The pick-up hose is inside the fuel tank connecting the baffle and the fuel pump. Kind of an "S" shaped, black hose about 18" long.Originally Posted by mr_maxime
Location: Northern NJ
Posts: 8,578
My VIN: 10757 1st place Concourse 1998
The pick-up hose is inside the fuel tank connecting the baffle and the fuel pump. Kind of an "S" shaped, black hose about 18" long.
David Teitelbaum
Location: Leonardtown, MD
Posts: 9,004
My VIN: 03572
That's the old common fuel pump whine. It happens when the gas in the tank starts going above 120 deg. F. I had the same whine and I had the spring in the pickup hose. So it's not just a problem with the pickup hose. I installed a fuel cooler and the problem never returned but that was before DMCH had that new pump. So I would just go with the new type pump when you get it home.
If your not home yet, you may be better off waiting till it cools off later this evening to try the drive then.
Posts: 1,243
My VIN: 10201
It's at my dad's now. I'll get a rental for the work week while waiting on the pump to arrive. I'm not risking getting stranded.
How hot are rpm relays supposed to be?
Location: Leonardtown, MD
Posts: 9,004
My VIN: 03572
The stock RPM will run very hot normally. That's one of reasons my first product was the solid state RPM relay. If you think the black case it hot, open the unit up and touch the relay coil. Don't really do that, you will burn your fingers. The relay coil is what produces the most heat.
Location: Northern NJ
Posts: 8,578
My VIN: 10757 1st place Concourse 1998
Putting a spring into the pick-up hose will prevent the fuel starvation problem but once the pump makes that noise, it is damaged and will continue to make noise. Eventually it will fail so replacing it is a good idea. The newer style combo pump unit is nice but pricey and there have been some reports of problems with them, the fuel sender and hot restart problems. I think they have cured them now.
David Teitelbaum
Posts: 1,243
My VIN: 10201
Drove the car around this morning. Fuel pump wasn't screaming.
I drive the car daily and had not had any issues but my drive is about 25 mins now. This is the first time I've driven it this far in 90 degree weather. My guess is that it was hot fuel causing starvation, but I'll be cautious and replace it with the new pump.
Location: Leonardtown, MD
Posts: 9,004
My VIN: 03572
What happens is the fuel pump provides more fuel than necessary and the returned fuel to the tank is about 1 or 2 degrees warmer than the fuel pumped from the tank (I did measurements to find that out). The heat comes from the extra fuel piped around that hot engine. So it takes about an hour or more of driving for the gas in the tank to reach above 120 degrees (I tested that also). That is the temperature my pump would start buzzing.
So far I've not heard of any buzzing complaints with the new style DMCH pump.
Location: Northern NJ
Posts: 8,578
My VIN: 10757 1st place Concourse 1998
The fuel gets heated by several different ways. The hot air coming out of the radiator, the cooling system piping running along the bottom of the tank, the fuel pump itself and the hot motor. One trick is to wrap a coil of tubing around the accumulator and run the fuel through that to cool it. Another is a big piece of thick rubber to deflect the air coming out of the radiator down and away from the fuel tank.
David Teitelbaum
Location: Leonardtown, MD
Posts: 9,004
My VIN: 03572
I had that rubber deflector and the pump was still buzzing. Yes, I was the guy that made the cooler wrapping pipe around the accumulator. That's what cured the problem.
Location: Northern NJ
Posts: 8,578
My VIN: 10757 1st place Concourse 1998
Once you starve the old style pump of fuel and it starts making noise, you have damaged it internally and it will always be noisy and fail prematurely. The fuel cools and lubricates the pump, when you run the pump and fuel does not go through it because the hose has collapsed (or kinked), the parts inside the pump wear out quickly. The old style OEM set-up with that rubber pick-up hose is VERY susceptible to kinking and collapsing and when it does you lose fuel pressure and damage the fuel pump. That fuel pump moves a LOT of fuel and can create quite a bit of suction. When the fuel gets hot, so does the hose and it gets soft and can easily collapse or kink if, when you install the pump, you turn it and twist the hose and make it tend to kink. My "cure" is to put a spring inside the hose to keep it from collapsing. It's been working fine for me for years. And all of the cars I have installed the spring in. The coil around the accumulator is OK but you have to worry if a rock could damage it and it reduces the amount of cooling available in the cabin a little. I suppose you could wrap the coil with some insulation to protect the tubing from damage and maybe regain some of the losses from the absorption of heat from the fuel. The rubber deflector also is a big help behind the radiator. Ultimately the fuel WILL heat up a lot. The newer style pump from DMCH may be better at handling heat, I don't know. Maybe insulation around the two cooling pipes running under the tank would also help. I think that's where the majority of the heat comes from. Bottom line, if your old style pump is making noise you have problems. Probably why the #7 fuse also melts. When that pump gets noisy it is going to be drawing more current.
David Teitelbaum
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Dave M vin 03572