Changed the fuel pump check valve
09-19-2004, 02:12 AM
#1
Three Wheelin'
Thread Starter
Changed the fuel pump check valve
Updated September 26th to add photos graciously provided by Terry Jenner
I had a lingering hesitation after letting the 968 sit for a week more more. It is gone within 50 feet of the garage, but still I would like to solve it. The DME relay, cap, rotor, plugs and fuel filter are all new so they are not the problem. The check valve should prevent the fuel system from loosing pressure when the car is not operating. I speculated that it might be the problem. I purchased the check valve before I changed the fuel filter and meant to change it then but I could not find where it went. After a lot of searching I found it today.
The secret is that the bottom of the fuel tank, is not the bottom of the fuel tank. It is a cover and the fuel pump is inside, the check valve is between the fuel pump and the hose to the fuel filter.
Here are the steps.
1. Disconnect the battery, or pull the DME relay.
2. Get at least the back end up on jack stands and some other jack stands or jacks under there in case something goes wrong with the primary.
3. At the back of the car find the cover on the bottom of the fuel tank. The back right corner is a separate piece that has two philips screws holding it in place. Remove this cover. You will be able to see the fuel line between the tank and the pump.
4. Take a hose clamp or vice grip + towel and clamp the fuel line near the tank.
5. Have rags and a large catch pan ready in case to catch any spill and release the clamp from the hose where it connects the pump. Some gas should drain.
6. Find the electrical connector beside the fuel filter and disconnect it. This is just in from the right rear (right from the back of the car facing forward) tire.
7. Have rags and a large catch pan ready to catch any spill and disconnect the fuel line where it enters the fuel filter.
8. There is a metal strap that runs from the back left to the front right of the fuel tank lower cover holding in in place. A single 13mm bolt holds it in place on the front right. Remove this bolt and allow the strap to hang.
9. You should be able to lower the cover which will have the fuel pump attached. Take the cover and fuel pump to somewhere comfortable to work.
10. You can now see the check valve. It is the 17mm bolt visible on the out side of the pump between the pump and the rounded pickup for the line to the filter. Gently pull the rubber plugs off of the electrical connectors to make room to work.
11. Place a 17mm wrench on the check valve and a 19mm wrench on the nut at the end of the check valve + fuel line combination and remove the 19mm nut.
12. Slide the fuel line off of the check valve.
13. Use a 17mm wrench to remove the check valve from the fuel pump.
14. Inspect everything to make sure it is clean.
15. Install the new check valve into the fuel pump. There is a copper ring that goes between the check valve and the pump.
16. Slide the next copper ring onto the check valve and slide the fuel line onto it.
17. Slide the final copper ring onto the check valve and reninstall the 19mm nut.
18. Check to make sure everything is secure and in the correct order which should be pump - copper ring - check valve - copper ring - fuel line - copper ring - 19mm nut.
19. Reinstall the lower fuel tank cover, strap and retaining nut.
20. Reattach the tank to pump fuel line and secure the clamp.
21. Reattach the fuel line to the fuel filter.
22. Check to make sure everything is secure.
23. Remove the clamp from the fuel hose.
24. Smell for fuel, watch for it to run, hopefully it will not. If it does reclamp the hose and look for the problem.
25. Reattach the final piece of the lower fuel tank cover.
26. Reconnect the electrical connector.
27. Make sure no gas is pooled anywhere.
28. Reconnect the battery.
29. Turn the key on but do not start the car for 10 seconds, repeat four or five times to let the pump repressurize the fuel system. This may not work, but it is a theory.
30. Go for a drive.
PS, you could insert "change fuel filter" at any point between 5 and 21. I spilled a lot more fuel when I changed the fuel filter than changing the check valve.
The hesitation mentioned earlier has not occured since changing the fuel pump check valve.
I had a lingering hesitation after letting the 968 sit for a week more more. It is gone within 50 feet of the garage, but still I would like to solve it. The DME relay, cap, rotor, plugs and fuel filter are all new so they are not the problem. The check valve should prevent the fuel system from loosing pressure when the car is not operating. I speculated that it might be the problem. I purchased the check valve before I changed the fuel filter and meant to change it then but I could not find where it went. After a lot of searching I found it today.
