Fuel pump relay issues

[James Ballentine]

Hello, I have searched around for post about fuel pump relay issues and have not found anything about it. I have a 2002 Silverado 2500HD 6.0L. So what I have done to get here to this point is the starter went out on the truck. While I had that out I replaced the crank sensor while I had access to it. When I put it back together I put the shield for the starter on in the wrong spot being that I was out in the cold and snow changing it out. When I went to start it the main fuse for the vehicle blew (didn't know what the issue was). I had it towed to the dealer around the corner to figure that out since I was already frustrated at that point and just wanted it back on the road. That was taken care of but driving on the highway it started throwing P0300 random misfire which the crank sensor just needed to have a relearn done on that. Now I drive on the highway and get above 65mph to 70mph the fuel pump relay blows, stranded i just swapped the daytime running lamps to get it back up and running to get off the freeway. Strange thing is that I can drive it all over town 60mph and slower and do not have any issues at all with the relay going out. But even just getting up to 65/70 and then slowing back down to 55 it went out on me. I am scratching my head and have googled and looked up a whole different types of ways to word the problem I am having and still come up with no answer. So if someone has had this issue and what the fix was it would be great. I miss driving on the freeway at times and taking back ways thru town but not always. Just those times I want to get A to B faster it is frustrating. Thanks Again

[richard wysong]

it may be the fuel pump is drawing to much power  but that doesn't explain why only on the hiway other than you are consuming more fuel at a more constant rate. what amp fuse is the fp? no performance issues before it cuts out? how many times has it done this?

[James Ballentine]

It has done it 3 times. I have not tried to drive about 65 again recently. So when I get on the freeway no warning on going out at all it just instantly cuts out. Its not the yellow 20 amp little fuse it is the relay right next to it same as DRL and AC relay the numbers on the top of the relay are 86 30 85 and 87. I was wondering if I am drawing to much power from the pump it probably is the original one in the truck. Just wonder why it would not blow the fuse first instead of the relay itself.

[richard wysong]

yeah it doesn't make sense, you might want to check the voltage and ground resistance to the relay

[richard wysong]

those numbers are the terminal numbers, there should be a part number on the original as well. it's very unusual for a relay to fail let alone 3 times. it's basicly just a switch that's triggered electricaly. can you determine what's failing on the bad relays? if you look at the relay it should have a schematic on the side. if its the solenoid failing it has to be either too much or too little current to the solenoid side causing the failure. if it's the switch side failing there may be signs of the contacts melting in which case it's probably the fuel pump drawing too much juice

[richard wysong]

you can pop the cover off the relay to examine/test it with a small screwdriver

[dna9656]

Richard is prolly on the real source, he's pretty sharp! I think you might consider why that fuel pump has a high electrical draw.... could the internal fuel filter be partially plugged, thus causing the pump to blow your fuse? I wish GM had an external filter on the trucks like they used to, this wouldn't help an internal filter issue, I do not believe they had a fine filter in the older external filter trucks and maybe this caused the internal fuel pumps to go hence the internal fuel filter...I donno. I would also check for any (on line or at a dealer) TSBs (technical Service Bulletins) I would trust my own on line search than that of a busy service writer who can't be aware of EVERY TSB out there.

[richard wysong]

Thanks Doug, I was thinking the same thing when I first read the post but you would think there would be some performance issues if the sock was that restricted.

[James Ballentine]

Thanks for the responses i will check it out here in a bit with my volt meter and take on the freeway to see if it will do it and then see what goes on the relay. I will post what i come up with on it. 

 

Update.. took it out for a drive and the relay failed. I swapped it out with a spare and drove back home. When I swapped the relay out I did notice a slight temp increase on the relay nothing to where I could not handle it just a difference from the spare. I opened the one that failed everything was physically fine. I put that one back in without the cover on and started it up. Worked just fine. So yeah I think the pump is drawing to much amps making the relay open on overload and kill it. I used a toothpick to push the relay closed with key off could hear fuel being called for in the engine. I used the pick behind it so it could not close when it was being started got the issue like what happened while driving at 70 no fuel. I did get under the truck and there is a external filter. I am going to start there and replace that see what happens. Next step would be replacing the pump if I still get the same issue. 

Edited April 30, 2022 by James Ballentine
update info

[James Ballentine]

So I replaced the fuel filter today. I took it for a drive and it did not die on me. The filter must have been clogged enough to make the pump work harder and cause relay to over heat and fail. I will post back again in a few days of driving around to confirm it. Thanks all for the replies. 

[richard wysong]

great! easy fix for a change. the more restricted the flow the higher the amp draw, amazing that it didn't have any drive ability issues. I wonder if your gas mileage may drop now

[James Ballentine]

Hopefully my mpg goes up or better than 12

[[email protected]]

On 4/30/2022 at 10:50 AM, richard wysong said:

you can pop the cover off the relay to examine/test it with a small screwdriver

Had a relay fail on my 2015 6.0L C4500 cut-away van chassis for RV. Hot a "Hi-Power" relay. Measured current draw and got 12 - 14 Amp.  Decided the pump was in process of failing so $700 later (drain & drop 50 gal tank R&R pump) BUT still measures 13 Amp.  Am thinking I have a poor ground for the pump. Will go after that next.

 Partially related issue. I want to put an external filter on the chassis. Discovered lots of dirt in my on-board generator that sucks gas out of the tank. Looking for suggestions on where to put a filter and what filter to get?

[richard wysong]

I would go with a spin on filter if you can find a place to mount it not much higher than the tank. brackets available at NAPA etc