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I'm troubleshooting my 2005 CRV - not starting. I had replaced the fuel sending unit as it was dead. The new one spun up and I put the fuel pump assembly back in. I understand the pressure should be around 50-60psi or so. The CRV cranked over, but still did not ignite. I manually applied 12V to the fuel pump assembly and gasoline came out of the spout. I could put my finger over it and there was not much pressure, definitely not 50-60 psi.

My question is - is this low pressure from the fuel pump correct? If so, there must be a fuel pressure booster unit in line somewhere else?

Can someone shed some light on this?

CRV cranks, but no ignition - on to more testing...!

EDITS AND MORE TESTING:

  1. I used a separate 12V battery and applied it to the fuel pump module - only produced a small low pressure stream.
  2. I pulled the assembly out and removed the fuel pump and tested it on a water bucket and it spit out water at a high velocity and it was difficult to plug it by hand.
  3. Put it back into the assembly and into a bucket of water and applied 12V to the assembly, and got a low pressure stream again...
  4. Then I took the pump out of the assembly to test for resistance in the pathway. Sucked on the discharge and could feel a definite high amount of resistance.
  5. Unfortunately the pathway goes into the assembly in a section where it cannot be taken apart (plastic welds) so I think over the 15 years, there may have been some build-up in the pathway....? That's the only thing I can think of.
  6. I may be resigned to buying a whole new assembly instead of just this way of replacing only the pump...ugh.
  7. Any of you have the experience where it's the assembly and NOT the pump motor that causes a blockage? The filter attached to the pump was fine. Also tried it without the filter and the same results.

EDIT 2:

  1. In case anyone is reading further, I could not get the expected pressure coming out of the assembly and I ended up buying a pre-assembled unit with the housing, float, and fuel sending pump. Installed it and worked like a charm. Still cannot figure out why my original repaired unit was not delivering as expected - only thing I can think of is some obstruction due to build-up in the delivery pathways. I may try to blow air through it in the future when I have more time.
  2. If you are testing for voltage at the cable/connector end from the vehicle, there is something you should know - when you turn the key to the ON position (without cranking), voltage is applied to the connector for just a few seconds, then disengages. I got fooled at first because I was only one person troubleshooting this and not quite familiar with the logic of all this. So when I to check the voltage, it was already off, which makes you think there is a continuity problem - so you check the fuse, pump relay, main relay and get confused, because they are all good - which means you should get voltage.
  3. However, when I extended the meter leads so I could see it while sitting in the driver's seat, I noticed turning the key to the ON position gave temporary voltage to the pump assembly, then shut off. The cranking the engine gave a continuous voltage to the assembly as long as you cranked the engine.
  4. Hence, that is when I understood the assembly was getting the voltage it needed, but perhaps no fuel was being delivered.
  5. Being by myself, it was difficult to try to hear or feel the pump at the back of the car, so that is when I decided to take a spare battery and apply voltage directly to the pump assembly terminals - which resulted in NOTHING! So you would conclude a fuel pump problem and you either replace the whole unit or just the sending unit.

1 Answer 1

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  1. There definitely is not a booster pump on that car with a gasoline engine.
  2. It’s not clear on how you applied 12 volts of power. Did you carry an auxiliary battery to the fuel tank and directly wire the battery to the fuel pump? If so there should easily be 50 psi or more. Question: how did you establish positive/ negative posts for the motor? (That is, was the motor spinning in the right direction?)
  3. If you did the direct wire 12 volt jump and aren’t seeing 50 psi or more, it’s possible you have a badly clogged fuel filter. Note, in tank fuel delivery modules do include an intake “sock”. It’s possible that sock is totally plugged with dirt and sludge.
  4. If you added the 12volts in a different way (through the engine compartment wiring harness? ), its very possible you are routing thru a Pulsed Width Modulation (PWM) device. What that device does is modulate the fuel pump power so the correct pressure exists at the fuel rail. I’m suspecting this may well be your situation. The PWM unit is located in fuel pressure module somewhere. That system should be controlled via a signal from the powertrain control module.
  5. A key input is fuel pressure. If that sender is not working correctly all bets are off.

Best way to test is key on, engine start and measure fuel pressure at the fuel rail with a gauge. Much safer too. Gasoline is nasty stuff for your health.

(edit) Brief discussion on Fuel Delivery Module and general terms.

Here's a fuel delivery module. It consists of a pump, a fuel level indicator system (typically a float and resistor assy), a plastic canister (which acts as a reservoir, so the pump always has fuel) even during high force turns and braking. There is also a simple sock type filter attached.

Fuel Delivery Module

Here is a fuel pump. It consists of a small sealed metal can containing a motor and impeller. It may be possible to just replace this component from inside the Fuel Delivery Module.

Fuel Pump

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  • See the edits in the original question - used a separate 12V battery and touched the pump assembly terminals while the pump was installed in the vehicle. The fuel filter was at the bottom of the pump - a small cloth-like filter/sack. It was not clogged, also tried it without the filter. There is no other inline filter that I know of on this model. Don't have means of measuring the pressure in-line yet... maybe tomorrow.
    – HDer
    Dec 24, 2021 at 6:42
  • Pump spin direction? Same pressure both directions? Funny. I had a motorcycle with fuel varnish in electric pump. Jammed pump = eating fuses. I was able to free the jam with momentary power in both directions. + / - and repeat.
    – zipzit
    Dec 24, 2021 at 7:08
  • I looked at the wire colors and matched it to positive negative, so the direction was correct.
    – HDer
    Dec 24, 2021 at 7:35
  • Not what I asked. PUMP SPIN DIRECTION? SAME PRESSURE IN BOTH DIRECTIONS? The wording of your problem is odd. Its not clear on if you replaced the fuel pump itself or just the fuel level sending unit (float +/or variable resistor unit). Your words The new one spun up Spun up? fuel level sending unit? That doesn't make sense. I've seen lots of screw ups, including wires misrouted on new manufactured parts. Hence my questions. Terms: Entire plastic gizmo including reservoir, sock = Fuel Delivery Module, Fuel pump = metal motor / rotor assy. Fuel level sending unit = float + resistr
    – zipzit
    Dec 24, 2021 at 17:25
  • The assembly had a housing, float sensing unit, and fuel pump motor. I kept the housing and float sensing unit and replaced the fuel pump motor only. As for the polarity, the connectors are designed to connect only in the correct fashion, so you cannot mix the leads up. When assembled, the exposed connector at the top for the fuel pump motor traces to a black (negative) and yellow (positive) wire. I connected to that polarity for testing.
    – HDer
    Dec 24, 2021 at 17:38

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