95 Jimmy SLE not starting

[95GMCJimmySLE]

so the car cranks but won't fire.

I had checked the fuel pressure and it held fine so that is ok.

I pulled a spark plug wire and held it to a head stud and didn't see a spark so I connected a probe to the negative post of the battery and stuck it into the spark plug wire and saw a spark. Not sure if it was a strong spark or not.

What should I be checking first?

Because the car won't start I don't have anyway of taking it to AZ to have it scanned to see if there are any codes. Thinking I may have to go see if they still rent those out so I can bring it home and check for codes.

[MT-2500]

Originally Posted by 95GMCJimmySLE

so the car cranks but won't fire.

I had checked the fuel pressure and it held fine so that is ok.

I pulled a spark plug wire and held it to a head stud and didn't see a spark so I connected a probe to the negative post of the battery and stuck it into the spark plug wire and saw a spark. Not sure if it was a strong spark or not.

What should I be checking first?

Because the car won't start I don't have anyway of taking it to AZ to have it scanned to see if there are any codes. Thinking I may have to go see if they still rent those out so I can bring it home and check for codes.

A lot of no starts do not set codes.
Unless the check engine light has been coming on flashing engine running before the no start.
Code reade may not help.

What engine and engine code?
What was the fuel pressure reading engine cranking?

On spark you need good hot blue spak that will jump 1/4 or more with a good loud snap.
Also check for good spark to more than one or all plugs.
Try spraying some carb cleaner into intake while cranking and see if it will fire.
Let us know if it does.
Pull several plugs and see if they are dry or wet on the ends.

[Tech II]

First, check to see if you have spark, coming out of the coil.....you are not going to get anything out of the distributor, if you don't have anything going into it......

If no spark, then possible coil or no trigger signal to coil...

If you have spark at coil, then check the cap, rotor and wires....

[95GMCJimmySLE]

Originally Posted by MT-2500

A lot of no starts do not set codes.
Unless the check engine light has been coming on flashing engine running before the no start.
Code reade may not help.

ok, well I don't recall there being any code before the no start so...

Originally Posted by MT-2500

What engine and engine code?
What was the fuel pressure reading engine cranking?

It's a 4.3L VORTEC, engine code W.
As for the fuel pressure reading while the engine is cranking, I didn't check, I'll have to do that.

Originally Posted by MT-2500

On spark you need good hot blue spak that will jump 1/4 or more with a good loud snap.
Also check for good spark to more than one or all plugs.
Try spraying some carb cleaner into intake while cranking and see if it will fire.
Let us know if it does.
Pull several plugs and see if they are dry or wet on the ends.

see, the 1/4" gap is what has me wondering. I recall checking for a spark once before years ago and recall using the header stud and seeing a bright blue spark jump from inside the plug wire to the stud. But when I tried doing that this time it didn't do it. Which first made me think it wasn't getting a spark. Then I connected a probe to the negative post and stuck the probe in the plug wire end. That's when I saw a spark but I thought it seemed weak and not as blue as I recalled from before.

I will try pulling more plug wires and pull some plugs.
I'll also try the carb cleaner into the intake to make sure it's not a fuel issue.

out of curiosity, say the spark isn't bright blue and doesn't jump very far, what would I be checking next?

Thanks for the response.

[95GMCJimmySLE]

Originally Posted by Tech II

First, check to see if you have spark, coming out of the coil.....you are not going to get anything out of the distributor, if you don't have anything going into it......

If no spark, then possible coil or no trigger signal to coil...

If you have spark at coil, then check the cap, rotor and wires....

because I do see a spark at the plug wire end, though I'm thinking it may not be very strong, I'm thinking that checking for a spark at the coil isn't going to do much for me. correct me if I'm wrong.

[Tech II]

If you have a weak spark at the coil, what will you have coming out of the distributor?

You should be using a spark tester....

If you have a healthy spark out of the coil, but a weak one out of the distributor, then you replace the cap and rotor, and possibly wires......

[MT-2500]

Originally Posted by 95GMCJimmySLE

ok, well I don't recall there being any code before the no start so...



It's a 4.3L VORTEC, engine code W.
As for the fuel pressure reading while the engine is cranking, I didn't check, I'll have to do that.



see, the 1/4" gap is what has me wondering. I recall checking for a spark once before years ago and recall using the header stud and seeing a bright blue spark jump from inside the plug wire to the stud. But when I tried doing that this time it didn't do it. Which first made me think it wasn't getting a spark. Then I connected a probe to the negative post and stuck the probe in the plug wire end. That's when I saw a spark but I thought it seemed weak and not as blue as I recalled from before.

I will try pulling more plug wires and pull some plugs.
I'll also try the carb cleaner into the intake to make sure it's not a fuel issue.

out of curiosity, say the spark isn't bright blue and doesn't jump very far, what would I be checking next?

Thanks for the response.

As to proper testing.

You need to do the test as outlined for us to be able to help you.

