Can anyone shed some expertise of this option?
October 2nd, 2018, 9:45 PM
#11
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Join Date: Feb 2018
Location: Currently the Candian Gander is wintering over in New York.
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Hi, it's me again, with a progress update. Apparently I am not out of the woods with my fuel delivery issues, yet.
A brand new tank.
A brand new sender unit.
Bubbles in the fuel line supply.
New 3/8" hose at the sender to first fuel supply pipe
New 3/8" hose at fuel supply to fuel pump.
New clear fuel filter. inline with pump inlet.
Aviation-type hose clamps at all connections.
With a vacuum pump, I can draw 15" of vacuum on the supply line, but I end up seeing air bubbles in the pump reservoir attachment.
If I use a gallon container of gas and drop the last rubber supply line with the filter in the container, the truck runs great. Plenty of fuel being supplied via the pump.
As soon as I reattach the line to the metal supply line, I can't get above 35 mph due to what appears to be fuel starvation.
I've tried pressurizing the tank, and have found no leaks or drops of gas falling off the truck like I did when the sender was faulty.
I am also not smelling any vapors which is why I am kind of stuck.
I even tried loosening the cap, thinking it might be vapor locking, but that wouldn't explain the bubbles in the line.
Maybe I could get a pump-up style water jacket tester and pump it up to a higher pressure than what I have been working with so far.
Thanks in advance.
A brand new tank.
A brand new sender unit.
Bubbles in the fuel line supply.
New 3/8" hose at the sender to first fuel supply pipe
New 3/8" hose at fuel supply to fuel pump.
New clear fuel filter. inline with pump inlet.
Aviation-type hose clamps at all connections.
With a vacuum pump, I can draw 15" of vacuum on the supply line, but I end up seeing air bubbles in the pump reservoir attachment.
If I use a gallon container of gas and drop the last rubber supply line with the filter in the container, the truck runs great. Plenty of fuel being supplied via the pump.
As soon as I reattach the line to the metal supply line, I can't get above 35 mph due to what appears to be fuel starvation.
I've tried pressurizing the tank, and have found no leaks or drops of gas falling off the truck like I did when the sender was faulty.
I am also not smelling any vapors which is why I am kind of stuck.
I even tried loosening the cap, thinking it might be vapor locking, but that wouldn't explain the bubbles in the line.
Maybe I could get a pump-up style water jacket tester and pump it up to a higher pressure than what I have been working with so far.
Thanks in advance.
October 4th, 2018, 4:13 PM
#12
CF Active Member
Thread Starter
Join Date: Feb 2018
Location: Currently the Candian Gander is wintering over in New York.
Posts: 185
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Trust the simple things to really screw things up.
It's fixed, thanks to B & L Auto Repair, 2601 Westchester Avenue, Bronx, NY 10461 (718) 892-2608. I have to give credit where credit is due. These guys fixed the problem.
I tried to pressurize the tank with air pressure, and all I got for that effort was a waste of 6 hours. so I thought, maybe a garage with an air compressor could do a better job. The garage wouldn't pressurize the line, but they had a smoke machine which puts out 2 psi and they found no leaks in the supply line, which was good to know.
The mechanic first thought maybe the cam lobe was worn out, but once I explained to him that I could use a gallon gas can with a fuel line in it, i could do pretty well running around, so that kind of ruled out a weak fuel pump or a worn out lobe on the cam.. When the mechanic drove the truck, he experienced the same thing i told him what was happening; fuel starvation above 35 mph.
He KNEW immediately that the paper filter in the carb was clogged. I have no idea how i missed it, because I had an inline filter which I thought was taking care of the problem, but as it turns out, the inline filter only stopped the bigger trash / rust. The stuff that got past that had clogged the carb filter.
With that changed out, we went for a ride and that was the first time I have been able to vroom past 60.
I was happy to pay them the $85.00 diagnostic fee. I consider it tuition for the education I received.
Note to anyone who has to replace one of these filters in the carb. Make sure to remove the spring-loaded check valve in the filter before installation. My '81 doesn't have one, and apparently it can cause enough of a restriction to lower fuel pressure at the carb inlet 3psi. That is another thing I would have missed.
It's fixed, thanks to B & L Auto Repair, 2601 Westchester Avenue, Bronx, NY 10461 (718) 892-2608. I have to give credit where credit is due. These guys fixed the problem.
I tried to pressurize the tank with air pressure, and all I got for that effort was a waste of 6 hours. so I thought, maybe a garage with an air compressor could do a better job. The garage wouldn't pressurize the line, but they had a smoke machine which puts out 2 psi and they found no leaks in the supply line, which was good to know.
The mechanic first thought maybe the cam lobe was worn out, but once I explained to him that I could use a gallon gas can with a fuel line in it, i could do pretty well running around, so that kind of ruled out a weak fuel pump or a worn out lobe on the cam.. When the mechanic drove the truck, he experienced the same thing i told him what was happening; fuel starvation above 35 mph.
He KNEW immediately that the paper filter in the carb was clogged. I have no idea how i missed it, because I had an inline filter which I thought was taking care of the problem, but as it turns out, the inline filter only stopped the bigger trash / rust. The stuff that got past that had clogged the carb filter.
With that changed out, we went for a ride and that was the first time I have been able to vroom past 60.
I was happy to pay them the $85.00 diagnostic fee. I consider it tuition for the education I received.
Note to anyone who has to replace one of these filters in the carb. Make sure to remove the spring-loaded check valve in the filter before installation. My '81 doesn't have one, and apparently it can cause enough of a restriction to lower fuel pressure at the carb inlet 3psi. That is another thing I would have missed.