GM techs help please

[Warlock28SXT]

One of my buddies has a 97 GMC sonoma with the 4.3 vortec in it. It ran fine the last time he drove it. He bought a new car and his truck sat for about 3 months. He kept it as a commuter for work. He tried to start it after sitting and it would just crank and not fire. I stopped by his place yesterday and we checked spark (good) and fuel (at the rail) has fuel. I did not check fuel pressure. So it has fuel and spark. You can hear the fuel pump run when the key is cycled. He also put a new battery in the truck last week. I read on a gmc forum that the coolant temp sensor could cause this or a dip in one psi of fuel pressure might also cause this? We tried a bit of staring fluid down the TB in case the fuel was bad and still nothing. Any help/direction would be great.
Thanks
Jason

[Ratickle]

One of my buddies has a 97 GMC sonoma with the 4.3 vortec in it. It ran fine the last time he drove it. He bought a new car and his truck sat for about 3 months. He kept it as a commuter for work. He tried to start it after sitting and it would just crank and not fire. I stopped by his place yesterday and we checked spark (good) and fuel (at the rail) has fuel. I did not check fuel pressure. So it has fuel and spark. You can hear the fuel pump run when the key is cycled. He also put a new battery in the truck last week. I read on a gmc forum that the coolant temp sensor could cause this or a dip in one psi of fuel pressure might also cause this? We tried a bit of staring fluid down the TB in case the fuel was bad and still nothing. Any help/direction would be great.
Thanks
Jason

Does it have the security system on it? If so, and screwed up, it will start for about 1 to 2 seconds but that's it. It has to be reset if so.

[Blue Oval]

Had a 98 Astro van traded in this fall,had to use jumper box to start,even with a charge in battery,once warm would start every time.Had the 4.3 in it,needed a fuel pump.

[Warlock28SXT]

Does it have the security system on it? If so, and screwed up, it will start for about 1 to 2 seconds but that's it. It has to be reset if so.

No security system. It does not start at all just cranks.

[inbetween]

where did you check for spark? At the coil wire or at a plug? Best, not easiest to check at the plug end of a couple wires. Dist. cap and rotors are notorious for no starts on those.

[scottc]

If you have spark and used starting fluid and still no start, you don't have any spark in the cylinder. Look at a bad cap, rotor or wires. Could als be a weak coil. The last thing it could be is the fuel rail under the manifold is leaking. Pull a plug and check for it being gas fouled. You would also have a very strong gas smell if this was the cause.

[Warlock28SXT]

where did you check for spark? At the coil wire or at a plug? Best, not easiest to check at the plug end of a couple wires. Dist. cap and rotors are notorious for no starts on those.

We pulled #1 & #2 checked spark at the plug. We also put new plugs in it just to be sure.

[Warlock28SXT]

Had a 98 Astro van traded in this fall,had to use jumper box to start,even with a charge in battery,once warm would start every time.Had the 4.3 in it,needed a fuel pump.

We will have to give that a try. I actually got him a new fuel pump assy a while back because he was told it went bad by a dealer. That time it was the ignition switch.

[Warlock28SXT]

If you have spark and used starting fluid and still no start, you don't have any spark in the cylinder. Look at a bad cap, rotor or wires. Could als be a weak coil. The last thing it could be is the fuel rail under the manifold is leaking. Pull a plug and check for it being gas fouled. You would also have a very strong gas smell if this was the cause.

There was not a very strong smell of gas under the hood. The plugs had gas on them. I just assumed it was from all the cranking he had done before. Would the fuel rail beging to leak from sitting? The gaskets dry out sitting?

[inbetween]

If you're sure you have spark and fuel, did you check compression?But it still sounds like there may be a secondary ignition issue. What color was the spark? Was it consistent? Sometimes a cap and rotor will mis-route the spark to the wrong cylinders due to moisture/corrosion inside the cap

[inbetween]

Look at the magnet inside the distributor. It's on the shaft, under the rotor. If it has cracks in it, that may cause a weak spark too

[Warlock28SXT]

Thanks for the replys guys. We will keep digging and see what we find.
Jason

[Warlock28SXT]

If you're sure you have spark and fuel, did you check compression?But it still sounds like there may be a secondary ignition issue. What color was the spark? Was it consistent? Sometimes a cap and rotor will mis-route the spark to the wrong cylinders due to moisture/corrosion inside the cap

Never pulled the cap it started pouring Sunday we called it for the day. We will have a look and see.

[Warlock28SXT]

Look at the magnet inside the distributor. It's on the shaft, under the rotor. If it has cracks in it, that may cause a weak spark too

I'll take a look after your sugestion about the cap and rotor are verified. Thanks

[Sydwayz]

Might also replace the coil "control module" which is the little football shaped piece the cap slips onto.

[Griff]

I don't know for sure if a 97 4.3 has them or not, but if it does, check the cam position sensor and crank position sensors. They will cause a no start condition. I think you're really going to have to put it on scanner. It will probably save time and $$ by the time you're done.

[Warlock28SXT]

Might also replace the coil "control module" which is the little football shaped piece the cap slips onto.

Would it cause an intermittent spark? We will check into that as well thanks.

[Sydwayz]

Yes, it could. It's a little electronic controller which affects the ignition. I don't know exactly how it works, but I've replaced it on several GMs over the years.

If you can get a hold of R'Addiction aka John, here on the board, he could lend some info.

[Warlock28SXT]

I don't know for sure if a 97 4.3 has them or not, but if it does, check the cam position sensor and crank position sensors. They will cause a no start condition. I think you're really going to have to put it on scanner. It will probably save time and $$ by the time you're done.

I think it has the crank sensor. We are going to try some of the things listed above and see what happens. I agree if we don't get anywhere a scanner is in need. We will get it scanned before we just start throwing parts at it.
Thanks

[Warlock28SXT]

Yes, it could. It's a little electronic controller which affects the ignition. I don't know exactly how it works, but I've replaced it on several GMs over the years.

If you can get a hold of R'Addiction aka John, here on the board, he could lend some info.

Ok Thanks we might be taking a look tonight. I had that problem when I was 16 on a ford, in my case it just died. I'm open for anything though, it's gernerally the simple things that bite you. Thanks again.

[Warlock28SXT]

Just wanted to say thanks for all the input on this. We went through and checked/did the suggested ideas to no avail. He has a chiltons book also so we went througha bunch of other things as well. Still no luck. Now after the truck sat for a few days with the temps climbing here it started. Oh so strange. Maybe it was a condinsation issue or possibly it was just flooded from when he first tried to start it, slow crank weak battery? I don't know exactly. We will see if it keeps running. I think I'm going to tell him to have it scanned anyway to see if it has any codes to possibly shed some light on this if it happens again.
Thanks again
Jason

[mrv8outboard]

it is fuel pressure. just not enough when it is cold. i have had a few like this. use a fuel pressure and verify its accuracy. the pulse limiter is also a possible culprit. the easiest way to test this is too pour a little gas down the throttle body and it starts and dies but once you do it a few times it will stay running because as it warms up it needs less fuel.

[Warlock28SXT]

it is fuel pressure. just not enough when it is cold. i have had a few like this. use a fuel pressure and verify its accuracy. the pulse limiter is also a possible culprit. the easiest way to test this is too pour a little gas down the throttle body and it starts and dies but once you do it a few times it will stay running because as it warms up it needs less fuel.

We never checked fuel pressure just that we had fuel at the rail, no fuel pressure gauge. I sprayed starting fliud down the TB with no luck. Still not 100% sure what it was. Jason