Fuel and Starting Issues

[wewantutopia]

Hello.

I've noticed that it is taking quite a bit of cranking to start my car (newish remanufactured IP 30,000 miles, newer engine 70-80,000 miles)

I have clear lines on the in and out barbs of the IP.

When I shut the vehicle off, immediately there is a flurry of little air bubbles leaving the IP out of the "in" barb back towards the tank for a few seconds. If I watch another minute or so, a big air bubble will go back into the IP from the return barb leaving the return line essentially empty.

Over night nothing else will change. In the morning there is still fuel in the clear line going into IP and basically none in the return line.

Anyone have any ideas where the vacuum leak may be?

[82vdub]

First, if the hard starting issue is when the engine is cold, check the glow plugs to make sure they are operational. If they are good (which means more than just voltage at the glow plug terminals), then you may have a restriction in the fuel line, fuel filter, or the tank, or the vent hose is plugged. You could try removing the fuel cap and see what happens, and you could remove the factory fuel filter and temporarily fit a clear inline filter to see if this removes a restriction, but I'm thinking that the vacuum leak isn't that, but a blocked line.

[TylerDurden]

The next step is to test with bottle feeding. If the issue resolves, there is likely a restriction in the supply side.

If the issue does not resolve, the likelyhood is a leaking main seal on the IP... sucking in air that turns to foam in the IP, the foam later turning to the big bubble in the return line.

Very interesting/lucky the entire line does not siphon back to the tank via the supply lines.

[Fatmobile]

If the air and fuel get pulled back toward the tank quickly once it's shut off;
there might be a fuel line restriction creating a vacuum on the input.

Either way air shouldn't come out of the pump when it's shut off.

I usually suspect the mainshaft seal. Because it is hooked internally to the pump input. This would normally cause air/foam coming from the pump output. Look for very small bubbles on the output while running. I know when there is air in the fuel it takes awhile to get rid of. Small bubbles will probably be present just because of the air going back to the tank and being pulled back into the intake.
The regulator and timing cover are a couple other places connected internally to the input but they don't have anything moving against a seal like the mainshaft.
It could also be leaking around the input banjo.

[wewantutopia]

Thanks for all the replies!

I replaced the fuel supply line from the filter to the IP input and the return from the out barb to the firewall; problem solved!

Not sure what the issue was but it's not there anymore!!

Thanks!