Need help ! 1999 Astro intermittent starting problems

Hi everyone,
This is my first time posting on this board. Any help is appreciated in advance, this problem is driving me nuts! My 1999 Astro 4.3 has had a problem with intermittent hard or no starting. Last year I had the same problem. When I checked the spark it would keep changing. I had a couple of cylinders not firing intermittently. I decided to do a complete tuneup , changed the fuel pump and filter and it ran fine until now. It seems that the problem occurs more in damp or rainy weather. The strange thing is I will go out in the morning and it won't start and try it again a few hours later and it will start right up and run fine. No codes are coming up on the obd11 system. I need to get this van running for a family trip in a couple of weeks.
Thanks,
John

Inadequate fuel pressure, fuel leaks, and secondary ignition may or may not set a code in the OBDII system. If there is a driveability issue, and no "Service Engine Soon" light, these are the areas to check first. These two systems are the "basics" and must be operating properly before continuing with diagnostics.

The fuel pump circuits are designed to energize the fuel pump continuously any time the key is in the START position. When the key is in the RUN position the fuel pump will operate provided the engine is running. If the engine stalls, or is not running for any reason, the ECM will shut off the fuel pump after approximately 2 to 3 seconds.

Fuel pressure test:
Install fuel pressure gauge to the test port near the distributor. Turn the key to the RUN position, (do not start the engine). While the fuel pump is running, fuel pressure must be 60-66psi. After approximately 2 to 3 seconds, the fuel pump will shut off. Fuel pressure must remain between 55-60psi for several minutes. A drop in pressure below 55psi indicates a leak. Most likely the fuel pressure regulator or the lines under the upper intake manifold are leaking.

The next step is secondary ignition. How long since the cap, rotor, wires and spark plugs have been replaced? Good quality cap, rotor, wires and A/C Delco platinum plugs are a must for this engine. Post back your results.

Thanks for the info. The cap, rotor, wires, coil, fuel pump, fuel filter, and plugs were changed about a year ago . The other day when it would not start I sprayed starting fluid into throttle body with no change which led me to believe that it is an ignition related problem. I was going to pull the engine cover off later on in the day to check for spark but when I got back to the van it started up. It ran rough for a bit and ran perfect once it warmed up. When I had this same exact problem last year I did get a code for an engine misfire. Something else that I noticed is that the needle on the fuel gague seems to be vibrating constantly, I'm not sure if it means anything but I'm just putting it out there in case it makes sense to you. I really appreciate your response and will check out the things you mentioned above.
Thanks,
John

I did the fuel pressure test and the results were as follows. When I turned the key on the gauge read 62 psi while the pump was running. After about 3 seconds the pump went off and the pressure was at 57 psi and held there for quite a while. I also checked the pressure at an idle and it was 56 psi. Like I said above the pump was replaced. I changed the fuel filter today and plan on doing the plugs (ac delco platinum), cap, rotor, and wires. Let me know what you think. Thanks a lot.
John

Prime pressure of 62psi is on the low side, but still within specs. The systems ability to hold pressure is good at 57psi. The fuel pressure at idle is low. Was the reading of 56psi taken before or after you replaced the fuel filter?

You mentioned a DTC for missfire at one time, hard starting then cleared up and ran fine. Those are both symptoms that could point to moisture in the distributor cap. Several things can cause moisture in the cap, but the most common is condensation forming after shut down as the engine cools. Make sure the PCV system is operating properly, and the vent holes in the distributor base are clear. If the distributor vent holes have screens, remove them.

Hey Chuck,
The pressure test was after I changed the filter. I just finished the tuneup and the engine seems to be running real good. The pvc system is working fine. I found that the distributor cap did have a white residue buildup in a few of the terminals where the wires connect and the same for the wire ends. I will have to use it a bit and see how it does in moist wheather since the problem was an intermittent one. The fuel gauge still has that vibrating needle, could it be a bad ground. Thanks again for sharing your knowledge and hopefully I won't be writing about this problem again.
Take care,
John

The white residue on the distributor cap terminals is silicone dielectric. It crystalizes when current passes through it. The silicone dielectric helps direct the current to where it belongs.

The fuel pump and the fuel level sender use the same ground. It's possible that a poor ground is causing the vibrating needle and the low fuel pressure readings. You can access the ground without removing the tank. If I remember right, the ground is on the left frame rail, just ahead of the tank, (follow the harness from the sender to be sure). Remove the bolt and clean the terminal and frame with sandpaper. Cheap fix if that does it.

