603 Air In Fuel Lines?

[New2MB]

I installed a used IP on my car yesterday and replaced the three hard, somewhat transparent fuel lines.

I got the lines from a local car parts place and they aren't as tight as the originals.

The one that travels from the center of the canister fuel filter with the arrow pointing out down to the driver's side of the IP is not filling up with fuel.

If I crack the line at the filter and then crank the engine the line will fill up halfway or so with fuel. Then I close the line, crank again and the IP drains the line and again the line is empty.

I think this may be causing poor fuel delivery because fuel is barely flowing out of the delivery valves. Not "squirting" as I have read here on a few threads.

However, I do have fuel flowing back through the return line.

I currently have a glass jar underhood to feed the IP and catch the return, I cut the tank out of the loop.

I know you're going to tell me to get the correct lines on there and I will, just wondering if this is most likely what is causing the poor flow of fuel from the IP.

[Aquaticedge]

Have you checked your lift pump? may have a failing one

[New2MB]

I can't say that I have, do I just pull a line off and see that it's pushing fuel?

I figured since the fuel was getting up into the canister filter that the lift pump was operating.

[Aquaticedge]

I dont know how to test it, I do know pulling the line and cranking would likely cause a massive mess

[Billybob]

Originally Posted by New2MB

I can't say that I have, do I just pull a line off and see that it's pushing fuel?

I figured since the fuel was getting up into the canister filter that the lift pump was operating.

It's not clear from what you've offered so far but, you have a container of fuel, a hose from that to an inline filter, from that filter directly into the lift pump on the side of the IP, there is a good hose from the lift pump outlet to the filter stand's inlet (the fitting furthest to the drivers side), then a good hose from the center outlet fitting on the filter stand to the IP inlet located on the driver's side of the IP, then a hose from the passenger side of the IP retern/outlet to the return fitting on the filter stand (furthest to the passenger's side, correct so far?

If your container of fuel you are drawing from and returning to is too small you willget bubbles from the return fuel if that hose doesn't empty below the surface, and if that happens you will get air bing sucked into the fuel being fed to the lift pump.

Anything down stream of the lift pump should leak fuel if a connection is not tight it will not ingress air because that part of the fuel system is under pressure. Any connection before the lift pump which is noy tight will allow air ingress which you can see in the inline filter if it happens before that or if the line exiting the lift pump is clear you can see bubbles in that.

Of course the correct lines along with the correct crush washers are eventually needed but fuel leaking out isn't as much a problem as air getting into the system at this point.

If you fill the secondary cannister filter before starting to attempt to bleed the fuel system you will make everything easier of course.

If you have an electric fuel pump moving fuel out of the container and creating positive pressure you should be able to fill and move air out of the system delivering to the IP pretty easily and straight forward. I don't understand how or why but perhaps the electric fuel pump pressure is interfereing with the lift pump operation somehow, to eliminate that possibility just use a section of hose and no electric pump from your fuel container.

[New2MB]

Originally Posted by Billybob

It's not clear from what you've offered so far but, you have a container of fuel, a hose from that to an inline filter, from that filter directly into the lift pump on the side of the IP, there is a good hose from the lift pump outlet to the filter stand's inlet (the fitting furthest to the drivers side), then a good hose from the center outlet fitting on the filter stand to the IP inlet located on the driver's side of the IP, then a hose from the passenger side of the IP retern/outlet to the return fitting on the filter stand (furthest to the passenger's side, correct so far?

Correct in the routing but I'm not so sure about the hoses being "good".

Originally Posted by Billybob

If your container of fuel you are drawing from and returning to is too small you willget bubbles from the return fuel if that hose doesn't empty below the surface, and if that happens you will get air bing sucked into the fuel being fed to the lift pump.

I'm not sure if the return line was always below the surface but I didn't notice any bubbles.

Originally Posted by Billybob

Anything down stream of the lift pump should leak fuel if a connection is not tight it will not ingress air because that part of the fuel system is under pressure. Any connection before the lift pump which is noy tight will allow air ingress which you can see in the inline filter if it happens before that or if the line exiting the lift pump is clear you can see bubbles in that.

I did not see any bubbles in the line exiting the lift pump, it appears to be filled with fuel at all times.

Originally Posted by Billybob

Of course the correct lines along with the correct crush washers are eventually needed but fuel leaking out isn't as much a problem as air getting into the system at this point.

