intermittent fuel pump

[jdw]

Hello to all. This is my first posting.

Recently my '81 spider developed a fuel delivery problem. Turn the key to ON, the low fuel pressure light stays on, and the electric fuel pump under the car is not running. Tried it again a few minutes later and low fuel pressure light flashed and then went out and fuel pump was operating normally. The next day the problem was back and then went away again.

I checked the #1 fuse in the secondary fuse box under the dash. Good fuse and good connection. I checked the contacts at the fuel pump and they are clean and making good contact.

After talking to IAP, my plan is to check for voltage at the fuel pump with the key ON, and also check the inertia switch for continuity. My theory is a failing fuel pump, a bad ground to the fuel pump, or bad/intermittent contacts at the inertia switch.

Here are my questions:

Where on the car is the ground connected from the fuel pump?
Can poor inertia switch contacts cause an intermittent fuel pump?
If the fuel pump is failing, will it work only part of the time?

At this point I don't believe it's a fuel filter problem because the fuel pump is intermittent. Thanks for your input.

[Roadtrip]

Hi jdw - Welcome to the BB. I think you analysis is correct. Check for good solid wiring before blaming the fuel pump. If you can "catch it in the act" use a test light to see if there is good current and a good ground at the pump terminals. I'm not sure if there's one in an 81 model, but check the spade connector along the fuel pump power wire underneath the trunk mat.

Quote:

Where on the car is the ground connected from the fuel pump?

[jdw]

Thanks for the reply, John.

I was able to check voltage at the fuel pump with the ignition key ON and the low fuel pressure light ON. No power being supplied to fuel pump. I then pulled the button on the inertia switch under the hood and then pushed it back in. Did this a couple of more times and heard the fuel pump power up and start sending fuel (whirring sound). With the inertia switch button pushed down, I spun it to the left and right. While doing this I could hear the fuel pump shutting on and off intermittently.

I believe that the contacts inside the inertia switch need cleaning. Based on what I read in the Alfa Owner's Bible (pg. 62),
I am going to take the unit apart and clean the contacts. I think this will solve the problem. I might look into buying a second inertia switch if I can find one.

The fuel pump on the car has one input and one output on opposite ends (straight line).

Thanks again for the info and advice. I appreciate it.

[John M]

Hey JDW:

Welcome to the board. If your inertia switch has two wires, you can bypass the inertia switch by jumping the wires together for a temporary fix. Just be sure to tape up the connection.

Best Regards,
John M