fuel pump shuts off

[holag]

I have a stroker based off of a 1994 4.0L that I installed in my CJ7. When I turn the ignition to run I hear the fuel pump prime, and after spraying starting fluid into the throttle body I can get the engine to start and run for about 10-15 seconds, and then it dies. I have discovered that the fuel pressure drops to zero at the rail not long after starting, and the voltage at the pump drops to zero right around the same time. However, the Jeep will still run for a few seconds either off of the starting fluid in the manifold or whatever pressure is built up in the line from priming the pump, so it is still getting spark when this happens. What I'm wondering is what can cause this to happen? I know the ECU activates the fuel pump relay via the same ground that activates ASD relay, so does this mean the problem is not related to the ECU and ASD circuit, or does the ASD circuit not control spark? Most parts of the Jeep are new, including the fuel pump, tank, lines, pressure regulator, etc. The ECU is from a 1992 jeep Cherokee with 4.0L and A/T. I spliced the 1994 harness into the CJ7 engine bay for wiring. The check engine light is not giving me any codes. Any ideas?
Thanks,
Gary

[yuppiexj]

Did you wire in a ballast resistor on the fuel pump circuit?

[holag]

I am using a Summit Racing high output electric fuel pump and the tech I spoke with at Summit said that I should not use a resistor with the fuel pump. I looked at some repair manuals and saw that Jeeps had ballast resistors up until 1993 and in 1994 did not use a resistor. Any ideas?

[yuppiexj]

Bypass it
Where the ballast resistor would go simply connect the 2 wires. (a blade type fuse will work in a pinch for troubleshooting)

One of my 90 XJs has run like that for thousands of miles.

IIRC it was added to quiet the pump due to soccer moms complaining about some noise in the back of the truck.

[jsawduste]

The ECU will shut down the fuel pump if it does not see a crank (ignition signal within 5 seconds (+/-) ) of the engine firing up.

My stroker did the same thing. Ran for a few seconds on the starting fluid.

Make sure you have a good crank signal to the ECU for starters.

Let us know what you find if that doesnt help.

[stuckys101]

Not to hi jack your thread or anything but I had the same problem, word for word. So I ran a wire from the fuse box to a toggle switch then to the fuel pump. Its only till I get my dana 60 and 14 bolt built and finish rebuilding a motor and trans, but yuppie said he put an IIRC on it to quiet it down. What is that and how do I do it because I hate hearing the sound of my fuel pump running all the time. Thanks.

[4.whoa]

iirc is - If I Remember Correctly. he was talking about the reason for the stock resistor.

[stuckys101]

i feel stupid now