Is it needed for FI guys to let the fuel pump prime before start Options

[carcus]

Just wondering. I have Bosch FI at Colorado altitude. My car will not start up right away unless I turn the key and wait about 10 seconds for the fuel pump to prime. All plugs and wires new, new fuel pump, and fuel filter. Moroso electronic conversion. New battery. I try to drive the car once a week. Just looking for advice. Car is a 1976 2.0 with 1973 2.0 engine. OEM fuel injection.

[McMark]

If you listen carefully, a lot of new cars will run the fuel pump for a few seconds when the driver's door is opened in anticipation of starting the car.

So it's normal, not just for our cars, but for all FI cars.

Fuel pumps should have a check valve to keep pressure from bleeding off quickly. I test drove a car yesterday before I left the shop, and now 15hours later it's still got full pressure in the lines. Almost none has bled off. This makes the next startup easier (without priming the pump). But if your system is bleeding off pressure over a couple hours or worse, then you'll have more need for priming the system before starting. If it is bleeding off, you may need a better quality pump (some cheap ones don't include the check valve) or you can possibly add an inline check valve. Just make sure the check valve is a bit oversize to avoid possible flow restrictions.

[BeatNavy]

But if your system is bleeding off pressure over a couple hours or worse, then you'll have more need for priming the system before starting. If it is bleeding off, you may need a better quality pump (some cheap ones don't include the check valve) or you can possibly add an inline check valve. Just make sure the check valve is a bit oversize to avoid possible flow restrictions.

Mark, I have a rebuilt, standard 3-port FI pump. Are those SUPPOSED to have a check valve, internal or supplemental on the line? My pressure does bleed off pretty quickly. I have the 2-port Bosch replacement ready to install whenever I get around to it. I want to simplify my fuel line routing in addition to possibly getting more reliable pressure on startup. I know this has been discussed a couple of times before, but I'm not clear about whether I have or need a check valve.

To the OP: I have found that cycling the key 2 or 3 times to build pressure, and depressing the accelerator while cranking (which I didn't realize was normal procedure on our cars until recently), results in it immediately firing up. If I don't do that, it has to crank for 3 to 5 seconds. In either case, I also have to feather the throttle, usually once, about 5 seconds after it fires up, otherwise it'll quit. Just once, like clockwork. Then the FP seems steady after that.