11 replies to this topic

[dykaar]

Even though I had replaced the crappy capacitors, as per the fix here, I still had an intermittant no start when hot. Turned out I missed some cracked solder joints. Specifically, all the joints where the relay is attached to the PCB. As shown by white arrows, the two in the middle are the coil attach points, and the two top are the relay cage. The picture is after soldering. Even with a jeweller's loupe the cracks were pretty subtle.

Also note that the PCB is two sided, so when you replace the caps, make sure the solder flows through. Yes, the board *should* have plated through holes, but better to make sure.

Since I hit all the relay points, I've been CEL free and the damn thing starts. Scary.

Attached Files

•  Volvo fuel pump relay fix.jpg   68.34K   88 downloads

[boltz]

That's some very sharp troubleshooting! Good work!

Oscilloscope prices have been falling lately, both for stand-alone units, and little pods that hook up to your laptop. I'm starting to wonder if an o-scope would help to find stuff like this.

-JH

[dykaar]

I have all sorts of test equipment as I'm an electrical engineer (you shoulda known since I can't spel).

Finding an intermittent requires patience and a jewellers's loupe. Once something outright fails, then you can break out the toys.

[boltz]

dykaar, on 29 May 2009 - 07:05 PM, said:

I have all sorts of test equipment as I'm an electrical engineer (you shoulda known since I can't spel).

Finding an intermittent requires patience and a jewellers's loupe. Once something outright fails, then you can break out the toys.

I'm just wondering whether if you had the scope on it when things seem to be running okay you might be able to spot some dropouts... it's a slow deterioration taking place rather than a sudden complete failure.

-JH

[dykaar]

I didn't put any test equipment on it, but I had some other issues (O2 low voltage on a new sensor) that appeared to have gone away at the same time, so electrical noise from the intermittent may have been causing problems elswhere. Or not.

The last time it failed no start hot, I jumpered the relay and drove home fine, so I knew it was the relay.

[lcc014]

dykaar, on 29 May 2009 - 06:04 PM, said:

Even though I had replaced the crappy capacitors, as per the fix here, I still had an intermittant no start when hot. Turned out I missed some cracked solder joints. Specifically, all the joints where the relay is attached to the PCB. As shown by white arrows, the two in the middle are the coil attach points, and the two top are the relay cage. The picture is after soldering. Even with a jeweller's loupe the cracks were pretty subtle.

Also note that the PCB is two sided, so when you replace the caps, make sure the solder flows through. Yes, the board *should* have plated through holes, but better to make sure.

Since I hit all the relay points, I've been CEL free and the damn thing starts. Scary.

Which caps. did you replace ?

Thanks,

Ching-Ho Cheng

[dykaar]

Ching-Ho,

If you google:

fuel pump relay fix volvo

You'll find:

http://www.matthewsv...opic.php?t=9681

Not being judgemental, but google skill has become as important as wrench skill in car repair.

[lcc014]

dykaar, on 31 May 2009 - 04:53 PM, said:

Ching-Ho,

If you google:

fuel pump relay fix volvo

You'll find:

http://www.matthewsv...opic.php?t=9681

Not being judgemental, but google skill has become as important as wrench skill in car repair.

dykaar,

Thanks for your link. I will replace the 2 caps. and then inspect all solder joints to find any cracks/micro cracks.

Ching-Ho Cheng

[lcc014]

I pulled my fuel pump relay and removed the cover. It is different than the one from dykaar. Mine only has 1 capacitor - 100uF, 25V. Upon close inspection of all solder joints, I saw one that the connection between ground (terminal 15) and pin 3 of the BTS432E (switch device) has some corrosion. I am going to touch up that solder joint. My relay uses 3 BTS432E switches.

Ching-Ho Cheng

Attached Files

•  0601_103137.jpg   206K   19 downloads
•  0601_103258.jpg   298.95K   19 downloads
•  0601_110141.jpg   103.75K   19 downloads
•  0601_103045.jpg   289.53K   13 downloads

[dykaar]

Ching-Ho,

Your's is a 95, mine's a 94. Your's looks pretty good. Hard to tell if the cap is pooched from your fuzzy pix. The solder joints look nice and shiny to me, but small cracks can be hard to see.

If the cap is bulged (not perfectly cylidracal), or actually puked its guts onto the board, its prolly OK.

If you have a cap laying around, then by all means swap it out.

good luck!

[lcc014]

dykaar, on 01 June 2009 - 04:14 PM, said:

Ching-Ho,

Your's is a 95, mine's a 94. Your's looks pretty good. Hard to tell if the cap is pooched from your fuzzy pix. The solder joints look nice and shiny to me, but small cracks can be hard to see.

If the cap is bulged (not perfectly cylidracal), or actually puked its guts onto the board, its prolly OK.

If you have a cap laying around, then by all means swap it out.

good luck!

dykaar,

The cap. looks perfectly cylindrical to me. For the time being, I don't have an extra one laying around so leave it along for now. I touched up the "corroded" solder joint and the one next to it (pin 1). Both looked bad under the microscope. I will keep my finger cross ....

Thanks,

Ching-Ho Cheng

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