('91 eddie) truck turns over but won't start

[huntinggunsa]

Truck cut off when I was passing atruck. asoon as it down shifted it cut off. It turns over and the motor sounds fine.
These are the parts I have check and replaced
all fuses good
changed ecu (replaced with ecu from manual 5 speed)
control modual
coil pack

she is getting spark and fuel. when I tried to start her when she sits for a while it will back fire the first time it turns over then nothing. any help will greatly be appreciated.

one more thing, the top end of the motor was rebuilt 2 months ago. I has been running flawlessly since, untill yesterday. I need to use it to for work tomorrow.

curtis

 

[Brain]

You mentioned a backfire on first crank - is that out of the tailpipe (true backfire) or the intake (frontfire)?...also that the top had been rebuilt not too long ago. If she is getting fuel and spark, it seems to me like it is a compression/timing problem, and the backfire only adds to that diagnosis. The cam chain tensioner could have been too loose and let the cam chain slip or jump a tooth or two. The crankshaft timing indicator should point straight up and camshaft timing indicator (both indicators are on the sprockets) should point staright down when the #1 piston is in the TDC position. If they arent pointing towards each other, then something slipped or jumped. Chains do stretch and tensioners do lose the ability to hold tension, especially after they have been compressed and held with a clip like would be necessary to do in order to work on the top end (camshaft removal). This doesn't sound like somthing I could get done tonight, but maybe you have more beer than me.

I don't think the '91 had a crankshaft position sensor, so I think that can be ruled out...

Let us know what the problem turns out to be. Good Luck

 

[jimbo74]

how sure are you on the fuel getting there? my truck cranked and cranked when my inertia switch tripped but it wouldnt start, unless i shot starting fluid down its neck, then it ran briefly and died.... finally i thought about the switch, and sure enough, i had accidentally tripped it..... pushed the button and on first crank it started up.... when trying to crank it with the starting fluid, it front fired on me a couple times..... fireballs coming at you out of the intake is bad

 

[huntinggunsa]

it was a back fire. the spark plugs are soaked in gas. I was thinking fuel pressure regulator or crank senser but I believe your right on the timing. I guess i will be taking the motor apart again.

 

[XonDubs]

my grand am did the same thing and it ended up being the brain box(ecu) but i see you replaced it....but it kept blowing ecus every week, got to the 8th ecu and took it in to a shop, they didnt find nothing, then one day i was taking out my stereo and found a ground of some sort(main ground i think) was disconnected in the engine bay by the firewall, maybe this could too be your problem???

 

[Jacked93]

any luck getting it fixed???

 

[huntinggunsa]

The verdict is in. a snapped timing chain is the cause of my headaches. should be done with it today. one more question, how do you get the dampner back on?

 

[Brain]

I'm not sure what you mean by "dampner". Sprockets... or tensioner?? Glad to hear I didn't misdirect you, also glad to hear that it is repairable w/o other issues.

 

[huntinggunsa]

the harmonic balancer is what I meant but I got it on and it runs good.
thankyou for everybodys help. It was very much appreciated.