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Hello everyone, the time has come for me to seek the wisdom of the all powerful b/board. My latest problem leaves me with a no start condition on my old nemesis, the dolphin blue 93 245 w/ LH 2.4.
The problem started while i was driving down a city road, Im cruising along around 40 mph and all of the sudden my engine shuts off, Ignition lights come on and i glide to the nearest parking lot. This happened to me once before, I simply restarted the car and drove off, so this time I did the same thing but nothing happened. I noticed that when the ignition was turned on, the main fuel pump wasn't turning on to prime the fuel rail.. so thats the main prob, I was able to jump fuse 6-4(L-side), it started up fine and i was able to limp home.
SO, Im 99.5% sure my no start is due to signal not being sent to my main pump. The system/fuel relay closes when ignition is on, as it should (not to mention it is only months old) and the main pump/Filter are bosch and are weeks old (both wires are connected). My in tank pump works as well.. for what its worth.
When I got home the first thing I tried was to check my relay plug with the ignition on to ensure i was getting 12v at pin 30 ( i kinda knew this anyway because the relay closes when ignition is on). Pin 30 was showing 12v as it should, but, when i tried to jump 30 to 87/2 nothing happens... nothing. No spark when the jumper leads touch, no fuel pump whirring.. nothing. Also at fuse 4 there is no voltage with the ignition on. This is pretty much the extent of my diagnosing skills, hence this thread. Ive read some things about the 25A fuse, not sure what that is exactly (is it on the fuse panel or in the engine bay?). Either way, at this point I'm thinking ECU, Am i wrong to think this? Car runs great when it starts 1-1-1 on both 2 and 6 on the obd. Literally just drove this car down to the keys with no problems, thank god it happened here and not there.
There is one more thing i can't piece together and then I'm done, this morning, I went to start the car hoping the problem was resolved and much to my surprise the car started!.... for about 5 seconds. So I'm thinking there might have been some residual fuel in the rail from me jumping the fuse panel to limp it home. subsequent restart attempts result in a kind of sputter start, like there is still fuel in the rail but not enough to start. SMH.
Im trying to resolve this problem by the end of the month as I just got hired full time with a local fire dept and need reliable transportation.
Thanks brick boarders
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Update. Good news bad news.
Good news, my volvo started again!
Bad news, I don't know why. I now have a gremlin.
I was testing the wires for continuity on both sides of the connector shown in the picture, I decided to also look at the harness for the ECU/ICU. I shut the ignition off removed both harnesses, checked for burns/shorts, plugged them back in, turned my ignition, and heard my fuel pump whirr to life. subsequently turned the ignition to start and she started!
Is it possible this is a relay ground issue. (86/1-2 i think?) or did unplugging/replugging my ECU have something to do with it?
my ECU is the 951, I've been trying to find a used spare to use for diagnostic purposes.
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Bypass that burned connector and don't look back. Lucid explained the "gremlin."
--
Art Benstein near Baltimore
The man who fell into an upholstery machine is fully recovered.
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"Is it possible this is a relay ground issue. (86/1-2 i think?) or did unplugging/replugging my ECU have something to do with it?"
If you had that Y-R wire connector apart (bad contact not yet bypassed), that action may have burnished the burnt connection clean enough to pass the needed current (about 7Amps). 86-1 and 2 are both grounded by the ECU:
-1 when ECU senses Key On
-2 when ECU gets Ignition signal cranking pulses (see start-run list below)
Start-Run Sequence 240 Series, LH 2.4
1) During starter cranking, the Crank Position Sensor (CPS) sends timing pulses to the Ignition Control Unit (ICU).
2-a) The ICU sends these CPS pulses to the Power Stage (aka Ignition Amplifier), to initiate timed spark voltage pulses from the coil.
2-b) At the same time, the ICU also propagates the CPS-based pulses to the Fuel ECU to allow FI operation (no ICU pulses means no FI operation).
3-a) The Fuel "System"* relay (previously energized at Key On) sends 12V power to the:
• Fuel ECU,
• Fuel (pump) relay coil + side (ECU controls coil ground)
• Idle Air Control valve (IAC) (ECU controls coil ground)
* The System relay is in the white case with the Fuel pump relay.
3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel pump relay by grounding the relay coil (– side) to power the fuel pump.
When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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disregard
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While chasing wires, I found a large connector underneath the dash, I think it goes from the fuse panel to the Ecu icu. I noticed one of the wires had burnt the plastic on the connector. The burnt wire is the same color as the wire running to fuse 4 and the wire that goes to 87/2 on the relay plug. Coincidence? I hope not. I feel that I'm really close I just have no idea where these connections go, also, with the ignition on there is no power to any of these wires,have not looked at the Ecu wires yet to see if it has any burnt wires.
Any guesses?
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I tried to post pictures but it proved to complicated.
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Yeah that looks kinda like mine.. so that goes into the engine bay through the fire wall?
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My turn to learn something surprising. Latest car we own are 91's. They do not have the connector you are showing. Learning the changes to wiring in the '93 is a hobby of mine, I guess, so would you describe the context of your photos? Is this under the dash on the passenger side? Is that the fuel relay I see in the background? This under the glove box?
This connector of yours may be serving the same function as the 12-position cabin-to-fuel harness junction in my photo (3x4) and even that was changed in '90 from a 3x3 nine position plug (I think it was '90).
So, you can see clearly it needs to be spliced around. When you do that, can you make the pumps run by holding down the clapper of the fuel pump relay?
