Fuel pump issue

[Marcarl]

My fuel pump won't run on it's own. Does fine when wired direct, but won't run in the circuit. The positive wire has momentary power when I turn the key on with the pump disconnected.

So where might be my issue.

It actually left me stuck just one block away from home tonight.... not nice, although it sure was quiet riding it downhill for about half the distance.

[bkuhr]

could be weak fuel pump relay, but I would suspect you are losing +12v on the grey wire at the relay. This comes from the TCI and also controls coil#2 and tach.

 

A TCI swap would be in order if available, but likely an issue with engine cutoff sensor feed to the TCI such as sidestand switch, emergency stop switch, tipover switch...

Black/white wire at TCI should NOT have a ground.

[dingy]

I probably have an extra fuel pump relay if you get to that point.

 

Gary

[bongobobny]

Carl, there is this one "relay" that isn't really a relay like a normal one. It works with the ignition circuit. When you hit the key, it energises the fuel pump for about 5 seconds and then shuts off. When ignition is detected it will then reenergise. It's function in life is to prevent the fuel pump from constantly running at startup or if the bike doesn't start. Hold on to those Dutch purse strings, they cost about $100...

[Marcarl]

Guess one thing I forgot, was that when I turn the key to ON I now hear a taping or clicking in the dash board,,, maybe that is related??? It does this for about 1\2 minute then stops.

[bkuhr]

Guess one thing I forgot, was that when I turn the key to ON I now hear a taping or clicking in the dash board,,, maybe that is related??? It does this for about 1\2 minute then stops.

sounds even more like fuel pump relay

[Marcarl]

So now I'm ticked!

Took off the windshield and the headlight and got to the relays, all nicely lined up on a steel bar under all that stuff, had to decide which relay was the culprit,,, kind of a guessing game seeing a nobody told me which one it was or is. All of a sudden the fuel pump is working again, at least for a few ticks but I wasn't sure what I was touching at the time,,, shucks we'll do this again,,, NO LUCK the second time, and I felt sure I was going to have to post the question: which one is it, for the wire colors didn't match up.

But then I thought, what have I got to loose? just hit one with a hammer and see if it cries out in pain, if it does it must be alive so the dead one has to be another. So I grabbed the closest hammer,,, it was a bit heavier than the last time I used it and I whaled away,,,,,NOT, but I did tap the relay on the steel frame and low and behold the fuel pump started running and runs fine since.

Now the question is: what's the chances of this thing continuing on working, or should I threaten it every week with that hammer? Should I replace it? or will it, should it keep working.

Professional opinions please!

[bkuhr]

Professional opinions please!

Do You Enjoy

Took off the windshield and the headlight

enough to keep doing it?

 

:witch_brew:nuf said

(gary even offered ya one)

[frankd]

Carl,

 

Make sure the relay(s) are plugged in all the way. If they are, unplug the relay and plug it into it's socket a couple of times to clean up the connector.

 

Frank

[dingy]

NO LUCK the second time, and I felt sure I was going to have to post the question: which one is it, for the wire colors didn't match up.

 

Professional opinions please!

 

 

Blue, Grey, Red/White & Black wires.

 

Settle down I don't want to see this post get deleted by the more experienced moderators.

 

Gary

[dingy]

I have 3 spares, if you need one, its yours.

 

Relay is about 1/2" longer than other relays in headlight bucket.

 

Gary

[Marcarl]

I have 3 spares, if you need one, its yours.

 

Relay is about 1/2" longer than other relays in headlight bucket.

 

Gary

Thanks Gary,, I'll take the one that works for ever and keep it on the scoot for a spare. looks like about a 5 minute job to change it, now that I know where it's at.

Let me know what I owes for it.

Carl

[twigg]

So now I'm ticked!

Took off the windshield and the headlight and got to the relays, all nicely lined up on a steel bar under all that stuff, had to decide which relay was the culprit,,, kind of a guessing game seeing a nobody told me which one it was or is. All of a sudden the fuel pump is working again, at least for a few ticks but I wasn't sure what I was touching at the time,,, shucks we'll do this again,,, NO LUCK the second time, and I felt sure I was going to have to post the question: which one is it, for the wire colors didn't match up.

