Expert: Sean Halliday - 9/22/2008

Question
QUESTION: Hello,
1988 volvo 740. I recently replaced the in tank pump assembly and still have a no start condition. I removed the fuel line (not vacuum line) from the back side of the fuel pressure regulator and steady stream of fuel came out of the FPR. Is the fuel flow direction into the injector rail and through the FPR or through the FPR into the injector rail? I am wondering if I have the fuel lines reversed into the in tank pump assembly.
Thanks for your help.
Pete

ANSWER: What is the fuel pressure from the feed hose to the rail?Does this car have 2 pumps or 1.Some models have an outer pump on the drivers side chasis at the rear wheel.There is also a relay behind the ashtray for the fuel pump,did you test this also?I cannot tell if you reversed the lines but  the return and feed are usually different sizes.

---------- FOLLOW-UP ----------

QUESTION: Thanks for your reply. I have not tested the fuel pressure. This car has 2 pumps, 1 in-tank and 1 outer pump. The fuel pump relay clicks and I have replaced it with a new relay. Prior to replacing the in tank pump I confirmed there was spark but I guess I need to do it again. I am leaning toward replacing the ECU as it is my understanding that it regulates the operation of the fuel pumps,but I would like to eliminate any other causes as a re-manufactured ECU is $300. Any Ideas? Is the return line smaller than the feed line from the tank?
Thanks
Pete

Answer
No spark could be the angle sensor.Its unusual for the ecu to go bad on these cars.The angle sensor is on the crank or flywheel pulley.It varies from year of car and model.The fuel must be at the proper flow first before you fix the spark,its supposed to be 45 psi at the rail and can only be tested with a proper pressure tester.The feed line is bigger coming from the tank and the smaller is the return.I would test the outer pump and fuel pressure.