posted by
someone claiming to be Chris B
on
Wed Sep 29 13:45 CST 2004 [ RELATED]
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I've been trying to diagnose a no start problem. This is a continuation of the original thread '240 fuel pump, or something else' started on Tues 9/28. So far I've determined that my fuel pump works if I jump fuse box terminals 4 and 6. Obviously, that means I am getting 12 volts at the pump with the fuses jumped. If I take the jumper off and measure the voltage at the pump I'm getting nothing, or close to it, both with the key in the ON position and when cranking. I took the cover off the relay and watched it and it is doing nothing when I turn the key to ON or when I crank it. I resoldered the relay as I read in the archives, and still nothing.
If the car sits for a few hours, it will start and run for a second or two. The first time I tried to restart it after letting it sit over night it ran for about 20 seconds. The longest since then is 2 or maybe 3 seconds.
Assuming the relay is good, what are the other possibilities?
Thanks!
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"I took the cover off the relay and watched it and it is doing nothing when I turn the key to ON or when I crank it."
Chris, like I said yesterday, the MAIN relay must come on when the Key is turned ON to power the AMM and ECU. Nothing will happen without it. The MAIN relay is the "upper" one, as you look at the uncovered relay with the coils on your left.
Power to the MAIN Relay coil terminal 30 comes from the 25 amp fuse, so you should find 12V there all the time. Back-probe the harness connector with the relay plugged in. Then check the coil ground side, terminal 86/1 (Yellow-black I think). It should also be at 12V, but should drop to 0V when the Key is turned ON—and the relay should click as the armature closes. Please let us know if these 3 things happen or not:
Terminal 30 has 12 volts
Terminal 86/1 also has 12 volts with Key OFF,
Terminal 86/1 then drops to 0 volts with Key ON (Via ECU pin 21)
If all 3 of those are OK, but the armature doesn't move, it must be mechanically stuck open somehow—something I've never experienced.
While you're at it, test for 12V with Key ON at terminal 85 (Fuel relay), just as a check on the 12 volts from the ignition switch (also required at the ECU).
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Thu Sep 30 13:30 CST 2004 [ RELATED]
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Okay, before I post the latest update I want to say thank you for taking the time to help me. Your help is much appreciated.
All of the tests you prescribed in your previous post checked out.
Terminal 30 has 12 volts
Terminal 86/1 also has 12 volts with Key OFF,
Terminal 86/1 then drops to 0 volts with Key ON
Terninal 85 has 12 volts with the key on
I watched the relay the whole time and nothing moved, the circuit stayed 'open' the whole time. I can physically move the armature very easily with my finger so I don't think it is physically stuck.
Just for fun I checked to make sure I had spark at the distributor and I indeed do. I knew I did, I just wanted to prove it to myself without a doubt.
It still starts and runs for a very short period of time on the odd occasion.
I'm hoping to try a good fuel relay tomorrow night. With all the voltage in all the right places and with the fact that the pump runs when bypassing the relay, I'm just not sure that it can be anything else. Is it possible for the fuel pump to run and still be not creating enough fuel pressure to keep the car running? I'm still uncertain whether the in-tank pump is working or not.
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Very puzzling. Could you try manually "energizing" the Main relay armature, by using a piece of folded paper to hold it closed? Then try starting?
That would provide the required voltage to AMM pin 5 and ECU pin 9, which must be missing if the Main relay isn't working right.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Fri Oct 1 02:18 CST 2004 [ RELATED]
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Progress! I "energized" both sides of the relay and jumped fuses 4 and 6 and it started and ran normally.
If I take away any of those factors, it won't start, but, if while running I remove the papers from the relay that were keeping the aramtures closed they remain closed and the car continues to run. If I turn the car off, it won't start back unless I rig the relay again.
Also of interest - I had fuses 4 and 6 jumped and I reached down to rig the relay. When I reached down to close one of the armatures they both started to 'buzz' clicking on and off about 1000 times per second.
