1996 S-10 Blazer No Start

[Big Buck Buster]

Originally Posted By: leech~~

Did you ever check the ignition switch it's self yet? It maybe wearing out, so when you turn it so far it turns over but when you go all the way it stops making contacted? Just because it turns over the starter does mean it is switching on the rest of the sensors if its wore out. My sons Blazer did the samething. I could spray a little WD-40 in it to make it work for awhile but it just went out all together in time.

I thought of that as well but he said he had spark while cranking?!

You said you checked and the dist is inserted correctly? It can be off and the computer makes up for it. That is what was wrong with my sons... WEIRD MAN, WEIRD!

I set the distributor before I drove it out of the shop on Friday. You have to set these with a scanner to get the correct cam retard. It is set to "0". Spec is "0" +/- 2 deg.

[leech~~]

Leech,

Did your sons have fuel pressure, spark, injector pulse while you were cranking it over?, or just when you would just tick it over?

Big buck, that is a good Q's. I will have to say, we hauled in to a dealer that time and he said it was the ign, switch. I too argued with him how that could be if it was turning over and he said that when you turn the key, the system had to run through all the system tests, and if one fails to test out the system will not let the motor start up. So he changed the switch and it worked? We had 3 no start issues when we had the unit where it turned over but would not start. 1) fuel pump 2) bad rotor & cap. 3) bag ign switch.

[putter]

im working on a 99 s10 pick up that has the same problem.im out of ideas on what to do. iv found two ways on how to start it.

it will crank all day and not fire but if you jump start it with another truck it fires right up and dont miss abeat.

heres what gets me if you stick your hand in the throttle where IAC valve is and plug that hole off it fires up. so i replaced the idel air and did the relearn procedure and drove it all day ran great until i let it sit over night and it wouldnt restart

what to do????

[Jeremy airjer W]

Big buck, that is a good Q's. I will have to say, we hauled in to a dealer that time and he said it was the ign, switch. I too argued with him how that could be if it was turning over

The ignition switch has several circuits built into it. One specifically to energize the starter solenoid, one for the radio/wiper, one for the brake/cruise/hvac/power windows, one for the trans, and the last is everything else including engine management. The odd thing is that if he is getting spark than we have to assume that power is getting out of the ignition switch through the "engine management" circuit.

Big buck, have you had the key in the run position and jumped the starter solenoid to see if it will start?

[Jeremy airjer W]

heres what gets me if you stick your hand in the throttle where IAC valve is and plug that hole off it fires up. so i replaced the idel air and did the relearn procedure and drove it all day ran great until i let it sit over night and it wouldnt restart

what to do????

These are especially sensitive to low fuel pressure. I wonder if plugging off the IAC port may have allowed enough vacuum in the intake to suck the poppets (mechanical injector) open. This is a real common scenario but usually the scenerio goes like this; the vehicle cranks over fine will not start, it will start with a shot of carb spray in the intake, once it starts it will run fine until you shut it off.

[leech~~]

Have you checked if you have bad or water in the fuel? Also, just because your getting spark through the ign, switch doesn't mean all the sensors are kicking in and you are getting fuel. Spark, fuel, compression.

[Jeremy airjer W]

Also, just because your getting spark through the ign, switch doesn't mean all the sensors are kicking in and you are getting fuel. Spark, fuel, compression.

[leech~~]

Impossible, if he's getting spark and fuel it has to run! Unless it is an intermittent problem where either one is cutting out. Or the gas is full of water and just not burning, which maybe highly unlikely? or the timing is screwed? Man, please let us know if you ever find out. Maybe we should start a pool on this deal?

[Jeremy airjer W]

Why do cars flood? To much fuel, not enough spark! So it is entirely possible for a vehicle to have spark and fuel and not start.

[Scott K]

also low compression, timing, plugged exhaust, weak spark, bad fuel, to much fuel can all cause a vehicle to flood.

[Big Buck Buster]

I didn't get a chance to work on it today. Had to get other things done before the Thanksgiving holiday.

I do have fuel on all cylinders. I even took a mini torch to see the volitility of the fuel in the cylinder. It ignites just fine.

I will double check the intensity of the spark the next time I work on it.

I will also try the jumper pack on the truck, though I don't think that this is it. Had the charger on the whole time I was testing to keep the voltage up.

It is not a timing issue. I had the distributor set at 0 deg. and drove it out on Friday evening to leave it sit outside till Monday.

Nothing unusual on the scanner readings.

airjer,

I am not sure about the cam sensor in the dist. having an affect on the startup. From what I have read about it, it is not using that reading until 1,000 rpm or higher. It uses the crank sensor on start up.

What is your take on the cam sensor on start up?

[Jeremy airjer W]

I am not intimately familiar with how exactly that works myself!

