Dash panel will work when OBDII is plugged in

astro
chevrolet

#1

1995 Astro Cargo, 4.3L, 230k miles. Got it from a friend who could not figure out what was wrong and sat for awhile. I had it towed to my house and been working on it the last two days. I’ve been looking at the posts here on car talk in regards of a “no start, has spark, distributor spins, and even starter fluid will not fire it up.” So from what I read it could be a few things… The crankshaft sensor could be bad, causing the no start. Or the security mechanism can cause a no start as well… Today I stumbled on something interesting. The instrument panel display “Showing Park thru First”, mileage and gages do not function “unless” the OBDII is plugged in, but still won’t start. Although the check engine light, brake indicator and seatbelt indicator will light up. First could this cause the no start issue, second could this be a bad ecu/pcu? Any advice would be great! Thanks in advance yall!


#2

Look at anything aftermarket and disconnect it. Strange stuff happens. I put in a powerpoint in a gmc van, tapped off a 2 way radio power wires because it was convenient, The van would not turn off if a light was plugged into the powerpoint even with the light off. figure that one out! Unplug the light then things were normal.


#3

How exactly is it behaving when it won’t start?
Crankshaft turning only slowly?
Crankshaft turning strongly, but no combustion?
Clicks but crankshaft not turning?

Define “sat for awhile”; i.e. how old is the gas?
Is this engine throttle body injected or port injected?

Assuming the starter turns the crankshaft over strongly but the engine doesn’t fire (no combustion), have you checked to see if you have spark?
Have you checked to see if the injector(s) is(are) firing?

NOTE: your OBD system, whether it’s I or II, won’t store codes if the engine won’t start. Ignore that and go back to basics. IF you get the engine started, then you can go back after stored codes.

There are a whole lot of possible reasons it won’t start. The ones you mentioned are just the start of the list. Knowing how long it sat idle and exactly how the engine behaves when you try to start it is(are) the first step(s) to select the right path to search; ignition, fuel, electrical, or sensors.

If you know anything about the engine’s performance when it last ran, that might help too.

Post back.


#4

No experience w/you make/model, but those dash lights are probably normal for when the key is in “on” but the engine not started. Usually there’d be an alternator or battery warning light on too. They light those up like that so you can make sure the warning bulbs are working. They’re supposed to go off when the engine starts.

I presume by what you way that it cranks ok – b/c you say the distributor is spinning – but doesn’t pop and start like it should. What tests did you do to prove it is sparking ok? B/c if you got good spark and you spray some starter fluid into the throttle body intake the engine should at least start up briefly. But you say it doesn’t even then? hmmm …

Well, then you may got something more serious happening. First thing to do is remove a spark plug. Is the tip wet looking? The engine may be flooded. It won’t start even with a good spark if the engine is flooded. If so, take all the plugs out and crank the engine a few times to expel as much gas a possible from the cylinders. Then let it sit overnight to let the rest of the gas evaporate. The next day install the plugs, spray some starter fluid, and see if will will start and run briefly at least.

Still won’t even pop at all? hmm … then you’d be looking at

  • low compression, do a compression test
  • plugged exhaust system, temporarily disconnect exhaust & see if it starts then
  • spark timing is way off, use a timing light to see if there’s a spark near or just before top dead center on number 1 during cranking.

Regarding the last issue, we’ve had reports here of folks mis-timing the engine in a way so it seemed correct in that it would fire just before TDC, but in fact is was firing on the TDC of the exhaust stroke rather than the compression stroke. So if nothing else seems to work, double check on that, as it could cause this symptom. Remember that the crank rotates two times for every one time the camshaft rotates. The spark has to occur on the correct camshaft phase, not just the correct crankshaft phase.

If I were venturing a wild guess, I think you may have a case of low compression or plugged catalytic converter. Best of luck in getting your Astro back on the road.


#5

For my Riviera, I used to carry a spare computer in the trunk. I think I paid $25 for it at the junk yard. Never really had the computer go out but it was a quick way to confirm that the problem was not the computer. I could swap it in about 5 minutes, just had to open it up and swap the prom too. In other words I have no idea but if you tried starter fluid and that didn’t work, that should rule out bad gas. So you’re into spark, compression, or timing.


#6

Is not a 95 OBDI ?


#7

The OBDII mandate was for all cars starting with model year 1996. I believe some manufacturers brought out new models in '95 and had OBDII systems incorporated into them in anticipation of the new mandate. I don’t know about the OP’s vehicle.


#8

I’m leaning towards this vehicle being OBD2 compliant

That’s only because we used to have a few 1995 GM vehicles in our fleet, and they were OBD2 compliant

And I think this vehicle has a CPI fuel injection system . . . I’m not sure if that’s the correct terminology

It has a central injector, with 6 plastic lines going to poppet nozzles

But we need much more information

Good spark?
good compression?
fuel pressure . . . post numbers, if possible
etc.


