It appears that the relay is bad.
Is there a source for these?
Kris

Most any auto electric shop should have them or even some electronic stores.

You might want to stay away from the chain auto stores as when they come carded in a plastic bubble and they are over priced.

You want to find one with the same current rating, like 15A and have the same symbols for the contacts as yours shows on the outside of the can.

Also 12 volt coil relays are as very common and can go for as little as $3.50+ in my neighborhood.

If you happen to find an volt/ampere meter along the way in your travels you might want to check the current draw of the pumps. This is an idea that there may be a reason why the relay stuck besides old age.
The pumps may be drawing to much current within themselves or some bad wiring in that circuit and causing the welding up the contacts.

Happy you found something!
Phil

Phil is probably correct.

One of my sources shows a special relay, but the wiring diagrams show a simple change over relay and those are very common.

Car alarm and car stereo installers use them. And my local DIY electronic supply store has them as well.
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Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

I am on Whidbey Island WA state. I have an analog volt meter and that along with my test light show a slight draw when the relay is out and #7 fuse is in.With the test light it pulses in time to the clock ticking. The previous owner had an after market relay in the glove box. With it installed my test light was back on bright. Could be that the draw is somewhere else.
Is there a simple test for that?

Kris

Yes there is a test or an elimination exercise that can be done.

You can disconnect the main pump underneath the car at the pump or you can lift the rear seat and do it there.
On a wagon I would choose the rear seat location as it just flips up.

On the drivers side under the carpet there is a connector that you can unplug.

You can also make current and voltage checks from there too!
If you get something less than a battery voltage reading there then you may have a frayed wire going to ground.

If you put your ampere meter in series with the pump by itself, straight from the battery with a long wire, so you can record the actual draw.
Then you can do the same thing with the completed circuit intact and see if there is a difference other than what tiny bit more the in-tank pump draws.


Give a good "look see" at the wiring from the rear seat area, backwards and forward, along the side of the car and farther back into the trunk area under its carpet too.
Access to the pump is through, a panel covered hole, located in the back hump, just left of the center area.

The floorboard/seating areas, along with the large trunks on these cars, can receive beatings from everything imaginable over of the years.

Phil

Phil,

I might be wrong, but I think what is wrong with Kris' car is a bad fuel pump relay. And I think the spare he found is either a faulty fuel pump relay or more likely, not the correct relay.

I have the Volvo green books and it clearly shows the main relay and the fuel pump relay as being different. In fact calling the fuel pump relay the fuel pump relay is a little misleading as it supplies power for both the air slide heater and the control pressure regulator heater as well and there in lies the difference in this relay.

The fuel pump relay Kris needs is not the cheap simple and easily available Bosch relay that is used as the main relay. The cheaper relay is sometimes called a change over relay because as the relay is powered up, one pole of the relay is switch off, while another is switched on. This means that one of the 2 switched poles on a change over relay has power all the time.

On the needed fuel pump relay, the 2 poles are both switched on at the same time when the relay is activated, one pole for the fuel pump and the other pole for the 2 heaters.

And if the spare relay Kris used is indeed a change over relay, then there would be a significant draw as either the fuel pump or the 2 heaters are being powered up all the time.
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Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

Hi Eric,

I will not dispute anything you have said about there could be a "special" relay. Nor will there be any doubt in my mind that it is later superseded by the same makers on both sides of the aisle on all later cars.

I have a 78 with the green books I purchased at the same time I bought the car. I have not used them much but they do have nice illustrations for teaching me about the car. Sadly or not that whole system got superseded.

I agree that it is most likely to be the relay that has a problem. My question is what made it fail.

The relay in question could fail for many reasons on this age car. I think the Lambda Sond system uses the relay you describe for controlling the O2 sensor and frequency valve may be the same type? I do not have access to my books or my car to check that. It's not that uncommon a relay in the relay world!

I was suggesting him to check out the circuit for excessive current draw if in fact the contacts were stuck together.
A blindly switched in relay, that was not the same, can be as likely a smoked one as well!

I suggested, for him to look at the side of the relay that tells you all you need to keep the circuit working as design. Provided the correct one is there to start.

As we have all learned, it is this studying of schematics that can provide knowledge or insight to make even more changes.
Hopefully for the better, before scraping the whole program as engineers do or in this case, the car! All of this for a relay that costs, a mere few dollars made in large quantities, even today and written into an electrical design idea sketched with a pencil or computer program with a catalog listing. Getting things scaled up or down to fit are just not that hard anymore! Its a well travel road by now but with societies caveats.

That meaning, there are many different "pin out" configurations as each manufacture wants a piece of the "money action" to do absolutely the same thing.
It Happens, day in and day out in everything made, even though, it's massively consumed!
Just a waste of time that creates more chaos! IMHO.

Its life, in an ever changing world that "mankind" appears to be never satisfied with. Be it driven by ideology or money making.

As long as these things will happen, you as a business operator or "I" as a lonely car owner, will have to follow what basic information we can find around us.

In your life, you figured out that you can out to make things work and even to a point to make it somewhat profitable.

