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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

i have fuel spark and compression and it still wont start

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Old Sep 8, 2009 | 12:09 PM
  #1  
affmondo22's Avatar
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i have fuel spark and compression and it still wont start

The title basically says it all. It stalled out when i was driving and never started after that. After i fixed a weak spark issue and replaced the plugs due to wet fouling, it still wont start. I have 45 psi of fuel pressure, the injectors are pulsing, and the use of starting fluid didnt help. The compression ranges from 155 at the lowest cylinder and 170 at the highest. And the spark can jump a 20000 volt gap (Approx 1/2 inch). What could possibly cause it to not start? My only thought would be the timing belt snapped, but that would have showed low compression in at least one cylinder. I am at a complete loss here
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Old Sep 8, 2009 | 12:21 PM
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From: the great Maine wilderness
look at the fsm... time to start testing....

first...check the csi time switch, then the vafm, then the coil, then dizzy... and so on....


here the link to the fsm
http://www.ncttora.com/fsm/1990-1995...5/contents.htm
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Old Sep 9, 2009 | 09:54 AM
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vafm is good, coil is good, dizzy is good, i donno about the csi time switch, but starting fluid did not help at all, so i dont think that would cause it. Does anyone have any other suggestions? Im seriously out of ideas.
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Old Sep 9, 2009 | 02:51 PM
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Originally Posted by affmondo22
... replaced the plugs due to wet fouling, ...
Any chance you've got an injector stuck open (causing an over-rich no-start)? If that's the case, starting fluid is going in the wrong direction.

You could start by disconnecting the electrical plug on the cold-start injector; that won't help if that injector is stuck open, but it might rule out an electrical issue on that injector.

Do check the timing; if the spark is at the wrong time you're just pushing fuel around. Be especially careful about the plug wires; you removed those to replace the plugs, and if they went back on in the wrong order it won't start.

After cranking for a while, are the plugs wet, dry, or something else? Wet plugs suggest one of the above problems (over-rich or spark-at-wrong-time). If the plugs are dry, then there must be no fuel going into the cylinder (though you seemed to have checked the logical culprits in that direction.)

Good luck!
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Old Sep 9, 2009 | 02:54 PM
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From: Temecula Valley, CA
first thing to do is make sure the spark plugs are firing at the right time- put a light on #1 and check that the spark plug is firing when the crank is at near 0.
If it isn't, then likely your problem is a little more than what you suggested (timing belt snapped). If the belt snapped, the cams and distributor wouldn't turn so no spark. But it's possible the belt jumped some teeth and now the distributor events aren't timed correctly with the cam or crank.
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Old Sep 9, 2009 | 03:44 PM
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I'm pretty sure the plugs got wet fouled when I was cranking the engine over and over for testing. I will try to get a timing light on it first chance I get tomorrow and if that seems good I'll be looking farther into an overly rich situation. Thank you guys for the responses. It's always good to have a direction to go in.
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Old Sep 11, 2009 | 03:30 PM
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I hooked the timing light up and figured out that when the number cylinder fires the timing mark was nowhere in sight. So the timing belt must have jumped teeth. I'm gonna try to pull the front cover off to make sure that's what it is though. Thanks for the help.
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Old Sep 11, 2009 | 07:31 PM
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i just double checked the timing to make sure of what i had found earlier, and it seems that the timing mark lines up on the first revolution, but after that it disappears? Does anyone know what would cause that? bad tensioner maybe?
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