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odd no start, no code, fuel starvation condition

1K views 6 replies 2 participants last post by  kevinfish 
#1 ·
Hi everyone:

I've got a 99 with a 2.7L with about 100k miles on it. Bought it in non-running condition from original owner's family. Car is in real nice shape. Always serviced right on time according to the guy I bought it from (but no paperwork to back that up since all the records burned up in the California Camp Fire).

When I first got it, I tried spraying some carb cleaner into the intake hose and it backfired so I was thinking it had a fueling problem and/or had jumped time.

The guy I bought it from was the (young) great grandson of the original owner and he overfilled it with oil so I was thinking he was doing some spirited cornering with it down on oil a bit and he starved the pickup tube which pumped the tensioner full of air.

Since I didn't have any records of a recent timing chain and water pump servicing I just dove in to that. Well, when I got in there the timing in fact had NOT jumped but since the chain was at least half way stretched I went ahead and changed/upgraded the chain, sprockets, and pump.

Now I'm reassembling and I wanted to try and test fire it so I could figure out what the *real* problem is. I've put back together enough stuff such that it *should* run but I'm not even getting a backfire (but the coils aren't being pressed down by the cam covers cuz I just have them stuck in there w/o covers and they seem to pop-up a bit and not really clamp onto the top of the plug so I'm guessing the pressure of the hold-downs keep them in tight contact together).

I have a fuel pressure gauge on rail input and it maxes out at 46 PSI after flipping the key on a few times. It holds pressure pretty well leaking down to about 33 after an hour or so.

I was going to check to see if the fuel injectors were even firing so I pumped it up to its normal 46 then pulled the fuel pump relay and cranked it and it seems to drop about 1 lb for every second of cranking. Would that be about the normal amount?

Any other ideas of what I can check or how to proceed?

TIA,
-Kevin
 
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#2 ·
here's an update:

my S and T fuses appear to be shorted to ground both sides with key on engine off.

My "N" (asd) fuse that appears to be upstream of both of those has like 12 and 10 volts in the different terminals when it's pulled. Obviously neither of those shots to either side of S and T (which it appears it should according to the 2000 intrepid schematics -- the closest I can get online).

My understanding is that S provides the high side for all the coils and injectors. I checked a green wire to a coil and it was grounded (but I seem to recall that was the high side, so that would make sense if it's shorted to ground long with S).

So am I on the right track here? Could whatever is shorting S and T to ground be the culprit?
 
#3 · (Edited)
here's an update:

my S and T fuses appear to be shorted to ground both sides with key on engine off.
The source sides of those fuses go to the load side of the contact of the ASD relay. When that relay contact is open, you would read 0 volts on both sides of those fuses because of the loads on those fuses being a resistance (whatever the combined resistance of their loads is) to ground. (When you say “shorted to ground”, are you determining that by measuring 0 volts or close to zero ohms? Hopefully you’re measuring volts not ohms because you shouldn’t apply the meter in ohms mode to an energized system.)

It’s only when the ASD relay contact is closed that you would read 12 volts on fuses S and T.


My "N" (asd) fuse that appears to be upstream of both of those has like 12 and 10 volts in the different terminals when it's pulled. Obviously neither of those shots to either side of S and T (which it appears it should according to the 2000 intrepid schematics -- the closest I can get online).
Fuse N is on the source side of the ASD relay contact. The source side of fuse N is always ‘hot’ as it’s hard wired directly to battery ‘+’. With fuse N pulled and ASD relay contact open, the load side of the fuse N holder is floating (connected to an open wire), so voltage could read anything.

My understanding is that S provides the high side for all the coils and injectors. Correct. I checked a green wire to a coil and it was grounded (but I seem to recall that was the high side, so that would make sense if it's shorted to ground long with S). Yes - correct, the being “shorted to ground” due to being connected thru the ign. and injector coils to ground.

So am I on the right track here? Could whatever is shorting S and T to ground be the culprit?
Again, their being “shorted to ground” is due to the resistance thru their respective loads (PCM on fuse T, ign. and injector coils on fuse S) to ground with the ASD contact open.

From the ‘02 FSM since I don’t have the ‘99 FSM loaded on my phone - I think this circuit is the same for all years, but will have to check:
(EDIT: Verified same for ‘99, except for ‘99 fuse T powers O2 sensors (including their heaters), EGR valve, and alternator field winding directly instead of going thru PCM.)
 

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#4 ·
Also from ‘02 FSM (should be same for all years):

The camshaft and crankshaft signals are sent to the powertrain control module. If the PCM does not receive both signals within approximately two second of engine cranking, it deactivates the ASD and fuel pump relays. When these relays are deactivated, power is shut off to the fuel injectors, ignition coils, fuel pump and the heat- ing element in each oxygen sensor.
I couldn’t find where it said, but my guess is that if the key is turned to Run without cranking, the PCM does not energize the ASD relay, or if it does, it de-energizes it after a few seconds of no cranking. I do know that power to the fuel pump is cut after a couple of seconds if ign. is turned to Run without cranking, so probably same for the other stuff.
 
#6 ·
yeah, you're right. I think the circuit is working correctly. The S fuse hots up for a second when the key is first turned on and when the engine cranks.

I'm actually kind of leaning towards it being plugged exhaust but I want to logic probe the coils and injectors first (merely because it's easier to test). I'm quickly running out of ideas other than that.
 
#7 ·
okay, I have verified I'm getting spark. However when I put my continuity light from the battery to the white/tan wire of injector #2 (the only one I could reach w/o removing the plenum) when the ASD relay is off the light is lit. When cranking my light goes off and there's no pulsing. So it tells me that the ASD voltage is reaching the green wire of the injector (when my light goes off) but there's no clamping/pulsing to ground happening by the computer.

How could this be happening to all the injectors (considering it seems that they should be functioning if the coils are functioning) or do you think I've just stumbled onto one bad port on the computer and should remove the plenum and check some others?
 
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