comparing fuel system relays

I have searched and looked over the various diagrams here and didn't find exactly what I was looking for...so if its there, just please point me in that direction and accept my apologies. This may be a stupid question to begin with, but I just want to double check something.....

I am upgrading to a newer ignition / electronic fuel system on an older car using a later factory setup. Everything has been mapped and the harnesses made - so far so good. Now I am at the power supply setup. The fuel relay is different but has the same connectors (30, 85, 86/1, 86/2, 87/1, 87/2). Do these designations have the same purpose on every relay (i.e., does "30" have the same function on any relay labeled "30"?). From what I can tell, it does, but I want to make sure as I'm going to modify it a bit to split the power load on the main fuel relay.

Thanks much. :)

They are supposed to. They are defined in DIN Standard 72 552.

You may find my ramblings on fuel pump relays - ie, they should be ECU controlled else alternator or air-flap or spark, but NOT simply IGN +12V, or oil pressure.

Yes, they are ECU controlled. What has baffled me is that they lump both fuel pumps (in tank and chassis) plus the O2 and injectors all onto one circuit. Typically one of the feeds on the relays either discolor or just burn/melt from the load over time. I want to use the fuel relay (which is light duty IMO) and use it to simply switch on (2) heavy duty 40A relays that will power 1.the pumps and 2.everything else (normally on that circuit). And of course all the relays will be fused.

Is 87/1 the same as 87a (and 87/2 = 87b)? IIRC, 87 is the supply feed to the component. So is 87/1 and 87/2 a switch/feed to two separate components?

I could cheat and go to a guy I know who has done this conversion and get his notes, but to be blunt, I don't like how he did it and need to crash-course learn this on my own to do it (IMO) better/correctly.

Thanks again.

Oldspark, I thought we got rid of the 86VW but am I being paranoid.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Don't mention 1985 vw quantum, bad relay or fuel pump? ...!!! Though I was going to reference it for the KAE 3.300.210 relay - it's a spark-sensing fuel pump relay that also powers on during initial power-up.
But that's for (IMO in general) stupid EFI systems that do include the fuel pump control.
Else for carby vehicles that have electric fuel pumps.


The main point with fuel pump relays is that they should be controlled by an engine running signal (eg, alternator, spark, airflap, ECU) and not by raw IGN +12V or oil-pressure (both of which fail international safety standards and most competition rules).
(Besides which oil-pressure to kill the fuel supply is moronic - it should kill the ignition! Or fuel/air for diesels.)


handyguy, it makes sense to all be on the same circuit logically - ie, one fail, they all fail.
But that doesn't mean the one relay. In fact often injectors are on their own relay & fuse and fuel pumps on a separate relay & fuse.
In part that is because fuel pumps must energise when IGN is first turned on; injectors don't - hence 2 separate circuits.


I like your DIY approach. And I like that you question (ie, don't like) the other solution.

But why not describe what YOU want, else what you don't like about the other solution.
Mind you, my preferred "universal" solution is in that abovementioned unmentionable link (SPST relay(s) and diodes from crank signal, alternator charge light or airflap etc).

But in your case, the ECU does control the fuel pump so I presume you have concerns/objections about the external wiring.
[It's not a Delco with an external "backup"(sic!) for the fuel pump - namely the oil pressure switch (morons!)..???]
Hopefully it is merely the sharing and stressing of the relay...


Admin note: Inclusion of "relay" in the above link kills the underlined blue text... "relay" is hyperlinked (whatever they call it these days)

Dang! I forgot my original reply. I'll blame that on Howard. (Sorry mate, I think THAT thread left me scarred, though having just re-read voltage drop problem, what battery to buy? ....)


handyguy, maybe docs like autoelectricsupplies.co.uk-bosch_terminal_designations.pdf might help.

Not that I deal with those numbers etc - hey! I only learned relay 30, 85, 86, 87 etc since staring on THIS forum! - but I'd assume the /1, /2 etc to be "junctions" off the same "terminal".

