Hello, I've got a 1994 Trans Am with about 150,000 miles on it.

At low revs it stumbles (taking off from a stop) and if I'm sitting at a stop light it'll stumble and if it's a long light the revs drop even lower and the car feels like it's going to die. If I let off the throttle around 2K rev or so it'll pop, like a backfire, but not quite as loud. It feels like it's quite down on power. I'm I'm cruising at around 2K revs it's fine, but if I give it more gas to pass or whatever it stumbles.

The fuel pump was just changed a couple weeks ago, but it's been running fine since then.

I'm thinking something with fuel. I haven't changed the fuel filter in ~5 years, and I'm thinking maybe some dirt or something got in the tank while I changed the fuel pump.

Or it could be the dreaded opti, but I hope not.

Any help would be appreciated. Car is an M6.

Thanks!

 

Ideas...

Clean MAF
Change that fuel filter
Check plugs and wires...when was last tune?

From what I have read, Opti would act up all the time, not smooth out after 2K rpm, but I am by no means an expert.

What was it running like before fuel pump change? I would try to rule out as much as possible before going forward. If it was fine, I think your theory of clogged filter may play out.

Jim

 

my 97 did this for a while. turns out it was bad upstream Oxygen sensors

i replaced both with Bosch sensors not the crap that summit sells. I got those first because they were cheap but they failed within 6 months

get ones with a warrenty if this is ur problem

 

Are loosing any coolant?Check the driveway.If this is the case,the water pump is dripping onto the opti.Hope this helps.

 

Almost forgot,might replace the coil wire.My02.

 

Sorry about all these posts,but I've been there,anyway,sitting in your driveway,with the headlights on,at idle,do you headlights flicker?That's the coil.
When my manifold air pressure sensor died,it acted like that as well.It's that black thing on top of the intake manifold.(did the mechanics mess around there and mess with the wireing?)Beer time,gotta go.My02.

 

Looks like Fatdog2 got it with the water pump. This is worse then my worst fear.

Anyone know where to find a waterpump/opti cheap in canada? Autopart stores are wanting 300+ for a rebuilt opti, a little to rich for my blood.

I would ebay from US, but worried about waiting for the parts to clear the border.

Also, any instructions on how to convert to the 'better' opti. (The vented one?)

Instructions on how to remove waterpump/opti and replace?

Thanks!

 

make sure it's the opti. there's a sticky at the top of one of these forums with the trouble codes. that sounds about right for the opti in canadian dollars. also not a cheap water pump. check shbox.com's site for some instructions. it's not that bad of a job, just have to jump in there and get her done.

 

Normally the opti will dry out,so get the water pump replaced.General Motors built the car in Canada,so,can't you get genuine replacement parts?(My mom was born there as well).

 

Hey bud, not sure where in Canada you are, but I'm in B.C. and Lordco auto parts is a great place for parts out here. I wouldn't buy anything from Canadian Tire, they're crooks. You can have parts shipped to you from Lordco. Check their website www.lordco.com

You can expect to pay about $600 for a new Delco Opti. They're not cheap, but do it right the first time, and don't get anything but a Delco.