fuel injection pump suck

[jimmystratos]

I'm trying to site the in-line fuel injection pump in a kit car - how high can the pump be above the bottom of the tank and still prime themselves?

TIA

[stevieturbo]

Generally speaking, efi pumps cannot suck. They must be either intank, or below the level of fuel in the tank, gravity fed.

If you mkust palce it elsewhere, feed/prime it with a low pressure pump, as long as it has adequate flow capacity to keep up with the efi pump.

[eliot]

ive got a bosch 044 pump and it will suck. Instead of having the fitting a the bottom of the tank, mine is at the top with a long metal pipe going to the bottom inside. The is then connected via normal hose on the outside at about the level of the bottom. It will always pull the fuel all the way up and over into the pump even from dry. Once it's primed, it pretty much just siphons itself out.
The idea behind it is, that if the car caught fire and burnt its way through the pipe the fuel tank wouldn't empty itself fueling the fire even more. (i.e. the only way to get fuel out of the tank is to pump it out). Fuel inlet is 15mm id.

[Pigeon]

That is the exception rather than the rule though. As stevieturbo says they generally won't suck unless they are primed.

When I converted my Volvo Amazon to fuel injection I didn't fancy mounting the pump under the car so I mounted it under the bonnet. The fuel feed line, after feeding the pump, carried on upwards to the inlet of an SU electric pump as fitted to many BMC carburetted vehicles; the outlet from the SU pump discharged into the fuel return line. I had a switch to run both pumps which I used to leave on while I was putting my seatbelt on. The SU pump would draw fuel up to above the level of the pressure pump and the pressure pump would then prime and I could switch the SU pump off, after which it had no effect and the system ran normally.

[eliot]

Pigeon said:

That is the exception rather than the rule though. As stevieturbo says they generally won't suck unless they are primed.

Yes agreed.