time to replace them. Jon at FIC is the best when it comes to injectors. The 88-89 had multecs and were terrible, going bad after 60-70k. The 90's and up were different, and Jon is the one that can give you the right advice. Hope some of this information helps.

FICINJECTORS

I believe you have typical multec injector failure. Those injectors are a wet coil design meaning that the fuel flows through the coil inside the injector. This was fine as the injector was designed for fuel only, The ethanol additive in today's fuel breaks down the epoxy coating on the coil windings causing a turn to turn short in the coil its self. This results in the symptoms you have. The easiest check for this is to unplug the injectors after the engine is warm and use a ohm meter to read the resistance of the coils. On your year they should read 16 ohms/ If any are below 12 i would say that you have found the problem. If any are below 10 then you have definitely found it. There is a bunch of our videos on the top of the c4 tech page that you should watch.. especially the one on "how to ohm check an injector" good luck and you can always call for free tech on my cell anytime 770 842 0882
thanks
Jon Banner
FIC

ED77KATR

Drove the car home from delaware today...still looses power here&there. i am going to try a thottle position sensor next..then im going after the injectors. thanks for the help everyone. Please continue to offer suggestions here. Ed

esham

Like Jon said, ohm out your injectors (hot and cold).

jeffp1167

my 90 has a problem sorta like yours. it stumbles, detonates heavily, and I found by disconnecting the EST wire the problem goes away.

jrzvette

If all else fails, and I know this would entail another trip across the state, but there's a Corvette specialist in Mt. Holly, NJ. The name escapes me now but maybe one of the other members here knows it.