Engine quit (Page 5/5)
theogre FEB 26, 10:00 AM

quote
Originally posted by maryjane:
The other thing to remember is that IF the engine is running and IF your oil pressure switch is good, the fuel pump can/will be powered thru the OP switch even if the fuel pump relay fails. But, a major bad connection at battery or at a fusible kink or at the battery junction can prevent the fp from recieving any power.

Many engine swap installs removed the OP Switch or wiring to it for F-pump. So you never get fuel running after long cranking like many OE Engine Setups.

Worse, If this swap was wire w/ OP Switch same as OE setup... @ minimum the OP Switch in the OP-Sender is fried to carrying the 2 fans + F-pump amps too
Can be OP-Sender and Plug has "melted" even tho OP-gauge still works.

Many car relays and some switches are 20a but only Resistive load @ best ~ 10a for motors and other Inductive loads.
OE F-pump relay is one of them and safely handle F-pump but not extra 2 fans even small "radiator type" fans likely used here.
The fans by themselves may "over load" 1 OE relay too.

IOW F-pump and other using same OE relay that have Heavy contacts then most others and may take a bit more DC power thru them. But you will start to burn the contacts cause contact resistance causing more burning and kill them fast when near or at the Inductive limit. Most Relay/Switches are 1/4 to 1/3 Inductive Load rated vs. X Amps "printed" on them. If you read a Data Sheet for a relay or switch that say nothing about Inductive Loads common to knockoffs parts then Do Not use whatever to control motors.
stevep914 FEB 26, 10:55 AM
I have the two cooling fans now on their own circuit with a 20 amp fuse. Seems to be fine thanks!
maryjane FEB 26, 11:46 AM

quote
Originally posted by stevep914:

I have the two cooling fans now on their own circuit with a 20 amp fuse. Seems to be fine thanks!


Sounds like you got it well in hand!!
Ya really should use an amp meter to check full load on the fans to determine fuse rating.
But, In most cases, fuse or circuit breaker is not there to protect the device..it's there to protect the wire insulation. All conductors (wire) have a temperature rating and it's the insulation that the manufacturer looks at to determine that temp rating. Once the heat breaks the insulation down, shorts to ground occur and that draws even more current and events cascade into a fire. Cheap wire can break down and cause problems just under the rating of the fuse or circuit breaker.
(in household romex type wire, you will often see it printed on the outside of the wire as something around 600°).

[This message has been edited by maryjane (edited 02-26-2023).]

stevep914 MAR 01, 08:07 PM
Thanks! So far so good, but I am going to continue to monitor this, and other electrical issues. We have very high salt content in the air here in Mazatlan, which corrodes anything metal. I even paint the underbody of the car annually to protect agains this. I am sure this deteriorates electrical stuff much quicker than most other places.