Houpty GT

Well all the problems are not solved yet. The air bypass valve was not working properly. When I put it in the freezer it opens most of the way and when I put it in the oven on warm it will close most of the way. If I hook it up to 12v it will completely close so I am going to check the wiring in the car. Does the air bypass valve get 12v constantly when the car is running or does it runn for a time interval?

My fuel pump failed to supply one liter of fuel in a 30 second interval. I am going to drain the tank and check the fuel screen today. A remanufactured pump was installed by the PO in september 06 but it has been very noise so it may be defective or a clogged fuel screen may have burned it up.

The car still made the chirping backfire noise though I think it may have sounded a little different. After this I will need to check the warm control pressure and the fuel injectors spary pattern. Can the injectors be removed without the special puller? I have seen some CIS cars where is it nearly impossilbe and others where it is not.

Dave
1981 911sc Targa

Houpty GT

I drained the gas tank using the plug underneath the car. The best tool for this is to use the top side of a 13/16" spark plug socket. If you pull out the rubber piece on the inside you can fit an extension in there and save yourself from buying a 22mm allen bit. The gas that came out was very dirty and had lots of junk in it. I decided that I need to clean the tank inorder to remove the rust.

I do not know what anybody else has done to clean a gat tank but I have read about using crushed rocks inside and shaking the tank and then to follow this up with some Muratic Acid to eat the rest of the rust. I am kind of worried about the plastic parts on the inside of the tank but I think they should hold up. The tank can then be flushed with water and dried.

The last photo shows the inside of the tank.

What about some type of coating to stop any future corrosion?

theiceman

There are companies who do this I am sure. I would try taking it to them. Ps is your car copper brown metalic ?

Houpty GT

The PO told me it is Rosewood Metallic. My girlfriend called it "brown" so I have banned her from riding in it, touching it, or looking at it. It has been repainted once but should be the original color. I have showed people the pictures of your car before and told them that other than the rims and whale tale, mine is exactly the same. That and I have not done the Hockey Stick Mod.

Houpty GT

I have read alot of things on the internet and the conclusion seams to bang some plant nuts, rocks, or chains around the inside, rinse with Muratic acid, then use por-15 http://www.por15.com/prodinfo.asp?number=S7Q&dept=12 to seal the inside of the tank. I think this would take me about 2 weeks to accomplish all this. I wonder if I can getthe sealer locally anywhere? I still worry about those plastic parts and the crossover tube on the inside of the tank. I guess the tank was never sealed by Porsche. Just shows that it was meant to be driven.

theiceman

check your paint code and the glasurit web site, you will know for sure. I did a search on sealing gas tanks and got tonnes of hits ..

post some pics when you get a chance, i'd like to see it .

Houpty GT

I found the POR-15 gas tank sealer at my local auto paint supply shop. I wrote down the phone number on the instruction sheet and called the company. What POR-15 told me is that the sealer will not adhere to plastic unless it is sanded down. I interpeted this as meaning the sealer will peel off the plastic parts and then clog the tank and por15 confirmed this.

I am going to just use Muratic acid to wash the tank, flush it with water, then pour a pint of 70% isoprpyl alcohol in there to dilute the water and speed drying time after I drain everything out.

Houpty GT

I decided to take a look at the pump while it was easy to access with the gas tank out. I noticed a little black thing in the fuel line that goes from the gas tank to the pump. I wondered if it was some sort of one-way valve but I knew what it was as soon as I took a closer look. The cap was not sticking out like it is in the first photo but was slide down further in the hose. I guess someone used it as a plug for the gas tank and left it in there. I hope the pump is still good but it may have been damaged from the restriction. I will have to test and see. It is interested to see just how many problems this car has had and to be knocking them out one at a time.

Has anyone rebuilt their one pump? Where can you get the parts?

theiceman

Well theres your WOT issue....

Peter Zimmermann

While you're at it, get rid of those rip & tear hose clamps and put a piece of o.e. hose and Norma clamps on.

FYI: Radiator shops do gas tanks, they hot-tank them and inspect. I just had the tank done on a '66 V-dub Beetle, they did a nice job and the tank came back paint ready. Two coats of primer and two coats of rattle can semi-gloss black and it looks new inside and out. The best part is, no chemicals to transport to the local hazardous waste site...

Houpty GT

I have a few questions about the fuel pump and the accumulator.

The accumulator has 3 hoses that go to it. 2 on top, those should be the input and output, and 1 on the bottom, I don't know why. The Bently says to check fuel delivery volume with the bottom hose. My pump failed that test. When I checked the fuel delivery with the input hose, it put out about 1.75 liters in 20 seconds. The current draw on my pump was 5.75 amps and spec is 4-6 amps. It is noisey however.

Why does the Bentley say to use the bottom hose?

What is the exact purpose of the bottom hose?

elpresidente

My 78 sc just started experiencing a starting issue today. The last time I drove it (Tuesday) everything was fine. Today it just keeps turning over, but not firing. Seems like it's not getting gas (yes there is gas in the tank). Any suggestions on where I should start to troubleshoot?

theiceman

I always suggest confirming spark first, as it is easier and safer, listen for the familiar whine form the CD box and hook up a spare plug and ground it to make sure.
After that is confirmed a fuel pressure test is next but the fuel pump an relay ( red ) always gets mentoned as suspect. If you want to check without a fuel guage jack up the car and either hook up a voltmeter to the pump and see if you actually have 12v while cranking. If you do i would imagine you can put your hand on it an feel it vibrate while pumping. Pete could probably confirm that . Of course if someone is strting your car with you under it all precautions should be taken.

As a quick test I think you can even swap your pump relay with one of the others to see if it starts.

Peter Zimmermann

Right on with the suggestion to swap the fuel pump relay with a known good one (the horn, for example). The fuel pump relay will (should) be red, the horn relay will be black - that's OK for test purposes. Next thing, take out (don't just look at) the fuel pump fuse and check it for corrosion or a broken metal section. If you can't remember the last time that you filled the car with gas you might not want to trust the gauge. I've had at least a half a dozen cars towed in to the shop where everything "seemed" fine, until we pulled the fuel gauge sender out of the tank and discovered that the tank was empty (the sending unit had failed)!

theiceman

wait a minute .. I resemble that remark ....