But then I thought, what have I got to loose? just hit one with a hammer and see if it cries out in pain, if it does it must be alive so the dead one has to be another. So I grabbed the closest hammer,,, it was a bit heavier than the last time I used it and I whaled away,,,,,NOT, but I did tap the relay on the steel frame and low and behold the fuel pump started running and runs fine since.

Now the question is: what's the chances of this thing continuing on working, or should I threaten it every week with that hammer? Should I replace it? or will it, should it keep working.

Professional opinions please!

 

This is your clue

 

It should only work for "a few ticks". It runs for about 5 seconds, or long enough to bring the fuel system up to pressure.

 

The second time you tried it the gas was at full pressure, so no ticks.

 

Sounds like you disturbed a poor connection when you removed the windshield.

 

Take it out, clean it up and add some di-electric grease to the terminals. Check all the grounds.

[Yammer Dan]

It is really simple. Just ride up hill. If it acts up turn around and enjoy the ride home.... Now is there a better answer here??

[dingy]

Thanks Gary,, I'll take the one that works for ever and keep it on the scoot for a spare. looks like about a 5 minute job to change it, now that I know where it's at.

Let me know what I owes for it.

Carl

 

It will go out tomorrow, or at latest Saturday. I have to go to Post Office to mail it.

 

Gary

[Marcarl]

This is your clue

 

It should only work for "a few ticks". It runs for about 5 seconds, or long enough to bring the fuel system up to pressure.

 

The second time you tried it the gas was at full pressure, so no ticks.

 

Sounds like you disturbed a poor connection when you removed the windshield.

 

Take it out, clean it up and add some di-electric grease to the terminals. Check all the grounds.

Thanks for the info, did it all as instructed. My guess is that either I had a bad connection, which I doubt because of the shape of things as I took them apart, or I have a relay that hung up, which is a better thought from my side. Either way, Gary is sending me another to carry with me in case I have another down time. Then it should only be about 5 minutes to get it running again.

Thanks again.

 

It is really simple. Just ride up hill. If it acts up turn around and enjoy the ride home.... Now is there a better answer here??

About the way it happened actually. I left home, and up the street to the stop sign, that's where it quit. To get back home there was a little incline before I could actually ride it downhill, until I got to the garage and then a couple of neighbours helped me push it in.

[Yammer Dan]

Warden and I took a drive in cage when we were a lot younger one night to look at moon. about 5 miles from where we were living to top of hill with good view. Her in nightgown and me in shorts. when we decided to head home cage refused to go. Can't remember why. But with me in my fruit of the Looms and her in nightgown that consisted of about 3 threads we rolled all the way home and into the drive!! Never could talk her in to doing that again??:think:

[dingy]

Carl,

 

Package went out today.

 

Gary

[Keemez]

Alright- I seem to be having the same problem here. The old "phantom out of gas syndrome" has struck me twice in recent history. Cycle the kill switch and no definite fuel pump running, then allasudden it starts working again.

 

Marcarl was right- the wire colors called out do NOT match what's up under the dash. There's 3 or 4 relays which energize when the kill switch is cycled- which dang one is the correct one? I see zero relays with the 4 wire colors called out. I guess I could unplug one relay at a time and see which one stops the pump from running, but nice move on the part of the folks that developed the service manual.

[Keemez]

Update: found 'er (trial and error). It is the relay all the way on the right side of the bike (left side as viewed from out front). Pic attached. The contact blades look pretty clean, but I roughed them up a little anyway for good measure.

 

Here's something I don't understand... if I turn the petcock off and allow the carb bowls to run more or less dry to the point where the engine stumbles and eventually dies, why will the fuel pump not continuously run at that point and try to refill the bowls? I'm talking about either while the engine is still running or when you cycle the key or kill switch to the run positions... conditions under which the pump would normally be running so long as the bowls are "empty" and more fuel is needed. It's almost as if the pump knows there's a vacuum on the the inlet side (because the petcock is off, remember) and until it sees some liquid inside the pump, it won't allow the pump to run. As soon as I turn the petcock back on the pump fires right back up again and everything operates normally.