That's not the same as saying 87a is a junction off 87 - 87 is the NO contact (connected when the relay energised) whereas 87a is the NC contact (Normally Closed - ie, relay de-energised as in its "normal on-the-shelf" contact position).


But I tend to design ground up (to meet top-down designs) else have to work out those DIN numbers so I design "functional" circuits - ie, I schematically draw the circuits - traditionally I never use(d) "physical" representations with 30, 87, 87a pin numbering.
Hence I work from the description of what is wanted. (I prefer not to infer the desire from a supplied circuit diagram, and I'll rarely decode a "wiring diagram" unless essential to me.)


Howard - no, "design ground up" was not a pun - you know I EARTH my designs. But they do burn top (non-earth) down.
[ I was going to say +ve down, but having worked with telcos where -ve is up for their +ve earth/ground systems... And I'd rather not comment on +ve chassis vehicles... ]

Dear oh dear - how some people have their bits of hijacking humor. If only they knew how it confuses some!

And don't forget good all 87b, essentially a twin SPST relay sharing a coil but separated outputs, think early hazard flashers.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Thanks for all the input....its priceless to me.

The car I am rewiring is a late 80's Volvo 240. They came with a Bosch ECU, but a Chrysler "shake and bake" ignition that like many super models, does not age well. I removed the harness from a late 80's 740 model as it has the Bosch EZK ignition system in it. The 740 system is also used by many who own older BMWs, Porsches and Audi's because its very adaptable, stand alone and makes the upgrade to turbo very easy.

What "others" have done in the past is to try to adapt the 240 system and wiring harness to the 740 set up.....mingling apples and oranges if you will. I prefer to lay in the 740 system and keep the color codes, routing, etc all OE - for diagnostic purposes if not for anything else. It keeps apples as apples. By "adapting" it as they do, there is also alot of mis-routing of harnesses. I also prefer a stock clean install. I solder, heat shrink, use OE clips and mounts, etc. When its done you would swear the Swedes did it on the assembly line 25 years ago. When I figured how to adapt the later cruise controls and AC systems to the older cars, I made a "handbook for dummies" (myself included as if its 5 yrs between upgrades, I want something as simplistic and plain English as I can get). I want to do the same with this. Many have done the EZK upgrade, but IMO, in a cobbled sort of way.

The "new" system will still be on the same "controlled" circuit - that is, the OE fuel relay. But instead of the relay itself handling all that current to supply the injectors, pumps, etc. (its delivered in a single 10-12ga wire and distributed on two 14-16ga wires...its this contact that fries over time) - it would be used as the switch to activate 2 more capable relays to handle the loads individually. The safety fuel/cutoff features WILL remain intact (one of my prime directives here....sorry, the sci-fi geek in me is showing itself; allow me to remove my rubber Spock ears and continue ). So when the signal cuts off the fuel relay, it would also kill the 2 larger relays handling the fuel system.

My hangup in this entire project has been the power supply - figuring it out so that I can modify it. Fortunately, both systems do use the same fuel relay.....now to figure out how they hook up. ?!

Your use of the "main" relay to drive others is an excellent method.
Although the main could drive a load and another relay, IMO why not take the load completely off by having it only power other relays?
That is a common technique, yet often overlooked. (I think of low-voltage cutouts or multi-battery isolators where the main sensing or control relay could switch other or bigger relays for more batteries or larger currents instead of buying more or larger "sensing" relays!)

Your prime directive is excellent - keeping the fuel pump relay operation true to safety requirements etc.

And your OEM look is well understood, though "wow!" - most I know will retrofit the entire "donor vehicle's ECU loom"; though that is in ECU-less carby vehicles.   
But I well understand the desire and work involved in the modifications. Yes - there is lot's to go wrong, but it can be quite straightforward (still a lot of work though).

FYI - I modify my 45 year old vehicle, and although I never cut into the original loom (I make adaptors else run separate wires), I have also started to stick to the original color codes - including adding the new colors pertinent to the newer donor models (from the same manufacturer).

I'll add this to see if its clearer to you than me. I may just be too close or looking at it too long to see the forest for the trees. I've added links to pics of these relays....hopefully they work ok.

