Been having a problem with low fuel pressure at the fuel rail,
I have replaced the regulator, checked the vauum to it,
put in a new GM fuel pump, checked power to the pump,
new gas filter, used a different pressure gage.
Still low pressure.
New fuel pump gets loud when going around turns/stopping
and i have 1/4 or less fuel in the tank. (no noise when 1/4
or more fuel in the tank)
Could the pulsator be leaking (dropping the fuel pressure)?
What if i just replaced it with a piece of fuel line and clamped
both sides?

TIA

Ed

You can do that I have done it before .

Thanks, Master Tuner.
I've trying to get this 4.9 to run right for 2 years now.

Ed

There is a special hose that GM uses when there is no pulsator. Regular fuel hose will work but not as long. The biggest differance you would notice with it removed is the noise level from the pump will go up.

Why not just replace it with a new one? They are in there to absorb the hammering of the pump.

A rubber fuel line will also absorb noise.Do you have the right fuel pump for that engine?

quote Originally posted by James Bond 007: A rubber fuel line will also absorb noise.Do you have the right fuel pump for that engine?

You are correct, it will. But a pulsator will absorb more. A pulsator is the same thing as a water hammer device on your houses plumbing.

Im pretty sure that it does something else too. I forget exactly.

Yea I think it also helps absorb vibration as well as noise. Be sure to lube the pulsator openings with petroleum jelly when installing. Like the Master Tuner, I use hose and clamps..............Paul

same problim with mine I think.

quote Originally posted by James Bond 007: Do you have the right fuel pump for that engine?

I got a GM replacement fuel pump for the 2.8
I'm running a PFI 4.9 with the 4T60E and '2240 ECM
as far as i know, the GM pump for the 2.8 should be plenty for the
stock 4.9
I've had low fuel pressure problems from day one of this conversion
(over 2 years now).
It runs about 38 to 40 PSI at idle. the only thing I haven't replaced in the fuel
system are the lines and the pulsator, I don't have any external fuel leaks
so that leaves me with a possible leaking pulsator thus the subject of this thread.

Thanks

Ed

I replaced the pulsator on my 4.9 swap and still have this problim. cheaked my injectors on my motor and found 4 bad ones. put 6 3.4 injectors in my motorand 2 of the 4.9 ones in and it runs tons better but still giveing me some grief.-B-

As I was told by theogre and someone else, the pulsator absorbs the pulsations in the fuel pressure created by the injectors and smooths it out for the pump. Without it, the engine can run poorly in some situations and the pump will wear out faster. I don't know what you mean about low fuel pressure, how high is it supposed to be? My 2.8 runs at 38-40 lbs at idle too.

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Thanks Aus!
More info at: https://www.fiero.nl/forum/Forum1/HTML/043357.html

The pulsators function is to dampen surges by the electric fuel pump and mimimize surging. You can run without one but IMO your are better off buying a new one and replacing it. Why change the design when the pulsator is not a detriment to performance. .

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