CIS fuel pump failure

mark 74 carrera · mark 74 carrera's Garage

Has anyone ever had their CIS fuel pump go out on them? I have a CIS fuel pump set up mounted in the front of the car. It pumps fuel to webers that first runs through a PMO pressure regulator and then recirculates to the tank.

The car broke down the other day and I eliminated everything except the fuel pump. I have spark, I have power to the fuel pump, I have zero fuel pressure at the PMO gage. The fuel pump was completely silent once I got it home.

A couple of days pass. I go out turn the key to the on position. I hear the CDI unit buzzing, I hear the fuel pump (yes, it suddenly came back to life.) I felt the fuel pump and it was vibrating. Went around and tried to start the car. YES, it cranked right up.

I know the fuel pump is the culprit. Here's the question. Do fuel pumps fail intermittently or do they just crap out.

Steve@Rennsport · 10-09-2007, 02:20 PM

Hi Mark:

You didn't say how many miles might be on that pump and if its the original one, but they do not last forever,...

Fuel pumps can be intermittent due to wiring/fuse issues, pump connector issues, or simply a worn out pump that has a damaged commutator or worn brushes.

If anyone ever ran the car out of gas, thats starts the "Death Knell" for the pump since they are fuel lubricated and suffer accordingly when accidently run dry.

azasadny · azasadny's Garage

Mark,
My fuel pump died this past May after being installed last December (5 months) and failed suddenly. It was replaced and the new pump is working well. I'm guessing mine was just defective but I'm wondering if these inexpensive fuel pumps (Facet, etc...) will last as long as the old CIS fuel pumps did.

mark 74 carrera · mark 74 carrera's Garage

Steve,

I think you nailed it. Long story short, I did run the car out of gas back in March. It was a used unit that I had installed as part of last year's restoration, so it very well could be suspect already. I probably finished it off by running out of gas!

Thanks for the quick response. Any recommendations on a possible change or upgrade while I am doing it? Does PMO sell a compatible fuel pump for my existing set up?

Thanks, Mark

Early_S_Man · 10-09-2007, 03:26 PM

Mark,

Check the current drain of the pump after a long drive to warm it up ... spec book says 8.0 Amp maximum, but I have heard of noisy, failing pumps drawing 16 Amps!

VFR750 · 10-09-2007, 03:44 PM

At LRP just last week a guy ran his Carrera out of gas on the track. He thought he lifted going into the left hander, and spun. But more likely the sudden loss of power broke the rear free.

After being towed back to the pits, he added a couple of gallons of gas, but too late, the pump was dead.

Luckily Dan Jacobs (Hairy Dog Grrrage) had a pump. 30 minutes later, car ran fine.

Steve@Rennsport · 10-09-2007, 10:25 PM

Quote:

Originally Posted by mark 74 carrera

Steve,

I think you nailed it. Long story short, I did run the car out of gas back in March. It was a used unit that I had installed as part of last year's restoration, so it very well could be suspect already. I probably finished it off by running out of gas!

Thanks for the quick response. Any recommendations on a possible change or upgrade while I am doing it? Does PMO sell a compatible fuel pump for my existing set up?

Thanks, Mark

Hi Mark:

Yessir, these Bosch pumps can NEVER be allowed to run dry, otherwise its "open-wallet" time.

PMO recommends the Bosch pumps for their super durability (with the above caveat). Just use the OEM one as long as you have their fuel pressure regulator. I've also had very good success with the older Bosch 914/6 low-pressure pumps but they are not inexpensive anymore.