97 blazer...cranks but won't start

Wants to crank. I notice when I turn the key switch on (not start) the gas gauge pegs out as if a super full tank and no fuel pump noise. At times, leading up to the crank but no start condition, I would turn the key on, hear the fuel pump and the gas gauge would indicate proper fuel level. When this happened, the vehicle ALWAYS started.

Here what I know now;

1. Fuel pump works. As indicated by the red auxellery jumper lead inside the engine well.
2. Good fuel pressure.
3. Starter checks good.
4. Battery hot and leads are cleaned.
5. Grounds in engine compartment and at fuel tank are cleaned.
6. Vehicle does have gas.
7. Air bag light stays on, even after pulling battery leads, letting set, and reinstalling.
This ABS light would come on and go off independently before the "crank but no start condition". So I'm assuming that the ABS might be its own problem; but not contributing to the crank but no start condition?
There were problems leading up to the no start condition. Vehicle began to become hard to start (but would start). After starting (at idle) if the gas pedal was pressed aggressively, the "service engine" light would flash on and off rapidly and the "ABS" light would come on. At this point the vehicle wanted to die. No appearent codes were given.
Now the "crank but no start condition".
Before this problem, the vehicle was sending the code for 3 o2 sensors. But a new fuel filter corrected this problem completely with no further appearent
problems. Then (about 4 weeks later) the "crank but no start". I do not think the fuel filter and the "crank but no start" problems are related.?
No other maintanance has been done to this vehicle that might cause this problem. At this point the manual I am using is useless...

Need your help guys.............

Thanks

GT

97 is a bad year for ign switch problems.
On the air bag and ABS lights you will need a full abs/sir capable scanner to test.
What is you fuel pressure reading engine off engine craking cold and engine runnning?
The red is a prime test but not a direct power to fuel pump the connection to fuel pump can be lost in a bad punp relay
To test fuel pump find the gray power feed wire to the fuel pump and check for 12 volts when fuel pump should be running.
If no 12 volts jumper it with a 12 volt fuse jumper and check fuel pump pressure.
You need 60/66 lbs of fuel pressure.
63-65 lbs of prerssure on cold engine cranking to squirt the injectors.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

Good fuel pressure? Would that be 60-66 pounds at least? Go to How to/technical sub-forum within the "Chevy Blazer" forum. Lots of good reading and troubleshooting info. Apparently, Chevy's Multi port sequential injection system which most likely resides in your intake, requires mucho pressuro all the time-o Road

Ok........I checked the fuel presure before and thought it was good. I will check a second time. If the fuel pressure is good what else could it be???
Yesterday I tapped on the interruptor switch (switch under the key switch). while cranking the engine. Thinking that maybe knocking off some corrosion on the tiny contacts in the switch box would help. No Go. Still cranks but will not start.


GT

Ok........I checked the fuel presure before and thought it was good. I will check a second time. If the fuel pressure is good what else could it be???
Yesterday I tapped on the interruptor switch (switch under the key switch). while cranking the engine. Thinking that maybe knocking off some corrosion on the tiny contacts in the switch box would help. No Go. Still cranks but will not start.


GT
Could and may be a thousand different things.
But needs proper testing at the time of no start to find out what it really is.
Give us your fuel pressure reading first.
MT

Ok...... As said before. If the fuel pump comes on, the vehicle will start. When I crank the vehicle, and it does not start, the fuel pump does not come on. So,the only way for me to check operation of the pump and pressure is by powering up the pump by the red wire (jumper to the pump) in the engine well.


gt

If the fuel gauge reads over full, it's an indication that the level sender in the tank has lost it's ground. The fuel pump and fuel level sender use the same ground. Follow the harness from the fuel pump module and check the ground connection, make sure it's clean and tight.

The ground for the fuel pump and sending unit are on the frame under the spare tire. That ground has been cleaned, retighten for a good metal to metal fit and greased. The problem still exists.
I do appreciate all the help.. But please keep sending suggestions. I'm presently working on a front end of a 94 GMC Jimmy 4x4 and this Blazer is my next project.

