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Discussion Starter #1
Rebuilt my fuel pump/sending unit assembly on this bike that had previously been garaged for years. New pump, sending unit, filter, regulator, check valve/hose, EFI fuel line & reworked the in-tank wiring.

When I bench test in a container of fuel the process runs flawlessly, pushing fuel through the system & out of the EFI line back into the container. The test wiring is switch controlled & the pump will continue to run until switched off. Gas fills the lines instantly. This is powered by another MC battery in my shop with leads attached to the fuel pump pins.

When I move the test to the bike & use the bike’s tank canopy connection & the wring harness plugged into the fuel pump, the pump runs for the 3 second duration at the flip of the run/off switch. However, no fuel is pulled through the lines. Repeated attempts in succession fail to move fuel. Spinning the starter for several seconds fails to deliver fuel, as well.

Has me a bit stumped. Would appreciate any input as to why this is happening & what I should attempt next. Would prefer that the next tank assembly install be my last : ). Thanks!
 

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If you did not make any changes to the setup between the successful test and the failure setup then make sure you haven't crossed the wires connecting (+) to (-) and (-) to plus (+). Could make the pump run backwards. JMHO
 
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Discussion Starter #3
Thanks, Rustyg. The pump has markings for positive & negative and I adhered to that during the successful bench test. The harness connector clicks into the pump one way only. If the pump was indeed running backwards would I not see bubbles exiting from the submerged strainer? I watched for this and there were none... no activity at all except for the running of the pump for the prescribed 2-3 seconds. Based on the bench test, this duration "should" be long enough to prime all lines & exit the EFI-to-fuel rail line. Appreciate any further suggestions...
 

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For a fresh install, you might want to cycle the ignition switch 5 or 6 times to prime everything before trying to start.
 

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Discussion Starter #5
Thanks. I cycled the ignition/off-run switch several times in the attempt to prime. Unfortunately, no fuel was moved. Afterward, I cycled the starter for several seconds to see if that helped... to no avail. The pre-bike bench test moved fuel immediately and steadily for as long as i engaged the pump (have a switch on my test leads). This is perplexing, to say the least.
 

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What brand, year and model bike are you talking about?
 

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Try this test. Locate the fuel pump fuse under the right side cover and unplug it. Make a jumper wire to connect the positive B+ battery terminal to the negative side of the fuse socket. Find the plus+ side with a voltmeter with the ignition on. Turn the ignition off. Plug the jumper wire into the negative side of the fuse socket and connect the other end to the battery B+ then turn the ignition on to run the pump continuously.
I use this method to drain EFI fuel tanks, spare hose connected to the tank bung into gas can.
Post back the result.
Edit: Note I said plug into the fuse socket negative side.
 

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Discussion Starter #9
Thanks, Schmidty. I’ve been out of town all day & just checked in. I’ll give this a try tomorrow & see what happens. Will post results.
 

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Discussion Starter #10
Okay, sir... tried the fuse lead test as follows: I determined the negative side of the fuel pump fuse slot and connected the lead from it to the positive battery terminal. The fuel pump activated and continued to run as long as the connection was made... REGARDLESS of whether the ignition was on or not, OR if the run/off switch was activated. This was not a "wet" test with strainer submerged. I wanted to share these results before venturing further. Thanks!
 

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Correct about the ignition on or off, I wasn't thinking ! You had constant B+ from the battery connection. Now ya gotta try it wet, the pump might just need more than 3 seconds the first time around. If it flows fuel then diss the jumper, plug the fuse back in and cross fingers the pump pumps fuel.
 

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Discussion Starter #12
Wet test attempted & no fuel pumped using the lead setup... same switch variations as previous. The pump will simply not pump fuel when it is connected via the bike's standard wiring, although it activates and "runs" as designed. Blows fuel out immediately when connected straight from bench battery. Thanks for any further suggestions...
 

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There are dumb questions - here goes :

Is there a "tip over " safety built into the bike wiring that would prevent fuel from entering the system? That is being bypassed it test setup?
 

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Discussion Starter #14
A good question, Wall banger. I do not believe this is the case in my situation.

However, the missing link dilemma appears to reside in the wiring harness. My orange and black wires were reversed at the canopy connection. There are three with a yellow occupying the center spot. I reversed the orange & black positions and the pump pushed gas through the system in the test reservoir! Wiring is important, huh? I began to feel that the bike wiring could be the only thing left to assess. Now, to reinstall everything and see if I indeed have enough pressure to flush the injectors.

Thanks to all of you for your input. I will update this post when, hopefully, the fueling system is finally off the task list.
 

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Hope ya found it. I been reading since first day. Coming up with everything I could think of. Finally decided it had to be some kinda wiring problem
on the bike. My guess was some safety thing.....Next guess was a sandwich bag in the tank sucking up !!!! :LOL::ROFLMAO::unsure:🤪
Good luck!
 

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Discussion Starter #16
Installed the tank, added a half tank of fuel & topped off the battery charge overnight. This morning she cranked and ran! I repeated the crank/run cycles several times just to assure I wasn't making it up : ). Sounded good to hear her for the first time. Thanks again for your input! I'll be back, I'm sure.
 

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Discussion Starter #17 (Edited)
Okay, folks...I’m back. This is still potentially an EFI issue so will continue this post for the moment.

Was really glad to get her busted off, but she didn’t sound right. Turns out my front cylinder is not working. I’ve verified plug gap...& fire to both cylinders via a spark tester. I added a few small squirts of oil into the front plug hole. Then, after slipping her into 5th gear was able to push her back & forth enough to hopefully spread the oil around via compression cycles.

Re-started engine & front cylinder still dead. Decided to return to y’all to verify next options. I have not performed a compression test as I don’t own a tester...yet. Since both plugs are firing I’m leaning toward the coil not being an issue. Is it possible the front injector could be failing to present fuel? If so, how best to check for this? Could be injector itself or associated wiring/connectors?

I’m selfishly trying not to consider faulty valves or rings at this point as she only amassed 15k miles before garaged. I do realize these items may be in play, but certainly hope not. I’m not receiving any type of check engine notification.

Hat in hand, I return to the forum for ideas & suggestions. Appreciate any & all input.
 

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Is the front plug getting wet after running the engine ?
You need a noid light to test for the injector signal. Low buck item at the auto parts store. You can pick that up when you're getting the compression tester.
Pop the front pushrod tubes to see that the rods are going up and down normally. Might have a dry lifter not pumping up.
If no codes are setting then it's most likely not electrical. The fuel system won't generate codes.
Check the injector harness under the tank. There were problems that the harness was tie strapped to the under tank frame to tight causing the injector wires to pull apart inside the insulation. The noid light would track that problem.
Post back results.
 

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Discussion Starter #19
Before I go shopping: The front plug is dry & clean. Regarding codes... I don't have an analyzer, just looking for any type of CEL on the dash and there was none while running.

The Noid Light kits I've checked online have 8 or so different lights noted as GM, Ford, Bosch, etc. Nothing about bikes that I recognize (this is a totally new tool to me). How can I ensure that the kit I acquire will have what I need? What should I look for? Thanks!
 

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The noid light kits are universal and work on most all injector harnesses. Harleys use the Delphi injection system now and the Magneti Marelli until 2001. I have a universal set that works with both systems and a few in the set never get used.
 
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