Ive got a 1993 12v with VE Injection pump. The engine & pump were rebuilt about 4000 miles ago with lots of upgrades... Hamilton 188/220 cam, big S300 (64/72) turbo, 5 x .012" injectors, M&H timing advance spacer... which leads me to my problem.

Last week I noticed fuel dripping from my vacuum pump and traced it to the ksb housing. Fuel is leaking between the m&h timing spacer and the ksb at a rate of 1 drip every 10 seconds or so. I confirmed it was leaking from the ksb flange by watching it drip with the help of a dental mirror.

I tried removing the timing spacer but the ksb still drips at the same rate. I tried replacing the o rings even though the ones provided with the M&H timing kit seemed to still be in perfect shape. To the best of my knowledge this wasn't an issue until 2 weeks ago.. only thing I did around that time was to turn in the main fuel screw 1 turn. Turbo spooled up faster, EGTS actually went down on the highway, truck ran great! I thought all was good.

I checked the ksb housing for any obvious cracks but can't see anything. I just don't know what else could be causing this flange to leak.
The engine runs perfectly, same as it did before, just leaks fuel, What am I missing? Could the pressure regulator in the injection pump connected to the ksb be stuck open ? or clogged?

Tomorrow I plan to remove this regulator valve and the banjo bolt on the fuel return line to make sure both aren't clogged and function properly, any constructive ideas are appreciated!

 

The area under the ksb flange is connected to the fuel inlet by a passage that runs in that web of the pump housing that is in the way of getting to the bottom pump to timing case mounting bolt. The o-ring should only be sealing against very slightly higher than inlet (lift pump) pressure, and a restricted return line should not be causing any trouble.

In the past, I have found that joint to like to leak in cold weather, FWIW -- normally 0 F and below, though.

I suppose it is possible that the relief passage mentioned above has some crud in it, which could be checked while installed in the truck. Otherwise, I would buy a new gasket from Bosch, and try again (you refer to them as o-rings, so I am not sure if you are trying to use regular o-rings as opposed to the bosch part which has an unusual lipped profile).

 

I have an aftermarket carter lift pump; my lift pump pressure is 10 psi with no leaks ; while its leaking it reads 9.2 - 9.4 psi. I did try to replace the bosch orings with some from napa.. still leaks.

I even tried removing the spacer but it still leaked at the ksb flange.. I just installed the M&H spacer with new oring less then 4K miles ago.. what would cause them to start leaking so soon? appears to be no issues with the bosch orings. The oring are stick up about .020" above the surface of the timing spacer.

I tried to source some new bosch oring but they aren't available locally; I'd have to order them.. I really need this truck to make money and can't afford to wait for the orings if they aren't even going to solve the problem.

I wish I could determine exactly what the issue is before i start guessing.. i realized the napa orings aren't the correct size.

 

Did you find anything that fixed the issue?

 

In the end I believe the m&h spacer cracked the ksb cap . Had to tig weld the crack and used some paper gasket I cut out from a sheet on both sides of the timing spacer. That’s fixed it .