cduzenberry

I have a 99 astro with 112000 Km on her that I have recently changed the plugs, wires, cap, rotor, coil, O2 sensors, NEW Injector system, New Injector Rails, and no engine fault codes. Cap and rotor, coil, were just changed a year ago as well. 2 new fuel pumps and a sending unit along with other replacement parts.

When the engine has sat for a day or 2 she does not want to start. Almost acts as if it is flooded.

Initial problem was that the motor would jerk and run rough when going down the highway with light pressure on the gas. Same goes for traffic start and stop that it would jerk badly. If you accelerate hard she runs good with no jerking. If you accelerate mildly or slow in traffic jerks. Once warmed up through out a day it settles out and starts over again if it sits and cools off.

They have been able to get a missfire code but not specific to a cylinder, and when they tested the PSI on all of the injectors before changing they all showed the same level. They cleaned the injectors and then after that I started getting the no after the vehicle sat for the weekend and I went go get in for Monday morning.

It has been on fiasco after another with a lot of time and money spent with my mechanic. ANY help would be greatly appreciated. This is my work vehicle.

Thanks
Duze

MarkSWilliams

I have a 99 Astro as well.
The problems that you talk about showed up on mine around the same mileage.

The rough running/jerking started first and then the cold/wet start problems.

On mine the problem was the coil.
It was shorting out to the bracket.
When it was cold and wet and it wouldn't start you could actually see it arcing to the bracket.

A replacement coil from Autozone or Murrays is around $35.

It isn't the easiest thing to change though, but doable if your paitent.
It sits up on top of the passenger side of the engine. near the throttle body.

Good Luck
Mark

old_master

The 4.3L engine is very sensitive to fuel pressure. It requires a MINIMUM of 60psi. Anything less will cause driveability concerns, most of which are noticeable on cold starts.

Connect a fuel pressure guage and turn the key to the "RUN" position, (don't start the engine). The pump will operate for about 3 seconds and shut down. While the pump is operating, notice what the pressure is. After the pump shuts down, the fuel pressure should not drop below 55psi for several minutes. Post your results here and we can continue with the diagnosis.

When was the last time the tank filter and inline fuel filters were changed? (how many miles)

MarkSWilliams

Well I thought I had mine fixed when I replaced the coil just recently.
But soon learned with the wet/cold weather we have had in Ohio lately that it was not.
As the stupid thing just wouldn't start.
Did not check the fuel pressure, thought of it but didn't go there cause like duze it smelled as if it was flooded.
We determined with the help of my Dad that we had plenty of spark from the new coil to distributor, but next to nothing coming out.
Took off the Cap which was new in 10/05, and the brass contacts were corred blueish green. Never seen one that bad.
Took it back to NAPA, and it was out of Warranty (1 Yr).
The old timer behind the counter said that there are two small holes on the bottom plastic plate of the distributor that GM put there for moister drains?
He said to stick a paper clip through the holes to clean out any dirt that might be plugging them.
We did this a put a new cap on.
The thing starts/runs good now and we are continuing to have wet/cold days.

Duze, I don't know how new your cap is but check it out if the Fuel pressure checks out okay.

drew300

my '97 developed a fuel pressure problem, that made starting difficult.
A GM service rep told me "minimum 60" psi for starting. I had 59 psi.
I changed the pump, it's been fine since.
I recommend trying a "starting fluid", like carb cleaner. Spray a little down the air supply tube, and see if it starts. That will tell you that spark is fine, and you have a fuel problem. Or if it doesn't start you have a spark problem.
Mine would start fine with fluid, and it requires less pressure to run, so it would run on my marginal fuel pressure.
Hope that helps, and it's pretty simple