How do you know its fuel pump not working? Volts at plug?

Tiny
BRIAN88888888
  • 1986 DODGE 600
  • 56,000 MILES

Car: 86 dodge 600 turbo convertible
no sound at fuel pump.I can only read 1.8 volt at plug, with ignition key ON. @ 8 volts at sending unit plug. Is this normal and is pump bad? The wires go up thru floor behind seat, where convertible roof retracts into. There looks like there are 2 relays, like on firewall. Could fuel pump relay be here? My Haynes manual is too vague! Can't afford mechanic right now.

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Sunday, September 30th, 2012 AT 7:40 PM

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Tiny
CARADIODOC
  • EXPERT
  • 26,026 POSTS

Better not be voltage at the pump; that would be a fire hazard in a crash. You must check there for the first one second after turning on the ignition switch or when cranking the engine. Those are the only times voltage will be there.

Did you check for spark?

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Sunday, September 30th, 2012 AT 7:49 PM
Tiny
ASEMASTER6371
  • EXPERT
  • 25,554 POSTS

WARNING: Fuel system pressure must be released any time a fuel line is to be disconnected.

Connect fuel pressure gauge C-3292 and hose adapter C-4749 or equivalent to fuel rail service valve.
On 1984-85 models, start engine and observe pressure gauge. On 1986-88 models, using ATM tester C-4805, place ignition switch in Run position and depress ATM button to activate fuel pump. Gauge should indicate 51-55 psi pressure. If pressure is as specified, remove gauge and adapter from fuel rail.
If fuel pressure is below 51 psi, install tester between fuel filter hose and fuel line and start engine. If pressure is now within specifications, replace fuel filter. If pressure does not increase, gently squeeze fuel hose. If pressure now increases, replace pressure regulator. If fuel pressure still does not increase, either the fuel pump is defective or the filter sock is obstructed
If fuel pressure exceeds 55 psi, remove fuel return hose from pressure regulator end. Install suitable length of hose to pressure regulator and place open end of hose into a clean container. Start engine and recheck fuel pressure. If pressure is now within specifications, check fuel return line for restrictions. If fuel pressure is not as specified, replace fuel regulator.

There should be 12 volts at the fuel pump plug, not the sender plug. The fuel pump will run for 2 seconds until the engine cranks and starts. Then it will run constantly.

Roy

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Sunday, September 30th, 2012 AT 7:52 PM

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