out of gas?

zone78 · 09-02-2000, 01:26 PM

i own a 69 mach 1 428cj w/4 speed.
the problem i have after the car is fully warmed up (sometimes 10 min or as long as 40 min) the car will act like it is out of gas.
The car will generally start back up after 3 or 4 turnovers and may travel anywhere from 100 feet to a mile before "ruuning out of gas" again.
I have replaced the filter on the sending unit in gas tank, the fuel line from gas tank, 2 new fuel pumps,and have had the carb professionally rebuilt,eacvh of these with no success. I have able to duplicate this in my garage and have seen the car run right out of gas at approx 2500 rpm. any help would be appreciated. thanks ken

Gearhead999 · 09-02-2000, 04:24 PM

First you should start at the beginning. Try taking the gas cap off car and see if it still "runs out of gas". Tank has to be vented.
Second, test the fuel pump at the carb before and after it acts up for both pressure and volumne.
Third, Are you sure it is running out of gas?? If you can duplicate it in garage. Spray some starting fluid or such in top of carb when it starts to lay down and see if it picks up.
If all this is OK, one through three. And it does pick up when you spray it. Check vacumn for leak.
Finally try another carb or raise float levels. You have eliminated everything else. I know you said that carb was "rebuilt" by pros, twice. But, maybe carb casting is bad.

Let me know how you make out, or what you find.

Ron1 · 09-02-2000, 10:49 PM

Checking the fuel pump output is a good idea. Your pickup in your tank could also be plugged. You might drop the tank, and check the pickup. Sometimes the screen filter can be solid with "gunk".

Ron

thunderbolt · 09-04-2000, 12:32 AM

It sounds a bit like a vapor lock problem. You might try a heat shield between the intake and the carb. Also electrical. Some times ignition dosen't work well when it gets hot. I would check all thoes connecteions also and maybe try a distributor rebuild if you haven't already done it.

66fastback · 09-04-2000, 11:27 AM

I was thinking like thunderbolt. First thought is vapor lock. Check and make sure the exhaust isn't too close to the fuel lines or the tank itself.

I'm not too familiar with the big block cars, but I know the 67's w/ the big block had a huge muffler in front of the tank, and both pipes fed into and out of this one muffler, and then down each side of the gas tank. This put off a lot of heat into the gas tank, and made these cars prone to vapor lock.

Ignition system would be my second choice. You've already eliminated the fuel pump and filter...two good choices, as well as the fuel lines, which are often rusted out in these old cars.

Good luck, and just be glad you're not here in Dallas. It's been 107-110 degrees for about a week now, and I don't have A/C in my car.

------------------
66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

Elvis · 09-05-2000, 02:20 PM

I'm sure all of the responders know a lot more than I do about these things but I had a similar problem last year with my '67. After driving me nuts for 3 months it turned out that the wire to the ignition switch was frayed. It would run OK for 10 minutes or so and then as the wire got hot the engine would start to run rough and eventually die.
Might be worth a check. E.

09-02-2000, 01:26 PM	#1
zone78 Registered Member Join Date: Sep 2000 Location: Wolcott,CT,usa Posts: 1	out of gas? i own a 69 mach 1 428cj w/4 speed. the problem i have after the car is fully warmed up (sometimes 10 min or as long as 40 min) the car will act like it is out of gas. The car will generally start back up after 3 or 4 turnovers and may travel anywhere from 100 feet to a mile before "ruuning out of gas" again. I have replaced the filter on the sending unit in gas tank, the fuel line from gas tank, 2 new fuel pumps,and have had the carb professionally rebuilt,eacvh of these with no success. I have able to duplicate this in my garage and have seen the car run right out of gas at approx 2500 rpm. any help would be appreciated. thanks ken

09-02-2000, 04:24 PM	#2
Gearhead999 Registered Member Join Date: Sep 1998 Location: Oviedo, FL Posts: 992	First you should start at the beginning. Try taking the gas cap off car and see if it still "runs out of gas". Tank has to be vented. Second, test the fuel pump at the carb before and after it acts up for both pressure and volumne. Third, Are you sure it is running out of gas?? If you can duplicate it in garage. Spray some starting fluid or such in top of carb when it starts to lay down and see if it picks up. If all this is OK, one through three. And it does pick up when you spray it. Check vacumn for leak. Finally try another carb or raise float levels. You have eliminated everything else. I know you said that carb was "rebuilt" by pros, twice. But, maybe carb casting is bad. Let me know how you make out, or what you find.

09-02-2000, 10:49 PM	#3
Ron1 Registered Member Join Date: Sep 1999 Location: Vancouver, WA USA Posts: 439	Checking the fuel pump output is a good idea. Your pickup in your tank could also be plugged. You might drop the tank, and check the pickup. Sometimes the screen filter can be solid with "gunk". Ron

09-04-2000, 12:32 AM	#4
thunderbolt Registered Member Join Date: Oct 1998 Location: Houston, TX, USA Posts: 380	It sounds a bit like a vapor lock problem. You might try a heat shield between the intake and the carb. Also electrical. Some times ignition dosen't work well when it gets hot. I would check all thoes connecteions also and maybe try a distributor rebuild if you haven't already done it.

09-04-2000, 11:27 AM	#5
66fastback Registered Member Join Date: Mar 1999 Location: Dallas, TX Posts: 208	I was thinking like thunderbolt. First thought is vapor lock. Check and make sure the exhaust isn't too close to the fuel lines or the tank itself. I'm not too familiar with the big block cars, but I know the 67's w/ the big block had a huge muffler in front of the tank, and both pipes fed into and out of this one muffler, and then down each side of the gas tank. This put off a lot of heat into the gas tank, and made these cars prone to vapor lock. Ignition system would be my second choice. You've already eliminated the fuel pump and filter...two good choices, as well as the fuel lines, which are often rusted out in these old cars. Good luck, and just be glad you're not here in Dallas. It's been 107-110 degrees for about a week now, and I don't have A/C in my car. ------------------ 66 GT Fastback 5.0, 5-speed, cable clutch, JBA's, 3.40 gears, EFI coming soon?

09-05-2000, 02:20 PM	#6
Elvis Registered Member Join Date: Jun 2000 Location: Sherman, Texas Posts: 188	I'm sure all of the responders know a lot more than I do about these things but I had a similar problem last year with my '67. After driving me nuts for 3 months it turned out that the wire to the ignition switch was frayed. It would run OK for 10 minutes or so and then as the wire got hot the engine would start to run rough and eventually die. Might be worth a check. E.