Fuel pressure drops from 62 to 0 psi in 3 seconds

[stevegriffith]

Is there anything other than a faulty pressure regulator or leaking fuel line that could cause the fuel pressure to drop from 62 lbs. to zero in 3 seconds when the pump stops running? The spider is only 1 1/2 y.o.. Could the pulsator cause this?

The upper intake is off. There was a faint gasoline odor when I removed it, but the odor is gone. I have turned the pump on several times, but there is no fuel leak or odor. Fuel flows through both the high-pressure line and the return line when the pump is activated. The pressure still drops rapidly (3 seconds from 62 to 0 psi).

Should fuel be flowing through the return while the pump is on and the engine is off?

Something that I noticed is that the fuel-line side of the intake is slightly cleaner, as if it had been washed by gasoline some time in the past, but there is still loose carbon build-up on the washed area, which tells me that it has not been washed down for some time, if ever.

Anyone have any ideas before I replace the spider?

1995 AWD Astro LT
4.3 Votrec (W)
CMFI
166,000 miles

[dunedog]

Have patience someone will have an answer for you.........

[NotDadsW41]

I don't know about the pulsator going bad. But that definitely sounds like the same thing that happened when the spider in my 95 when went bad.

[kings-x59]

my bet is on the spider, but yes the pulsator going bad can do that. The pulsator is only slightly worse to get to check out and/ or replace. I followed a thread on another astro safari board a few years back where the poor guy rebuilt his entire fuel system and intake from the ground up trying to solve a similar problem only to finally find out it was the pulsator. considering where the pulsator is, it would certainly short circuit your fuel pressure with absolutely no smell of gas.

[LaGrasta]

Isn't the spider replacement a free dealer repair for this year, good up to 200k?

[sfeaver]

The free replacement is only in California I believe.

If you were to pinch off the return line, and let it pump up, you could see where the fuel is going. If it isnt going into the engine, that its leaking back through the feed side.

[GEJ]

The free replacement is only in California I believe.

If you were to pinch off the return line, and let it pump up, you could see where the fuel is going. If it isnt going into the engine, that its leaking back through the feed side.

Excuse my incent comment/question because I don't know.Wouldn't you create damage if you did pinch off the return line because it is there for a reason??.

[sfeaver]

Yes it is there for a reason, however for testing pinching it off wont cause any harm. Just do it long enough to check out the pressure gauge. It is actually listed in the service manual.

To check the feed side, it says to pinch that line off as the pump pressureizes the line. If it holds, then it sais to check for a partially disconnected pulsator. If no that then to replace the pump, which probably means the check valve is faulty.

If pinching the return side holds the pressure up then the regulator has failed. Only other option would be the injectors leaking down, but you would smell gas and flood the engine out.

Scott