98 s-10 not starting

[andy001]

I have a 1998 s-10 4.3L that is not starting. Problem seems to be mostly when it is wet out. this past summer I replaced the plugs, cap, rotor, wires. Last night it did it again so I swapped out the coil from my running blazer and also the sending unit on the distributer (I think thats whats its called) but still nothing. It turns over fine and in the past I have been able to get it started after some doing. not this time though...any thoughts?

[MT-2500]

You need good hot blue spark to more than one spark plug.
If you have good hot spark check that fuel pressure.
You need 65 lbs on a cold start to squirt injectors.
Will it start with a squirt of carb cleaner.
If so you have a fuel delivery problem.

[andy001]

it tried to start the other night with starting fluid..once and that was it. I started it sunday morning and when i came home at 10pm it was raining..tried to start it and nothing.

[MT-2500]

Lot safer to use carb cleaner.
Have you got spark and fuel pressure?

[andy001]

Haven't checked that yet. Why would it be such an intermittent problem though?

[MT-2500]

When no start check for good spark and fuel pressure.
You can not leave home with out them.
MT

[andy001]

ok I will. If for example I have bad spark, what would you think to try? wires?

[MT-2500]

Unless you just want to throw parts at it I would try.
Proper testing to see what the problem is.

[andy001]

UPDATE:
Worked on it again last night. I did not check for the SES light being on before I started the car. I did check for spark in 3 of the cylinders (bright blue) I took the valve cover off the exhaust manifold to check the lifter position (to rule out that the timing chain was broke) Swapped out the computer with the one in my blazer. There is fuel at the plug (they were wet) I did not check fuel pressure ( did verify that there is fuel up to the throttle body by depressing the bleeder valve) checked the resistance at all the pins that connect to the computer ( and compared it to the blazer) I'm at a total loss......

One thing that has never been replaced (truck has 197,000 miles) is the fuel filter...could this be it?

[MT-2500]

In your other post we talked about proper testing or just throwing parts at it.

Are you still throwing parts at it or you ready to do some proper testing to find the problem?

If so start with fuel pressure test.
You need 65 lbs of fuel pressure for a cold start.
Not just a squirt of fuel at valve.
Let us know what the fuel pressure is reading.

[andy001]

LOL.. your right..I'll do that tonight and report back. Thanks for the kick!

[andy001]

Checked fuel pressure last night. 64psi when the pump is on ..drops to 54-56 psi for 5-8 min. It possible (considering that the truck has 197,000 miles) the after so much cranking I'm now getting excessive blow-by..and a loss of sufficient compression?

[MT-2500]

Fuel pressure is good.
And you are getting good hot spark to all plugs right?

I would try a squirt of carb cleaner and see if it will start on it.

If it will not start with a squirt or two of carb cleaner.

More testing is next step.

Pull dist cap and check for cracks or moisture.
Make sure plug wires are not crossed.
And make sure rotor is pointing to the 6 as in picture with it on TDC compression stroke.
http://files.automotiveforums.com/ga...hp?photo=51302

Other things to check for is injector pulse to injectors.
Pull plugs and see if they are wet with gas or black on the end.
If dry on the end you have a fuel delivery problem.
On compression you can run a compression test.
Make sure all cylinders are even and up to or over 125 150 lbs.
Another good tool is a vacuum gauge.
When cranking the engine you should have some vacuum or suction on the intake.
And last but not least pull dip stick and check oil level and condition.

[andy001]

it seems that I am getting good hot spark (bright blue)
tried carb cleaner..nothing

checked for cracks and moisture ..none
plug wires not crossed

have not checked the rotor position..how could it be off?
plugs are (were ) wet
going to do a compression test tonight
oil is good, level is good

[MT-2500]

Originally Posted by andy001

it seems that I am getting good hot spark (bright blue)
tried carb cleaner..nothing

checked for cracks and moisture ..none
plug wires not crossed

have not checked the rotor position..how could it be off?
plugs are (were ) wet
going to do a compression test tonight
oil is good, level is good

If it has jumper time or dist gear striped rotor position will be off.
Always check it.

If plugs are real wet they may not fire.
Clean or replace them when you are doing compression check and post back compression readings.
MT