Thanks

GT

Proper testing.
At time of no start check for good 12 volt power to fuel pump.
If power to it and good ground and pump no run check out pump and wiring plug in to it.
If pump runs check out fuel pressure.
If gauge pegs out at same time of no fuel pump run it points to ground or wiring.
For proper ground.
Check for voltage on ground wire.
And remember 97 is a bad year for ign switches.
Check all power feeds to and from ign switch.
Good Luck
MT

I will check all the grounds. I know where the ground is above the spare tire and at the battery. Tell me where exactly the rest of the grounds are and I will gladly check them.
As wrote previously. I tapped on the Interruptor switch (located under the ignition switch on the column) while cranking the vehicle. No start. Thinking, by tapping on the switch it could knock some corrosion off of the contacts in the switch.
I did replace an Interrutor switch in this vehicle about 40k miles ago. It did fix the problem of total cut out while driving.

Thanks

GT

Any takers.............Let me know where all the grounds are located on my 97 Blazer so I can check them?

Thanks


GT

That is a tall order.
Your best bet for a complete wiring diagram on power feeds and grounds can be found in a factory repair manual or the all data one year online repair info sub 24.95$ us plastic a year and 10 minutes set up time.
And you are set to go for a year.

http://www.alldata.com/products/diy/index.html

A good volt/ohm meter will test your grounds and power feed voltage.
Good luck
MT

Ok...... As said before. If the fuel pump comes on, the vehicle will start. When I crank the vehicle, and it does not start, the fuel pump does not come on. So,the only way for me to check operation of the pump and pressure is by powering up the pump by the red wire (jumper to the pump) in the engine well.


gt
MT, Just like to add my 2 cents. It really sounds like he is having trouble with his ignition switch. I had my 96 blazer do the same thing with me. I ran a 12volt lead striaght to the fuel pump and it ran great. Traced the signal only to find that my ignition switch that I replaced 1 year ago was bad again. Replaced it and that was the end on that.

MT, Just like to add my 2 cents. It really sounds like he is having trouble with his ignition switch. I had my 96 blazer do the same thing with me. I ran a 12volt lead striaght to the fuel pump and it ran great. Traced the signal only to find that my ignition switch that I replaced 1 year ago was bad again. Replaced it and that was the end on that.

Your 2 cents is welcome Gabe25 and.
Yes it could be the ign switch.
97 is a bad year for ign switchs.
MT

Just like to add my 2 cents. It really sounds like he is having trouble with his ignition switch. I had my 96 blazer do the same thing with me. I ran a 12volt lead striaght to the fuel pump and it ran great. Traced the signal only to find that my ignition switch that I replaced 1 year ago was bad again. Replaced it and that was the end on that.

Gabe25
I replaced the interruptor switch (switch below the key switch) about a year ago. The problem it was causing was a complete shut down of the vehicle while at hiway speeds. Then it would come back on and shut down again. I removed the interrutor switch and sure enough there was corrosion building up on the very small contacts in the switch. If I remember correctly, there were about 6-8 very small contacts in the switch box. I assume that the vibration from the vehicle moving would be enough to make contact and send power to the needed components. Powering up the vehicle again. I
have read that this "interruptor" switch has caused a multitude of weird problems. I would not be a bid surprised if the interruptor switch was again the root of my problems now. I have tried to knock on the switch thru the hole in the steering colunm in an attempt to free up the contacts. I did this while trying to start the vehicle. This however did not work. I do have an interruptor switch on hand but I want to look at all possible problems before doing the "just replace a part and see if it works" deal. I guess if there is a way of bypassing the interrutor switch and sending power down the line. If the vehicle starts then that would solve the problem.?. Wonder where you would put 12 volt in that colunm to check that?

Thanks



GT

In cases like yours. I would just replace the switch. Those switches have several contacts that sends voltage to many different components. Fuel pump, Instruments, Starter, ect. Being that you have a spare. I’d change it. There was a write up about cleaning the contacts in and reinstalling it. This was a while back. Let us know how you make out.