The fuel relay is wired as such:

30:   Power supply from fuse
85:   Jumpered to 87/1; and an 18ga wire not shown on the schematics-?
86/1: ECU Terminal
86/2: ECU Terminal
87/1: ECU Terminal, and to 86 on a 40A "radio suppression relay"
87/2: 14ga wire to fuel pumps; 18ga wire to O2 Sensor

The "radio suppression relay" (no idea why they call it that) is a 40A relay (like the ones I want to use to split the circuit up). They are plentiful and work great - I use them for everything from driving lights to pusher fans for the AC. Its wired as such:

30: Power Supply
85: Ground
86: Switch
87: To component(s)

And here's a link to a scan of the OE schematics I'm using.

Thanks again.

Dammit - your links work fine.
Dammit - I've been looking in my Mitchells EFI book.
Dammit - it has the LH for 87-88 240 (& 740, 760, 780, & 82 & 83-86 240 DL & GL). (Earliest Volvo is 1970 ES; latest are the '88s as mentioned.)

I'm not adding any info - I'm just cursing and letting you know. (... that I have that info...)

"Radio Suppression Relay" - probably because it was once used to power a relay and when off, it suppressed its sound (and power consumption etc). Else using the relay provided clean power to the radio, hence eliminating noise...
Yeah - some names are ridiculous. I think I prefer on-off or SPST, but I work from and use "circuit" diagrams so names and labels are usually unnecessary.

I'll compare those bluddy Volvo diagrams later....

UPDATED:
It's later...
Yep - "radio suppression" probably because it removes injector etc noise from the radio supply.

And I assume the 87-88 740 LH EFI, hence the radio interference suppression relay. (It's also a fixed (locked) dizzy with electronic timing...?)

That fuel relay is merely 2 SPST relays in a single package BUT one relay has a series diode in its coil, hence only actuating if the polarity is correct.   (As with spike-suppression diodes, I prefer to mount diodes externally and use ordinary relays.)
The first half (SPST) is energised (grounded) by the ECU (#12, Red) which connects (Brn) fuse #1 +12V to (BluY) the Air Mass Meter (hot-wire) and ECU #9, as well as actuating the radio interference suppression relay which powers the Air Ctrl Valve and injectors (Grn).
It also actuates the polarity-dioded other half (SPST) which supplies the "Lamda Sond" - I presume (heater for the) O2 sensor (green) - and the fuel pump via fuse 11 (pink)

[ No color logic. I'm used to schemes where a green base color means indicators/flashers, blue is accessories, red is lights... ]


Anyhow, that "fuel pump" relay looks ok in that splits the injectors from the pump - ie one contact for each.
But I am surprised the first half is not the polarity protected relay... Why worry about wrong polarity to the pump if you have already supplied it to the ECU?

EFIs I deal with usually have a polarity sensitive relay (from the IGN) that connects power to the ECU - typically a DPST relay which also feeds the injectors, though that could also be 2xSPST.

Fuel pumps are usually a separate relay controlled by the ECU (though some include external oil-pressure bypasses etc which - as I have repeatedly stated - is silly if not moronic).   


The 2 systems (yours and my "typical" EFIs) seem similar though I think mine are more straightforward - ie, relays based on IGN with only the fuel relay being ECU controlled.

But have I got your system analysis right so far???

I'm following some of this Peter, I'm assuming take the 85 lines out and feed separate 40 amp Bosch/Tycho style relays with inline 1N4004 diodes.
Most of the SPST (4 pins)are normally 40 amp rating, the SPDT (5 pin) versions are 30/40 rating. Those shown in the photos just have a different pin (round) style.
N.B. Those colours you referred to are old UK Ripaults/Lucas.
Volvo and Saab NEVER followed any logical wiring colours, UK, German DIN etc.
Volvo STILL go their own way and Saab went to Opel/Vauxhall (Holden) after the GM takeover.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

So the Prince of Darkness shed some light...
That would explain the root of my wiring - my Jap vehicles being derived from Hillman & Rootes Group. With experience, wiring diagrams become unnecessary.

howie ll wrote:

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... SPST (4 pins)are normally 40 amp rating, the SPDT (5 pin) versions are 30/40 rating.

