94 850 Turbo keeps blowing fuel pump relays

Post by **Carbon15** » 06 Jul 2015, 13:32

The filter was changed with the pump. If I jump pins 1 and 3 the car will run for a few minutes, then the relay blows. Is there a fuel pressure sensor that's maybe telling it to shut down?

Post by **misha** » 06 Jul 2015, 14:38

Nope....there is no such a thing on a '94.

Like we told you before....relays DON'T just blow themselves out without a reason.There is either a massive load on fuel pump circuit or some kind of short.The only thing which confuses me is why the fuse for fuel pump is not blowing before it blows relay.

Disconnect fuel pump connector in the trunk and turn the key to position II.If relay don't blow itself off,your fuel pump is the culprit.Maybe it's shorted inside.

Post by **erikv11** » 06 Jul 2015, 15:18

misha, check out this post though:

Carbon15 wrote:I hard wired the relay, still got only a few minutes of run time. What tells the relay to shutdown, and does anyone know where that is?

To OP: Is the ECU (or something) cutting out power to the relay circuit? Are the relays you tried getting cooked, or are they all actually fine?

Post by **Carbon15** » 06 Jul 2015, 16:08

That's the weird part. I hot wired one, and inadvertently plugged in one that I though was blown. Car started right up for about the five minutes.

Post by **Carbon15** » 06 Jul 2015, 16:10

I'll be scanning the wiring next, problem is the car is about 45 minutes drive away in the garage I was working on it in.

Post by **misha** » 06 Jul 2015, 17:41

erikv11 wrote:misha, check out this post though:
Carbon15 wrote:I hard wired the relay, still got only a few minutes of run time. What tells the relay to shutdown, and does anyone know where that is?
Read & responded:

misha wrote:Immobiliser.
But...it will turn the car off in a 2-3 seconds....not few minutes.
I would replace fuel pump.
Blowing fuel pump relays,turning engine off after a few minutes....the symptoms are pointing to a bad fuel pump.

Post by **abscate** » 06 Jul 2015, 18:57

Ok..what does a " blown relay" mean?

Are they on fire?
Not working?

Please clarify

Post by **Carbon15** » 07 Jul 2015, 05:05

The fuel pump shuts down as the relay disconnects.

draser · Post by **draser** » 07 Jul 2015, 07:09

So basically the relay opens up. No melted or welded contact or anything. If there's a fuse anywhere in the pump circuit, it's of correct size, and it does not blow, or open, then pump's fine. If you jumper the relay contact does it stay on?

Post by **erikv11** » 07 Jul 2015, 07:53

Yes, these questions have already been answered more than once in this thread
- yes there is a fuse, it doesn't blow
- if he jumpers the relay, fuel supply still stays on only for a few minutes