If you fill the secondary cannister filter before starting to attempt to bleed the fuel system you will make everything easier of course.

The filter was filled and I removed it to verify that it was still topped off, it was.

So how is it that the canister is full, the line going from the lift pump to the canister is full but the line coming back out of the canister and going to the IP keeps drying up?

Originally Posted by Billybob

If you have an electric fuel pump moving fuel out of the container and creating positive pressure you should be able to fill and move air out of the system delivering to the IP pretty easily and straight forward. I don't understand how or why but perhaps the electric fuel pump pressure is interfereing with the lift pump operation somehow, to eliminate that possibility just use a section of hose and no electric pump from your fuel container.

No electric fuel pump moving fuel out of the container, just pulled the lines that would normally go to the tank and dropped them into a glass jar filled with fuel.

[Diesel911]

On the older models there is a pressure test, a volume test and an Vacuum Test (at the Fuel Inlet) for the Fuel Supply/Lift Pump.
I am guessing that there are similar tests for the newer models.

Have you tried driving it yet?

[New2MB]

I'll see if I can figure out how to test the lift pump.

I haven't tried starting it yet, I'd like to get the weird noise figured out first.

[Billybob]

Sorry for the "interrogation"! Just trying to understand if the facts are as they should be, from personal experience it's sometimes easy to get things reconnected in a configuration that on the surface appears correct but in function is total f@#*ed up!

I will assume that in this predicament you've used the starter for what seems like a sufficient period of time to bleed or push any air from the fuel lines and filters leading up to the IP.

If this is true and from the previous post everything else is straight I think you have to look at the lift pump not delivering sufficient volume and/or pressure.

You can test it situ with some type of adapter and gage for pressure, volume is measured by capturing the return flow over a period of time.

For the volume measurement you get the flow started and use a container to capture the return flow for a period of time and then compare it to the spec, it either is or is not.

For the pressure you need to get into the pressure loop after the lift pump and measure the pressure. The factory method uses a special banjo bolt to which a hose and gage are attached, and a double length banjo bolt to Siamese that second banjo fitting into place. You need an additional third crush washer and they should be new in order to seal things up correctly.

An alternative is to fabricate your own method to access the pressure loop; one way to accomplish that is to get hold of a spare banjo bolt for the 60X filter stand. Either the smaller fuel inlet bolt or the larger outlet-IP bolt, although the large canister filter bolt would work also. Then you need a smaller banjo bolt and a small banjo fitting and crush washers, you can easily find such a small bolt and fittings as the IP oil feed line on 615/616/617 engines! Then drill and tap you spare 60X banjo bolt for the 61X small banjo bolt. Attach a gage to the small banjo fitting, then to read the post lift pump fuel loop pressure, remove the standard banjo bolt from the loop, install your modified bolt/fittings/gage and after you sufficiently bleed the air from the loop you will be able to read directly the pressure in the loop.

From your earlier and related threads it seemed like the issue was isolated DV lack of fuel, but it sounded like you where getting fuel from other DVs. That indicates that the lift pump on that IP was functioning enough to pressurize and fuel the IP. It might be the quickest and easiest diagnostic to swap the lift pump which appeared to be functioning from your original IP with the one on your replacement IP which appears to be, assuming everything else is straight and it's been bleed and spun enough, non-functioning.

The only hoses that are a real issue to effect fueling will be any attached pre-lift pump which could possibly suck air; post-lift pump if they leak it will be messy and unless the leak is massive won't prevent fueling of the IP.

[New2MB]

Thanks for the help, I haven't had to deal much with IP's other than replacing them so I'm coming up to speed slowly.

I spent 3 batteries worth of cranking getting fuel through the IP so I think I did enough cranking.

I'll try swapping lift pumps although I don't recall the old IP squirting fuel out either, a similar flowing as to what I am getting now.

The more I think about this though it seems that a lack of fuel would not cause a lack of fuel pressure.

If the IP gets fuel, it will pressurize it.

If the IP gets insufficient fuel, shouldn't it still pressurize it and 'squirt' it out even if it's a small amount?

If the IP wasn't getting any fuel then it wouldn't be coming out of the DV's and I wouldn't have any coming back through the return line.

I need a separate jar for the return so I can see when and how much I'm getting.

I just found my fuel pressure gauge so I'll see if I can get it hooked up. Couldn't I just hook it in-line on the inlet line to the IP? Or even in-line just after the lift pump?