coelcanth

at least, i think it's not the relay...

1992 honda civic:
fuel pump takes a long time to prime when first starting, especially after a rainy night.. even after slight drizzle..

first i re-soldered the original relay.. problem seemed to improve immediately but eventually came back after a few weeks, and got as bad as needing a five or ten minute wait to prime.
then we were at a shop getting new tires and the nice canadian mechanic wanted to clean the throttle body for free to improve a poor idle issue (and it did help) and this seemed to also help the priming issue.. was it my imagination or did we just have good dry weather for a spell?
anyway, after another while the problem came back (idle is still good though).
next, i bought a cheap non-oem relay off ebay (made in Taiwan). problem solved for maybe a few months or so but now back up to a three or so minute wait to prime when starting after rain.

since the issue seems moisture related, i cleaned out most obvious wiring connections under the hood and filled plugs with dielectric grease but i notice no change.
i also cleaned the ground connections ring terminal on the thermostat housing, but i don't see how this could be related since the pump primed while these were all off and disconnected.

one other job i did in the meantime (to solve a stalling-at-speed issue) was replacing the ICM, distributor cap, rotor, and coil (all made in Japan except icm).. no change to priming symptom ..but it did give me wicked interference and make it impossible to listen to my favorite radio station while the car is running....

tony_2018

check your grounds.

coelcanth

any ones in particular ?

mk378

The four small wires that connect to the thermostat housing, which is near the starter.

If it's not the main relay or the grounds, the ECU is bad. Often replacing the major capacitors in the ECU, and cleaning up any damage due to leaky capacitors, will fix it.

coelcanth

yeah.. those grounds were the second thing i tried, like i mentioned in the original post..
i don't think it could be them since the pump primed fine while they were disconnected

i hope it's not the ECU, but i'll look into it

muellersfan

^^^

oresama

I had this exact issue! Through process of elimination, I ruled out everything but the ECU ( i didn't have a spare to test).
Sent my ecu to a refurbishing service i found on ebay and they changed out all the capacitors, and the fuel pump primed right away after installing the refurbished ECU.

JasonHi

as the others said ECU is bad. I had this problem before and tried a spare one I had laying around and it fired right up.