EFI Questions/Problems, wont hold pressure

The Ford 5.0 swap (Project CJ-5.0) is now complete and the fit is great. The hydraulic clutch it working fine and the exhaust is done. I am still trying to sort out a few of the vacuum lines/attachments.

The fuel system is all new from the tank to the fuel rails. New ploy tank,BBK fuel pump,fuel pump relay,fuel pressure regulator,lines,filter,even injectors due to all but 2 of the old ones being clogged.

Fuel pressure is set at 45 psi and hits & holds it at startup.The engine starts fine and idles well,,for a while.However after a minute or so pressure dropps to zero and the motor dies,,same thing when throttle is applied.

I tried swapping in a preformance pump and relay, thinking that the auto zone pump was just not keeping up, and the relay was old and worn out,but the problem still exists. I have set the pressure regulator as high as 65psi at idle,,,but same results. I hit auto zone last night for a Fuel Injection basics book and will be doing a bit of homework trying to find a solution.

This is the first time I have messed with Fuel Injection so my knowledge base is limited.
Has anyone else who has done a EFI swap had similar problems or know of possible solutions?

 

start by checking that all of the fittings are tight also check that you are not using the return line for pressure and that pickup tube is not plugged may be filter is plugged i know you said tank was new but i ran into same problem with a new tank being contaminated it kept plugging fuel filters

 

All fittings tight, no leaks. Filter and lines are clean but I blew them out with compressed air anyways. Return line is on the same end of the fuel rail as the pressure regulator.
Sometimes the pressure rises as the pump relay kicks on as it is supposed to do,,but it isnt constant like it's supposed to be. Looks like whatever sensor that tells the computer to turn on the relay isnt doing it's thing.:? Does the same thing (pressure bottoms out) when I run a jumper from the pump to the battery to make it constant on.
And I thought I was home-free when it fired up.

 

if pressure drops off with the pump direct wired to power then the pump has a problem or the pressure regulator is malfunctioning. Either the pump can't keep up with the engines requirements or it has an internal issue. what is the PSI and flow ratings for thepump?

 

The pump is a new BBK High Preformance unit made for modified Mustangs, it puts out over 80psi. It's rated at 50 gallons per hour @70 psi. The regulator is also new, a manually adjustable Holley unit that mounts on the factory fuel rail. The return line is following the regulator. Im running out of ideas.

 

try isolating some components under load. Connect a hose to the fuel pump outlet at the fuel rail and dump it back to the tank. Direct hook up pump to battery and let it run for a few minutes to see if it maintains flow or drops off . If flow is maintained then the pressure has to be lost at the rail. Try the hose trick on the return line to see if the pressure regulator is returning too much fuel and not holding pressure.The only other thing that it could be is some injectors are sticking open but I can't see them leaking bad enough to case complete pressure loss.

 

Another thing to do is hook up a pressure gauge, start the vehicle, then shut off and pinch off the return line. If it holds pressure then it has to be the regulator. If not then something before the regulator, i.e. an injector sticking open, pump pressure falling off, etc.

 

Oddly enough I recently helped a buddy diagnose the same thing, he had a Holley TBI on a 4.3 GM V6. It would start fine and idle for about half a minute. We replaced the Holley with a factory GM TBI and it worked fine. Not much help. We tried 2 different pumps too and didn't help. I'd call Holley and ask them.

What about the fuel filter, is it rated for that pressure?

 

Some ideas:
1-The fuel filter should be between the pump and the engine. Pumps do not like to pull fuel through a filter.
2- Dirty filter or pick up screen
3- low on gas?

 

ALso where is the fuel pump mounted in relation to the fuel tank?

 

I believe I have isolated the problem.

Somthing is either pinching the feed line on top of the tank or somthing in the tank is blocking the pick-up. I took the lines off and blew them out,all clear. Pressure regulator is holding,,,sooooooo,,,looks like I get to enjoy dropping the tank again. Will have to be next week sometime,,right now I am packing up for a 4 day camping trip.

PS: Pump is mounted on the frame rail below the passengers seat and lower than the tank.

 

OK, got the tank pulled out a couple days ago and found the problem. The fuel line was slightly pinched between the top of the tank and the body. Enough fuel was flowing for it to run at idle, but once the rpm's came up and the fuel draw increased it completely collapsed the line. Ran a hard line and now it's running strong but a bit rough because all the vaccum lines arent in place yet. Will be finishing things up as time allows but should be registered and on the trails VERY soon, baring any big problems.

Got the exhaust wrapped up, used Thrush welded chamber (Flowmaster clone) mufflers, nice and quiet but still with a mean sound to them and wrapped the pipes with a heat insulating wrap to keep excess heat away from fuel and brake lines as well as the trans and t-case. Got the clutch slave cylinder remounted, had to move it back about 1 and a half inch to get the clutch fully disengaged.Still need to figure out why the brand new 1-wire alternator wont throw a charge though.

Still need to wrap up the little stuff like finish mounting the gauges in the dash and mounting the seats and seat belts. Seatbelts came out of a Huey MEDEVAC helicopter, and they include a very cool shoulder harness system which allows movement but sharp impacts locks it in tight. Cant use the shoulder straps with the stock seats so plans are to replace them with racing type seats. Funny how it's the little stuff that really eats away your time.

Project CJ-5.0 will be tearing up the roads & trails soon.

 

Most 1 wire alternators require you to rev the engine fairly high to energaize the regulator. Once energized they will charge at idle. Try reving the engine to 2500 or 3000RPM and see if the alternator starts charging.