The secret is that the bottom of the fuel tank, is not the bottom of the fuel tank. It is a cover and the fuel pump is inside, the check valve is between the fuel pump and the hose to the fuel filter.
Here are the steps.
1. Disconnect the battery, or pull the DME relay.
2. Get at least the back end up on jack stands and some other jack stands or jacks under there in case something goes wrong with the primary.
3. At the back of the car find the cover on the bottom of the fuel tank. The back right corner is a separate piece that has two philips screws holding it in place. Remove this cover. You will be able to see the fuel line between the tank and the pump.
4. Take a hose clamp or vice grip + towel and clamp the fuel line near the tank.
5. Have rags and a large catch pan ready in case to catch any spill and release the clamp from the hose where it connects the pump. Some gas should drain.
6. Find the electrical connector beside the fuel filter and disconnect it. This is just in from the right rear (right from the back of the car facing forward) tire.
7. Have rags and a large catch pan ready to catch any spill and disconnect the fuel line where it enters the fuel filter.
8. There is a metal strap that runs from the back left to the front right of the fuel tank lower cover holding in in place. A single 13mm bolt holds it in place on the front right. Remove this bolt and allow the strap to hang.
9. You should be able to lower the cover which will have the fuel pump attached. Take the cover and fuel pump to somewhere comfortable to work.
10. You can now see the check valve. It is the 17mm bolt visible on the out side of the pump between the pump and the rounded pickup for the line to the filter. Gently pull the rubber plugs off of the electrical connectors to make room to work.
11. Place a 17mm wrench on the check valve and a 19mm wrench on the nut at the end of the check valve + fuel line combination and remove the 19mm nut.
12. Slide the fuel line off of the check valve.
13. Use a 17mm wrench to remove the check valve from the fuel pump.
14. Inspect everything to make sure it is clean.
15. Install the new check valve into the fuel pump. There is a copper ring that goes between the check valve and the pump.
16. Slide the next copper ring onto the check valve and slide the fuel line onto it.
17. Slide the final copper ring onto the check valve and reninstall the 19mm nut.
18. Check to make sure everything is secure and in the correct order which should be pump - copper ring - check valve - copper ring - fuel line - copper ring - 19mm nut.
19. Reinstall the lower fuel tank cover, strap and retaining nut.
20. Reattach the tank to pump fuel line and secure the clamp.
21. Reattach the fuel line to the fuel filter.
22. Check to make sure everything is secure.
23. Remove the clamp from the fuel hose.
24. Smell for fuel, watch for it to run, hopefully it will not. If it does reclamp the hose and look for the problem.
25. Reattach the final piece of the lower fuel tank cover.
26. Reconnect the electrical connector.
27. Make sure no gas is pooled anywhere.
28. Reconnect the battery.
29. Turn the key on but do not start the car for 10 seconds, repeat four or five times to let the pump repressurize the fuel system. This may not work, but it is a theory.
30. Go for a drive.
PS, you could insert "change fuel filter" at any point between 5 and 21. I spilled a lot more fuel when I changed the fuel filter than changing the check valve.
The hesitation mentioned earlier has not occured since changing the fuel pump check valve.
Last edited by BruceWard; 09-26-2004 at 03:57 PM.
09-19-2004, 11:09 PM
#2
"Introducing the new tech writer for the kcws, Mr. Bruce Ward! " I wish, anyway... this is some great stuff, Bruce, keep it up! If you want to host yoyur tech articles anywhere, I'd love to put them on the web site.
Regards,
Regards,
09-20-2004, 12:10 AM
#3
Three Wheelin'
Thread Starter
Hey I know I am a little far away, but I was hoping to be honorary KCWS.
Please feel free to repost anything I post along with corrections where I make mistakes!
Please feel free to repost anything I post along with corrections where I make mistakes!
09-20-2004, 02:28 PM
#4
Nothing "honorary" about it... lol You are a full fledged member in good standing, no worries there. 
Regards,
Regards,
09-25-2004, 12:58 AM
#5
Three Wheelin'
Thread Starter
I have not put about 50 miles with 10 starts (6 cold) on the car in the last two days. Some of this was highway, some city and a 15 minute traffic jam. I have noticed faster starting times, which may be attributable to the cleaned starter, a more stable idle and stonger performance while the car is warming up.
