94 850 Turbo keeps blowing fuel pump relays

[BEJinFbk]

If you have 10.5 at the relay, what is battery voltage?
If there's a significant difference, you may have bad
contacts in overload relay 2/31, ( position 106 ).

105 Overload Relay .pdf

(229.51 KiB) Downloaded 242 times

Overload relays 105 & 106 don't monitor voltage, as
previously stated in this post. They just provide an auxiliary
set of contacts for accessories that go on and off with the
ignition switch to prevent an overloading of the actual ignition
switch contacts. If the contacts are failing, there could be
extra current draw that reduces voltage and blows fuses.

[BEJinFbk]

Several things going on here: there's this overload relay that monitors current for the pump, so when car quits you can check volts on blue/red wire that powers relay contact. Then, there's the relay coil voltage on yel/gray wire coming from ecu which can be checked when engine quits. Fuse for pump is 15 amps. There are also 2 grounds, one for relay coil in electrical box and one for pp under the rear seat. The coil gnd can be ohmed to chassis, use meter lower ohm scale, wire at relay socket is black, and pump gnd is black also. You should read zero ohms for gnd wires.

If you're talking about the fuel pump relay, #2/23,
please call it the fuel pump relay to avoid confusion.

[Carbon15]

Other research mentioned the cam position sensor and crank shaft position sensor. I swapped these out from my parts car and still no start. As a test we did a spark test, now getting no spark. The ignition system is pretty new. Is there a sensor that may have went bad causing no spark?

[BEJinFbk]

What is your battery voltage?
If you aren't running high enough,
you can have all sorts of trouble.

[Carbon15]

It was low from all the attempted starting. Put it on charge last night and gave up for the night.

[Carbon15]

Read 13.6 on the battery, still a no start. Question, the currently install Cam Position sensor came out of a 98 S 70 Turbo, is it compatible with my 94 850 Turbo?

[BEJinFbk]

So... 13.6 at the battery,
What's showing on pin 15
at the fuel pump relay socket?

[Carbon15]

Honestly didn't have a chance to check, had to strip out the last of the parts off the 98. It's going to the bone yard today. I'll check and get back to you.