HDJ81 Fuel suction hose/filter, wow!

[finderscuba]

with it's the walbro model that you choose .?

FRD-1
It provides 4.5 to 7 psi which is plenty. It is a flow-through design that will allow fuel flow even if the pump fails. And it is pretty quiet. I cannot hear it at all except for a quiet tick tick when I turn the key on.

Cost me $85 plus shipping. I ordered from Auto Performance Engineering.

Dave

 

[emil55]

Any other ways to remove those one way bolts? I'm not being successful. I hear my air chisel calling

I could open one of one way bolts and it was enough for access to tank panel. I layed down to fix back of left bolt and friend opened the bolt.

 

[John Galt]

You are lucky to have a fuel pick-up access panel. On my '74 I had to remove the tank to access the fuel pick-up assembly.
I removed the clogged pick-up filter, cleaned the tank and reinstalled with new hoses and NO pick-up filter. The pick-up filter in the tank is a bad design, especially if dropping the tank is required for maintenance. Therefore I added an inline filter after the fuel sedimenter instead of an inaccessible filter in the tank.

 

[gifu]

On my 74... was able to pull the sender and use a long pry bar to break the sock off and super long needle nose to fish it out.
Dumb design indeed.

 

[barrett1]

My truck seems to be running fine but I am getting a big negative pressure issue and sucking sound when I loosen the metal fuel cap after any drive of reasonable length. I also checked the vent check valve and mine is also reversed with "to engine" facing toward the back of the truck toward the end of the vent tubing. I have read this vent line is for positive pressure but don't know for sure. I am wondering if anyone also has this issue and maybe it is supposed to be used in this (reverse) direction as this vent is more for positive pressure (think tank is hot and needs to vent pressure out). Maybe this valve is also used in another application where it is actually placed in the correct direction for which it is labeled. Can anyone confirm that has the knowledge?? Also, I am getting ready to clean out the filter for the fuel pickup as the author of this thread did but I really don't understand how this would fix a negative pressure issue as the fuel pump sucks fuel out of the tank. Doesn't the tank need to vent to atmosphere somewhere to replace fuel being taken out with air from atmosphere?? Although my truck is running well, I do worry about the extra strain of the fuel pump working against the developing increase in negative pressure and this is why I want to solve this issue.

 

[MobySlick]

My truck seems to be running fine but I am getting a big negative pressure issue and sucking sound when I loosen the metal fuel cap after any drive of reasonable length. I also checked the vent check valve and mine is also reversed with "to engine" facing toward the back of the truck toward the end of the vent tubing. I have read this vent line is for positive pressure but don't know for sure. I am wondering if anyone also has this issue and maybe it is supposed to be used in this (reverse) direction as this vent is more for positive pressure (think tank is hot and needs to vent pressure out). Maybe this valve is also used in another application where it is actually placed in the correct direction for which it is labeled. Can anyone confirm that has the knowledge?? Also, I am getting ready to clean out the filter for the fuel pickup as the author of this thread did but I really don't understand how this would fix a negative pressure issue as the fuel pump sucks fuel out of the tank. Doesn't the tank need to vent to atmosphere somewhere to replace fuel being taken out with air from atmosphere?? Although my truck is running well, I do worry about the extra strain of the fuel pump working against the developing increase in negative pressure and this is why I want to solve this issue.

Hey Barret, just stumbled across this thread after having done the exact same as you this weekend due to the same symptoms (though I also broke apart the check valve, so will be replacing that ). I read another thread where a user tested the check valve and the gas cap, and they believe that the check valve is indeed correctly oriented and for positive pressure, and the gas cap is what's used to equalize negative pressure (being higher up it's better if it pulls air in).

I'm at the stage where I think I'm going to buy a new gas cap and check valve (I don't have the hose diameter to check my gas cap, and it's probably original i.e. 30 years old), along with replacing all of the fuel lines as they're impossible to take off without breaking them. But having seen this thread I'll also be checking out that screen, though I agree with you on not understanding how it could cause vacuum.

