posted by
someone claiming to be hiram6
on
Sun Oct 16 08:22 CST 2005 [ RELATED]
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Hi all, I'm going nuts trying to figure out the previous owners wiring workaround on my fuel pump wiring. I'm trying to "put it back the way it's supposed to be" but so far have just succeeeded in totally confusing myself.
Here's what the PO had in place. He had an orange wire coming from somewhere back in the dash that provided 12V+ to the number 11 fuse directly via a fuse tap, bypassing whatever Volvo had designed. Best I can tell, based on my Haynes manual and the 700FAQ here on this site, it seems that this fuse (for the in-tank pump) is supposed to receive 12V+ via a fat pink wire that comes from pin # 87/2 on the white fuel pump relay. With the relay in place, no 12v+ is coming from that pin. But the relay is clicking, and seems to be working correctly. I even swapped it out with a new relay to test it, and I'm getting the same results.
If I pull the relay, and use the jumper wire described in the FAQ, the fuel pumps (both) operate, but with the ignition OFF, as well as ON. The FAQ makes it sound like the jumper wire test should only work with the ignition in the RUN position.
Does anyone have a legible wiring diagram showing the wire colors for the fuel pump relay and associated fuse panel slots for the fuel pumps? My haynes manual has completely useless wiring diagrams that are printed so small I can't read the wire color codes.
I need to get this figured out without taking it into a repair shop, I know they will kill me with labor costs to diagnose this!!
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posted by
someone claiming to be hiram6
on
Sun Oct 16 13:39 CST 2005 [ RELATED]
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I've neen reading through the $25 dollar award thread started by JersVolvo, and now I'm wondering if I have an ECU problem with getting power to fuse #11. So, not to be dense, but where is my fuel ECU located? Seems like the other thread says it's under the rear seat, but I'm not seeing it. Do I have to pull up the foam padding and carpet to get to it?
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...now I'm wondering if I have an ECU problem with getting power to fuse #11.
Power to fuse 11 should come from Fuel relay 87/2, as you determined earlier. For that to happen, the Fuel relay must be energized by the ECU providing a ground on relay terminal 86/2, as noted in my other response.
We still don't know if your FI system is Bosch LH2.4 or the Regina, which is common on non-turbo 700s of the early '90s years. The original Bosch LH2.4 ECU is known to fail in providing that critical Fuel relay ground. The Regina ECU doesn't have that problem.
If your air filter outlet duct has the inline Air Mass Meter (AMM) with a flat, 6-pin plug, the FI system is Bosch. If it has a 2-pin plug to a temp sensor it's Regina — in which case the Ignition Coil is also different, with an odd-looking coil and heatsink on the left strut tower.
Either FI ECU is located behind the passenger's side kick panel. If yours is Bosch and the last 3 numbers are 561, it's a "known suspect". I don't know if it's covered in the FAQ or not, but a SEARCH on 561 should get a lot of hits — stuff about pink label vs white label that I don't remember, since my 940 has the Regina FI.
PS - Any time you post or reply, it's a good idea to get the car's YEAR up on the subject line (like here) for easy reference, if it's not there already. Things change with time, so knowing the year is important.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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posted by
someone claiming to be hiram6
on
Mon Oct 17 03:51 CST 2005 [ RELATED]
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Thanks Bruce, I'll check my ECU to see if the model # falls in the suspect range. Appreciate your help!!
Good catch on my missing the year in the drop-down box, I usually do that, just had a brain-cramp on my first post, although I did post the year and the fact that it's a Turbo in a later post.
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Sorry I overlooked that Turbo part. So it's definitely Bosch FI, and probably a 561 ECU.
Forgot to ask if the pumps run for a brief 1-2 seconds when you turn the Key On (but don't try cranking).
The ECU controls the Fuel relay then too, but not the under same conditions as for cranking and running. If the Key On part works, it would verify that the basic relay and pump circuits are OK. If not, it seems more like an ECU problem.
>>Does anyone know if the usual 561 failure (Fuel relay ground) also prevents the short pump run at Key ON?<<
I guess I should post this question, and will.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Hi Bruce,
Could be with the turbo he won't have a -561, but that model isn't the only one that suffers the hybrid failure. The turbo version (-563?) might be same vintage and I expect the -967 and -939 types are updated like the N/A versions -951 and -933.
Also I have working -561 ECUs that never pre-run the pumps, so I don't use that as a troubleshooting clue anymore.
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Art Benstein near Baltimore
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Hi,
I'm not certain which fuel system you are troubleshooting, but the only on-line reference I know covers a bit of LH2.2 and LH2.4 years with their 1989 schematic. It is the Russian site in case you already have been there:
http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm
--
Art Benstein near Baltimore
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posted by
someone claiming to be hiram6
on
Sun Oct 16 10:06 CST 2005 [ RELATED]
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Sorry, my car is a 1990 740 Turbo.
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Does anyone have a legible wiring diagram showing the wire colors for the fuel pump relay and associated fuse panel slots for the fuel pumps?
I have the Volvo diagrams for the '93, which I suspect are the same as your '90, whether Bosch or Regina FI.
Main/Fuel Relay---
30 - Brown +V in from Fuse 1. Goes to Main relay coil+ and Main & Fuel relay armatures
86/1 - Red, Main relay coil ground from ECU #21 when Key is ON
87/1 - BL/Y Out from Main relay to ECU #9, terminal 85 Fuel relay coil+, RS relay coil+, IAC valve, etc.
86/2 - Y/Black, Fuel relay coil ground from ECU #20 when Timing pulses are recieved from Ign. CU
87/2 - Pink, Out from Fuel relay to pump(s), and O2 sensor heater
Assumed this is not a turbo car. May be some differences if so.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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