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BF225A HP fuel pump

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weathered

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My engine quit running the other day out of the blue. The first thing I thought of was fuel. Checked the external water/fuel separator seems fine. Checked low pressure bulbs and they were clear no water. I emptied them and they filled back up when I was turning over the motor(not starting just turning over ). Still clear no water. Listened for the high pressure pump when key ignition turned to on and didn’t hear anything. I took apart the VST took out the HP pump and tested it. Surprisingly it ran. Hooked it back up again and just used the female side of the connector power wire to test it. It ran. Then I tested the male side of the connector with key on and multimeter hooked into the connectors 12v showed on my volt meter for a few seconds and then back to zero. So far everything seemed fine. Then I connected the connectors back together and tested the key on again. Nothing. No volts no pump on and no idea why. I did this testing several times and I can always get 12 volts on the male side of the connector when separated but when I connect to the female it shows 0 volts. I even took apart the connector and have the two pins connected manually. Same issue. I have never run into any thing like this so I’m wondering if anyone has any suggestions what could be causing this voltage drop. Thanks!
 
Up front, I'm no Honda 225 guru. Never worked on one.

Just pointing out that this could be a wiring or connection problem.

A partially broken, multi-strand wire can ohm test "good" (providing continuity) or deliver full voltage for your meter to see if only one wire strand is still intact. But that same wire will not be capable of delivering enough amperage for any appreciable work.

That's why it"s often necessary to load test that circuit. Often, a sealed beam headlamp works well but an 1157 or 1156 auto lamp bulb is sufficient to do this. About 2 amps I think.

Poor connections behave similarly but can often be more of a pain to test.

For example, if the contact points of a relay assembly inside the main relay are pitted, dirty or mis-aligned, the same resistance to current flow can exist.

It is also important, in cases like this, to keep in mind that the issue can be on the ground side of a circuit. But your testing to make the pump run has already eliminated that here it would seem.

There are differing techniques for load testing but most important is to isolate the ECU (or any computer) from the wiring being tested before power is applied.

Often the test bulb will light when power is applied so it's important to wiggle and jiggle the wire or connectors while watching for any dimming or brightening to make an accurate assesment.

Again, I'm not telling you this is the problem. Just pointing out that it might be.

Good luck
 
@jgmo I agree with testing with some type of load. Light would be best. I have a test battery I can get a good idea of full power light and compare that to what I’m getting at the 2p connector. I’m not excited about replacing the main relay if that’s the issue. Lots of electrical clipped on the housing that has to move before I can get to it. I do have the pins pulled from the connector so I can clip those off and test when I connect those bare wires to rule out loose wires.
 
You might want to check out the fuses. Looking at the wiring.diagram the main relay gets and delivers power through a few fuses. Sometimes just pulling a fuse, checking it for continuuty and putting it back can knock off enough corrosion to have it make better connection. A little contact cleaner helps too.
In the days of glass fuses, just giving them a little turn in the holder would sometimes fix a problem quick.
Just an idea.
 
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