Hey, maybe someone can help, I have a 99 blazer 2wd, 73000 miles. When I drive on rain or very hot and humid, stop and then return about one or two hours later, the truck wont start. It will crank, lights will be on, dash on and radio on, but no start. I'll try to start it every 30 min or so, and all lights on, full crank but no start. Then 2 or 3 hours later, starts like nothing ever happened. I took it to dealer, they put it on the computer but no codes came up. Can anyone tell me where to start looking?
Thank you!

change you cap and rotor.

Don't change one or the other, change both.
time for a tuneup including....

Air Filter
Fuel Filter
Spark Plugs (Ac Delco preferred with proper gap set)
Cap & Rotor

try the MAP sensor. just had it changed on my parents truck. it was a 98. as soon as it would rain it wouldn't start. we played with it for a while and finally got it to start and then shut it off and it wouldn't start again. changed sensor and works fine now. before changing that we did a complete tune up.replaced the disturbuter, had a crack in it.

Wouldn't it be smart to do proper maintenance first with a tuneup before replacing random sensors?

Not challenging you, just being logical.

I have a question----- What made you go to the MAP sensor? What diagnostics did you do? Just curious.

don't know. installed at a shop. i'm guessing OEM. no codes were read on the computer.

I had a rough idle and I reseated the connectors on the computer on the passenger side wheel well and all is great now!

If the engine computer grounds are iffy, the whole engine won't run properly.

Reseat your computer connections. All 3 or 4 of them.

mine ran fine once it was started. it was getting it to that state. well opened the computer shell and found out some water got in that as well so you might want to reseal that. i have a 95 blazer and i've never had any problems with the computer so i'm not touching it.

I had an oil pressure gauge that liked to twitch every once in a while and the idle was really bad.

Once I reseated the connectors, everything has been great.

well then if everythings fine then i wouldn't worry about it.

You notice the thread starter has not responded?

How lame.

Thank you for all the answers, Im going to do the tune up recommended by BlazerLT, this week, then i'll post results.

thanks again.

Thank you for all the answers, Im going to do the tune up recommended by BlazerLT, this week, then i'll post results.

thanks again.

Also, use the right AC Delco plugs and gap them properly.

Don't use Bosch platinums.

Do a complete tuneup.

I agree with the tune-up logic, but doesn't a faulty Map sensor show up as a code?

it never set off the code. it never had a problem when it was running. if it would have it might have triped it.

it never set off the code. it never had a problem when it was running. if it would have it might have triped it.

Comon bro, stop telling people to take shots in the dark and do the logical thing first which is a full tuneup with fuel filter.

You NEVER just tell people to randomly start replacing sensors with no backing reason.

like i said.we did a complete tune up.replaced the disturbuter and then changed the sensor after it didn't work.

Well let's have this guy do the tuneup first and then work from there.

My Service Trucks are all Chevs!

Very Common, look inside the center of the cap for carbon deposits ,my own personal truck did the same thing!

Luckly I had a new Cap/Rotor in Stock !

Mr.Rob

Lic Mech Auto/Truck/Trailer Ect....

did u fix ur problem? mine started acting up the other day after being fixed for a year. can't see how the sensor would be bad again.even if you put water on the motor and let it soak it won't trigger it. any luck fixing yours?

In his cse it sounded like condensation and moisture getting into the cap.

When the cap is cooling , it will contract and draw air in with the moisture if it isn't properly sealed.

how would i be able to check this or fix it. i didn't put the cap in. a shop did it. it still wasn't fixed when we got it back from the shop a year ago and then after a while it wnt away. they said the computer had to relearn. i think theres a vac line to it from what i've read. could there be something with that or the cap its self?

yes, a bad cap and rotor will cause this.

they changed it a year ago. could it be doing it again?it runs fine. i ran it hard sitting there and then shut it off and tried to start it and it wouldn't. if i keep trying even if its cold after about 20-30 starts it will run and once its running its fine. we tried putting injector cleaner in since its never been done. a friend of mine said the injectors could be getting water on them and not letting it run.

Hold on.....20 to 30 starts or tries?

Ummmm, did you check your fuel pressure? Perhaps your interrelating problems.

