The Official 356Talk Forum

I have at last installed the Airtex and will use it as a primer.
After sitting for some weeks, how long should I keep the button pushed before trying to fire the engine?
Greg

Till you get bored. Listen to the pump, it will run fast then slow down and virtually stop when the carb bowls are full.

Greg Frick: If you will call us about your pump (I realize it was 2 months ago) we will be glad to help you resolve your issues. After all you expect service after the sale! 800.356.2964 al zim

Hi Al.
The Piersburg pump was installed 10 years ago and run as the only pump. I bypassed the mechanical pump.
Upon disassembly I found the Piersburg to have power but would not pump. The Airtex pumped usng the existing wiring.
The new installation is set up to work as a primer pump and not to run all of the time. It is about double the size of the Piersburg which I hope means greater volume.
I think either pump would by just fine as a primer.
No worries here,
Greg

I can now offer this assessment of the project.

The entire system operates far more efficiently if attention is paid to where the fuel comes from and not just where you want it to go. This advice is the result of several hours of methodical trouble shooting and true Sherlock Holmes style deduction.

I got the pump in backwards blowinig bubbles into the tank instead of feeding the fuel pump at the rear.

Duh...
Greg

Greg, I just had exactly this problem with a brand new Carter fuel pump in a replica spider. Difference in my case was that it was connected up correctly with the OUT port connected to the pressure regulator and thence to the carbs. Same issue, air blowing in to the tank and when I put my finger over the out line it sucked my finger in. It was just one of those days though. It was a 15 minute job that eventually consumed 4 hours with 4 runs to the parts store and one to Walmart.
I guess it makes up for those days when everything goes boringly smoothly.

I recently just installed the Airtex fuel pump. It was easy peasy. I just had to pickup a length of 5/16" fuel hose, and two additional 90 degree angle fittings and a length of 14 awg wire. I also added an inline fuse holder with a 10amp blade type fuse.
I bolted the unit to the diagonal member where there was already an existing hole.
I already had a spare GM (momentary) rear trunk release button that fit in the area for the sunroof switch. The little pump works like a champ. I'm pleased.

I’m going to mount mine forward of the engine where the fuel line runs past the transmission. I’m going to take the hot lead from the coil so that it only has juice when the key is on. I’m also going to put a push button in plain sight, in the engine compartment for priming purposes only. My reasoning is that the electric pump puts out a constant pressure relative to a stock mechanical fuel pump which sends out a pulsating pressure, and if there is a fuel leak due to the mild yet additional pressure I want to be able to see it so I can take my finger off the button immediately. Engine fires can ruin your day, and they do happen. Ask me how I know. To me the inconvenience of having to get out of the car and open the engine compartment is negligible.

Hello John

From memory,
The instructions say to mount the pump vertically, with the inlet at the bottom and the outlet at the top.
Also, it's a pusher pump, not a suction pump. So fitting it at the front of the car is better than at the back.

Regards
David

Under the passenger floor board. That way you can hear it running. ...........Jim.

I've a couple of comments on electric fuel pumps. There are (at least) two basic technologies. One uses a reciprocating diaphragm like the original fuel pump in my early 911. These pumps "rattle" and when the carb float chamber is full, the rattle slows or stops until more fuel is needed. The down side of these pumps is the pressure pulse can result in uneven fuel level in the carbs and may be harder on the float valve (WAG on my part). These pumps operate much like the mechanical pump native to the car. I prefer the 2nd type, turbine pump, as the fuel delivery is smooth and pulse-free. An example of this pump is https://carter.opticatonline.com/part/c ... -fuel-pump. And, finally, a pure opinion: I installed this Carter pump under the passenger floorboard and eliminated the mechanical pump altogether. Happiness!

Pumps push fuel better than they suck, hence Jim Liberty's advice to put the pump up front is best.

Last year in Spain, at the 356 International, a fellow participant could not get his car to run. We finally determined it was the fuel pump. I had an extra with me, so I pulled it out of my stash, and start changing it over. A real pain in the parking lot, or along side of the road. As I was starting, he said, "By the way, I think there is an electric pump under the floor board. Yup, I found the switch under the dash. Off he went. Nice backup.

I’ve been wrenching on cars since around 1977, and I’ve learned that if the fuel pump is at or below the fuel tank level, then it makes little difference if it is mounted at the front or the rear of the vehicle. Only when the level of the fuel pump is mounted above the level of fuel tank does its location matter, as a pump can not push fuel very far initially until it is primed. Also, every fuel pump that I’ve ever installed (solidly) at the rear of a vehicle was audible from inside the vehicle, because once again, physics. Sound is the way mammals brains interprets vibration. Vibration is transmitted through the entire structure of the vehicle because it’s made out of metal. It’s like your sitting inside one huge loud speaker. No matter what, I personally would never introduce a fuel pump to the inside of a vehicle that transports my family. Personally I have been on fire with gas all over my shirt, running around trying to put the fire out like in the movies.