Too much pressure in top tank on a 2910 CAV pump?

[gordonhirt]

The CAV fuel pump top tank gasket catastrophically failed on the back side of the tank facing the engine and began leaking a lot of fuel on my Ford 2910. I removed the top tank while the pump was on the tractor, installed a new gasket, bled the lines and restarted the tractor. The new gasket failed almost immediately. Concerned that I may have misaligned the gasket when I did the repair on the tractor, I removed the pump and installed the gasket on the bench to make sure I could see that the gasket was correctly installed. I reinstalled the pump and It started leaking again almost immediately. I removed the pump, made a custom gasket out of slightly heavier gasket paper, used a thin layer of gasket sealer on both sides of the gasket, reassembled the pump, waited the appropriate amount of time for the sealer to set then reinstalled the pump and restarted the tractor. The gasket started weeping fuel within a minute and started releasing a needle thin spray of fuel at the gasket line. It seems that there is just too much pressure in the top tank due to an internal leak. Is there another fix I can try before sending the pump out for repair?

 

[Dieseltech]

The CAV fuel pump top tank gasket catastrophically failed on the back side of the tank facing the engine and began leaking a lot of fuel on my Ford 2910. I removed the top tank while the pump was on the tractor, installed a new gasket, bled the lines and restarted the tractor. The new gasket failed almost immediately. Concerned that I may have misaligned the gasket when I did the repair on the tractor, I removed the pump and installed the gasket on the bench to make sure I could see that the gasket was correctly installed. I reinstalled the pump and It started leaking again almost immediately. I removed the pump, made a custom gasket out of slightly heavier gasket paper, used a thin layer of gasket sealer on both sides of the gasket, reassembled the pump, waited the appropriate amount of time for the sealer to set then reinstalled the pump and restarted the tractor. The gasket started weeping fuel within a minute and started releasing a needle thin spray of fuel at the gasket line. It seems that there is just too much pressure in the top tank due to an internal leak. Is there another fix I can try before sending the pump out for repair?

What you call a top tank is the governor CONTROL COVER, not a tank. Question, is the FUEL TANK VENT WORKING? If the vent is plugged that will cause your trouble too with leaks. If done correctly NO SEALER should ever be used on that cover gasket.

 

[farmersamm]

What you call a top tank is the governor CONTROL COVER, not a tank. Question, is the FUEL TANK VENT WORKING? If the vent is plugged that will cause your trouble too with leaks. If done correctly NO SEALER should ever be used on that cover gasket.

Is the tank building too much pressure when not vented? I have the same problem on the pump on a Perkins. Haven't done much about it, except tighten the 2 small cap screws to no avail. It's not a catastrophic leak, but it does run fuel down the side of the block.

EDIT..........my problem is the governor gasket, the one that has a lead seal on the wire connecting the cap screws.

 

[Dieseltech]

Is the tank building too much pressure when not vented? I have the same problem on the pump on a Perkins. Haven't done much about it, except tighten the 2 small cap screws to no avail. It's not a catastrophic leak, but it does run fuel down the side of the block.

EDIT..........my problem is the governor gasket, the one that has a lead seal on the wire connecting the cap screws.

That gasket will fail anyway over time, but a plugged tank vent will make it worse. Listen closely after engine has run two/three hours and with engine off remove the fuel cap, if you hear air rushing past then tank vent is plugged, or cap vent valve is not working, causing tank pressure to RISE as fuel heats up. I repair a lot of those pumps and when any leak starts on the CAV DPA pump it's wise to have the pump completely resealed.

 

[gordonhirt]

What you call a top tank is the governor CONTROL COVER, not a tank. Question, is the FUEL TANK VENT WORKING? If the vent is plugged that will cause your trouble too with leaks. If done correctly NO SEALER should ever be used on that cover gasket.

I understand about the sealant and had noticed that the original gasket didn't have any sealant. It seems like the area under the governor control cover shouldn't be pressurized to the extent where fuel sprays out of the gasket. I was wondering if there was an internal pressurized area that was bleeding pressure into the area under the Governor control cover. I had a temporary issue with a replacement fuel tank cab that was not the venting type but have corrected that by installing a venting type fuel cap. Is there a separate fuel tank vent on the Ford that I haven't seen?

That gasket will fail anyway over time, but a plugged tank vent will make it worse. Listen closely after engine has run two/three hours and with engine off remove the fuel cap, if you hear air rushing past then tank vent is plugged, or cap vent valve is not working, causing tank pressure to RISE as fuel heats up. I repair a lot of those pumps and when any leak starts on the CAV DPA pump it's wise to have the pump completely resealed.

Well you just described another symptom I had. My tractor is supposed to have a vented fuel cap, but I was sent an unvented one by mistake from an online supplier when I specifically ordered a new vented cap. After driving the tractor for a couple of hours, there was definitely what I thought was suction when you removed the cap but it could have been pressure. What I remember most is rushing air and difficulty removing the cap until the pressure equalized. When the supplier wouldn't admit their mistake and send me a vented cap, I didn't actually get a vented cap, I simply cut a notch in the fuel cap gasket to allow air to enter the tank which seemed to alleviate pressure issue but maybe by that point the damage had already been done to the pump. I will definitely take your advice about having the pump completely resealed. Is that something I can do myself with a seal kit? Where is the tank vent located? Between the fuel return lines, a new filter and cleaning the tank vent, it seems I have a good amount of maintenance to do in addition to resealing the pump. Thanks again for your in-depth diagnosis and advice.