Fuel Relays being killed - Help :)
Fuel Relays being killed - Help :) If this doesn’t belong here I’m sorry!
LS Swapped a 66 C10. First start up and things went well for about 15 mins, then truck died just as someone cut off the key.
Traced it down to a bad relay, replaced, and it fires right back up for about 2 mins before it killed that one too.
So two questions:
1) any one have any idea what would cause relays to be eaten like that? I’d have expected a fuse to blow first if there was a wiring issue.
2) any reason why LSs won’t start if the constant hot is jumpered to the fuel pump wire? Fuel pump came on that way, but engine wouldn’t start back up, and I can’t think if a reason why not but maybe I’m missing something.
Thanks!
LS Swapped a 66 C10. First start up and things went well for about 15 mins, then truck died just as someone cut off the key.
Traced it down to a bad relay, replaced, and it fires right back up for about 2 mins before it killed that one too.
So two questions:
1) any one have any idea what would cause relays to be eaten like that? I’d have expected a fuse to blow first if there was a wiring issue.
2) any reason why LSs won’t start if the constant hot is jumpered to the fuel pump wire? Fuel pump came on that way, but engine wouldn’t start back up, and I can’t think if a reason why not but maybe I’m missing something.
Thanks!
If this doesn’t belong here I’m sorry!
LS Swapped a 66 C10. First start up and things went well for about 15 mins, then truck died just as someone cut off the key.
Traced it down to a bad relay, replaced, and it fires right back up for about 2 mins before it killed that one too.
So two questions:
1) any one have any idea what would cause relays to be eaten like that? I’d have expected a fuse to blow first if there was a wiring issue.
2) any reason why LSs won’t start if the constant hot is jumpered to the fuel pump wire? Fuel pump came on that way, but engine wouldn’t start back up, and I can’t think if a reason why not but maybe I’m missing something.
Thanks!
LS Swapped a 66 C10. First start up and things went well for about 15 mins, then truck died just as someone cut off the key.
Traced it down to a bad relay, replaced, and it fires right back up for about 2 mins before it killed that one too.
So two questions:
1) any one have any idea what would cause relays to be eaten like that? I’d have expected a fuse to blow first if there was a wiring issue.
2) any reason why LSs won’t start if the constant hot is jumpered to the fuel pump wire? Fuel pump came on that way, but engine wouldn’t start back up, and I can’t think if a reason why not but maybe I’m missing something.
Thanks!
One Reason it won't start with it jumped is the PCM needs to see an rpm signal, if it doesn't see it then it won't even try to keep the motor running
Check your wiring at the relay. Make sure they aren't loose in any way. Check where your relays are grounded. Check voltage at your relays. How old is your fuel pump?? I'd check what voltage is getting to the pump too. If it's an older/failing pump it could be trying to draw too much thru the relay killing them off.
One Reason it won't start with it jumped is the PCM needs to see an rpm signal, if it doesn't see it then it won't even try to keep the motor running
One Reason it won't start with it jumped is the PCM needs to see an rpm signal, if it doesn't see it then it won't even try to keep the motor running
Relays are grounded through the fuse block which is directly grounded to the head. Should be good there.
fuel pump is a brand new aeromotive 340. Wiring is all new too, so I’m a bit stumped.
For the PCM RPM signal, how does having the relay jumped change that? Does the ECM fuel pump control wire somehow manage that? That’s the only thing not connected when jumped?
thanks!!
Thanks for the reply!
Relays are grounded through the fuse block which is directly grounded to the head. Should be good there.
fuel pump is a brand new aeromotive 340. Wiring is all new too, so I’m a bit stumped.
For the PCM RPM signal, how does having the relay jumped change that? Does the ECM fuel pump control wire somehow manage that? That’s the only thing not connected when jumped?
thanks!!
Relays are grounded through the fuse block which is directly grounded to the head. Should be good there.
fuel pump is a brand new aeromotive 340. Wiring is all new too, so I’m a bit stumped.
For the PCM RPM signal, how does having the relay jumped change that? Does the ECM fuel pump control wire somehow manage that? That’s the only thing not connected when jumped?
thanks!!
What's the condition of the Alternator?? Maybe you're having a voltage spike.
Have you popped open the bad relays to see what's going on in there?? Might help to narrow things down. But most likely there's a bad connection somewhere in the fuel pump circuit
Have you popped open the bad relays to see what's going on in there?? Might help to narrow things down. But most likely there's a bad connection somewhere in the fuel pump circuit
Last edited by 91 Z28; Dec 11, 2023 at 12:36 AM.
