short video of the output of a 617 stock lift pump. http://www.youtube.com/watch?v=narBhZQLCg8

Where is the stock lift pump located? Is it built in to the injection pump?

Its on the side of the injection pump. The hand primer pump is part of it and sticks up out of the housing.

You should stretch your relief valve spring, those pressures are right at the minimum.

yeah, and thats even with the fuel plumbed in a closed loop which artificially jumps the pressure. subtract about 4 psi for both idle and load. I have another complete new lift pump. Is it worth stretching the spring, or should I just swap em? Thats the original lift pump

Is the LP new new? If so I would replace it. Rebuilding them is fairly easy but the seats of the valves need to be lapped. There was a great thread on it somewhere with pics of how pitted the LP could become.

Stupid question but where is the relief valve spring/housing located...could one post a picture??

   

(08-10-2009 09:25 AM)winmutt Wrote:  Is the LP new new? If so I would replace it. Rebuilding them is fairly easy but the seats of the valves need to be lapped. There was a great thread on it somewhere with pics of how pitted the LP could become.

Its new new out of the box. Got it a while back when I airlocked the car for about a week 250 miles from my house. At the time, I was convinced it was the lift pump.

What did you do to relive the air lock?

I first filled the fuel tank (original air lock reason), drew fuel all the way up through the lift pump with a hand vacuum pump, ( I could have used the hand primer pump, but I thought that was the problem) cracked all the injectors and cranked the hell out of it with my foot to the floor. That was not working very well, (partially because of a VO system plumbing complication which was the root cause of the continued air lock), otherwise it would have worked fine.

I then used a questionable method I have used on a number of IDI ford 7.3s with a mechanical lift pump (which works AWESOME for air locks on those trucks by the way depending on where you connect the pump). I took my hand vacuum pump, disconnected the return line, closed all the injector lines, hooked the vacuum pump up to the return line from the engine and drew it down to 30 inches of vacuum.

I had someone crank the motor over. I kept pumping the vacuum pump while they were cranking, keeping high vacuum on the return on the theory of- fluid may move easier being pulled and pushed at the same time. Started after about 10 or 15 revolutions, quickly disconnected the line and re-plumbed it while it was running.

This only worked because of the oddball plumbing on the car. It would not have worked if the return line was still hooked up to the filter head.

weird I have replace the injectors in my car several times! and I put it back together with out pumping it or doing anything just crank until it start! usually 1 min of cranking or so it self bleeds for me

its all about the plumbing I have going on. If it were stock, Id probably be able to un-airlock it as easily. The main issue at the time was a fairly boneheaded mistake I made.

Supply and return travel through separate electric switching valves. The vehicle is hard plumbed so that it is always running in a closed loop, and the return line is only used when you activate the return valve. This works just fine 90% of the time and mostly is a nice benefit for fuel restriction and winter heat retention.

The other 10% is when some air gets sucked into the closed loop and stays there. You then have to open the loop with the return valve. My mistake was that I had the return valve running off of a relay that was itself signaled by a key on source. The key on source was affected by cranking, like most vehicles.

What this meant was that I would hold the button to open the return line, crank the motor to start it up and the act of cranking would inadvertently close the return valve and line, keeping the air within the loop. Whoops.

Took a little while to realize just what the issue was. I have since added an emergency push button switch that reroutes power to the return valve directly from the battery in the even of another air lock.

OK that makes more seance sound like a cool set up anyways!