Just a quick cursory thought.

it tries to start like the engine turns over and then the started disingages because the engine kicks over goes to about 900-1,000 rpm and then shakes to a stop. the only thing i noticed is the the intake looked a little wet and had a strong smell of gas even after it sat all night. do u know what the psi ratings are for this motor. its a v6 4.3 vortech.sfi.would i be able to pull a plug and see i'm not getting fuel. the engine runs a little rough but after running some cleaner and running it hard it seems to be a little smoother.

If your smelling gas, remove your plenum and go back and inspect your work from when you installed your CPI unit.....

Did you install a new nut kit?

...after you get the plenum off, turn the key on BUT DO NOT START IT!!! Look and see if the lines or the regulator are leaking.

it doesn't have a cpi. gas mileage is very good and it doesn't smoke. it has the sfi injection. it doesn't look washed either.

Sorry 'bout that, got my wires crossed.

Ok, sequential not central. Individual injectors fed by a fuel rail and you smell gas. At this point, I would say that you may have an injector that is drolling. When you shut off the engine, the residual pressure in the fuel rail is being relieved via the drooling injector. When you go to restart, you now have a flooded condition.

Without the proper tools and from your posts, I would recommend a shop to perform the work. However......guess you don't have a fuel pressure guage....... yeah, better have someone check it for you.

but it also does it right after sitting all night. and if u drive it when its wet it works fine. starts fine and everything.

Wait, you said this was only when it was hot and humid?

Now you are saying if it runs and you shut it down it won't start back up.

This is weird and confusing.

Hey BlazerLT, the original thread was started by someone else and metallica came into it.

Sounds like a fuel supply problem.

He needs to verify spark at the plugs first. We know it isn't air.

If not, it is fuel.

what r ur ideas on the issue? how would the spark plug look. after running it this afternoon. and it cooled off it now starts with no problems. it only does it in certain weather. any other day after shuting it off it will start back up.

When it won't start, check to see if it lost its spark.

i felt the exhuast manifold and each cyinder feels warm. after trying to start it a few times it will start. about 20-30.

First off

STOP trying 20-30 times to start your truck.

All you are doing is wearing your starter AND flywheel off and drinaing your battery for not reason.

As I asked before, go and try to see if there is spark when it won't start.

when its not starting the engine kicks over and runs for about a second and then shuts down. when it running its fine. it keep doing this after plugs,wires,cap were replaced.

AGAIN,

Check if the plugs are getting spark when this is occuring and the truck will not start.

Have you replaced the fuel filter lately?

getting spark to each plug. fuel filter was replaced last time. the truck is only driven on the high way.115,000 are on it.

No, I mean when it is faultering and won't start.

Check to see if it is getting spark when it won't start.

all of the plugs are getting spark. the computer isn't telling any codes are being set.

This thread is getting stck or I'm losing something here.

In a previous post you mentioned a '98 and no make other than your parents or something. Then in another post you mentioned a '95.

1. What year, make, model whatever or we talking about.

2. Read the posts a little better, BlazerLT is trying to help you and he does give good advice, just slow down and listen to him and follow a methodical approach here.

3. If you are not getting any codes set, either soft or hard ones, it must be something that is out of the loop.

the SES light isn't being set and i don't have a scanner to check which ones are being set from starting. its a 98 chevy pick-up,4.3 vortech V6. 115,000 miles

If the light is not on, you have no codes. Soft codes will turn the light on but the light will then go out. Hard codes set the light on but it will not go out.

when it stalls out after trying to start the SES light isn't on. only if you turn the key off and back on.

Oh my, sounds like your describing the bulb check function. The SES or MIL (malfunction indicator light) will always light up when you turn the key on. It will not go out until after the engine has started.

That doesn't mean that you have codes. Only when it lights. If there is a code, the light will go out after starting and within 2 or 3 seconds it will come back on indicating that a code has been set. Does this happen?

no. what i mean is that it comes on and then i start it and the engine runs for a second and then shuts down and the light never comes back on. unless you turn the key off and back on. the only light that lights up is the check gauges light.

ok, I reread your posts.

