Fuel Pump Conundrum

[davidw99]

Here's the scoop. A week ago Monday my Bug's engine slowed to a stop much like no fuel. I pulled over and after a few minutes the car started. It went for about a mile and same thing. Tried it again with the same result. I called AAA and had it towed home.

Fuel filter was dry. Tank half full. Fuel flowed from the hose to the tank. I could blow bubbles into the tank. No fuel came out of the pump when I turned the engine by hand. I hadn't had a fuel problem in the seven years since the rebuild. I figured it was the pump.

Ordered a new pump. Alternator car so alternator pump. Researched fuel delivery problems. New pump came but still no gas when turned by hand or when turned by key. The pump does push gas out when the lever is pushed by hand when the pump is off the car thus indicating that fuel is flowing to the pump and the pump works.

The push rod extended 4 - 5 mm out of the flange when the engine was turned by hand as indicted on www.vw-resource.com. However, Bentley says the rod should extend 1/2 inch (13 mm).

My questions.

How far should the rod extend from the flange when at its greatest height?

If it is meant to be 1/2 inch, why is mine only extending 4-5mm? Could something have happened to the engine to change the push rod extension?

Should I try it with a generator push rod? (Yes, the car does have an alternator and the push rod in the car is the one that has been there seven years).

A piece of the old flange broke off into the engine. Is this a cause for concern?

Thank you in advance for any insights.
_________________
Dave

'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."

'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.

[Aussiebug]

David,

Is the car a super or a standard bug? If it's a standard bug - these have a small metal gauze filter the size of a pencil stub which sits above the outlet. These do corrode and collapse, allowing rust flakes etc to block or partly block the outlet and starve the engine of fuel, but will then slowly leak fuel into the lines so the car can be started a few minutes later (been there - done that). Plastic replacements are available.

It still allows you to blow back into the tank, but the rust flakes can settle over the outlet again.

Superbugs have a sock on the end of the fuel line which exits the SIDE of the tank rather than the lowest part, so they don't usually get a problem like this.

NEVER use the longer 108mm push rod on a squat round fuel pump or you will probably wreck the pump - you MUST use the 100mm pushrod.

Make sure the bakelite flange is sitting down flush with the case and make sure none of the cone part inside the case has broken off. If it has you have to dig the remains out as best you can. When fitting a new flange, it should be a snug fit but should still slide in with just a gently push - some of them at a too-tight fit, in which case you need to sand the outside of the cone down so it's a snug fit. A really tight flange/cone will swell internally with heat and grab the pushrod, stopping it moving through it's full range so the pump cant pump properly.

Remember too that it takes some time for a new pump to fill with fuel, so it can take some cranking to get the engine to fire. Sometimes it pays to pre-fill the float bowl before starting - the engine will run for enough time to get the pump working well.

The small clear filters SHOULD look almost empty when they are new - the outlet is down inside the paper cone so only the bottom of the paper has to get wet for the fuel to flow out. As the filter clogs up the fuel rises up the paper cone to find fresh paper and so a FULL filter is a clogged filter and should be replaced.

Hope that helps.
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

[davidw99]

Thank you for your reply.

It is a Super. I did have to sand the flange a little to insert it into the engine but the rod does move in the flange. I replaced the filter so that isn't the problem. I will try filling the float bowl to get the car started.
_________________
Dave

'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."

'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.

[Her74buggy]

I just went though a similar problem. It took two new pumps to get it sorted. Check my post and answers.

http://www.thesamba.com/vw/forum/viewtopic.php?t=6...highlight=

One thing is the rod. Mine was worn down on the pointy end so I replaced it for $3. Measure yours to make sure it's 100mm. I doubt it would be worn down that much though. Aussiebug and a few other great resources posted on my thread and there are a bunch of photos so it may have your answer.
Good luck

[Tim Donahoe]

Concerning the length of the fuel pump rod as it sticks out of the flange, someone on this forum once said that Bently was incorrect about the one-half inch--when the engine has an alternator.

I can't remember who said it, but he mentioned that the half inch figure was for generator models.

Tim

[Her74buggy]

[Aussiebug]

And if I remember right, the rounded end of the rod points down.
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

[davidw99]

[davidw99]

[davidw99]

Go the car going. I think I was to impatient before. This is the pump I installed. A little tight getting it onto the studs but easier to tighten the inside bolt.

http://www2.cip1.com/ProductDetails.asp?ProductCode=VWC%2D113%2D127%2D025%2DGOE

Thank you for all your help. It's good to be able to kick things around.
_________________
Dave

'73 Saturn Yellow Sports Bug that has undergone a full pan off restoration. "Herbert IV."

'67 Sedan. "Bellamy." Currently being "refreshed" and recently repainted.