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drew1 drew1 is offline
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Join Date: Jul 2000
Location: greenwood,sc usa
Posts: 2,383
The fuel pump is running with just the switch on. It has to be cranking or you can pull the relay & jump terminals 30 & 87 in the socket. Using a jumper, made out of at least #12 wire & a couple spade terminals, is how I test the fuel pump flow & system & control pressures.

From the fuel pumps, you have a check valve on the outer pump, and a accumulator in line to the filter & fuel distributor. What happens when you crank is the pumps run, the thermo switch runs the 5 th injector for a short period if you're cold, & the warm up regulator drops control pressure to richen up the mixture. If you don't have enough difference in system pressure & control pressure you get no fuel through your injectors.

What can happen to hurt cold cranking is bad check valve letting gas run back through the tank when pumps are off. This would probably hurt warm cranking too. The accumulator could be bad. This holds gas under pressure to help warm & cold starting by holding gas under pressure to keep the pressure eqaulized & some in the line to fuel distributor. It is easy to check, just take the screw out of the bottom & see if you get gas meaning its bad. When you work the flap, you drop the control pressure making the ratio of what system pressure you have to control pressure high enough to send fuel through the injectors. This could indicate either the check valve or accumulator. You really need a guage to see if you loose pressure quik (it's bad) when pumps are off to check the check valve.

Sionce you already had pressure in the lines, the accumulator & check valve may be good. If you're pretty sure about this you need to check the 5th injector setup.


wife has 924 turbo
Old 04-01-2003, 06:31 PM
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