#9

First of all, thank you all for the replies!

My main goal is to see if the engine will fire up first just using starting fluid before worrying about fuel delivery. Just don’t want to sink alot of $$$ unless I can get it to run for at least a few seconds with starter fluid. I’m not sure how much psi is going thru the fuel rail, but it will “spit” a good amount after cranking the engine a few rotations and pressing the valve…

Now to answer some of the questions I’ve seen…

One of the first questions was "how long did it sit?"
It sat for about 2 years… I poured Sta-bil in the tank mixing 5 gallons of fresh fuel. On the fuel Guage it shows 1/4 of a tank now.

1995 - 1996 Astro Crossover?: Learning something new everyday with this Astro. I saw someone ask about the year VS parts. Now it is a 1995 Astro 4.3L vortec, but it does have the 1996 parts (distributor and crankshaft position sensor) that are on the 1996 and up Astros VS a different style distributor and no crankshaft position sensor on the 1995 and older Astros… I found this out as well after going to the autoparts store.

Testing for spark: what I’ve done is pull each spark plug out from the distributor cap (1 - 6) and saw a good solid yellow arc from the cap to the plug wire.

Now the bad news is I will need to purchase a new distributor “Cost $116.99 OEM Brand New” because the molded notch that the thread screw attaches the distributor cap was broken off. I did not see this untill I took the distributor cap off. It was missing a screw on the opposite end facing the TB. Though I was still getting spark, I could wiggle the distributor cap pretty good.

Engine compression: Though I don’t have a compression tester, I can rent one from autozone as well. Probably will do it this weekend and give the results.

Now the motor turns in my opinion “just right”. Not to fast like it has no compression and no pop-offed timing chain “since the distributor is spinning and shows 40psi on the oil pressure guage .” And not to slow in no signs of mechanical damage “thrown piston or push rods.”

Again my first goal before sinking to much $$$ is to let it fire up a few seconds using starting fluid to see it it will at least fire up at that.

From what I’ve read and watching videos it sounds like the Crankshaft Position Sensor or the Built-in Security from the ignition key causing the “no-start” issue.

I saw one video of a mechanic who unplugging the Crankshaft Position Sensor and it caused the engine to completely die. Not sure if the distributor still sparked, but it definitely killed the motor…

Another video showed a mechanic trouble shooting the Built-in Security ignition causing the engine not to start, but then it cleared up by itself. So that was a waist of 20 minutes. lol

I might take a gamble and replace the Crankshaft Position Sensor and of course change out the distributor to get that issue taken care of.

If anyone has any other ideas of a no start, has spark and will not start evening using starting fluid with no back-fire, please feel free to share your thoughts! Thanks!


#10

Before you buy any parts, I suggest you do a compression test on all 6 cylinders, dry and wet

If it’s too low for the engine to start, then you may want to consider having this van towed to the junk yard. No offense, but I don’t think a 1995 Astro cargo van is worth much, even if it actually were running

If you do a compression test, please post the numbers


#11

For Stabil to work it has to be poured into the tank and mixed before storing the car. It won’t help old gasoline. You have to get it to start & run briefly with spraying starter fluid tho, before making any assumptions about potential problems w/ the fuel system.


#12

Hey db, yeah, that’s my goal this Saturday. I plan on renting a compression tester on each cylinder and see what I got…


#13

Woo-Hoo! Happy camper on this Cold Saturday Afternoon! Well, it turns out to be a bad fuel pump. I guess I was not shooting enough starter fluid in the TBI.

I did rent a fuel and compression tester and just checked the fuel first. Had 0 (Zero) fuel pressure. So that’s what got to me thinking “maybe I’m not adding enough starter fluid?” So I held a 3 second shot and walla! Instant crankage! Must of been using it too sparingly…

Now it’s time to run up to NAPA, buy a fuel pump and bring this Astro back to life! Muhahaha! :wink:

Before I get myself carried away, I’ll check and make sure it is getting power to the pump first. But most likely after 230,000 miles, I would believe the fuel pump would be bad…

Thank you all for the help eveyone!

Remember, FASTEC is your Best Friend!


#14

Thanks for the update OP. Yeah, be sure the pump is getting proper power before replacing it. Good idea if you replace the pump to replace the fuel filter at the same time. A partially clogged fuel filter can wear out the pump faster. Best of luck.

Edit: It’s tough to spray too much starter fluid into the TB b/c if you spray too much any excess will be quickly depleted as the engine cranks. So it will quickly pop and briefly run even if you spray too much. I’d guess I typically spray for 10 seconds when I do that test. So better to error on the side of too much than too little I guess when doing that test. Good to know.