Loud hum/and very warm by access panel for fuel pump and sender

[papanoel]

I was driving and noticed a loud hum. Thought it was fans but it wasn't. after about 30 minutes of driving pulled over and Traced it to coming from the access panel to the fuel pump and fuel sender. The access panel was extremley warm. Its 55 degrees here in nyc right now.

So any thoughts on whats going on? It seems somethings wrong with the fuel pump. but car was running fine.

in case its relevant the car ate the alternator/water belt up earlier today and i had to replace it. Car almost overheated but i noticed it and pulled over before any coolant started spewing out. Car did go high above 220 though for about 30 seconds.

[Nicholas R]

A lot of fuel pumps hum. The louder it gets, the hotter it's getting. Not much you can do about it; eventually it will fail. Could be a week, could be 5 years. The only thing you can do is keep the gas tank more full with gas so that the pump is being cooled more by the gas.

[DMCMW Dave]

I was driving and noticed a loud hum. Thought it was fans but it wasn't. after about 30 minutes of driving pulled over and Traced it to coming from the access panel to the fuel pump and fuel sender. The access panel was extremley warm. Its 55 degrees here in nyc right now.
.

It's normal for that panel to be warm. It's directly inline with air coming from the radiator as you drive.

Some fuel pumps are noisier than others, some get noisy when warm, it's may mean it's on the way out, or the pickup hose is collapsing, or it's just a noisy one.

A failing fuel pump won't generate enough heat to be noticeable at the floor, it is immersed in gasoline (unless the tank is empty, then it's immersed in 13 gallons of air and separated from that floor panel by at least another inch or two of air.)

[hmcelraft]

The fuel pump ground goes through the inertia switch mounted either on the left foot panel wall or on the lambda mileage/light meter bracket on the lower front bulkhead by the left foot. That switch can be the source of current resistance that can heat the pump and cause it to hum - sometimes really loud. It was one of the original recall items and should have been replaced. The fuel pickup line in the fuel tank can also be weak and collapse, also causing a hum. Connections are the more likely issue.

I would suggest that you check the ground continuity and the power connections for the fuel pump. Are any of the fuses melted in the fuse box (#7)? Is the RPM relay deformed (overheated) in any way? These are additional sources of electrical resistance applicable to the fuel pump.

[papanoel]

Thanks guys I drove it home 40 miles with no issues but it occured to me... could be related to a cold start issue my car has developed in last few weeks?

[papanoel]

Thought I'd ressurect this thread instead of making a new one since I've had an issue again.

My fuel pump overheated and car stalled out on me the other day in 75 degree weather in the city.
Fuel pump was extremely loud and high pitched hum for a few minutes as i tried to get to my parents apartment in manhattan.
Once i got there the car stalled as I just double parked. I waited for it the pump to cool down about 20 minutes restarted and moved to park the car.

Tank was 3/4 full.
Fuse 7 was hot but not overly hot.
None of the relays seemed excessivley hot or damaged.
Pickup hose and fuel pump was replaced by PO 3 years ago. Its a Hervy bosch style fuel pump.

I guess i need to check the ground connection at the fuel pump and check to see if the pickup hose has somehow collapsed.

Any other thoughts?

[David T]

Thought I'd ressurect this thread instead of making a new one since I've had an issue again.

My fuel pump overheated and car stalled out on me the other day in 75 degree weather in the city.
Fuel pump was extremely loud and high pitched hum for a few minutes as i tried to get to my parents apartment in manhattan.
Once i got there the car stalled as I just double parked. I waited for it the pump to cool down about 20 minutes restarted and moved to park the car.

Tank was 3/4 full.
Fuse 7 was hot but not overly hot.
None of the relays seemed excessivley hot or damaged.
Pickup hose and fuel pump was replaced by PO 3 years ago. Its a Hervy bosch style fuel pump.

I guess i need to check the ground connection at the fuel pump and check to see if the pickup hose has somehow collapsed.

Any other thoughts?

You need to make sure the pick-up hose is not collapsing (soft) and the filter in the tank is clean, no dirt or other junk. If it still makes noise the pump should be replaced.

[Bitsyncmaster]

John at Special T thinks the noisy pumps and burning #7 fuse is caused by electrical resistance. I have tested one standard fuel pump with an adjustable power supply while still running in my car with the engine running. That one pump could keep the normal fuel pressure all the way down to 7 volts on the fuel pump. When the voltage on the pump goes lower the current does not increase, it goes down a little.

So my feeling is the noisy pump and #7 fuse melting are not due to bad connections.

I also had pump noise with two pumps. I ran temperature testing of the fuel in the tank and once that gas got above 120 deg. one pump would start to "whine". I designed a cooler for the return line into the tank and have not herd any pump noise since. But it looks like the new DMCH pump/sender also fixes the pump noise without the need to do the cooler modification I did.

[DMCVegas]

Are you having excess pressure in the tank when the fuel gets hot? You can tell by when the fuel pump stars to whine, pull the gas cap off, and use a screwdriver or something else to force the flap on the inlet restrictor open. You should feel, if not hear a loud whooshing of fuel vapors discharge out. Likewise, the loud humming of the fuel pump will immediately stop.

I had the exact same issue of a noisy fuel pump when the fuel warmed up, and it was a defective Carbon Canister.

[papanoel]

You need to make sure the pick-up hose is not collapsing (soft) and the filter in the tank is clean, no dirt or other junk. If it still makes noise the pump should be replaced.

So if the hose is collapsed any quick fixes? I saw new ones are pricey. Josh at dpi has one that's a whopping 80 bucks. And dmch has old style kind for 42.

[Chris 16409]

I took Dave M's advice and ran a dedicated ground from the inertia switch to the metal shifter plate that bolts into the frame. It's an easy mod to do. I'd rather not have my fuel pump ground shared with about a half dozen other accessories. I also looked into the wiring that feeds fuse #7. One of the wires is a thinner gauge that feeds into the lambda relay. My guess on the reason was because this thinner gauge #7 wire combines with another wire on a terminal feeding the lambda relay. If this wire in question was as thick as the other #7 wire, it would not have fit the crimp in the terminal. So I rewired this particular pin on the lambda relay socket so that I could use a thicker gauge wire. Now the #7 fuse is fed by better wiring. All of this in combination with a "hot air dam" seems to keep my fuel pump quiet.

[papanoel]

Well it seems the 3 year old pickup hose was collapsed/kinked. Tank was nice and clean as expected.

I decided to just upgrade to the new DMCH Fuel pump/sender unit regardless.
I don't want to keep worrying about issues with the old system.

I plan on selling the pump, the sender, baffle and all related parts if anyone is interested.
Previous owner installed bosch style pump from Hervey 3 years ago. less than 4000 miles of use.