Loud fuel pump whine!

[REVHARD05]

so i got the car up and running the other day and it has developed a loud humm from the gas tank, I took the pump out tested it on a battery charger it ran good, no loud noise. Then i replaced the fuel Filter, (strainer looked good) no help. So i am convinced that either It needs a new fuel line or it needs a regulator. I am just thinking about running copper line from the filter to the rail. Easy fix? I was thinking about making some sort of "snake" by taking some soild wire and running it through the line to clear obstructions? I was thinking about takeing the wire threw the line from the reg to the filter when the wire reaches the end i would tie an (implement) on the wire and pull through? ( May be that would work?) Worst case, I dont think that the copper would interfear with the Fuel, plus it would let me run a slightly larger line so i wouldnt run the risk of running lean because of a lack of volume fuel suppy.

So lets hear what you would do? I know i can also get a "new" line but whats the fun in that?

[jlevie]

First, try blowing out both the supply and return hard lines with compresses air. Unless they've been damaged and pinched there little chance of them being the problem. The soft lines are another matter and could have internal failures that is restricting flow. Just replace them. But be sure to use injection rated hose.

While a whining pump can be the result of a restriction in the fuel lines, a clogged filter, or bad FPR. in most cases a noisy pump is simply one that is at the end of its service life and needs to be replaced.

[xwill112x]

my fuel pump got really loud in my m42 car just before it died.

[REVHARD05]

yea i know that the loud pump is a sign of failure, but i had the pump in another car 2 hours before this and it ran fine. Plus the car sat for a while (4 years) before i fixed it. so it looks more like obstructions to me. thats guys

[jlevie]

If the car has sat for a long time with an empty or only partially full gas tank, the odds of it now having a lot of rust in the tank are quite good. Not only will rust plug up the filter and the intake screen for the pump, bit it is also very abrasive and will wear out a pump in short order. Pull the pump and sensor an use a stick to stir the bottom of the tank. If there is a layer of rust there you will see and feel it. The fix for a rusty tank is to replace it or acid clean and seal the tank.

[REVHARD05]

I have some Muratic acid What ratio?, and what would i use to seal it with?

[jlevie]

HOW TO CLEAN AND SEAL YOUR GAS TANK:

While you can get a little bit of the sediment from the tank with it in the car, the rust on the baffles and other internal surfaces will still be there. Below is my tank saga...

A twenty year old car with a steel gas tank can have a surprising amount of rust in the tank. That rust can and will clog the pump inlet screens and filter and cause the high pressure pump to have a short life. While a new tank will certainly fix that, you can clean and seal the tank for a lot less money.

My 87 325is suffered from this. The car ran fine on the street but the first time I took it to the track for a test & tune it was as if the car had a soft rev limiter that decreased by 500-700rpm per lap. Some particulate matter did come out of the tank when I drained the gas, but with the in-tank pump out I could see a layer of crud in the bottom of the tank that was about an 1/8" deep. On the track that stuff got stirred up, clogged the inlet screens & filter, and starved the engine. It also ate up the internals of the high pressure pump. Rust is a fairly abrasive material.

The first attempt at a fix was to have the tank acid dipped and install new pumps & filter. Either they didn't leave the tank in long enough or the acid was a bit depleted, but the result was less than satisfactory as the next time I had the car on the track the high pressure pump started buzzing and I ran into the same starvation issue.

After taking the tank out again and sloshing about a gallon of fuel around I got loads of rust out of the tank. The new filter was heavily loaded and the inlet screen of the high pressure pump was also loaded up. And the cross-over pipe was completely plugged. This time I was determined to get all of the rust out and follow that up with sealant to lock down anything that was left and prevent further rusting. I used a gas tank sealer kit from Eastwood, but went a bit further than they suggest.

The tank, having been recently acid dipped had no varnish in it. So a simple wash with a strong TSP solution removed the remaining organics. I made up a simple plug for the hole where the in-tank pump mounts that could easily be removed. Think of a round disk of plywood with a bar on the bottom and a couple of screws to snug the bar up. Drop that into the opening, rotate slightly to
engage the lock ears on the tank and tighten the screws. The remaining openings were closed up with pieces of a freezer bag held in place with rubber bands.

About a gallon of diluted acid in the tank was about right. That was enough to slosh around well but not so much as too make the tank too heavy. I used an acid mix sold for cleaning masonry that's composed of Hydrochloric and Phosphoric acids at about double the normal dilution. Over the course of a couple of hours I'd slosh and flip tank every fifteen minutes to wet all parts of the tank with the solution. At the end of a couple of hours I drained the tank and disposed of the pretty well spent acid by reacting it with limestone gravel.

To flush the tank I made up a right-angle spray nozzle with plumbing fittings and a 1/4" hose barb. That allowed the nozzle to be inserted into the tank and a high velocity stream sprayed into all corners. This was done with the tank at about a 30deg angle (drain plug hole down) and the fluid collected into a bucket. When the water ran clean and no more loose junk came out I repeated the acid treatment and flush. It took all of one Saturday and part of Sunday to get the tank to the point that no more rust could be seen and nothing was being flushed out of the tank.

The last steps were to use the acid etch from the Eastwood kit, flush with acetone, and apply the sealer. Before putting the sealer in the tank I removed the cross-over pipe and sealed those openings. After the sealer had been applied and before it had a chance to harden I blew out those openings and the tubing that runs across the top of the tank with compressed air. After drying for a couple of days the tank was reassembled and reinstalled in the car.

Once sealed the inside of the tank had a fairly uniform white coating. I did see a few specks of matter that I wasn't able to flush from the tank, but those were well locked in place by the sealer.

Cleaning and sealing the tank is pretty labor intensive. But at a total cost of less than $80 it is a lot cheaper than a new tank (~$400 for this car).