Fuel pump failure symptoms

[myslateblue911]

I am having some problems with my 83' SC. In speaking with my mechanic he said that a faulty fuel pump could be the culprit.

In your experience, what are some symptoms of a failing or faulty fuel pump?

[Al S]

Just replaced one on a 83C.
Engine was cutting out randomly, misfiring under full throttle.
At first suspected the coil, new one did not help.
Fuel pressure was fine on the first test, then somewhat later on a second test a bit low.
Pump noise was not overly loud.

Hope this helps..

[jlex]

May want to check voltage drop on the pump to see if it's offering greater resistance than normal.

[boyt911sc]

Originally Posted by myslateblue911

I am having some problems with my 83' SC. In speaking with my mechanic he said that a faulty fuel pump could be the culprit.

In your experience, what are some symptoms of a failing or faulty fuel pump?

Test the fuel pump and measure the following:

• Check the maximum fuel pressures it could deliver (min. 90 psi.).
• Measure the volumetric flow (1 liter per 30 sec. or more).
• Optional: Measure the current (amperage) draw when the pump is running. Normal current would be around 8 ampere.

Tony

[GH85Carrera]

And replace the fuel filter even if it is fairly new.

The fuel pumps are not insane expensive and not too bad to replace.

[kltarga72]

I replaced the fuel pump, filter and then several months later I had the same intermittent problems Al S experienced. Fuel pressure was good when tested. Replaced other items, coil, had Bob Ashlock rebuild CDI, electronic ignition. A year later I was really having bad day with the engine missing and pulled into a church parking lot. I left the engine running and opened the engine lid and listened for a couple minutes, engine was idling correctly and then I heard a odd noise coming from the fuel pump. I placed my hand on the fuel pump and could feel it cut in and out. This was a Bosch F/P that caused all the aggravation, nothing else I fought that battle for well over one year. Someone suggested I may have had a Bosch F/P made in China, sounds right.

[boyt911sc]

Originally Posted by kltarga72

I replaced the fuel pump, filter and then several months later I had the same intermittent problems Al S experienced. Fuel pressure was good when tested. Replaced other items, coil, had Bob Ashlock rebuild CDI, electronic ignition. A year later I was really having bad day with the engine missing and pulled into a church parking lot. I left the engine running and opened the engine lid and listened for a couple minutes, engine was idling correctly and then I heard a odd noise coming from the fuel pump. I placed my hand on the fuel pump and could feel it cut in and out. This was a Bosch F/P that caused all the aggravation, nothing else I fought that battle for well over one year. Someone suggested I may have had a Bosch F/P made in China, sounds right.

Lash,

What model year was this car? Just curious. Thanks.

Tony

[kltarga72]

Originally Posted by boyt911sc

Lash,

What model year was this car? Just curious. Thanks.

Tony

Tony,
1972 S

[kenzinger]

Myslate - I see that you've posted a similar question about other CIS components. I am also chasing down what I think are fuel delivery problems. Might be worth telling us all what your issues are rather than asking for the symptoms of a failed [insert part here], would be helpful for others that are searching the forums looking for solutions to their issues as well

[myslateblue911]

Originally Posted by kenzinger

Myslate - I see that you've posted a similar question about other CIS components. I am also chasing down what I think are fuel delivery problems. Might be worth telling us all what your issues are rather than asking for the symptoms of a failed [insert part here], would be helpful for others that are searching the forums looking for solutions to their issues as well

Kenzinger,

I have an intermittent complete loss of power. I press on the accelerator and the car feels like it is going to die. I will downshift and I have power again. I might drive the car for a minute or two (or 10 seconds) and will seem fine and then it will happen again. Total loss of power. Along with this the car will backfire. This has happened twice now. After the first episode I replaced the fuel filter. I took it on a short drive just to run a quick errand after I replaced the fuel filter and the car was fine. About a week later I took it on a longer spirited drive (getting it up to temperature) and about 10 miles from my house the same thing happened only worse this time. Not only did I have complete loss of power multiple times trying to "nurse" the car home, but it backfired more than the first time and the car actually died twice......Sound familiar to anyone?

[myslateblue911]

Question on the fuel pump itself. Looking at the Pelican parts replacement list, they have a Bosch replacement for my 83' 911 SC and then they have a genuine Porsche Parts fuel pump for more than twice the price. Is this simply a "name brand" vs a "generic" or is there a substantive difference in the quality between the two different fuel pumps? (you get what you pay for?)

[boyt911sc]

Originally Posted by myslateblue911

Kenzinger,

I have an intermittent complete loss of power. I press on the accelerator and the car feels like it is going to die. I will downshift and I have power again. I might drive the car for a minute or two (or 10 seconds) and will seem fine and then it will happen again. Total loss of power. Along with this the car will backfire. This has happened twice now. After the first episode I replaced the fuel filter. I took it on a short drive just to run a quick errand after I replaced the fuel filter and the car was fine. About a week later I took it on a longer spirited drive (getting it up to temperature) and about 10 miles from my house the same thing happened only worse this time. Not only did I have complete loss of power multiple times trying to "nurse" the car home, but it backfired more than the first time and the car actually died twice......Sound familiar to anyone?

Instead of collecting the different symptoms for WUR, CDI, FP, ETC. problems, why don’t you post the problems you are having with your car. When you visit your doctor, you tell him what is your problem and let him diagnose you. Not the other way around. What you are doing is a shotgun style troubleshooting approach. It might work if you get lucky. But you can not rely on luck for troubleshooting unless you want to replace one part after the other (trial and error method).

Tony