In cases like yours. I would just replace the switch. Those switches have several contacts that sends voltage to many different components. Fuel pump, Instruments, Starter, ect. Being that you have a spare. I’d change it. There was a write up about cleaning the contacts in and reinstalling it. This was a while back. Let us know how you make out.


Gabe25:
I was at the parts store and something in my head said to pick up a new
interruptor switch. I might just go ahead and replace this switch because I'm running out of ideas. Some parts stores get a little anal when you try electrical parts and then take them back. I have had good luck with my parts stores in this area. Hell, I give 'em enough money...
I think you have talked me into the interruptor switch change out...
If it is the interruptor switch, I can't believe that Chevy has not done something to fix this thing. This little switch has caused people more types of problems than I care to count. Me as well...

I will let you know how it turns out.

Thanks


GT

Your so right. That is one of the biggest trouble that make you go nuts over. Good luck and let us know what comes out.

Gabe25:
It is not the interrutor switch. I replaced it yesterday with the same results. I do however think I found the problem. Got to looking at the wiring diagram and noticed what was in line with the fuel gauge and the fuel pump. The fuel pump oil pressure sending unit. Located on the drivers, back side of the block. Could not even free it with a wrench. It appeared to be frozen (corroded) to the block. I knocked on the sending unit with a wrench a couple of times and the vehicle fired right up. Let it run, shut it down and it fired up again. Third time it was back to the same no start condition. I did not have time yesterday to take the sending unit out and clean everthing (wife had surgery). I'm pretty sure this is the problem. I will have more time today, I hope.
So now I can remove the new interrutor switch and replace it with the old switch. If it starts, the new switch is going back and I can put the dash back together.
Will let ya know how this turns out. This might be one for the records !!!


Thanks

GT

The oil pressure sending unit is only a saftey switch to keep engine running if the fuel pump relay fails.
It is not to shut off or turn on fuel pump power.
Go to your fuel pump relay and check for power to it and power to gray fuel pump power feed wire.
If power to gray fuel pump wire check that fuel pressure.

It's not the interuptor switch, contacts at the ECM, grounds. The thing started shut it off and it started again. The next day I was going to take it to a mechanic to scan it. Got up before work. It started, put it in reverse and it stalled. Tried to start it and did the same thing. Gas gauge pegs out to the right and no fuel pump. More help please....


GT

With the ignition switch ruled out, the only other thing I've seen cause this situation on my '97 is the EEM. Same exact symptoms. Replaced the switch again, only to have the same "no start" problem. Had to take it in. The shop took 2 days to diagnose it down to the EEM.

Check the large connector around the wiper motor (center of firewall), plus the plugs by the EEM itself. Make sure they're properly seated.

the only other thing I've seen cause this situation on my '97 is the EEM. Same exact symptoms. Replaced the switch again, only to have the same "no start" problem. Had to take it in. The shop took 2 days to diagnose it down to the EEM.

Check the large connector around the wiper motor (center of firewall), plus the plugs by the EEM itself. Make sure they're properly seated.

Mike:
What is this EEM? Where is this thing located? I will check it and anything else around it. It very much sounds like a connection or something that breaks contact. Either by vibration or corrosion (ground). If it is the (what I think it is) the ECM (located to the left sitting on the coolant tank), I pulled it out of the vehicle and used top grade contact cleaner on it and all the connectors that went to it. Let it dry and reassembeld. Same problem. Turn the key to the on position, gas gauge pegs out to the right and no sound coming from fuel pump, but engine cranks. The other day I was on my way to the shop to diagnos it but the thing started and when put reverse it stalled. So I keep plugging.
I was a bit surprised it was not the interrutor switch. Having about the same weird problems. But that was handled in the previous posts.
I will check your suggestion this afternoon in my shop but right now it's time for some OT at the job that pays.

