Thread: designated relay for fuel pump

I have never seen a Bosch relay fail unless it is been exposed to too much current. Put a new one in and you should be fine, make sure to use a 30 relay.

The different color Nissan fuses designate different styles. Some are SPST, some are DPDT, and such.

I have multiple fuses on it,Mike...Theres a 40 amp on the fuse block,then a 15amp fuse inline between there and the relay.I saw relays fail on occasion in my car audio days usually in alarm systems like the starter kill,or door locks back in the day when the relays werent built in to the alarm brain....but yeah,it was not really common.
Like I said this relay is unknown age and it was in a bucket of parts thats been in ,y garage for many years.


Thanks for the Nissan relay info...heres what I ordered to replace it...its the same part# as I have/had now
Bosch 12V 20 30A Relay 0 332 209 150 Mechanical Life 1 000 000 Cycles | eBay

I am really glad its just the relay and not the new pump...and I am also glad I mounted the relay on the trunk side of the strut tower,so I dont have to take the seat out

I've had the same one inline to my fuel pump for about 12 years now.

Heres an update.
After my original install,I thought the relay died...however,it was only overheated apparently.I figured this out over time as I had problems again after putting a new relay in....in fact the car is running on the original relay now after I did another upgrade to the wiring.

I have had a steep learning curve here on this setup,and I wanted to share my findings as I go.
(1)In the original install,I used 14ga wire from the relay to the pump even though AEM states that a min.12Ga should be used in their instructions...my fail here.I didn't think that little difference would matter,and its what I had available at the time.
(2) I grounded the pump to the factory harness like the stock pump and grounded the Relay to a rear strut bolt...however,I only used a 18ga wire here...again. My bad on this.Its just what I had available at the time.

While on a long drive ,I suddenly lost fuel pressure again and was dead on the side of the road.
I noticed the relay was hot and put a jumper on the plug and the car started right up.(it does have less FP when not on the relay,but runs fine)
That got me thinking that the wires are the issue and the relay was overheating from the wires being too small for the AMPS being pulled from this AEM 320 pump

Heres what I have done since to try to remedy the situation...
(1) rewired the power from the relay to the pump with 10 Ga wire instead of 14Ga
(2) replaced the 18Ga ground to the relay with a 10Ga tot he strut bolt.

I re-installed the original relay that I though was dead just to test it and everything is good so far...so the relay was just overheated ,I guess.And it seems like my Re-do has helped...so far.Time will tell,I suppose.
I have ordered another NEW relay to put in just in case the heat damaged this one.I want peace of mind of having a new one..lol

cliff notes,

do it right with bigger wire the first time,dont skimp,and you wont be broke down on the side of the road suddenly from an overheated relay.

Yeah I used 8 gauge wire for power and ground on mine.