Nathan Plemons

Alrighty, I've noticed that my car has real screwy quirk that is about to drive me mad. At least 75% of the time when I start my car and put it in reverse it will start to move but as soon as I let off the gas it will start to sputter and die. I can put the car in any other gear or hold my foot on the clutch, regardless the drivetrain is completely disconnected and it will do this. Most of the time I can tap the gas and it'll come right back to life, but even that is strange. Usually I have to tap the gas a few times, the first time usually does NOTHING. It feels as it does when you press the gas and the car is off, you know just doesn't feel right.

Anyway, I thought it might have something to do with the car being cold, I never have the opportunity to park so I don't have to use reverse to get out, so I don't know if it does it in a forward gear or not, but I really don't think it does. It gets even stranger, today I parked on a fairly steep uphill incline. No big deal, I get in start the car, put it in neutral and let it idle down and sit there for a lot longer than usual as I got my sunglasses from the center console and put them on. Then when I put the car in reverse all is fine, I back up just a little, press the clutch to go for first and the car just starts to sputter, I hit the brake to keep myself from rolling back any further and look at the tach, it's trying to lope around 300 rpms, naturally it hit a few licks and died, the gas didn't do anything. I go to start it back and it turns over a lot longer than normal before it starts, finally it hits real slow and again tries to lope around 300 rpms. I hit the gas pretty hard this time and it came to life and I didn't have any more problems getting out of that parking lot.

I drive all of a mile, maybe a mile and a half to sonic. I get my food and eat, but when I start to leave, car fires up fine, put it in reverse pull out slowly, start to put the car in 1st and it tries to sputter again. I am able to save it and go about my merry way. The car NEVER misses a lick while driving, only this strange reverse issue. Even then like I said it doesn't do it every time. I have noticed that it will NEVER do it if the car is good and warm. Obviously the mile or so wasn't enough to get it up to full operating temp.

It's about the strangest thing I've ever seen. The next time it happens I need to look at my fuel pressure gauge and see what the deal is. The problem is that's hard to do because I'm usually looking behind me when it happens, by the time I can come around I've either got it back or it has already died. It is very rare that it actually dies, but I have to fight with this far more than I think is normal. I am out of ideas because I can list the things it ISN'T.

Computer program - did it before the cam, thus with stock computer as well
any of the mods I did with my cam
fuel injectors - did it before and after I have replaced the fuel injectors
fuel filter - did it before and after I have replaced that.
plugs, wires, coil - these were done with my cam and it did it before / after

Any ideas would be appreciated, it's not a major issue, just kinda an annoyance.

Nathan Plemons

Yup, the overwhelming response is just what I thought. It's got me stumped.

Rich B.

OK; I'll take a shot - bad fuel pump. Low pressure at idle; adequate pressure when up to 1200 - 1500 or higher. Since reverse bogs the engine big-time, it shows up in reverse more often that forward.

You can't get an accurate pressure reading from the digi-dash. You need an external gauge, taped to your windshield (unless you have a good buddy).

Anything below 34psi means restricted line somewhere; clogged fuel filter(s); leak in the line; or bad fuel pump.

...My $.02...

LWesthaver

Nathan, that's a really strange one. I can't imagine what reverse gear has to do with it. Regardless of what gear you're in, when your foot is on the clutch the engine is disconnected from the drivetrain and should not be getting bogged down. Are you sure it isn't just a cold-start problem unrelated to reverse gear?

Does your car have a "cold start valve"? Is it functioning?





[Modified by LWesthaver, 9:46 PM 12/18/2001]

BBA

I had an '82 I was working on do that once upon a time. Turned out the coil power wire ( the one that conencted to the "BATT" terminal on the distributor ) was broken internally, and throwing hte car in reverse torques the motor just enough the 'other' direction to seperate the wire conductors and kill the ignition.

Nathan Plemons

Rich, I have an autometer fuel pressue gauge, it reads about 38 psi at idle and cruise, when I hit the gas it jumps just like it is supposed to so I don't really think it's a fuel pump problem, again I haven't been able to see the gauge while it does it. I know the gauge works plenty fast enough, it's perfectly timed to engine load, and if I'm low on fuel I can punch the gas and just watch my fuel pressure fall as I slosh the gas away from the pickup, naturally the engine then sputters which sends the gas back to the pickup, and we go through a nice little cycle.

LWesthaver, that's even more interesting. When I left work today I was parked in the same spot, instead of putting the car in reverse I just held the clutch and coasted out of that spot, then when I put it in first it took off just fine, no problems whatsoever. That's another reason I don't think it's really related to engine load, how much do you load an engine backing downhill? The car shouldn't have been any warmer than it was the other two times it did that to me today, infact it was probably colder because I spent less time coasting backwards than I had spent earlier looking for my sunglasses than I had spent with the car idling in neutral. No it doesn't have a cold start valve.

BBA, that's a thought but it never seems to do it when the car is at full operating temp, also when I'm backing out of my garage in the morning it will do it and I can usually rev it enough to keep it going. It's a very rare that it will completely die. Once it does it takes longer cranking to get it started back, like there is no fuel, yet as soon as it fires the first time it never acts up again. It seems like a loose wire would cause trouble under any driving conditions, I torque the motor like crazy because I drive like mad and it NEVER misses or hesitates at all.


I appreciate all the ideas, but I don't think we've hit it yet. Keep the ideas rolling, I'll try to keep shooting them down so as to defy all logic.


[Modified by Nathan Plemons, 10:36 PM 12/18/2001]

Rich B.

That doesn't sound right...I run low plenty of times, and there's no bog when I punch it...Maybe a pickup problem??? Fairly easy to pull the sender/pickup and check...

Nathan Plemons

I mean like way low, as in I'm already hunting for a gas station and the reserve light is on. maybe it's an LT1 thing. If I ease into the throttle it's fine, I mean if I downshift and completely hammer it, such that it makes the car squat. I've never really thought about it, I just thought that would be a perfectly normal thing for it to do. I'll start a poll to see how many people's cars do the same thing, just to see how common it is.

BBA

Nathan, Not that your problem is a faulty wire somewhere, but with the 82, the problem would ONLY show up when you first put it in reverse. If you drove the hell out of it it had not problem. The only difference is in reverse, the motor torques in the opposite direction than in any forward gear or with any hard acceleration.

For what it's worth, there are not very many things that will cause a problem like you describe, but a bad electrical wire definitely IS one that I have personally seen.....

Nathan Plemons

That's true, but I don't understand why it only seems to do it when cold. I hate electrical problems so I'm really hoping that's not it.