I tip my hat over to you and many "thanks" for being on the BrickBoard to share your expertise.

Phil

Phil,

The Volvo green book I am using is specific for 1976 only and there are differences, one being the Lambda system, which did not get used until 1978.

But that is part of the fun of working on old Volvos? The kind of fun that can put one in a straight jacket!!

And don't get me started on standardized parts!! I tell anyone that will listen that if I wanted to stock an example of every automotive engine air filter every made for cars and light trucks, I could not fit them in my shop. And that does not include motorcycles, industrial equipment, farm equipment, generators, lawn mowers, go karts, weed whackers, etc, etc.

And if you remember the Apollo 13 accident, this kind of nonsense almost cost the lives of 3 astronauts when the crew had to change their CO2 scrubbers aka a glorified air filter.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

I borrowed an amp meter from the previous owner. With the relay out the draw is .1 with the relay in it is .9 . Is that enough to warrant the new special relay. Eric do you have it?

Kris

A 1 amp draw is too much. And a .100 amp draw is on the upper limit of acceptable. How many amps with fuse #7 removed?

I will check to see if I have the relay in stock tomorrow when I get to work. If I don't, it is stocked at a local warehouse.

Did you check the schematic on the side of the relay? If it is possible, can you read all of the numbers? The relay should have 85, 86, 30, 87 and ?
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Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

I do have the fuel pump relay in stock.

Send me an email at: "e_hamlet" at @hotmail dot com

"I do have the fuel pump relay in stock."

If it's not too much to ask, could you give us the Bosch # for that relay Eric?

I ask because I used to have a '76 and might have "saved" one. It sounds much like the Main headlight relay for later 200/700/900, minus the diode that Art mentioned.



--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Good question. Seems obvious, yet so far no part numbers have been conveyed at either end of this thread.

My 1976 green manual shows the relay with the arc quenching diode arrangement, but if the physical pinout allows, the sort of dual form-A (DPST) contact arrangement used in the later headlight relays would function here.

Referring to the Quick Reference Parts book (QRP) as I am certain you are, the headlight relay is 1324749.

The fuel pump relay (for 76-77) part number mentioned in that QRP and corroborated in VADIS and RPR's catalog has two listed; the 1324492 (which I suspect is the original unit with the diode) and 1324749.

The headlight relay is also used in the k-jet lambda sond, and according to QRP, to my surprise, also in 240 power windows.

The isolated contacts are labeled 87 and 87b on the 4749 as contrasted to 87 and 87c for the diode-equipped 4492.

Wonder which one Kris wants to pull out.

--
Art Benstein near Baltimore

Women and cats will do as they please, and men and dogs should relax and get used to the idea. -Robert A. Heinlein

I am looking for the fuel pump relay at least at this point.

Kris

Volvo part number: 1324749
Bosch part number: 0 332 015 006
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Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

How many wires to the suspect relay?
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Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

5 wires.

Check the schematic on the side of both the old fuel pump relay and the spare relay that you found, but it seems like you need the special relay.

The special relay is available from Napa for at least $34.99, but that is a little more than Volvo's suggested list price of $34.51.

I should have the correct new original Bosch relay for $25.00 plus shipping or a new aftermarket copy of the same relay for $18.00 plus shipping.


--
Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

I believe you are once again giving the correct advice, and that is because you have real and relevant experience and are not just extrapolating and theorizing.

The relay is special because it has internally a diode in series with its 87c terminal. This is not (Phil) to be confused with a flyback diode across the coil -- it is a special arrangement to keep the relay contacts from arc damage by dumping the pump's magnetic collapse energy into the resistive loads of the air slide and CPR heater.

Without that circuit, it could easily happen an unprotected relay's contacts would weld and allow the fuel pump to run after the engine has stoppped (safety) and after the car is parked (battery discharge).

Granted, an ordinary form A relay could be used with the addition of a 3-amp diode, but my assumption here is we are not interested in modifying the system over the internet, but having a plug-and-play correct part replacement. That is why I emphasized in Kris's other thread that this relay is a special and not to be replaced haphazardly.

Here is that post: battery_fine_yesterday_today_deadany_quick_check.html

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Art Benstein near Baltimore

He who obtains has little. He who scatters has much. -Lao Tzu

1st, I want to mention to Kris that he can drive the car with the faulty relay, but you have to remove the relay or the fuse when the car is not being used to save the battery until you get a replacement for the relay.

2nd, Thank you Art for the kudos.

And here is my long overdue thank you for your vast knowledge and willingness to share said knowledge.

FYI, Bosch updated the relay in question and removed the diode and the relay now has a double contact set up that isolates the two circuits when the relay is not energized.

A similar set up is used in the later red block starter solenoids. I use the available tap on the starter solenoid to provide temporary power to an electronic ignition while starting on old Volvos with old style ignition coils that have the integral ignition switch and armored cable.

--
Eric

Hi Performance Automotive Service (formerly OVO or Old Volvos Only)

Torrance, CA 90502

We usually have them in stock.

What part of the world are you located?
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502