The fuel pressure should be at least 45 psi and I'm not sure but it might even be 65 psi. It doesn't really matter for you don't have the necessary guage to read it from the rail.

Now, in a previous post, you were asked by BlazerLT if you ever changed your filter. You answered a year ago. Did you check it lately or changed it? If you don't have a enough pressure it will be hard to start but once started it might continue to run because it doesn't need as much. Most tech manuals will give a key on engine off pressure and an engine running pressure.

Check the fuel filter..... PLEASE

how come it starts ok and its only when it rain or is humid out it doesn't want to work. if its nice out it starts like its brand new. like i said after they changed the fuel filter the first time it didn't fix it. but i will try any way. if this doesn't work what could it be?

There have been so many posts on this my head is spinning.

You said that you were having problems as if it was today. Westminster has been clear all day according to the weather channel.

Was it today?

Perhaps your coil is breaking down in which case, as BlazerLT told you, check for spark. Next, I don't see how rain or humidity would affect the fuel delivery but I am always willing to learn.

Have your coil checked.

how come it starts ok and its only when it rain or is humid out it doesn't want to work. if its nice out it starts like its brand new. like i said after they changed the fuel filter the first time it didn't fix it. but i will try any way. if this doesn't work what could it be?

Now did you check for spark like I said when the engine will not run?

i wasn't able to because it ran after i got it started. from what i can tell it is. right around each exhaust port its warm but no where else on the manifold. that was when it wouldn't start. all six of them so i'm guessing it is. i think we checked it last time and all of them were firing.

i wasn't able to because it ran after i got it started. from what i can tell it is. right around each exhaust port its warm but no where else on the manifold. that was when it wouldn't start. all six of them so i'm guessing it is. i think we checked it last time and all of them were firing.

I have no idea why you are telling me the manifold is warm around the exhaust ports. Of course it is, it is an exhaust port, exhaust is HOT.

Stop talking about the manifold, it has nothing to do with this.

When the engine will not start, pull each spark plug cable from each sparkplug and test to see if you are getting spark. I don't care if someone in the past did it, I am asking YOU TO DO IT next time this happens.

What I want to see is if the coil is overheating.

theres a heatsink on it and at the bottom of it theres some corriosion or something on it. could it be arking from here? the heat sink isn't hot. its barely warm. does that help any? i'll check the spark next time it starts to mess up.

We are helpless until you tell me if the spark is there when it is acting up.

I'll wait until then. Go for a long drive and get the engine really up to temperature and cme back and tell me.

we were racing it back and forth on a back road. had it up to about 4,000. my dads going to drive it to work tomarrow which is about a 1hour from were he lives and he's going to run it in 3rd or 4th gear the whole way. i'll let u know when it does it. if it is the coil how come after a few startsit finally runs. and it runs fine.

I thought you said 20-30 starts.

yea. about 20-30.

we were racing it back and forth on a back road. had it up to about 4,000. my dads going to drive it to work tomarrow which is about a 1hour from were he lives and he's going to run it in 3rd or 4th gear the whole way. i'll let u know when it does it. if it is the coil how come after a few startsit finally runs. and it runs fine.

Then why did you say a couple here?

You need to get your shit straight bro.

I am feeling like I am being jerked around.

well he took it to work today and no problems. i'll post when it acts up.

Thank You To All That Posted Answers To My Problem, Last Week I Went To Buy The Cap And Rotor, And When I Got Back On The Truck It Would Not Start, It Was Raining Also. I Waited Until It Stopped Raining, Changed The Cap And Rotor At The Autoparts And Started Right Up!!!

Hopefully The Problem Is Gone...

Thanks Guys!

change you cap and rotor.

Don't change one or the other, change both.
time for a tuneup including....

Air Filter
Fuel Filter
Spark Plugs (Ac Delco preferred with proper gap set)
Cap & Rotor

Woot! I WIN!

howdufigure?

Hehe, my father's truck did the same thing.

hey blazerlt? on what year are your plugs you fixed? my wifes blazer runs like crap and i think i remember the gauges glitching at one time.. its a 94 blazer 4.3 cpi i posted a thread you can read if you want.. thanks