dabigboy

Hi all,

I bought a 1999 1500 Express conversion van with the 5.8L V8 about two and a half years ago. It's been a fabulous family hauler, road-tripper, and general workhorse, but last year it developed an annoying issue that I have been unable to crack. Much web searching has yielded some possibilities, but none that have panned out into a solution.

Symptoms:
- Van will randomly fail to start. It turns over OK, but does not run.
- Often, during one of these non-start scenarios, it fires briefly and seems to be turning over, but does not sound normal...almost like only one or two cylinders are "chugging" the engine over a few times before dying. The best description I can think of is that of a "shudder".
- During this non-start issue, it occasionally sounds/feels like the engine is stopping abruptly at times, or even trying to crank backwards just a bit (this is just my impression). When this happens, the instrument lights/odometer dim severely, like the system voltage has been pulled down.
- Occasionally, after the engine goes through its shuddering/chugging routine, I'll see light colored smoke (oil, possibly...looks like it might be a bit blue).
- Sometimes the van starts perfectly, like nothing is wrong. It may go days, or even a week or more, before the problem returns.
- If I can get the engine going, it generally keeps going. But, while still cold, I usually get a stumble if I punch the gas (this can result in a stall if I am not careful). Once the engine is warm, it runs perfectly at all throttle and RPM settings.

Corrective/diagnostic action taken so far:
- Replaced the entire fuel pump/sending unit with a new Delco unit, based on research indicating this is a weak point on these vehicles, and can result in hard starting but otherwise normal running, due to high fuel pressure demands at startup. After the pump replacement, we got probably a month or so of trouble-free operation out of it. Initially I took this to mean that the pump had been the issue, but I'm hesitant to think a brand new Delco pump would exhibit similar issues. Also doesn't explain why it stumbles when cold, but runs perfectly fine once warmed up.

- Replaced fuel filter
- Pulled a spark plug to inspect condition. Looked OK, though this was a while back. Probably going to pull one again this week to see if there is any sign of oil on it.
- Checked codes. As I recall (again, this was some time ago), the only code was for multiple misfires on one cylinder. I assumed this was just a symptom of fuel pressure issues....perhaps it's something more?

Side note, may or may not be related....I replaced the starter while all this was going on, and that starter is already going out. It appears that the bendix clutch is slipping. I wonder if this would be caused by the engine kicking back?

Does this sound like a familiar scenario to anyone? It's got me stumped. I'm reasonably handy with car repairs, but most of my work has been on older European and Japanese sports cars with Bosch fuel injection. This van appears to be a somewhat different animal. Really want to get this thing going for our vacation next month, I'm not looking forward to cross-country driving in my work car (a Yaris....!)

Thanks!

Matt

canucklehead

Those vortec 350's require iridium plugs. Lots of folks throw double platinums in. when they wear out the gap gets too big and you get a weak spark. Which can cause cylinder misfire, and very hard cold starting.
If you are only getting random misfire codes, then I would double check your ignition system. Starting with the plugs, plug wires, and under the dizzy cap. Another issue on those engines is the dizzy cap gets oxidation on the 8 points on the underside. Clean them with emery cloth, and hit the tip of the rotor as well.
Make sure your ground strap is good, and there is good contact there. If your new starter is not cranking well, it could be a voltage loss along the way from the battery to the starter, and the ground strap back to the battery.

dabigboy

Good call on the plugs....I pulled one tonight and it's a Delco 14, which I understand is platinum. It seems to be in pretty good shape, maybe just a bit sooty? I've attached a pic. It was definitely not oily or moist in any way. Gap was about 0.65", everything I've found so far calls for 0.060" on this vehicle, so it wasn't off by much.

I was griping in my head about some cheap DPO who stuck in the wrong plugs, but when I checked O'Reilly's to see if they had the iridium plugs in stock, he mentioned that their system shows the platinum plugs as being original/recommended equipment....so I guess I can't really blame a PO if that's the information that is going out. I'll probably order some online (it's a bit cheaper).

Also popped in the new starter, it cranks super fast. Pretty sure I'm getting good voltage, at least as far as the starter is concerned. I didn't have any sudden hangs while cranking, or any sound of trying to turn backwards, as the engine pretty much didn't even try to run tonight.

I didn't have time to get into the dizzy tonight, but will be doing that either tomorrow or Saturday. Thanks for the advice!


Matt

SnlpeR

pull the cap on the dizzy and check for play on the rotor
there should be a little play...

if you turn the rotor by hand and it rotates enough to lift the rotor and shaft.....then it might be a little too much play

dabigboy

Canucklehead, you nailed it! I pulled the cap today and found quite a bit of carbon buildup where the center of the cap touches the rotor (both parts were dirty). But perhaps more importantly, the rotor had obvious water damage. In fact, there was standing water in the top of the rotor! Is this due to a design flaw?

I cleaned up the rotor and cap, put them back together, and she roared to life. Woohoo! Then I went ahead and did the correct fix.....stopped by O'Reillys for a new cap and rotor.

I'm pretty confident this is the root of the problem, as I tried once again to crank the van before starting work today, to make sure it wasn't just having a "good day". It barely fired.

The points on the cap were so bad I thought they were white plastic at first. I'm a little concerned that it will get moisture again, but at least now I know the drill. I did apply a generous portion of dielectric grease around the perimeter of the distributor to help keep the moisture out.

SnipeR, thanks for the tip. I checked, the rotor does indeed have some play, but doesn't feel like it's going to lift out or anything.

Thanks again for steering me in the right direction!

Matt

canucklehead

I think because of reduced airflow under the doghouse, condensation builds up under the cap. Plan on cleaning those 8 points every 6 months or so.

solwav

Glad to hear you resolved the issue canucklehead has good info, I read the post and would have sent you in a different direction. It is always nice when your truck is working right again because as life and Murphy's law work when life kicks you in the rear your truck has a problem at the same time, good to hear your rolling again.