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Yeah - the NO contacts are 40A as usual - it's the spring-loaded NC contacts that are de-rated.

Volvo and SAAB - what do you expect from those northern pagans (bless their souls). But give me a Viggen any day....


And yes - the split relay feed could be done various ways. A single diode (polarity sensitive) relay could feed others - ie, the IGN could go to an 86 via a diode and that relay (30, 87) power the ECU and another relay (for injectors), or the diode could simply feed both relay's 86 direct. Or 85 if it's ground switching (sticking to convention).   

At the moment, handyguy's wiring seems ok - but that's based on my Mitchells info (I haven't considered his linked diagram), and ignoring the "polarity" diode - ie, should it be in a master upstream power relay?


Anyhow, back to the revolution. (Demonstrations in Melbourne (Aust) against the distribution of wealth...)

Viggens? You surely meant the Grippen? Nice piece of kit, especially the 4+ Gen with Israeli avionics and missiles but unfortunately you will be getting F35s, what you the Japanese and the Israelis REALLY want are F22s pref. for the Israelis preferably devoid of US avionics and software.
recently saw some spec on the Israeli MB tank, individual Recaros, individual flat screen displays, all weather 360deg. vision, active and passive defences, individual AC, on board self diagnostics and ah the irony, a German gun!
Joking aside all other tanks are target practice for the Merkavas, Abraams, Challies and Leos.
As for that Aussie joke the Collins (note; Swedish origin) buy US or GB nukes, cheaper and more reliable.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Nah - Viggen - the Grippen is too small.

Ah yes, the might Collins. Probably a case like Jindalee (OTH Radar) - totally incompetent management (I wonder if they eventually signed off to start the Jin contract - it still wasn't signed-off 6 years into the project!).

I hope our F35s don't have the US software, though maybe if they fly back at the Equator as our F18s did, we can get a refund for "lack of delivery".

Our navy uses Bofors - or used too. Never a problem using a neutral countries weapons - we never fired ours either. (Well, not in "war".) But German guns should be good - plenty of practice, and they invented DU (we just use Depleted Uranium on out batteries). But we still have out rail guns...

What I came to the conclusion of was the system (fuel relay) as it exists does control one HD relay to run the injectors, IAC (idle air) motor, etc. through 87/1. However 87/2 has two wires at the terminal: approximately a 14ga and a 16ga. I used the 16ga to feed the O2 sensor (heater) - light duty load, IIRC about 1.5A. I then used the 14ga to feed Pos 86 (switch) on a second radio suppression relay, which then runs the 2 fuel pumps. Thus, the only real "load" on the fuel relay is the O2's heater wire. Its typically 87/2 that discolors and/or melts over time. IIRC, the fuel pumps alone have a constant draw of 15-20A.

Volvo has been known for the skimpy wiring to begin with. I'm floored at the heavy loads (especially in the 700/900 series) where a 20-25A continuous draw will be carried on a 14ga single wire (about every other car in the yards will have either the fuel pump or AC fuse melted in the holder). I've developed a habit of splitting these loads into multiple relays and with larger wiring on about any I get ahold of. The older Volvos had chronic wiring issues, especially those in the early to mid 80's when they made the harnesses in North America. They used a wire with a plastic-like insulation that got brittle and split/corroded and prematurely failed. There was such a bitching about it that Volvo sold the "updated" harnesses to the end user at something like a 70% discount. They began making the harnesses in Belgium (special ed schools did much of it) and they were night and day using a more pliable and heat resistant wire as well as copper connections (replacing aluminum).

What I like about doing this swap/upgrade is that not only does it get a far more improved and efficient ignition system, but the harnesses for it - from the 740 model - was mostly all contained inside the cabin under the dash so its very well preserved in comparison to the 240 setup that baked it under the hood. I typically use Techflex loom/sheathing when making my new harnesses which is not only slick looking but also protects against the heat. And all of the relays are relocated inside the cabin now also.