See Ya

GT

Mike:
What is this EEM? Where is this thing located? I will check it and anything else around it. It very much sounds like a connection or something that breaks contact. Either by vibration or corrosion (ground). If it is the (what I think it is) the ECM (located to the left sitting on the coolant tank),

GT

EEM/ECM = Same thing, just depends on who calls it what.

I should have said Electronic Engine Management.

That's the name they gave it where I had mine replaced (Rebuilt Napa Unit that was flashed at a GM dealership)

What caused mine to short out was a large connector up on the firewall, by the wiper motor. My mechanic said the connector was loose, causing it to arc (I sort of doubt that, but what's done is done). It's possible I may have knocked that connector around a bit when I replaced the pulse board on the wiper, but that was 2 years prior to the EEM failing. And, the connectors have positive locking latches on them, so it's rather hard - but not impossible- for them to be loose.

Just my opinion.

Mike:
Just too much OT. I can't turn the money down. I might have a chance to check that connector today. If you can think of anything else I can check while I'm out there?
The blazer is still doing the same thing. Cranks, starts and runs good (when it wants to).

Thanks


GT

EEM/ECM = What caused mine to short out was a large connector up on the firewall, by the wiper motor. My mechanic said the connector was loose, causing it to arc (I sort of doubt that, but what's done is done). It's possible I may have knocked that connector around a bit when I replaced the pulse board on the wiper, but that was 2 years prior to the EEM failing. And, the connectors have positive locking latches on them, so it's rather hard - but not impossible- for them to be loose.
Just my opinion.


Mike, you were right. I got to looking and sure enough it was that large connector. Next to the power brake booster on the firewall. Behind a plastic 8 or 10 inch cover that swings down to hold or protect the harness/ connector. I pushed together the two barb hooks on the plastic cover,
swung it down and there was what appeared to be an intact connector.
As soon as I touched it it popped apart. The hook/ latch on the back side had been unhooked and was being held together by the tension of the
rubber boot on the female connector to the male connector.
Here about 2 years ago I installed a power brake booster and I might have tugged on the wiring harness and unhooked the connector. But it still ran.
I guess it took that connector 2 years to vibrate to a condition that I was having.
It did start and I took it over to the shop. I want them to scan it. The air bag light is still coming on and there is a A/C leak. If they can fix those
problems, the one last thing is a new muffler and that will end the problems on that truck.

Many thanks Mike.


GT



ps................... This might be a neccessary check for the rest of the folks out there who are having the same problem I was...

You guys are freaking genius's. After changing my plug wires 96 Jimmy wouldn' start and figured out fuel pump wasn't running. After much checking on interweb and on vehicle I found the fuel pump relay wasn't getting it's 12v kickon signal .After much bad info, long story short after about 10 hours searching I found this thread. Pulled that cover down and immediately saw connector was pulled back about 3/8 of an inch. Took a pair of channel locks and squeezed it back together. Voila. Jimmy runs again after 2 weeks.

We had a 96 that would crank and not start, it gave no codes, after it died while driving. After many tests and new parts and sensors there was a small crack in the timing cover that when warm was causing an alignment issue with the crank sensor! Not the issue here but may help someone else!!!

I am having same problem. Fuel pressure is 65 lbs when key is turned on and does not leak off. Primed down draft with gasoline and 1/2 cylinders hit. Have replaced 3 ignition switches since I owned for about 10 years. All GM parts. Parked on Tuesday night, running fine, Weds. morning would crank but not start. My 1st thought is ignition switch but I will check connector by brake booster.

Does this engine have a MAF sensor....

Does this engine have a MAF sensor....yes

new info. after getting a GOOD fuel pressure gauge this is what the facts are. turning on ignition shows a 55 lb fuel pressure that falls immediately once fuel pump cycles off. cranking shows a 62 lb fuel pressure that holds for 7 seconds and then falls to zero rather quickly. both of these were tried 5 times with the exact same results. however i will add that priming the downdraft with gas did not result in ignition. it did hit on 1-2 cylinders. is this possibly the so called spider under the intake.