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Progress! I "energized" both sides of the relay AND jumped fuses 4 and 6 and it started and ran normally.
Doing 2 or more things at once confuses things, especially since "energizing" the Fuel relay is redundant to the 4 to 6 jumper. My thought was to try the paper trick on (just) the MAIN relay, in an effort to isolate or localize the problem.
If I take away any of those factors, it won't start...
The "factors" taken away being:
1. Main relay,
2. Fuel relay,
3. Fuse 4-6 jumper?
This confuses me because factors 2 and 3 are essentially redundant. The jumper just puts voltage to the same place where the Fuel relay does, feeding pumps, injectors, etc. But the voltages DO come from different sources (more on this below).
Are you saying saying it won't start with (just) the Main relay "energized", AND the 4-6 jumper in place? Or with 4-6 jumper swapped for blocking the Fuel relay armature?
What happens, pump-wise, if you just block the Fuel relay armature? (Key Off, no 4-6 jumper)? If they run, do they sound as strong as with the 4-6 jumper? Do they sound stronger if you add the jumper while they're running?
but, if while running I remove the papers from the relay that were keeping the aramtures closed they remain closed and the car continues to run. If I turn the car off, it won't start back unless I rig the relay again.
All I can suggest for now is to really check out the 25 amp fuse and it's connections. It may have shown 12V on a meter, but not be flowing enough current to "pull" the relays in (just enough to "hold" them) — especially with the starter drawing big time. (Grasping at straws here.) The 4-6 jumper voltage comes from the common hot side of fuses 6 thru 10, and is likely to have more "capacity" than a weak/dirty 25 amp fuse supply.
Also of interest - I had fuses 4 and 6 jumped and I reached down to rig the relay. When I reached down to close one of the armatures they both started to 'buzz' clicking on and off about 1000 times per second.
Please try the "rigs" in the normal sequence (Main relay first, then pumps), and see what happens:
1. Block the Main relay closed, then
2. Install the 4-6 jumper and try starting
Whether or not that works, remove the 4-6 jumper, block the Fuel relay (Main still blocked) and try again. To my thinking, 4-6 or Fuel relay rig shouldn't make any difference—except for the difference in voltage sources.
That buzzing is probably a clue but I can't connect it to anything yet.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Fri Oct 1 06:33 CST 2004 [ RELATED]
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Quote: All I can suggest for now is to really check out the 25 amp fuse and it's connections. It may have shown 12V on a meter, but not be flowing enough current to "pull" the relays in (just enough to "hold" them) — especially with the starter drawing big time. (Grasping at straws here.) The 4-6 jumper voltage comes from the common hot side of fuses 6 thru 10, and is likely to have more "capacity" than a weak/dirty 25 amp fuse supply.
That's funny because I had that same thought but I haven't figured out quite how to check that.
I checked just blocking the main relay closed and installing the 4-6 jumper and nothing happened but I will try it again tonight when I get home just for the sake of completeness.
In my mind, the buzzing would indicate that the relay is fine because both armatures were moving. I could be wrong, though. I have acquired another relay to try tonight, just for the sake of it.
I will try your suggestions one more time and report back tonight.
Thanks for your help.
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Chris,
I didn't have a way to check/prove the 25A fuse path till I got to the end of this post, so jump to the bottom if you want. But in any event, I would take a close look at the Battery + terminal, where it starts. The smaller red lead feeding the fuse is known to suffer from corrosion—poor terminal contact and even corroded, broken wire strands. Same for the fuse contacts. Any signs of heat there means resistance and voltage drop. At this point I would replace the fuse on principle.
You seem to have a good grasp of how these things work, and these relay circuits are fairly simple—maybe you can draw a simple diagram like I have (my Bentley translation). One of us might have a revelation.
1) I have the Main and Fuel relays as 2 blocks--Main on the left, Fuel on the right.
