ROME

I'm having a slight problem with my car as of the day before yesterday. It's been wanting to stumble under medium to heavy acceleration (at higher rpm's), but at idle and normal acceleration it basically runs fine. Late yesterday I hit a right-hand-turn on ramp fairly quickly and, with three or four resounding pops, my car died cold. My car ALWAYS starts immediately, but after it died this time it took about 15 seconds of cranking (while coasting) to get the engine to hit at all. Eventually (with a couple of stumbling pops) it cranked and everything worked relatively fine, although the accelerator seemed to be slightly less responsive during initial acceleration.

Whatever was causing this slight burble at speed became an engine killer under hard cornering. Someone please tell me if this sounds like a problem with my fuel filter, fuel pump, or whatever. Thanks!

Rome

Steve85

I've had this problem for some time now but only when my fuel is below 1/2 tank. This has led me to believe it's fuel starvation at the pump. My pump now whines and will be replaced tomorrow evening (along with the sending unit, fuel gauge never reads below 3/4 tank). Give me a few days to drive the tank down and I'll let you know if the new pump fixes it...

Hot Rod Buick

Not sure what year your car is, but I just had the exact thing and it was my Opti Spark.

DRAGRACR

I have to agree with ski2tee. When I am below 1/2 a tank mine will stumble under heavy acceleration. Sounds like fuel starvation to me. Do you have access to a fuel pressure guage? This will tell you for sure if you are loosing pressure. Tape it to the windshield and watch the pressure under acceleration, and if it drops then there is your problem.
:cheers:


[Modified by DRAGRACR, 11:42 AM 2/27/2002]

yoslambo1@cs.com

when you are low on gas ...if you take a corner all the gas goes to 1 side & you are not getting gas to the injectors for a brief moment. this will cause the car to fall on its face....i suggest you keep your car full of gas. that will cure your problem. i believe later c-4's tanks are set up to fix this problem? what year is your car?

SPD DMN

If it does it when you are not in a turn, it sounds like the Opti. If it only does it in long turns, and your under 1/3 tank, then it is most likely fuel starvation because of the inadequate baffles in the fuel tank.

ROME

Well, the day before these problems started I had spent some time detailing my engine. I went back after the problem arose and revisited all of the connectors I had unplugged and rechecked them with a good solid wiggle. I took the car out for a good hour drive last night and it ran harder than it ever has! :)

I'm supposing it was just a loose connector somewhere, but I don't trust problems that fix themselves if ya know what I mean! I'm going to pick up a fuel pressure gauge to see how my flow checks out. The problem had originally arisen prior to me topping off the tank. At the point the car actually died under hard cornering, I had just filled her up.

My car has a ZZ3 crate engine with a Hypertech distributor setup and MSD-6AL ignition. It's a full-on aftermarket setup as opposed to the stock Optispark unit. The entire new engine package has less than 15K miles on it so I feel like any problems are probably not related to worn out ignition items.

I'm going to change out my fuel filter just as a precaution, and look toward upgrading (or augmenting) my fuel pump with an aftermarket high flow unit. If anyone has any suggestions regarding high performance fuel pumps that complement the Vette well, I'd like to hear about it.

Rome




[Modified by ROME, 10:19 PM 2/27/2002]

SPD DMN

If yours is a MAF car, it could have been the MAF connector.

Mr Mojo

Methinks Opti also, I'm having the exact same problem except for teh cornering problem.
I'll let you know what happens with mine.

ROME

Here's my latest update. The car flat DIED on me way out in the midnight boondocks between Shreveport & Monroe, LA. I jiggled a few wires under the hood and luckily she decided to crank up. Made the rest of the 70 miles without a hitch.

I happened again yesterday. Had to coast off the interstate with the engine popping and sputtering. As soon as I dropped under 40mph the car died.

I ended up trying one thing at a time under the hood before it finally cranked for me. It was the loom that feeds the fuel injectors that runs beneath the throttle body. It also connects to the IAC valve and TPS sensor.

I jiggled that loom and the car started as if it didn't have a problem in the world. On initial inspection I couldn't find any raw wires, etc that looked out of place. The previous owner did the engine switch, and you can tell this is the original loom that 'survived' the engine swap.

Without going too far into trouble shooting that mass of wire, my plan is to simply buy a new top-end loom and replace the whole thing. I'd love to hear some of you guys' advice on this. I'm betting the loom gets costly, but I'm thinking this one could use a replacement anyway. TIA

Rob

BBA

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[Modified by BBA, 3:51 PM 3/9/2002]