Fuel pressure specs on it is 55/61.

You will need 59-60 lbs fuel pressure engine cranking to squirt injector.
You can not leave home without it.
The carb sray into intake will help aid you to see if no start is fuel delivery problem.

As Tech II says check spark with spark tester and start at coil and check spark at all plug wire ends.
Spark should be blue and jump over 1/4 in with a good loud snap at coil and at all plug wire end.

If you can get codes checked post back any code no.

Let us know on fuel pressure engine cranking and on spark test and carb spray test.

[95GMCJimmySLE]

Sorry I haven't posted back, been busy...

Originally Posted by Tech II

If you have a weak spark at the coil, what will you have coming out of the distributor?

You should be using a spark tester....

If you have a healthy spark out of the coil, but a weak one out of the distributor, then you replace the cap and rotor, and possibly wires......

oh, ok. I'm sorry, when you said to check for spark I wasn't thinking of checking for the quality of the spark.

Originally Posted by MT-2500

As to proper testing.

You need to do the test as outlined for us to be able to help you.

Fuel pressure specs on it is 55/61.

You will need 59-60 lbs fuel pressure engine cranking to squirt injector.
You can not leave home without it.
The carb sray into intake will help aid you to see if no start is fuel delivery problem.

As Tech II says check spark with spark tester and start at coil and check spark at all plug wire ends.
Spark should be blue and jump over 1/4 in with a good loud snap at coil and at all plug wire end.

If you can get codes checked post back any code no.

Let us know on fuel pressure engine cranking and on spark test and carb spray test.

I understand the need for proper testing, that's why I came here to ask instead of just throwing parts at it.

Not that I wasn't trying to do all the test but I had loaned my fuel pressure gauge to a friend and while I was waiting on him to bring it over I decided to check the spark with a spark check I had picked up on my way home from work. I first checked the spark at the coil as suggested. I got a good spark there. Then I check for a spark at the plug wires. I got little to no spark there. Since I was still waiting I figured I would remove the cap and rotor to see how they looked. Well the posts of the cap were pretty corroded and the tip of the rotor didn't look to good either. My friend showed up with the gauge but since I had found the cap to look pretty bad and a very weak to no spark at the plug wire ends I decided to replace the cap and rotor without checking the fuel pressure while cranking. Remember I had checked the fuel pressure previously just not while cranking. Besides, without I good spark it doesn't matter so I figured get that corrected and if need be do further diagnosing after. Well after replacing the rotor and cap the car fired right up on the first try.

I let it run for about 30 minutes and it ran fine without any codes. So I took it out for a test drive and it felt good but during the drive the SES came on. Had the codes pulled and it's P0131 and P0134, bank 1 sensor 1 O2 sensor. Correct me if I'm wrong but that sensor is located before the cat, basically near the transmission pan under the passenger front seat correct?

Thanks for all your help. I had never known about a spark tester until now, it's a handy little tool.

[MT-2500]

Originally Posted by 95GMCJimmySLE

Sorry I haven't posted back, been busy...



oh, ok. I'm sorry, when you said to check for spark I wasn't thinking of checking for the quality of the spark.



I understand the need for proper testing, that's why I came here to ask instead of just throwing parts at it.

Not that I wasn't trying to do all the test but I had loaned my fuel pressure gauge to a friend and while I was waiting on him to bring it over I decided to check the spark with a spark check I had picked up on my way home from work. I first checked the spark at the coil as suggested. I got a good spark there. Then I check for a spark at the plug wires. I got little to no spark there. Since I was still waiting I figured I would remove the cap and rotor to see how they looked. Well the posts of the cap were pretty corroded and the tip of the rotor didn't look to good either. My friend showed up with the gauge but since I had found the cap to look pretty bad and a very weak to no spark at the plug wire ends I decided to replace the cap and rotor without checking the fuel pressure while cranking. Remember I had checked the fuel pressure previously just not while cranking. Besides, without I good spark it doesn't matter so I figured get that corrected and if need be do further diagnosing after. Well after replacing the rotor and cap the car fired right up on the first try.

I let it run for about 30 minutes and it ran fine without any codes. So I took it out for a test drive and it felt good but during the drive the SES came on. Had the codes pulled and it's P0131 and P0134, bank 1 sensor 1 O2 sensor. Correct me if I'm wrong but that sensor is located before the cat, basically near the transmission pan under the passenger front seat correct?

Thanks for all your help. I had never known about a spark tester until now, it's a handy little tool.

Bank 1 sensor 1 Is first sensor on bank one side.
Bank one side is the side with no 1 cylinder.drivers side.

Look real close the sensor by transmission pan may be Bank 1 sensor 2.

Also codes do not say replace part but check it out.

And check that fuel pressure low fuel pressure can set codes also.

[MT-2500]

Code 131 and 134 refer to 02 sensor heater circuit problems.
Check for proper 12 volt voltage to heater circuit and also good ground and wiring/plugin.