1964 fuel injection unit leak

[Patrick C.]

Last week I noticed a small amount of gasoline on the passenger side valve cover. Closer inspection showed a leak (drip) at the base of the fuel injection pump flange just below where the cable enters. Difficult to tighten the screws even with a 90 degree screwdriver. This is a 380 fuel injection unit. Do I need to pull the whole FI unit from the adapter manifold to reseal the flange? Any other suggestions to make sure i just do this once?

Pat

[Don H.]

Re: 1964 fuel injection unit leak

I would suggest you pull the unit (fairly easy) & remove the high pressure pump. It might just need a new gasket but you want to be sure the fuel meter mounting surface is true. If it is coming from the pump and not from where it mounts to the fuel meter, you need the pump rebuilt. Do not let it go, a gas leak can be a disaster. Good luck, Don H.

[Patrick C.]

Re: 1964 fuel injection unit leak

Thanks Don

How will i know if I know if the pump is leaking? Where will It leak from? Its a rather small leak, more like a small drip.

I actually think its leaking from the flange with the 5 screws and gasket but I'm not 100% sure. I want to make sure I only do it once.

Can I rebuild the pump at home? Special tools or parts?

Pat

[Don H.]

Re: 1964 fuel injection unit leak

Pat,
The leak should be easy to pin point, dry everything and then use separate towels in each area. Watch it closely and it should be apparent where it is coming from. If the pump needs rebuilt, I would recommend you send it out if you have never done it before. The pump is the heart of the unit and if rebuilt correctly will last a long time. Good luck, Don H.

[William C.]

Re: 1964 fuel injection unit leak

Don't forget the seal on the shaft, common source of leaks. Hopefully it did not create a groove on the shaft, but new shafts and seals are readily available.

[Patrick C.]

Re: 1964 fuel injection unit leak

I checked the shaft seal and it was fine. We pulled the fuel injection unit and replaced the pump gasket and trued the surface. Put it back together and fired it up. Unfortunately the plug at the front of the fuel bowl was also seaping gas. We gave up for the night. Has anyone had this problem before? Can it be fixed without removing the fuel injection unit again? How do you go about sealing that? New plug?

[Richard M.]

Re: 1964 fuel injection unit leak

I had a similar leak in a 61 unit a few months ago. Jim Lockwood and John DeGregory were a great help offline to help me figure it out. It was my first fuelie rebuild. Check just under the lower mount screws where the pump mates to the fuel meter. Check under the snout of the pump to see if it's from there, then dripping down lower.

It is possible that the pump shaft seal is at fault. If so the pump needs a rebuild and new seal and shaft if it's scored. The fuel meter mount boss is another possibility. I learned it is a common fault. When the screws are tightened over time, the more they're tightened, the more susceptible to leak. The aluminum warps.

I would suggest you get the entire fuel meter looked at by a expert, but for reference this is exactly what I went through....

Some photos. The engine was running fine, but I had some drips on the valve cover after engine break-in. I took the unit off of the engine, removed the FM, then the pump. I previously rebuilt the pump with new shaft and seal so I had confidence it wasn't leaking there.


You can see a gap at the lower mating surface of the pump body when I rocked the pump.


Here is a video showing the fault...

https://youtu.be/pVjKjdhMB2M

With Jim and Johns guidance, I was able to repair the mating surface. Here is a sequence showing before and after. I used a flat bar and sandpaper to get the area flat using rough paper then final lapping with fine grade. I also could have used a machinists table or glass plate.


If it's the pump, best to have it rebuilt.

Rich

[Bill W.]

Re: 1964 fuel injection unit leak

Patrick,
New plugs are available from several of the rebuilder people. Carefully drill a 1/8" hole above the centerline of the existing plug, do not let the drill penetrate very far into the cavity behind the plug. Use a scribe of other sharp pointed tool to remove the welsh plug, it should come right out. Remove the monel filter screen and clean it, replace screen. Coat the inside of your new welsh plug with the gasoline resistant sealer of your choice and set it in place. Now for the scary part....seat the new plug with a hammer or possibly a piece of hard wood you strike with a hammer. Job done! Good luck. Bill

[Michael J.]

