99 Northstar - Rough Starting

[truant]

Hey! My northstar (a jasper reman) is a little rough starting. New battery helped increase crank RPM some, but engine sounds the same. Essentially it sounds like it is coughing for the first few turns before it gets enough fuel in to sustain itself. A dealer told me once that the fuel pressure regulator might be bleeding back and so there isn't enough fuel available until the pump turns on again..

Anyone have experience with this kind of thing? New plugs, wires with motor install, original coilpacks with 100k on them. Engine runs smooth otherwise.

[kev2]

a starting point would be to get a fuel pressure gauge on it and check pressure, as well as how long it holds pressure -a leak down test. Gauge is often available as a loaner or rental at auto parts stores.... Let us know if when it starts if there is a black smoke plume OR if engine looses coolant.

Some things you can try 1) run the systen diagnostic check, CK for codes. 2) when starting first time....turn key to run position for @3sec then turn off then try to start it, this would give a pressure build up as fuel pump would run during 3sec try.

Also what year, model? I do not see it...

Sorry I see it now ....got lost in posting screen. 99 northstar.

[Ranger]

Just pull the vacuum hose off of the FPR at idle. If fuel leaks from the nipple, R & R it.

[daniel812]

Larry,

Wouldn't you see the leak from under the car if it was leaking from there?

[Ranger]

No. There is a rubber diaphragm inside the FPR that separates fuel from manifold vacuum. Fuel pressure on the lower half and manifold vacuum on the top half. When the diaphragm leaks, the fuel gets sucked into the manifold causing a rich fuel condition. By removing the vacuum hose, the fuel then leaks out of the nipple, pushed by fuel pressure.