Fuel pump relay hot as hell blowing fuses

[xxannihilationx]

I have 97 4.3 s10. The number 9 which is a ecm/fuel pump fuse keeps blowing. after messing around, i noticed the relay is getting fvking hot as hell where you can barely even touch it. when this happens the fuse blows. so far i have changed the fuel pump and swapped a friends ecu in and it is still doing the same thing. everyone tells me its a bad ground but where in the hell am i supposed to start? hopefully this has happened to someone before and they can give me some insight

[992drjimmy]

If this were my truck, First thing id do is swap the relay with a different one. Dont buy one, swap with another that is the same.
Find out which wire coming off the pump if ground and run onother one to be sure its grounded good. Second be sure the ground wire coming off the relay is good. I wonder if the relay is bad and shorting inside. Hope so for you as that would be easy fix.

[xxannihilationx]

just tried that and the grounds seem to be good test light... I'm starting to think it could be the voltage regulator?

[992drjimmy]

Maybe pull the alternator and have that checked out.

[xxannihilationx]

its for sure charging and i have an extra one sitting in the garage should i try and throw it on?n how could that be blowing the fuse just curious?

[capspauld]

Are you talking about the voltage regulator on the alternator or some other one?

[xxannihilationx]

eh to be honest i have no clue where it is located...i was reading in a repair manual and i was looking at electrical diagrams and noticed it was on the circuit that is popping fuses. i figured this would make since that it could be the voltage regulator because it only pops them when i accelerate. it will idle forever. is the voltage regulator in the alternator itself?

[xxannihilationx]

oh and btw i called advance auto parts and they told me it was like 35 dollars for a voltage regulator

[capspauld]

Yeah I think the voltage regulator is usually on the alternator. Maybe there is more than one but I dont really know.

[CatDaddy52]

You obviously have a high resistance somewhere in that circuit. Have you checked the f/p connector for corrosion or looseness that would cause high resistance?? This is a known issue...that's why many new f/p manufacturers include a new connector pig-tail to install with new pump. High resistance will cause excessive heat throughout the entire circuit (fuse, relay included)...seems you are running just below the threshold of the fuse limit at idle & when you demand higher fuel volume (acceleration), the pump has to work harder (more current), then you cross that threshold & the fuse pops.

[S10dude]

i had the same problem...it's the fuel pump !...even if it's running at the correct pressure . i tried changing filter to see if it corrected problem , but it did not . replaced pump and heat was gone ....Fixed !

[xxannihilationx]

Quote: Originally Posted by S10dude

i had the same problem...it's the fuel pump !...even if it's running at the correct pressure . i tried changing filter to see if it corrected problem , but it did not . replaced pump and heat was gone ....Fixed !

well i thought that would be it to but i replaced the pump and the filter and its still doing the same thing. the new fuel pump did come with a new connector. thats whats leading me to think its a voltage regulator.

[xxannihilationx]

ok bump for help

i have changed the alternator, fuel pump/filter, computer, new relay.

im so boggled with this. i havent drove my truck in over a month and im getting extremely frustrated with it. i don't have the money to just take it to a shop and have them charge me 50 dollars an hour. any help please? i need this thing running again.

[my_nightmare]

I had one of these issues in my past on a customers truck. We installed a fuel pump in it.
1)check the ground near the fuel pump on chassis. (alot of times it looks connected good but I usually take a small disk grinder or sandpaper and sand the chassis and the washer-wire eyelet where the bolt goes thru to make sure it connects good.)
2) on some models the ground connects to the bed with an optional ground to chassis in front of bed or rear near light connections( i call these the oddball ones...they rare)
3) if you got omn meter or power probe.., start at relay and probe the wire checking to see where the most resistance is... get under truck and check to see if any wires ripped or bent badly(it causes relays to get hot)
4) when u installed f/p.., u did put the new connector on end of old wires? and soldered the connections..right? i have had rare ones pop up from the crimped connections..they would work but would fail at random times.
5) on some of the cheap made f/p pumps.., the internal connector from the inside going to the outside may be defective... I have seen new ones from various parts houses be like this....

Hope this helps...
L8taz

[xxannihilationx]

my nightmare, thank you for the helpful info. i went through all of that and still didn't find anything but i did ohm some grounds and found some that weren't good and it helped my volts stay up while my compressors were on. anyway, i found the problem. about 2 weeks before all this happened i pulled my head unit out and put it back in. apparently, the wiring harness that goes to the fuel pump relay, coming from the fuse panel runs behind the headunit. idk how it happend but i pulled my headunit out and it hasnt blew yet! it must have been grounding out on the unit or something. so thank you all for the help!

[kickflipking_04]

I know this is an old thread but I'm having the same problem. So when you say head unit do you mean your CD player just maken sure cause I took mine out the day before all this started and I wonder if our trucks maybe haven the same problem....

[deathphoenix99]

head unit=radio.

[kickflipking_04]

Yea Thats what I was saying thanks.

[Billbobagns]

I have 97 S10 and can't find fp relay or prime wire. Can anyone help me?

[deathphoenix99]

relay is in the glove box behind the hidden access panel on the left side.

[Billbobagns]

Quote: Originally Posted by deathphoenix99

relay is in the glove box behind the hidden access panel on the left side.

Found those. There are three identical relays there. Any Idea which?

[Billbobagns]

Quote: Originally Posted by Billbobagns

Found those. There are three identical relays there. Any Idea which?

Also, where it that Prime connector. I've looked all around the engine compartment for a red wire hanging lose with a female connector, but can find non.