Re: 94 Accord and fuel pump relay symptoms...sorta, see post
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Re: 94 Accord and fuel pump relay symptoms...sorta, see post
| jim beam | 09 Feb 2008 18:28 |
> : Howard Goldstein wrote: > : > : first things first - have you repaired/replaced the main relay? [quoted text clipped - 36 lines] > What would be a symptom of this, would I get the first relay 'clunk' > but not the second 'clunk' that energizes the fuel pump for 2 sec? the first clunk is when contact is made, and the fuel pump comes on. the second is when the pump is turned off again - it's a safety feature that prevents the pump puring gas into a flaming engine compartment in the event of a crash. if your pump is being switched on, but not off again, yes, there's something wrong.
can't recall the code reading procedure on your vehicle, but if the light is on, there will be one. where you read it from is another matter.
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| Howard Goldstein | 09 Feb 2008 18:18 |
: Howard Goldstein wrote: : > : first things first - have you repaired/replaced the main relay? : > : > Damn it I rewrote this article and snipped out the bits where I : > originally wrote that I resoldered everything on the old main relay's : > PCB, saw no change, got a new one, no difference. : : ok. : : : > : > (FWIW I *think* the tests rule out the main relay since its second : > relay won't ever close if both ECM leads off of it are at +12....)(?) : > : > I've also been all over the grounds like stink on you know : > what... Good ground to the body from the main relay and at the two : > ground leads on the A connector on the ECM : : it's possible it's the ecm, but unlikely unless you've shorted some : leads. best way of finding out is to get another one from a junkyard : and test. in my area, they're about $35. what code do you get from the : old one when the check engine light is on?
This is what's so frustrating. There shouldn't have been anything shorted, didn't even jump another car. I see it's about $39 on ebay and another $12 shipping which is probably what it'd cost to drive up to the nearest junkyard that had it for $35 so that's an option, especially if someone else has seen what I see.
With the test jumper installed the CIL stays on continuously even after the second relay comes on. I think that means it doesn't have any codes.
: : other than that, check the ignition switch itself - they tend to fail at : high mileage, particularly when the key is part of a heavy key chain : with lots of junk on it.
What would be a symptom of this, would I get the first relay 'clunk' but not the second 'clunk' that energizes the fuel pump for 2 sec?
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| jim beam | 09 Feb 2008 15:01 |
> : first things first - have you repaired/replaced the main relay? > > Damn it I rewrote this article and snipped out the bits where I > originally wrote that I resoldered everything on the old main relay's > PCB, saw no change, got a new one, no difference. ok.
> (FWIW I *think* the tests rule out the main relay since its second > relay won't ever close if both ECM leads off of it are at +12....)(?) > > I've also been all over the grounds like stink on you know > what... Good ground to the body from the main relay and at the two > ground leads on the A connector on the ECM it's possible it's the ecm, but unlikely unless you've shorted some leads. best way of finding out is to get another one from a junkyard and test. in my area, they're about $35. what code do you get from the old one when the check engine light is on?
other than that, check the ignition switch itself - they tend to fail at high mileage, particularly when the key is part of a heavy key chain with lots of junk on it.
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| Howard Goldstein | 09 Feb 2008 14:53 |
: first things first - have you repaired/replaced the main relay?
Damn it I rewrote this article and snipped out the bits where I originally wrote that I resoldered everything on the old main relay's PCB, saw no change, got a new one, no difference.
(FWIW I *think* the tests rule out the main relay since its second relay won't ever close if both ECM leads off of it are at +12....)(?)
I've also been all over the grounds like stink on you know what... Good ground to the body from the main relay and at the two ground leads on the A connector on the ECM
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| jim beam | 09 Feb 2008 14:37 |
> Anyone ever repair a funky ECM by opening it up and cleaning up any > bad solder joints? Will the ECM avoid sending fuel if it sees [quoted text clipped - 41 lines] > - Anyone have a compatible ECM they'd loan me to do a swap check if > I've ruled out everything else? first things first - have you repaired/replaced the main relay?
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| Howard Goldstein | 09 Feb 2008 13:06 |
Anyone ever repair a funky ECM by opening it up and cleaning up any bad solder joints? Will the ECM avoid sending fuel if it sees something "wrong" at its sensors although there aren't any codes stored? Should I toss the ECM at this point?
Long nauseating details and plea follow:
Recap: 94 Accord with the classic main relay (PGM-FI) symptoms (no fuel pump sound for 2 seconds as required when starting, check engine light on, can't start) with a twist: It only fails in a cold car when ambient is around above about 70F/27C, *and* leaving the key in the II (IGN) position for anywhere from 1 to 4 minutes has always allowed the second relay and then the fuel pump to kick in, CIL goes off and we're off. Never a problem while driving, and if the engine is warm it's never a problem starting. It also isn't a problem when the entire car has cooled to the low 60s/low 20s F/C or below. Cranking it doesn't help.
What I've done: I've verified there's no 12v back at the fuel pump when this happens but for good reasonI've measured battery voltage at the relay pins 6 (good) and 1 (bad) and back at the ECM A25&B1 and A7 (these are the connections to the relay) where it's good and bad (both at Vbatt). I've jumpered the service connector and the CIL stays on all the time. I've got good grounds at the ECM A connector and the PGM-FI.
What seems to be busted: WTF is up with my ECM? The skiz show the fuel pump relay in the PGM-FI won't close unless the ECM pulls down its A7 (which is PGM-FI pin 1). It doesn't pull it down, not unless the car is left in II/IGN for a couple of minutes under the conditions above.
Some specific questions:
- What else am I missing?
- Does the ECM look for other things, a sensor in a sane range or something other than battery voltage coming off of PGM-FI 6, before it'll turn on the fuel pump for the 2 seconds?
- Is it worth cracking open the ECM to reheat any obviously flakey solder joints? Can the ECM be cracked open easily?
- Anyone have a compatible ECM they'd loan me to do a swap check if I've ruled out everything else?
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