[putter]

Originally Posted By: putter

heres what gets me if you stick your hand in the throttle where IAC valve is and plug that hole off it fires up. so i replaced the idel air and did the relearn procedure and drove it all day ran great until i let it sit over night and it wouldnt restart

what to do????

These are especially sensitive to low fuel pressure. I wonder if plugging off the IAC port may have allowed enough vacuum in the intake to suck the poppets (mechanical injector) open. This is a real common scenario but usually the scenerio goes like this; the vehicle cranks over fine will not start, it will start with a shot of carb spray in the intake, once it starts it will run fine until you shut it off.

its got a newer fuel pump and regulator it holds 58 psi. these are electronic injectors if im thinking correctly.

sorry big buck i dont want to get are post confused togeather but alot of the same stuff going on here

[Jeremy airjer W]

these are electronic injectors if i'm thinking correctly.

If its a 4.3 liter than it has a both a electronic fuel injector and a mechanical fuel injector (poppet valve)

The part on the left with the two prongs is the actual electric fuel injector that plugs into the CPI unit. The part on the right is the poppet valve which clips into a hole right above the intake valve. The injector doesn't care how much pressure there is but the poppet valve needs 58 to 59 psi to open. Literally a pound short on psi and they will not work.

There have been plenty of people that have found out that if they have low fuel pressure they will start with a shot of carb spray and stay running until they are shut off. One of the theory's discussed here is that once the engine is started there is a greater difference in pressure (vacuum) between fuel and intake air. The vacuum helps "suck" the fuel out of the poppet valve which allows it to run even though the fuel pressure is not adequate enough to start it.

[deadeye]

That would be why the aftermarket spider puts the electronic injector down where the poppet would be? I aways wondered what the exact reason for that was.

[Big Buck Buster]

This vehicle wouldn't start by spraying carb cleaner down the intake either. Not an injector problem.

If I get to working on it tomorrow, I will be checking for weak spark.

[Jeremy airjer W]

That would be why the aftermarket spider puts the electronic injector down where the poppet would be? I always wondered what the exact reason for that was.

That is considered a muti-port conversion upgrade and not a direct or common aftermarket replacement. You can readily find both in the aftermarket. I have not seen or installed the multi-port conversion as of yet. After the great CPI failure of the late 90's early 00's you really don't have to many issues with them. Occasionally you'll get one with a bad injector or pressure regulator which both can be serviced individually.

[putter]

Originally Posted By: putter

these are electronic injectors if i'm thinking correctly.

If its a 4.3 liter than it has a both a electronic fuel injector and a mechanical fuel injector (poppet valve)

The part on the left with the two prongs is the actual electric fuel injector that plugs into the CPI unit. The part on the right is the poppet valve which clips into a hole right above the intake valve. The injector doesn't care how much pressure there is but the poppet valve needs 58 to 59 psi to open. Literally a pound short on psi and they will not work.

There have been plenty of people that have found out that if they have low fuel pressure they will start with a shot of carb spray and stay running until they are shut off. One of the theory's discussed here is that once the engine is started there is a greater difference in pressure (vacuum) between fuel and intake air. The vacuum helps "suck" the fuel out of the poppet valve which allows it to run even though the fuel pressure is not adequate enough to start it.

I never thought of it that way makes perfect sense but it has 58psi and holds. I will double check all the fuel pressures agian. I did have a 5.7 last year that wouldnt run after i put head gaskets in it and it turned out to be all the injector tips must have froze while i had them out.

[Big Buck Buster]

I have got some great news today. I checked the spark again, but increased the KV setting to 30, then 40.

Weak spark was the cause. Replaced the coil, and re-tested at 30, and 40. Has great spark at both settings now.

Started right up.

This deffinately was an interesting one.

[deadeye]

At least you got it done!

[Jeremy airjer W]

The old weak spark trick!

You ever run into one that has a wire broken internally at the coil? The plastic sheathing will be intact but the wire inside will be broke. They will usually start and run until they get work and then intermittently stall/start. I've had a few over the years and they get me every time!

[Big Buck Buster]

I have not had the luxury of running into that one yet.

I couldn't believe it. I had it set to 20kv then 25kv, still nice blue spark. When I went to 30kv, and above, no good spark was available.

The boss couldn't believe it either, till I showed him.

I even put the old coil back on to verify the fix. With the old one: NO Start! Put the new one back on: Started right up.

Lesson learned on this one. I will be checking the intensity of the spark on them a lot closer next go round.

Thanks for all the suggestions and comments on this one!

[The_Duckslayer]

That would have had me going forever... I don't have any test equip for that. Just the old yep it's sparking off the screwdriver or whatever. Glad you shared that one... I will know more what to look for in the future. Have a great day././Jimbo