Re: 1964 fuel injection unit leak

Patrick,
New plugs are available from several of the rebuilder people. Carefully drill a 1/8" hole above the centerline of the existing plug, do not let the drill penetrate very far into the cavity behind the plug. Use a scribe of other sharp pointed tool to remove the welsh plug, it should come right out. Remove the monel filter screen and clean it, replace screen. Coat the inside of your new welsh plug with the gasoline resistant sealer of your choice and set it in place. Now for the scary part....seat the new plug with a hammer or possibly a piece of hard wood you strike with a hammer. Job done! Good luck. Bill

Willy knows of what he speaks, he has fixed several of my '64 380 units with this very same problem.

[Patrick C.]

Re: 1964 fuel injection unit leak

Thanks Bill

Just one question. Should the fuel level in the bowl be high enough to leak out the welsh plug?. I was thinking that good design practice would have the fuel level below the plug? Any recomendation on the sealer to use?

Pat

[Don H.]

Re: 1964 fuel injection unit leak

The advice above is right on. If you want more info, John D. gave a detailed explanation recently how he replaces the welsh plug. Do a search and you should be able to find it.

[Patrick C.]

Re: 1964 fuel injection unit leak

I had a similar leak in a 61 unit a few months ago. Jim Lockwood and John DeGregory were a great help offline to help me figure it out. It was my first fuelie rebuild. Check just under the lower mount screws where the pump mates to the fuel meter. Check under the snout of the pump to see if it's from there, then dripping down lower.

It is possible that the pump shaft seal is at fault. If so the pump needs a rebuild and new seal and shaft if it's scored. The fuel meter mount boss is another possibility. I learned it is a common fault. When the screws are tightened over time, the more they're tightened, the more susceptible to leak. The aluminum warps.

I would suggest you get the entire fuel meter looked at by a expert, but for reference this is exactly what I went through....

Some photos. The engine was running fine, but I had some drips on the valve cover after engine break-in. I took the unit off of the engine, removed the FM, then the pump. I previously rebuilt the pump with new shaft and seal so I had confidence it wasn't leaking there.


You can see a gap at the lower mating surface of the pump body when I rocked the pump.


Here is a video showing the fault...

https://youtu.be/pVjKjdhMB2M

With Jim and Johns guidance, I was able to repair the mating surface. Here is a sequence showing before and after. I used a flat bar and sandpaper to get the area flat using rough paper then final lapping with fine grade. I also could have used a machinists table or glass plate.


If it's the pump, best to have it rebuilt.

Rich

Richard

thank you, i checked the pump and shaft carefully and it was not leaking. We surface the mouting surface similar to your pictures until the high spots were gone. Then a new gasket. Its not leaking now but i am getting seepage from the welsh plug also. I am hoping that fixing that will end the leaking.

Pat

[Patrick C.]

Re: 1964 fuel injection unit leak

Patrick,
New plugs are available from several of the rebuilder people. Carefully drill a 1/8" hole above the centerline of the existing plug, do not let the drill penetrate very far into the cavity behind the plug. Use a scribe of other sharp pointed tool to remove the welsh plug, it should come right out. Remove the monel filter screen and clean it, replace screen. Coat the inside of your new welsh plug with the gasoline resistant sealer of your choice and set it in place. Now for the scary part....seat the new plug with a hammer or possibly a piece of hard wood you strike with a hammer. Job done! Good luck. Bill

Do you do this on the car? Or do i remove the fuel unit again?

[Bill W.]

Re: 1964 fuel injection unit leak

Patrick, The fuel level is above the bottom of the welsh plug and normal driving (turns or braking) will increase the level behind the plug. In addition fuel that is normally bypassed away from the nozzles is discharged into the cavity behind the plug where it flows back into the float bowl. So fuel is ALWAYS behind the plug. As for a sealant, I use epoxy. Bill