TR4/4A TR4 Fuel Pump

[Alex_McMillin]

In following up from my fuel odor investigation, I have narrowed it down to the fuel pump. The carbs were fine, no strong odor from the trunk, but a lot of moisture around the fuel pump. So I figure I might as well give the fuel pump a going over. When I removed the glass bowl, fuel started spitting out quite rapidly. Is that normal? Is it simply draining the fuel sitting in the lines? I could see maybe a little bit, but this was pretty steady and continuous stream of gas. If this is normal, do I need to drain the tank first? I would like to remove the entire unit, clean it up, and replace any and all the gaskets. This all being an effort to combat the fuel odor I'm fighting. My first attempt made it worse and I heard about it.

........Alex

 

[Mickey Richaud]

Hi, Alex -

Have you checked to make sure the tank is vented? This should not be a closed system, and if the vent is plugged, it may the the source of your issue, especially given this latest information.

Just a thought...

Mickey

 

[MGTF1250Dave]

Aloha Alex,

The fuel flowing from the pump with the sediment bowl removed is normal. The fuel pump is lower than the tank and is gravity fed, so if left open it will drain the tank. If you have a small amount of gas in the tank, parking the car on an incline might raise the pump above the fuel tank level. The alternative is either a clamp on fuel hose, some type of plug/cap for the fuel line into the pump or drain the tank.

 

[TR3driver]

Or install a shutoff valve in front of the pump, like the earlier cars had.

 

[StevenCO]

A new fuel pump this fall solved my pesky fuel odors. Wish I'd done it a couple years ago.

Removing the sediment bowl:

- the pump is gravity fed (the tank is higher than the pump) so removing the sediment bowl will drain the tank pretty quickly. A plastic hose clamp for the incoming flexible line is a great thing to add to your car tool kit; vice-grips work in a pinch.
- a fuel shut-off valve is a great addition to the inlet line; remember the flexible line from body to pump is 5/16". It's fairly easy to find lawn mower or garden tractor fuel shut-off valves esp. Briggs and Stratton.
- if you add a shut-off valve, why not add a clear plastic fuel filter too? Simpler than cleaning the sediment bowl then hoping to get the bowl to seal... by the side of the road in the middle of a long road trip.
- if you have a cork sediment bowl gasket, soaking it first can help you get a good seal.

Rebuilding or Replacing the pump:
- it's silly easy to remove and rebuild your fuel pump. Kits are cheap.
- it's cheap enough to replace the pump, so that's what I did. Last month I bought the Moss reproduction pump with the primer, but apparently the inlet and outlet were machined wrong by the manufacturer and the screw-in fittings to correct this are both 1/4" -- for inlet and outlet. Since the inlet should be 5/16" and the outlet is 1/4", this isn't ideal. It might work if you have a 5/16" metal line flush at the end of the olive washer, but replacement inlet lines are NLA from Moss and I wasn't going to cut my original metal inlet line.
- so I ordered a repro pump with primer from Rimmer Bros UK, along with a complete fuel line kit. Their part was spot on. I'm not Moss-bashing; this was my first Rimmer order after a couple decades buying from Moss. But I do think Moss should offer a complete fuel line kit.

Reverse of Removal:
- there is no trick to reinstalling the pump. If you feel like you're forcing it, slide it off and try again. It might be possible to get the lever on the wrong side of the cam, but you'd have to really work at it. When it's lined up it goes on easy.
- don't forget to put back the little bracket for the oil pressure line on the rear bolt of the fuel pump.

Steven

 

[TR3driver]

- if you add a shut-off valve, why not add a clear plastic fuel filter too? Simpler than cleaning the sediment bowl then hoping to get the bowl to seal... by the side of the road in the middle of a long road trip.

OTOH, even a teaspoon of liquid water will block a typical paper element filter, while the sediment bowl will hold many times that much without being affected at all. I've been forced to the side of the road by a blocked paper element filter more than once, while I have never, ever needed to clean the sediment bowl while on a trip. It's more the sort of thing I do every few years as part of routine maintenance.

If you do opt for a replacement pump, be sure to check how the main pivot pin is located in the body. There were some reproduction pumps a few years back where the pin was just staked into the body, and they sometimes came loose with disastrous results.

Oh, and this tool will make changing the pump a lot easier:

(Thanks to Justin Wagner)