2) The 2 armatures are common, and are fed from the 25A fuse, via terminal 30, which also feeds the Main Coil + side.
3) The Main relay is picked when ECU pin 21 lead grounds the Coil - side 86/1, and Key On +12v feeds ECU 18.
4) Main output 87/1 feeds AMM 5 and ECU 9, before cranking starts
5) Key On +12v also goes to Fuel Coil + 85, as you tested
6) The Fuel relay is picked when ECU 17 grounds the Coil - side 86/2. (But only if ECU gets a "spark OK" from Ign. CU)
7) Fuel output 87/2 goes straight to the Main pump, with a branch to Fuse 4 hot side. A 2nd leg feeds the O2 sensor heater, the injectors, and the IAC valve.
Those are the ins & outs of the Fuel Relay. Note that the Main coil and all the outputs are fed from the 25A fuse (which may not be up to it?). However, the 6 to 4 jumper voltage (different source) can feed everything by backing up from Fuse 4 to 87/2, and (with both armatures blocked or energized) back out from 87/1.
So I'm thinking that when it ran with both armatures "energized" with paper, AND the 6 to 4 jumper in place, the jumper was supplying voltage that should be coming from the 25A fuse, but was maybe not up to the job. If you have a long enough wire, you could BYPASS the 25A fuse with jumper from the Hot (left side) of any fuse 6 thru 10, over to the FI relay and back-probe it in at terminal 30. (Remember it's unfused so just try it long enough to see if it will start.)
P.S. Under the No Stone Unturned category, you could also try burnishing the relay contacts with something like a business card—but nothing too abrasive.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Fri Oct 1 14:34 CST 2004 [ RELATED]
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I feel like such an idiot but it was the 25amp fuse. How much more simple does it get? It was pulling 12 volts with no load but not enough current to drive the relay with the starter running. The fuse holder practically crumbled in my hand this afternoon. I pulled the leads out of the holder and jumpered them together and the car started and ran just like it did before it quit.
So, the question becomes, where can I find a fuse holder like that? Do they have them at the local parts store or will I need to visit one of my friendly neighborhood Volvo dealers?
Bruce, I thank you for the time you took to help me. Without your guidance I probably still would have been bumbling around with the fuel pump. I'll be back on the road tomorrow.
Thanks!
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Chris,
Glad to get the good news. We'd still be groping, but for your diagnostic efforts. It sure took me long enough to consider the different voltage source (fuse jumper) as being the key factor.
I think NAPA has the fuse holder, which splices in with crimp-type butt splices. They probably have the crimp tool and splices too. Or maybe Radio Snack.
I was all ready to tell you how to eliminate the 25A fuse, which Volvo did in '91. Since then, the Main FI feed is a 16A fuse in position 6, which is actually not used in the older LH cars like yours—even tho' it's labeled as "Main Pump". I think it IS the main FI fuse in non-US cars with K-jetronic. You could run a wire from there (with a 16A fuse) to terminal 30 in the relay harness plug. But maybe some other time, eh?
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Sat Oct 2 02:56 CST 2004 [ RELATED]
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Great, I'll make a run to NAPA or Autozone today to see what I can find. 25A fuse elimination isn't a bad idea but I think I'll just leave it as is for now. That's a crazy place for a fuse if you ask me, but I'm not Swedish, so what do I know.
Again, thanks for your help.
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I would like to know if you can get your hands on another relay and try it.
I have just bought another 88/245 wagon the owner that I got it from said that one of the fuel pumps was gone and that Volvo wanted to much to replace it.
Check the wires coming out of the back of the fuse panel to see if there is power. If yes then check the power to the fuel pumps at the pumps check and clean the ground wires they go bad. Then see what happens. You may need some one to turn the switch while you check power at the pumps. Check the connection at the pump under the rear seat it maybe gumed up as mine was.
The owners kids had spilled COKE in the rear seat and it messed up the connection for the high pressure pump.
