Fuel Pump Rebuild

Technical articles by owners, for owners.
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Squiggas
Posts: 49
Joined: Sat Oct 13, 2007 10:22 am
Location: Sussex, England

Fuel Pump Rebuild

Post by Squiggas » Sat May 19, 2012 10:23 am

I decided to rebuild my fuel pump because every time I left the pinz for a few days without use it would take ages to start. It wasn't always like that and it was getting worse.

I'm not a mechanic. This was very much a DIY job.

These are the bits I used for the rebuild:
A fuel pump repair kit, part number 712.1.08.560.0
A 13mm open ended spanner
A medium flat head screwdriver
A small flat head screwdriver
Two hose clamps
Some grease

The repair kit contained these parts:
fp2.JPG
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The idea was to remove the fuel pump, change the old parts with the new parts and then put it back again. Easy right? Well, yes it was actually.

To gain access to the fuel pump I removed the engine cover and then took off the air filter. Here it is:
fp1.JPG
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See the wet patch under the fuel pump. Something is definitely wrong!

Before removing the hoses from the pump I clamped them about 2 or 3 inches from the end to minimize fuel spillage. The manual says to pull the hoses off. I found that I had to twist them to get them off. Then they came off quite easily.

I tucked the hoses out the way and used the 13mm spanner to remove the two nuts at the base of the fuel pump. They are not the most accessible nuts, but fortunately I found that after loosening them about a quarter turn with the spanner they came off the rest of the way by hand.

I removed the two washers and the pump lifted off easily. I also removed the push rod that was sticking up beneath it and the black plastic bit that the pump sat on. I looked at the base of the fuel pump and saw the lever which gets moved by the push rod. I pressed it with my thumb and petrol squirted out like from a water pistol. Something to look out for!

This is the removed fuel pump, nuts, washers and push rod. There is a gasket still on the push rod:
fp3.JPG
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I'm glad I took this picture because I had to refer to it later when I reassembled the pump.

User avatar
Squiggas
Posts: 49
Joined: Sat Oct 13, 2007 10:22 am
Location: Sussex, England

Re: Fuel Pump Rebuild

Post by Squiggas » Sat May 19, 2012 10:38 am

Here is the black plastic bit, which guides the push rod:
fp7.JPG
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Before opening up the fuel pump I gave it a quick clean with a paper kitchen towel. In hindsight this was a mistake. I should have spent a few more minutes to clean it more thoroughly which would have made the job a lot more pleasant and saved time in the long run.

Being very wary that springs might pop out, I cautiously removed the top cover. It came off easily and there didn't seem to be any danger of bits popping out, although there was still some petrol inside so I ran outside so that it wouldn't spill on my dining room floor.

Here's what I found:
fp4.JPG
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At this point I realized that I wanted to keep the inside clean, but the outside was dirty. I really should have given it a good clean before I took it apart.

Straight away I recognized two parts from the repair kit. It's not obvious from the picture but there is a gasket sitting on top of the diaphragm.

I swapped the old for the new and replaced the cover, making sure that it would be a clean seal.

Now time to open the lower section:
fp5.JPG
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Aha, the large part is here but it won't come out.

User avatar
Squiggas
Posts: 49
Joined: Sat Oct 13, 2007 10:22 am
Location: Sussex, England

Re: Fuel Pump Rebuild

Post by Squiggas » Sat May 19, 2012 10:57 am

The reason it wouldn't come out is that it was held in place by the lever below. I then used a small screwdriver to remove the rectangular side panel:
fp6.JPG
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The compressed spring looks scary but it was easy to dig out with a screwdriver.

Looking through the panel with the spring removed I could see how the pump works. The lever pivots on a rod which is held in place by two circlips. I removed the circlips and the rod to release the large part.

I'm glad the repair kit came with two circlips because I managed to knacker mine as I removed them

I replaced old with new again. I had to press down on the metal disc to make the plunger open up below it to get the lever in place. Sorry, no picture of this but it's obvious when you see it.

With all the bits reassembled I packed a fair bit of grease around the lever and gave the black plastic part a good clean.

The pump was easy to refit to the vehicle. I made sure all the gaskets went in the right place and tightened up the nuts.

Then it was time to see if it worked. The pinz took ages to start. I gave it 10 second bursts with a 30 second wait between each burst so that I wouldn't overheat the starter motor. I turned off the ignition between each burst so that I wouldn't overheat the ignition coil.

Hoorah! Eventually it started up and idled perfectly. I ran it for 5 minutes and looked for leaks.

I did find a leak - from the front carb. I was worried that I had done something wrong but after replacing a rubber gasket and tightening up a few bolts there were no more leaks.

Job done.

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