freaky relay wiring

[johnomac]

Found some freaky wiring on my new delorean, theres a 6 pin relay unplugged and the socket for it has a wire bridging 2 of the terminals, should i put the relay back in? There is also a plug unplugged and in its socket (in the relay compartment middle relay socket nearest the engine), another wire bridging the gaps. i also found a switch in the tray on the binnacle and i have no idea what it does or where it goes, thanks in advance for help!

[bozzzydmc]

sorry buddy!

can you post some pictures of what you think your problems are ....otherwise we are struggling !

[ChrisS]

Which 'number' are you talking about, if its 16 thats the RPM relay. If the relay dies you can jump two pins so the fuel pump runs and get you home.

[johnomac]

took some pictures, but cant get them from my phone to the computer. the jumped relay is 11, and the other jumped one was six pins and wasnt fixed down so im guessing its the hot start relay.

[ChrisS]

johnomac Wrote:took some pictures, but cant get them from my phone to the computer. the jumped relay is 11, and the other jumped one was six pins and wasnt fixed down so im guessing its the hot start relay.

OK well relay 11 is the A/C Panel Illumination and some cars have the relay removed and a wire used so the panel only lights up when the headlights are on as that panel gets hot.

The hot start relay is loose at the top of the relay compartment, its a white relay base...that should have NOTHING in,,no wire or relay. If it has then you have a problem with your cold start system and someone has tried to hide the problem by putting the jumper in the hot start relay. The problem could be the thermotime switch, which is screwed into the lh side of the water pump, has died or the fuel accumulator is going bad. But the hot start relay from memory does not have 6 pins...

The RPM relay has 6 pins and is number 16 on the diagram. Have you got a black or green relay where relay 16 is shown? It clips to the underside of the relay tray

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[johnomac]

Not sure about the green relay, but the black one was unplugged when i found it. I expected i would need a new accumulator and thermotime switch so thats kind of a releif that it isnt something else. What are the symptoms of a bad or no rpm relay? i will have a looky tommorrow and see what matches up. Thanks, John

[ChrisS]

johnomac Wrote:Not sure about the green relay, but the black one was unplugged when i found it. I expected i would need a new accumulator and thermotime switch so thats kind of a releif that it isnt something else. What are the symptoms of a bad or no rpm relay? i will have a looky tommorrow and see what matches up. Thanks, John

Black is the original DMC part, the green is an equivalent Volvo part. Its sounding like you RPM relay has died (not uncommon) and someone has wired up the fuel pump to run. With out the relay the car will not start...well unless someone has wired up the terminals 30 and 87

Can you hear a buzzing sound coming from the RH side of the engine when its running? That is the Frequency valve for the lambda system and wont run if the relay is disconnected but there is a jumper wire to run the fuel pump

[NickT]

As ChrisS said about the RPM/ Fuel pump relay.

The originals can be fixed by replacing the NE555 timer chip.

53p from Maplins and 19p for the 8 pin DIL Socket (so you can change the chip in the future without unsoldering)

A pic of your relay would confirm the replies you've had.

NickT.

[Rich H]

Quote:If it has then you have a problem with your cold start system and someone has tried to hide the problem by putting the jumper in the hot start relay. The problem could be the thermotime switch, has died or the fuel accumulator is going bad.

Bit of a contradiction that

To clarify, assuming the relay in question is the hot start relay...

The thermotime switch fires the cold start injector during cranking, but only for a few seconds and only while the engine is cold. There is an obsession with this device being the cause of cold start troubles - it isn't. DeLoreans will start quite happily with this device disconnected entirely.

The purpose of the accumulator is to prevent hot fuel vapourising in the fuel pipes after the engine is turned off. If the fuel evaporates in the fuel lines, then the engine will not start because it needs petrol to run.
If your engine is hot and needs to be cranked for some time before it starts then this is the likely culprit.

The hot start relay is used to bypass the thermotime switch, so that the cold start injector will fire during cranking whether the engine is hot or cold. By firing the cold start injector it gives the engine a squirt of fuel to get it running whilst all the vapour in the lines is cleared out. Using the hot start relay is a quick fix for a dodgy accumulator.

[johnomac]

Ok checked today, its a black relay like the one in the picture, and when i disconnect the jumper wires the car wont start, so i just need a new chip for the relay?
I also found relay 20 and 21 missing?

[Rich H]

johnomac Wrote:Ok checked today, its a black relay like the one in the picture, and when i disconnect the jumper wires the car wont start, so i just need a new chip for the relay?
I also found relay 20 and 21 missing?

Do you actually have the relay in the car? It's just been disconnected?

You can send it to me and I'll do it for the cost of the bits and postage if you want.

20 & 21 are thermal trips, disigned to go open circuit under overload. They are about the size of two sugar lumps and have only two connections - either spades or threaded posts. One is for the door solenoids, the other is for the cooling fans - although other devices may have been tapped off them.