Hi Chuck,
I was away for the past week and had my son use the van. It was fine until he attempted to start it in the rain a few days ago and it would not start. He went back to the car the next day and it fired right up. Today the service engine light went on and gave me a code 0420 (Catalyst system efficiency below threshhold bank 1). The intermittent problem seems to be more so in the rain or damp weather. The distributor, cap, rotor, coil, wires, and plugs are all new. Let me know if the 0420 code could be causing my intermittent problem and what I need to do. Thanks a lot,
John

The diagnostics in the GM shop manual for P0420 go into great detail, (quite lengthy) and still is not 100% conclusive. Basically it has you inspect for exhaust leaks, dents or holes in the exhaust system, electrical connections and wiring, etc, etc and then replace the catalytic converter if everything tests ok. Replacing the converter doesn't always keep the light off though. GM issued a TSB a while back that said the VCM could be reprogrammed to "widen" the parameters for setting the P0420 DTC. The DTC will set with one failure, and the SES light will come on. The VCM turns off the SES light after 3 consecutive drive cycles when the test has run and passed. (I have seen that take up to 2 weeks!) The history DTC will clear after 40 consecutive warm up cycles where no failures were detected. (Never seen that happen!) It’s possible, with certain things covered in the diagnostics, to cause an intermittent concern such as yours. I think I would manually clear the P0420, and then concentrate on secondary ignition. If the P0420 returns, you might be forced to troubleshoot it.

Hi Chuck,
Thanks for the response. I cleared the code. I am not sure what else I can do with the ignition. I replaced the distributor with a brand new one along with the cap and rotor last week. The coil was replaced last year, and all the wires, and plugs were just changed when I did the distributor. If I missed anything let me know. I am leaving for a 1,300 mile trip in the morning and am hoping we make it. I think I'll be ok unless I have to start it in the rain. I'll keep my fingers crossed. Thanks again,
John

I have exactly the same vehicle as you and I have exactly the same symptoms. Hard start or no start when damp, quivering fuel guage needle.
My oil presure needle moves around alot too when trying to start. I might check that fuel pump ground. I can't think of anything else.

Well the van made the 3000 mile trip to Florida and back to NY. I had no problems starting it and it ran great but I did not run into any rain at all. The 0420 code popped up at the end of my trip and had to be cleared quite a few times. I also got the codes 8900 and B107 twice which I could not find on my code list. Any idea what they are for? How do I troubleshoot the 0420 code?
Thanks, John
I will check the fuel sender ground!

OBDII DTC's are set in the format of a letter and 4 digits ie. P0420. The 8900 and B107 don't follow the format, try rechecking them.

The P0420 has to do with poor performance of the catalyst and diagnostics are VERY lengthy and go into great detail concerning O2 sensors, their circuits, along with many other circuits and the catalyst. Might be best to leave this one to a professional to diagnose for you. There was a TSB out that involved widening the parameters for setting the P0420, might want to check with your dealer on that too.

For the first time in 2 weeks the Astro van got rained on and sure enough it won't start. When the rain stops and the car sits for a while it will probably start right up. Do you have any suggestions aside from what I have already replaced. (complete distributor, dist. cap, rotor, wires, plugs, fuel filter, coil) or should I be looking back at someting I replaced.
Thanks, John

Certainly sounds like secondary ignition. Next time the engine is running well, take a spray bottle filled with water and very carefully direct a spray to each component until the engine stalls. An old windex bottle works well, the kind you can adjust the size of the spray. After you spray a component, wait a few seconds before moving on to something else. If you get too much water in there, you won't know what caused it to stall.

I have had a misfiring problem when it rains and also the starting problem when it is wet outside and in the morning when it is damp. I finally found a problem with the wiring harness going to the computer. It was in the bunch of wires going to the black connector to the engine control. It is mounted right next to the battery under the hood, all of the connections (4) face forward. if you are facing the battery it is the lower right connector. The pigtail of wires was looping around and scraping on the inner fender. I unwrapped the bundle of wires and found one burned about 90% through.
I soldered in a new section and rewraped the wires.
I could see a spot on the inner fender where it was arcing to ground, there was actually a rusty spot there.
I have had the misfiring and the wet start problems for a while and now all of those symptoms have vanished completely. It is also running smoother than it has in years. It now has about 132K on it and is running better than it did at 80k.