Is my fuel pump bad?

Verdict is in!

It was the fuel pump. Having rebuilt it and re-installed it, the car is transformed.

I wanted to take the pump apart to try to verify if that was the problem anyway, so I ordered the top-side rebuild kit from Agri-Parts for £12.95 on eBay for the David Brown 990 on Monday and it was here in Ireland by Thursday. The kit included both valves, the diaphragm and attached rod, seal for the glass dome, the seal for the block, the seals for the valves, and a new spring. Not included was the screen that sits under the dome.

You can get one here: S.40568 Fuel Lift Pump Repair Kit for David Brown 990 (900 Series) | UK Supplier

If you just want to buy a pump, they are cheap from those folks, too: S.63034 Fuel Lift Pump for Case/IH, David Brown | (K311939, K909944, K944997) | UK Supplier

Following the factory workshop manual, I had the pump out in about 40 minutes. Cleaning and rebuilding it took about an hour with help from my kids. Putting it back was about 20 minutes, but it's not much fun. Doing the back bolt is much easier from under the car, by the way. The biggest pain was that there is a plastic fuel line between the reserve valve and the pump and the fitting on the pump wouldn't rotate without taking the whole plastic pipe with it. I ended up taking the pump off the block and unscrewing the pump from the plastic pipe by turning the pump around and around! My car is an early one so there were no lock tabs on the bolts holding the pump to the block. When I put them back, I used blue thread lock to make sure they stay there.

The pump is an original AC unit with "Made in England" casting and "AC" at the top of the dome. I was surprised to find original AC parts inside the pump. It appears from the marks on the screws that hold the valves down to have been rebuilt once before, but it must have been ages ago given the age of this:

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There was not anything obviously wrong with the diaphragm or valves. There was crap in the screen filter and a little bit of sediment in the pump, but nothing that would be problematic. But, after I put the rebuilt pump back on the car, there is no more air! I think that like @sdibbers had seen on his car, the old diaphragm and valves were just not working well any more due to age and fuel changes, and somehow pumping air into the system.

Thanks all for your assistance. Very happy with this outcome since it was the easiest solution, and cheap!

Cheers,
Karl
 

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Excellent thread! I currently have bubbles in the fuel pump and bad idle, given the cost of the tractor fuel pump I have ordered one!

Will post result.
 
Ok, car was running terribly on way home, I had to pull over several times to rev and clear it to carry on, loads of bubbles in pump. Pulled it off when I got home and it was full of sediment. I will need to clean out the tank but until then I will need to fit a filter before the pump to protect it and the carb? Will clean out carb tomorrow (joys of an SC).
 
Do you guys think putting the filter before the pump will cause any restriction issues? Makes sense to me to protect the pump.
 
Do you guys think putting the filter before the pump will cause any restriction issues? Makes sense to me to protect the pump.

I put one on 12 years ago, it is still in good shape, and works great. You can get universal filters with both 5/16" and 1/4" line size for a few dollars at the parts store. Some kits even come with hose clamps.
 
I put one on 12 years ago, it is still in good shape, and works great. You can get universal filters with both 5/16" and 1/4" line size for a few dollars at the parts store. Some kits even come with hose clamps.

Something like these:

5/16 Inline fuel filter. Clear plastic (Lot of 3 Pcs ) | eBay

Also if you have replaced your fuel line with soft rubber hoses then get some chose shut off clamp grip pliers. You can avoid getting covered with fuel and a lot safer as well.
 
That’s great, they are the ones I have from Sealey. There isn’t a huge amount of room for the filter, From the reserve fuel union to the pump but I think there is enough.
 
Hi, They're fairly standard threads and fittings so try a local agricultural parts supplier.

Colin
 
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