The van has been sitting for a while, but started fine 2 weeks ago. A few days ago it cranked fine, but the fuel pump didn't do the normal
2-second pressure up when the key was first turned on.
I can get the fuel pump to run if I jumper the fuel pump relay, so the wiring to the pump and the pump itself seem to be OK. I tried swapping the ASD relay with others (they all have the same PN, and all show the same resistance between the coil terminals), but nothing. I tried jumpering from B+ to the coil +, still nothing.
What else can I try? Is there a fuel pressure sensor that thinks the pressure is up, so doesn't tell the pump to run? I don't think it's the Hall effect, since it doesn't come into play until it starts cranking.
Remove the 60-pin connector from the SBEC and inspect the pins and sockets for corrosion; clean the pins by pushing a pencil eraser straight down onto each pin, and packing the sockets full of Ox-Gard or Noalox.
Check all of the fusible links carefully; it sounds like one or more of them may have popped. Of course if this is the case you'll have to find the cause or the new link will pop, too.
No.
I don't think it's the Hall Effect Pickup, since the 3.0 doesn't use one. The 3.0 does tend to develop problems with the *optical* pickup in the distributor, and with the wiring between the distributor and the SBEC, so you can check for that by disconnecting the battery negative cable for a few minutes, reconnecting it, cranking the engine and then checking the flash codes. However, that probably isn't the problem since you say the fuel pump isn't energized with initial key-on.
To check the computer codes:
With the engine off, switch the ignition key on-off-on-off-on, leaving it "ON". Do not go to "start", just "on" during this procedure.
Watch the "Check Engine" or "Power Loss" light. It will turn on, then go off, then will begin to flash-out any trouble codes that have been stored. For instance, if it flashes:
Thanks for the tips, Daniel. I'll try these tonight and hopefully get it going. I wanted to donate it to my church (they in turn donate it to those who need cars but can't afford them), but they won't take it if it isn't running. And since I can't sell it (tried twice, can't even get an offer at $800, and it's in pretty good shape), and it's not doing me any good sitting in my driveway, this seemed like a good option.
Just curious - what is it that tells the fuel pump to quit pumping before the engine starts? The pressure regulator only holds the pressure at a certain level and returns the excess back to the tank, right? But that's with the pump running continuously. Something tells it to stop when the key is on but the engine's not running.
The initial "Bzhhhhht!" that you get from the pump when you turn on the key is just a timed pump pulse of (nominally) 1 second. The purpose is to pressurize the system for engine startup. It's not necessary to monitor the pressure, because as you know, the pressure regulator makes sure there's no overpressure.
Update: removed the SBEC connector and cleaned it, didn't see any signs of corrosion. While I had access, I unplugged and replugged all the electrical connectors under the battery. Then put everything back together. Still no fuel pump. Tried to get the codes to flash. Several times. Nothing. Jumpered the fuel pump relay so the pump runs whenever the key is on. Won't start. That indicates to me that there's no spark. Verified that with a timing light. So am I down to fusible links? The only one I saw was one to the alternator, so I must not know where to look. Seems strange that the computer won't blink, though - it should at least give the 55=end of codes, right? I'll go back at it tomorrow, check any fusible links and the wiring to the distributor.
Excellent indication that you've got a blown fusible link upstream of the SBEC. Common causes of this include (but are not limited to):
-Oxygen sensor wires shorts to one another or to ground (can happen if they fall on the hot exhaust manifold)
-Radiator or condenser fan motor seizes
Not if it's not getting power, which it evidently is not!
Let's make sure we're not jumping the gun, though -- check the pull-apart main disconnect in the positive battery cable about 5 inches down from the battery terminal. It feeds everything *except* the starter. Lift its locking tab and pull it apart. If it is internally broken and/or corroded, clean it up or replace the battery cable assembly.
I don't find that on mine. The clamp has 2 cables - one goes to the starter, the other to the fuse block, with a junction there to another large wire that goes to the alternator. So everything but the starter must be fed from the fuse block. Sounds like I should look between the fuse block and the SBEC for a fusible link, somewhere inside that wire bundle. Or does it run to the fuse block under the dash before it comes back to the SBEC? Seems like a bit of a mess until I look under the dash of my 95 Isuzu Trooper, then it seems like a model of simplicity by comparison!
(((Just curious - what is it that tells the fuel pump to quit pumping before the engine starts?))) If the PCM doesnt see that the engine is running after 3 seconds, it shuts down fuel and spark thru the ASD relay, You know that you are getting fuel but possibly loosin spark, go to the windshiled wiper resorvoir and under neath it is where you will locate the fusible links, look at them and gently pull on each one to see if any are broken/burnt.If all ok Check b+ to PCM with a test light for voltage.If ok Check the 5 volt power supply to the sensors for a short to ground. A short to ground on the 5 volt power supply to sensors such as: MAP, TPS, A/C PRESSURE TRANSDUCER, EGR POSITION, etc. will cause the vehicle to die out and may cause the PCM to be a no response. All this of course would be easier using a scan tool to see acuall values and be able to acuate spark and fuel systems, so taking it to a repair facility may be the next option. Good Luck Glenn Beasley Chrysler Tech
Good idea, Matt. There's power to the fuse block, all the lights and gauges and everything else works fine. With the key on, there's power to 4 pins of the SBEC connector - 3 on the left side bottom row, 1 just above them on the middle row. So there's power to the SBEC, but it won't flash codes and won't turn on the fuel pump or spark. Sounds to me like it's time for a different SBEC. Opinions?
First you need to check the schematic in the FSM to ensure that the 4 pins that have power are the only ones that should have power. If the SBEC needs power at 5 pins, then it may not be the SBEC.
Looking at the 60-socket connector with the wires facing away from you, the cavities are numbered thus:
Top row (all the way across, disregarding the central bolt post):
1 (left) through 20 (right)
Middle row (all the way across): 21 through 40
Bottom row (all the way across: 41 through 60
Cavity 3 (top row, 3rd from left): Direct battery voltage
Cavity 11 (top row, immediately to right of central bolt post) AND Cavity 12 (immediately to right of cavity 11) are the grounds. Check for continuity between them and battery negative.
Grounds are good, but no power on pin 3 with key on. Also, found a little corrsion on 2 pins at the firewall connector, and more when I pulled the boot back. Cleaned them up, but made no difference. Where does the red and white wire for pin 3 go? I expected to see it coming through the firewall connector, but didn't. Is it time to rip the bundle apart? Are there fusible links in there?
A 94 Caravan has but one fuse link; the one between the alternator output stud and the battery. Everything that -was- protected by fuse links the year before is protected by fuses in 94.
Yep, checked em. I expected the SBEC to be powered by the "ignition" fuse under the dash, but that one has power and a good fuse. But pin 3 isn't connected to any of the pins in the firewall connector, that's why I'm confused. There aren't any matching red with white stripe wires in that connector, so if it's supposed to be connected, it isn't. I guess I can pull apart the wire bundle and track it down.
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