removal of pulse damper and stalling

[scotts93sho]

I recently changed my fuel pump with one from APE (190). At the time I debated in removing the pulse damper and replace it with the new rubber hose. I droped the tank a second time and put it in. Since this install, the car now somethimes stalls when I am slowing to a stop or pushing in the clutch for a turn etc. If I am very gentle with the slow down, it seems not to stall. Quick stops and it stalls almost every time. I am temped to put that damper back on (3rd time the tank will be down). Has anyone else had a similar problem?

 

[sdpatt]

If you had disconnected the battery, you may first want to try the idle speed reset procedure. See the link below.

http://www.shoforum.com/showpost.php?p=90952&postcount=2

 

[olympic]

The 190 is known to over pressurize the system in some cars. It flows more fuel than the FPR can bypass. You may want to check you fuel pressure.

 

[ckinart]

I installed an APE 190 lph pump in my '94 about 1.5 years ago and removed the pulse dampener at that time. I've had no stalling problems since. However, as olympic mentioned, my fuel pressure is a little on the high side (I've already replaced the FPR with no real improvement). I would first try the idle reset as sdpatt has suggested, then maybe look into fuel pressure. You may also want to consider cleaning your IAC valve. After that, perhaps look into your VSS (I had very similar symptoms to those you describe, along with no cruise control, and a new VSS fixed both of those problems).

Good luck!

 

[FAST4DR]

The stalling is most likely a over rich condition as the rev's come down. With my 255 lph pump, as the rev's came down the fuel pressure went up. Opposite of what is supposed to happen.

The 190 and 255 pumps are flowing so much fuel that it causes over pressurization of the fuel pressure regulator because of it's small passages. As rev's climb the manifold pressure drops and open the fuel pressure regulator diaphram allowing more fuel to flow and the pressure drops. The car is supposed to increase fuel pressure as the revs climb, not drop it.

So as you are driving along you have, lets say 40 psi fuel pressure, and then as the revs drop and the fuel pressure regulator closes, the fuel pressure goes up to say 48 psi, too much fuel is being pushed through the injector for the given pulse width and the car suddenly goes rich before the car can compensate for it and it stalls.

I put in a 155 lph pump and the car idles perfect now.

Will

 

[masho95]

I have the 190lph pump in my car and I didn't bother to reinstall the fuel pulse dampner when I put it in. I've never had any problems with it, especially with stalling like that.

 

[yamahaSHO]

The 190 (and 255) will have wierd effects as it will give too much pressure. Your computer will overcompensate and lean it out. I'd change that out.

 

[ckinart]

The 190 (and 255) will have wierd effects as it will give too much pressure. Your computer will overcompensate and lean it out. I'd change that out.

Too bad that info wasn't better known about two years ago when nearly everyone on the forum who commented on the subject of fuel pump replacement/upgrade said that the 190 lph was the way to go...