fuel pump Hotwire issue ??

[HUENEMEGN]

How long do fuel pump “ Hotwires “ last ? Im asking because I’m have a intermittent start/no start .
I see my fp gauge has zero pressure and no sound of the pump priming . I had also used the jumper wire behind the alternator to prime the pump and it would make the car start but not all the time . Today was one of those days it wouldnt prime so the car wouldn’t start .
I pulled out the pump from the tank, checked all the connections . They look good and tight . I benched tested the pump and it works . I reinstalled everything, tried to start the car , still no pressure . Then I went ahead and bypassed the fp Hotwire ( so like stock) and I heard the pump prime. Then it started the car . I then went back to reinstall the Hotwire and it works again . No issues . This has been happing here and there . Should I replace my Hotwire ? Or can it be a bad relay ? Hotwire is about 15+ years I would say.

DW400 pump
e85
Newer sending Unit
Old Hotwire

 

[scgnx2]

I would definitely suspect the relay is bad.
Some kits mount the relay by the gas tank and there exposed to the elements. Had to replace my relay last year as it failed even though it was mounted under the hood.
The funny thing about it was if I disconnected the battery and reconnected it the relay would click and function for awhile. It would eventually stick open again. Easy fix tho

 

[HUENEMEGN]

I would definitely suspect the relay is bad.
Some kits mount the relay by the gas tank and there exposed to the elements. Had to replace my relay last year as it failed even though it was mounted under the hood.
The funny thing about it was if I disconnected the battery and reconnected it the relay would click and function for awhile. It would eventually stick open again. Easy fix tho

Exactly. My relay is at the rear of the tank just chilling .

 

[dynoman]

Relays opening & closing under load eats up the contacts . When I worked at GM as an automation electrician , I would carry spare relays in my tool box for machines that cycled hundreds of times a day . The most damage is done when the relay is opened under load . Change the relay and open up the old one and you will see what I mean .

 

[HUENEMEGN]

Relays opening & closing under load eats up the contacts . When I worked at GM as an automation electrician , I would carry spare relays in my tool box for machines that cycled hundreds of times a day . The most damage is done when the relay is opened under load . Change the relay and open up the old one and you will see what I mean .

I would try that . Now I just remembered that not that long ago , the fuse in-line the Hotwire was burnt/melted . I replaced it but it didn’t make the pump prime . Most the times I would fix it by using the prime wire behind the alternator but I notice it would take a few touches and a few seconds to prime . It didn’t prime immediately . Like it struggled and then it would fully prime . Weird !

 

[Chuck Leeper]

the fuse in-line the Hotwire was burnt/melted .

Bad ground or shorted somewhere.
Or pump is going south and overloading the fuse holder.

 

[HUENEMEGN]

Bad ground or shorted somewhere.
Or pump is going south and overloading the fuse holder.

Okay . Something to consider . The pump has low miles as I don’t drive the car much . Ever since I changed the burnt fuse it hasn’t happen . I checked it yesterday as well .

 

[Chuck Leeper]

Okay . Something to consider . The pump has low miles as I don’t drive the car much . Ever since I changed the burnt fuse it hasn’t happen . I checked it yesterday as well .

And I just changed the pump on my friends 55 Chevy/LS car.
Same story... It had a pump 2 yrs ago, got very little use.
He went out to take a ride... Pump primed, let out a squawk and died.
I did an autopsy. The pump, sock, and filter were all corroded, rusted.
I posted the pics.

Fuel pump autopsy....

Just did an "autopsy" on a 2 y/o Walbro pump. BI: 55 Chevy/LS combo. A Tanks Inc tank & in-tank pump, external regulator. Car sees very little use and sits in a temp controlled garage. Maybe 500 mi/yr. Pump E10 premium with Stabil added. Initially, the car would sputter, start, die. Owner pulled...

www.turbobuick.com

 

[dynoman]

I would try that . Now I just remembered that not that long ago , the fuse in-line the Hotwire was burnt/melted . I replaced it but it didn’t make the pump prime . Most the times I would fix it by using the prime wire behind the alternator but I notice it would take a few touches and a few seconds to prime . It didn’t prime immediately . Like it struggled and then it would fully prime . Weird !

As the contacts get burned it becomes a high resistance connection which will raise the current draw on the circuit and possibly blow the fuse . A few touches on the prime wire is the same as cycling the relay contacts a few times until it makes a good enough connection to start the pump .

 

[dynoman]

Also like Chuck said , a bad ground will raise the resistance of the circuit and cause high current . If you have 10 gauge wire feeding the pump it will need at least 10 gauge wire for ground .

 

[BEATAV8]

Yes adding 10ga ground from the fuel pump to the battery up front is a big help performance wise. Also using a beefed up intermediate harness in the tank with dual power and dual ground wires is a huge help too.

 

[Chuck Leeper]

A starting point.....

Diagnosing Voltage Drops Electrical Automotive Troubleshooting

Voltage drop is one of the most common electrical problems showing up in automotive shops today. This article features the symptoms of voltage drop, basic procedures and grounding tests to keep you safe.

www.fluke.com

 

[HUENEMEGN]

Does anyone know a Hotwire relay part number to buy at local parts store ? Or do I have to order ?

Happen again . Twice just now. No fuel pressure .
By simply tapping on the Hotwire relay , I get fuel pressure again and the car fires right up .

 

[1KWIKSIX]

Maybe try Caspers’ Electronics

 

[Chuck Leeper]

Most all ap stores should have them.
We use Bosch.
Before you replace it, find out what's causing the failures.
All pins clean AND tight when it's plugged in?

 

[HUENEMEGN]

Most all ap stores should have them.
We use Bosch.
Before you replace it, find out what's causing the failures.
All pins clean AND tight when it's plugged in?

I haven’t taking out . Still in the back bumper . It’s old. Maybe around 13 years old.

 

[HUENEMEGN]

I haven’t taking out . Still in the back bumper . It’s old. Maybe around 13 years old.

Can I get a part number or a picture of what I’m looking for when I go to the Autoparts store . Or just take it out and have them cross
Reference with Bosch ??

 

[Chuck Leeper]

Google it... there's 1000's of hits.

 

[HUENEMEGN]

Can I get a part number or a picture of what I’m looking for when I go to the Autoparts store . Or just take it out and have them cross
Reference with Bosch ??

Google it... there's 1000's of hits.

I did . Came up with nothing . That’s why I asked here.

 

[scgnx2]

Just replacing the Relay module may or may not fix your issue. The female connector terminals in the plug can be corroded or damaged which can cause intermittent contact. Here’s a better solution which is reasonable priced :