BTW, I saw your earlier remark expecting 12V on fuse 4 with ignition on. That's not the case. You will only see it there when the fuel pumps are triggered, which does not happen unless the car is cranking or running, and for a second when you first turn the key on. Maybe you meant that. Only for a second. Do you have a map? Mine shows a 2x12 (24-pos) connector between the cabin harness and the harness leading to the rear of the car, but the yel/red wire in it is in position 23, one of the end terminals, where your burned one is one removed from an end position. That one is located in front of the hood release (driver side) and runs the tank pump from fuse 4.
--
Art Benstein near Baltimore
A chicken crossing the road is poultry in motion.
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Yes all of this is underneath the passenger dash, that is the fuel relay but it is a spare being used for diagnostics.
Not sure what you mean by spliced around, you mean disconnecting @ the connectors and hard wiring?
When I wrote about fuse 4 I meant I was expecting to see a ash of light on my test light when I turned on the ignition, just for a few seconds as the fuel pump primed the fuel rail. Either way I have nothing, even when I attempt to start the car. Zero voltage at all times going to fuse 4. I consider this my main problem especially with evidence of burns on the connector. I'm just curious as to where that connector goes when it enters the engine bay.
I believe you are correct about this being the 93" versio. Of the 3x4 connector
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"I'm just curious as to where that connector goes when it enters the engine bay."
My guess is that wire (Yellow/Red) probably doesn't go into the engine bay, but connects Fuel relay 87-2 to Fuse 4 input, at which point it also branches off back to the Main pump, with 2 more connectors along the way (one under the back seat I think).
I also think Art was suggesting you cut that wire on either side of the burnt connector, then bridge the gap with a short spliced-in wire of the same or larger gauge. I'd probably just use crimp splices, as that should be a dry location.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Ok thats what I thought just checkin. Im going to test that yellow/red cable today with my test light and see if its getting power when it should before I cut it. could this burning/short/whatever have occurred from me jumping the fuse panel to get home?
Either way I hope this can be of some help to people with the same prob, thats the whole point right!?
Thanks for your prompt and helpful responses.
I will follow up if this works, (fingers crossed)
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About where it goes, if it is indeed the same function but with added pins, I think you can follow it, or at least the yel/red wire breakout back to the FI relay (system and fuel pump) and you'll see how that part of the harness, including the red/blk wire needs to go through the firewall to connect all of the engine controls to the ECU and ICU. Unfortunately, there are no harness drawings available -- and I'd really be happy to be wrong about that.
Splicing around the connector will be your practical fix, because that pin/socket is forever untrustworthy now. If you can't cut off the ends and use a butt splice, then you'll just have to use two butt splices and a short hunk of wire.
About power on fuse 4, yes this would be the fix. Sorry for the misunderstanding.
I'm grateful for your explanation. To me, that is an entirely inadequate connector for fuel pump current after 20+ years in service. I will refer many to this thread learning what you taught me.
--
Art Benstein near Baltimore
When a clock is hungry, it goes back four seconds.
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You did some good testing but I suspect that when it fails its because you aren't getting good "solid" voltage thru fuse 6.
You had success when jumpering jumpered 6 to (Left sides) but the voltage was coming from the "always hot" side of fuse 6. It probably wouldn't have worked (that time) if you tried to get voltage from the right side of fuse 4. Well, maybe enough to show 12V on a meter, but that only takes a trickle. Try cleaning the fuse 6 contacts and see what happens.
And get a 12volt test light. It's better than a meter where marginal voltage is a possibility. (I call it "ghost voltage".)
As for your other observations:
"when i tried to jump 30 to 87/2 nothing happens... nothing. No spark when the jumper leads touch, no fuel pump whirring.. nothing."
• That's consistent with my hunch. You are completely bypassing the pump relay, but not delivering anything from the 30 terminal because it got nothing from nothing to deliver (from fuse 6).
"Also at fuse 4 there is no voltage with the ignition on."
• That's normal, if the fuel relay hasn't picked yet.
"Ive read some things about the 25A fuse"
You don't have one, since it was replaced by fuse 6. But it was known to cause the same problem you're having now, for the same reason.
That so-called "prime cycle" at Key on is not really required for starting, but it's a nice-to-know indication that the basic fuel supply system is putting the voltage where it's needed. If it was really important, it would at least be mentioned in the maintenance "literature".
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Ok thanks, when I get home I'll clean the fuse clips and see what kinda voltage fuse 6 is pumping out.
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OK, but remember a voltmeter won't show you marginal voltage. Six AAA batteries will look as good as a fresh Diehard, but won't drive the starter.
Get a 12V test light (incandescent preferred to LED).
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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K got a test light (needed one anyway) fuse 6 lights up fine on both RH and LH side with ignition off. Fuse 4 does not light up at all even when the ignition is on. This would point to the relay correct?
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Just tried three different spare relays, none work. Time to start chasing wires.
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Can you hear or feel the relays click twice as you turn the key to start the engine?
As I recall there is a connector in the harness near this relay that can get corroded and cause poor connections. This can also happen at the relay connector.
Dan
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Yup all three relays I tried click closed when ignition is turned on, however this does not correspond with power to fuse 4. See my latest post below.
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i question the functionality of your fuel pump relay despite it being new.
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Right, but even with the relay out of the equation I'm not able to jump it through the relay plug. So the relay is not my concern. However I have a few spares, and it won't hurt to try it.
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