Thanks
Rodney
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posted by
someone claiming to be Chris B
on
Thu Sep 30 03:35 CST 2004 [ RELATED]
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Yes, I have access to another relay. Hopefully I'll get to try it tonight. I am beginning to doubt the relay though, becuase when I force the pump to run by jumping fuses 4 and 6 the car still doesn't start.
What about the AMM? Is there a good way to test it to know whether it is working or not? I've read in the archives that this can cause a no start problem.
Another issue that might provide a clue is that I think my fuel mileage has been deteriorating recently. My odometer hasn't worked for some time, but I'm pretty sure a tank of gas hasn't been lasting as long as it used to. I don't know if that's a symptom of something related or is a whole other issue to deal with.
Thanks!
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What year is the car?
When you jumper the fuel pumps, can you hear the pump running? If not, the pump might just be dead.
The relay should cause the pumps to come on for a couple of seconds when you first turn the key to the "II" position... so if the relay isn't coming on for a second or two initially, it could still be faulty.
Depending on the year of the car, it might not even have an AMM.
--
If you listen to the radio in Portland, OR, you may know me as "Portland's Favorite Soul Brother!"
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"The relay should cause the pumps to come on for a couple of seconds when you first turn the key to the "II" position..."
No offense Dylan, but please don't perpetuate this myth. It's only true for '89 and up 240s. I don't know about 700/900, but I believe on 240s it came in with LH 2.4.
On the older bricks like yours, and some I've had, the Fuel relay should NOT energize to power the pumps until the ECU sees a "Spark OK" signal when cranking—either from the Ignition CU, or directly from the Coil negative teminal #1 on older K-jet cars. That green (electronic) relay that you've shown "looks" for that signal on terminal 31b.
This is a built in Safety Feature designed to prevent fuel flow on an engine that can't run (i.e. is upside down in a ditch).
Like you maybe, I have actually had some of those earlier cars run the pumps in KP II, but it was due to a defective Fuel relay, which defeated the "no fuel to a dead engine" safety feature, but otherwise worked OK.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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How can you change it so the pump comes on with the key prior to ignition signal or cranking like the old days before the safety feature. I would like to build fuel pressure prior to cranking.
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It's been like that (no fuel if not cranking) since '76 that I know of (different method but same intent). IMO, it's better to get some oil moving before firing.
But that said, the newer ones like my '93 940 do (intentionally) buzz the pumps for a second at KB II. So it's a moot point I guess
I'd never tell you how to do it (liability concerns), but somewhere I saw one once with +12v wired thru a momentary (spring loaded OPEN) switch to the Fuse 4 left contact.
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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posted by
someone claiming to be Chris B
on
Sun Oct 3 02:11 CST 2004 [ RELATED]
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Is there a reason you would want to do that? Are you having trouble starting currently? If it ain't broke, don't fix it.
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I'm getting slow starts when cold sometimes. I think it is starved for fuel so I thought running the pumps before starting would make sure that when you start cranking the fuel pressure is there. I though it would start faster. My car cranks fine it just doesn't start right away sometimes. No real pattern but generally it is after it cools down. Fuel pressure meets specs. check valve holds pressure for a good period of time.
Any ideas??
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posted by
someone claiming to be tomjp
on
Sun Oct 3 02:26 CST 2004 [ RELATED]
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We red block owners don't want to give up million-mile longevity to be at 1500 rpm on the first spark like a honda. But it sounds like starting a tractor.
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That's what I like about this board, you learn stuff.
My mistake then. Hopefully anyone that reads that post will read your follow up as well! Thanks for correcting me.
Perhaps my fuel pump relay is defective... I'm pretty sure I can hear the pump run for a moment before I actually crank the car...
Perhaps I'm just hearing things.
I will check the relay though...
I never claim to be right 100% of the time!
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If you listen to the radio in Portland, OR, you may know me as "Portland's Favorite Soul Brother!"
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