I wonder if anyone knows the bolt sizing details for the seat bolts? I absolutely destroyed my tamper-proof ones trying to take them off hahaha

Please let me know if you've done anything since which fixed the issue.

 

[barrett1]

Hey Barret, just stumbled across this thread after having done the exact same as you this weekend due to the same symptoms (though I also broke apart the check valve, so will be replacing that ). I read another thread where a user tested the check valve and the gas cap, and they believe that the check valve is indeed correctly oriented and for positive pressure, and the gas cap is what's used to equalize negative pressure (being higher up it's better if it pulls air in).

I'm at the stage where I think I'm going to buy a new gas cap and check valve (I don't have the hose diameter to check my gas cap, and it's probably original i.e. 30 years old), along with replacing all of the fuel lines as they're impossible to take off without breaking them. But having seen this thread I'll also be checking out that screen, though I agree with you on not understanding how it could cause vacuum.

I wonder if anyone knows the bolt sizing details for the seat bolts? I absolutely destroyed my tamper-proof ones trying to take them off hahaha

Please let me know if you've done anything since which fixed the issue.

I have worked on this issue and found significant improvement. First, my 81 is a 1990 so it has a metal gas cap that seals with a rubber seal. I do not have the plastic one, which to my knowledge only let's out positive pressure anyways, does not allow air inward to correct negative pressure. I took the check valve off which is at the rear of the truck. I sucked air one way, then the other. If it is oriented as labeled (opposite how it was originally installed on my truck), with to engine closer to the front of truck, it will allow better air to come in to tank and vastly improved my negative pressure issue. Truck has minimal negative pressure when I open gas cap after long drive and does not stumble anymore at high rpm. I did install a fuel filter on end of line which terminates in frame to prevent dust ingress. Curious if you will see good results from this process also??

 

[barrett1]

I have worked on this issue and found significant improvement. First, my 81 is a 1990 so it has a metal gas cap that seals with a rubber seal. I do not have the plastic one, which to my knowledge only let's out positive pressure anyways, does not allow air inward to correct negative pressure. I took the check valve off which is at the rear of the truck. I sucked air one way, then the other. If it is oriented as labeled (opposite how it was originally installed on my truck), with to engine closer to the front of truck, it will allow better air to come in to tank and vastly improved my negative pressure issue. Truck has minimal negative pressure when I open gas cap after long drive and does not stumble anymore at high rpm. I did install a fuel filter on end of line which terminates in frame to prevent dust ingress. Curious if you will see good results from this process also??

Also, I did take the check cover off tank and my tank and screen were perfect with no debris or dirtiness, so that does not confound the issue or solution.

 

[MobySlick]

I have worked on this issue and found significant improvement. First, my 81 is a 1990 so it has a metal gas cap that seals with a rubber seal. I do not have the plastic one, which to my knowledge only let's out positive pressure anyways, does not allow air inward to correct negative pressure. I took the check valve off which is at the rear of the truck. I sucked air one way, then the other. If it is oriented as labeled (opposite how it was originally installed on my truck), with to engine closer to the front of truck, it will allow better air to come in to tank and vastly improved my negative pressure issue. Truck has minimal negative pressure when I open gas cap after long drive and does not stumble anymore at high rpm. I did install a fuel filter on end of line which terminates in frame to prevent dust ingress. Curious if you will see good results from this process also??

I haven't driven mine anywhere (have to do timing belt and am scared the 9 year old belt will break at any moment) but just starting it in my driveway with the lower tube with no check valve I did see an improvement. The real test of course would be a longer drive, as I let lots of sir in when I first took my fuel cap off.

I'll see if I can test my plastic fuel cap to see if it relieves negative or positive pressure (mines a 1995), if it's the former I'll buy a new one, if it's the latter than I don't see how this system could work correctly, given both entrances would be only for relieving positive pressure. Regardless I'll be changing my fuel hoses and that should help, as there will be less ways for the air to enter the lines

I'm glad yours is working well though! I would advise against any water crossings with your system however, as with the check valve positioned in the opposite direction it will suck water in.