[studelover]

I have just finished my 66 2+2 convertible and I am having a problem with what I think is the fuel. At 60 or 70 mph the car cuts off like it is running out of fuel. I pull over and wait a few minutes and it starts. The car is ok at 40 mph and below however when it gets to highway speed it cuts off. The repair guy I had switched the gas tanks with a ac Catalina it has the two lines coming out of it. I also replaced the vent tube kit in the trunk. so say it's the wrong sending unit. I'm at my wits end.

[Txbobcat]

Possibly fuel pump is too weak to pump enough gas for 60 70MPH. Possibly water in fuel causing problems. Buy a can of berrymans b12 and put it in the gas. Also check/replace fuel filter if you have one

[Heybuck]

Mate, you have described my recent experience to a word.

My '66 Grand Prix had NEVER let me down in the 16 years I've had it until last February when I took it on a long road trip Melbourne to Adelaide and return in a couple of days.

200 kilometers into the trip I noticed it seemed to be running out of fuel. It was very hot (about 90F+) and I initially thought it was vapourising as I was pulling up a long hill. The car was heavily loaded and I was doing about 60mph.

Pulled up and it was idling well, nothing seemed amiss so off we went again. Within 2 miles and going downhill, the fire went out completely. Pulled up and it restarted and idled easily.

We then pulled the fuel line off the carb and cranked the engine. Fuel ran quickly into a bottle we put over the line. So we pulled out the bronze sintered fuel filter where the fuel line goes into the carb.

The car then ran strongly again so even though the bronze filter seemed clean and posing no restriction at all, we assumed we had cured the problem.

Another 5 miles and it was starving for fuel again. Our last option was to pull the fuel line off where it enters the fuel pump, REMOVE the gas tank cap and blow compressed air down the line. I heard a faint "whump" and you could then hear air bubbling back into the tank.

Replaced the line and the car ran like a swiss watch for the rest of the trip.

So what we had done is blow out the fabric filter sock inside the tank. I later found that the air had split the sock and that allowed fuel to run freely. The old sock was totally blocked and rotten.

My car had NEVER had the tank removed and certainly the fuel pick-up had never been removed in 50 years.

I'm suggesting that THIS will be your problem too. It will be NOTHING to do with the fact the tank pick-up is an A/C type unit. I presume your guy simply blocked the return fuel inlet???

Pull out the tank, order a fuel sock AND a new seal and locking ring from our hosts AMES and reinstall. Bit of a fiddle but all worth it.

Let us all know how you go?

Ian

[66 Wagon]

I've never experienced the problems you guys have had but thanks to you Ian I might know, if it ever happen to me,
what can cause trouble like the described. I propably had torn the engine apart before I even think about the gas tank, if ever.
Great to learn something new and I hope studelover get his car up and running without further problems.

[studelover]

Yes, I think you are right about the sock. I have replaced everything else. My question now is I have looked all over for a replacement sending unit. I was on E-bay and found an ad that said the 1966 Chevy full size car sending unit is the same as the one on our 1966 Pontiac. It came in the mail today. I have never seen my sending unit so can you tell me if this is true? I quess the measurement of the new one will have to be just like the old one in the tank. The new one is a non vapor design. it looks right however without a pic of the original I am guessing.

[Heybuck]

Originally Posted by studelover

Yes, I think you are right about the sock. I have replaced everything else. My question now is I have looked all over for a replacement sending unit. I was on E-bay and found an ad that said the 1966 Chevy full size car sending unit is the same as the one on our 1966 Pontiac. It came in the mail today. I have never seen my sending unit so can you tell me if this is true? I quess the measurement of the new one will have to be just like the old one in the tank. The new one is a non vapor design. it looks right however without a pic of the original I am guessing.

If you need a new sending unit/fuel pickup because your existing unit has failed, then I suggest this will do the job for you.
http://www.ebay.com/itm/401115733595...%3AMEBIDX%3AIT

BUT, if your gauge is working OK, then all you need to buy is the sock, a new seal and a new locking tab. Our hosts here (AMES) sells these.

Keep us informed how you get on with it. I think a lot of guys with these cars are living with 50+ year old fuel socks and I can tell you all from experience, once they give up the struggle, its going to leave you stranded.

Ian

[Heybuck]

Originally Posted by studelover

Yes, I think you are right about the sock. I have replaced everything else. My question now is I have looked all over for a replacement sending unit. I was on E-bay and found an ad that said the 1966 Chevy full size car sending unit is the same as the one on our 1966 Pontiac. It came in the mail today. I have never seen my sending unit so can you tell me if this is true? I quess the measurement of the new one will have to be just like the old one in the tank. The new one is a non vapor design. it looks right however without a pic of the original I am guessing.

I just re-read your post on this and I have a bad feeling that the Chevy unit is NOT the same as a Pontiac. I seem to think the Chev unit is on the edge of the tank whereas the Pontiac version lays flat on the top. Might be wrong about this but I don't think so.
Ian

[Heybuck]

Originally Posted by Heybuck

If you need a new sending unit/fuel pickup because your existing unit has failed, then I suggest this will do the job for you.
http://www.ebay.com/itm/401115733595...%3AMEBIDX%3AIT

BUT, if your gauge is working OK, then all you need to buy is the sock, a new seal and a new locking tab. Our hosts here (AMES) sells these.

Keep us informed how you get on with it. I think a lot of guys with these cars are living with 50+ year old fuel socks and I can tell you all from experience, once they give up the struggle, its going to leave you stranded.

Ian

Just one more point. If you buy the unit off eBay, all you need to do is block off the smaller diameter inlet tube. This tube simply allows fuel to run back into the tank via the return fuel line from the fuel filter located just under the alternator. BUT ONLY ON FACTORY A/C EQUIPED CARS.

In your case, you indicate your car does not have factory A/C so in that case, no return fuel line. So you simply block this tube off and you have nothing more to worry about.

[Old Goat 67]

And, another note.

Pull the sock off, throw it away, put an inline can type filter anywhere between tank and inlet to fuel pump, Happy Motoring!

Did this when my GTO was brand new (because I had the same problems you describe on two other GM cars back then), never a problem in 49 years!

[studelover]

Hi All, dropped the tank today and found what was causing all the problem. Pulled the sending unit out the tank nothing in the sock however the sending unit itself was full of rust. I was packed in there so much so we needed a drill to break it up. I ordered another sending unit so I cleaned the old unit put a new sock on it and put the tank back. When the new sending unit comes I will drop the tank again. Thanks for all the help. I got a sending unit from Van auto parts.

[studelover]

Originally Posted by Heybuck

I just re-read your post on this and I have a bad feeling that the Chevy unit is NOT the same as a Pontiac. I seem to think the Chev unit is on the edge of the tank whereas the Pontiac version lays flat on the top. Might be wrong about this but I don't think so.
Ian

You are correct. The Chevy unit is not the same as our Pontiac. So if somebody tells you it will fit(Bobs impala) don't believe it!

[Willshire]

Inline tube makes this part i think