 

At this point I'm wondering if instead of a pump relay issue, maybe I had plugged vent lines. I poured a little solvent in both ends of the vent and blasted 100psi air through them repeatedly (yes, the gas cap was off so I didn't blow the tank sky high). I'm pretty sure they're clear now, even though I suspect they were before because I had done that about 18 months or so ago when I first picked the scoot up.

 

Dingy, do you still have a known good spare relay that you're willing to part with? Might not be a bad idea for me to carry one along juuuuust in case.

Edited July 5, 2012 by Keemez

[frankd]

These fuel pumps don't have electric motors running them, they have a coil of wire that is energized which creates a magnetic field. This moves a diaphram that pumps the gasoline. When you hear a click, the coil has been energized, and compresses a spring. That spring applies pressure on the diaphram, which creates fuel pressure. When the fuel is used, and the diaprham is at the end of it's stroke, a set of contacts inside the fuel pump close. This applies voltage to the coil again, and the diaphram moves to the other end of it's travel (and the contacts open). This cycle is repeated over and over, but because the carbs. eventually get full and the needles block the fuel from the pump, the diaphram also stops, even though voltage is applied to the wire feeding the fuel pump. When enough fuel gets used, the fuel pump diaphram pumps replacement fuel, and moves. Now when you shut off the petcock, the pump will create a vacuum on the inlet, and this will prevent the diaphram from moving to the end of it's travel and closing the contacts again, so the pump quits making noise.

 

Back in the old days when cars had carbureators, some hot rodders used electric fuel pumps. They worked the same way...click, click, click. My buddy had the cam lobe that moves the mechanical fuel pump wear out in his Corvair, so he installed a Stewart Warner electric pump. However, the electric pump would wear out the contacts and stop working. He would take it apart on the side of the road, and clean the contacts up, and then replace it ASAP. The fuel pumps in 1st Gens. seem to last though. I don't think I've ever heard of anybody having to change one on a 1st Gen.

 

To tell if it's the pump or a wiring/relay/TCI problem, I'd measure the voltage on the wire to the pump. If there is voltage there and you have problems, it's the pump, or the fuel filter or screen in the tank is clogged with crud. If the voltage to the pump goes to zero, you have a wiring/relay/TCI problem. If you don't have a meter you could use a small light or a test light.

[Keemez]

To tell if it's the pump or a wiring/relay/TCI problem, I'd measure the voltage on the wire to the pump. If there is voltage there and you have problems, it's the pump, or the fuel filter or screen in the tank is clogged with crud. If the voltage to the pump goes to zero, you have a wiring/relay/TCI problem. If you don't have a meter you could use a small light or a test light.

 

I did a fair bit of troubleshooting. At first I thought maybe the pump was clogged up with some junk so I took it off the bike and disassembled it slightly (pulled the cover off)- it was spotless. Applied power to it using battery charger and it runs as commanded- I'm calling the pump good.

Then I thought maybe the filter was full of debris. Once I had it cut apart it also appeared spotless. Took the fuel sender out of the top of the tank- petcock screens are spotless although there is some minor rust in the tank in general. But since the screens look good I'm not worried about it.

Relay seems to be energizing and de-energizing with every throw of the kill switch or ign key- the contacts in the connector were pretty clean but I gave them a little more bite just for good measure.

As I mentioned in my last post the only other thing I suspected might have been wrong was plugged vent lines from the tank, and I made sure that's not an issue. The bike runs great otherwise so I am skeptical of a TCI (or associated wiring). Both times that it did this was when the tank was getting closer to empty, but still had maybe a gallon left in it.

[Keemez]

Ok- there is definitely something "weird" going on. It did it again today.

Conditions: 79*F, mostly sunny, cold start fine and ran for about a mile (moderated speeds no greater than 40mph) before starting to stumble and eventually dying again. I was actually able to get stopped and open up the gas cap (somehow my key comes out of the ignition in pretty much any position) before it died. I figured if there was a vacuum lock going on, as soon as I opened the cap and fuel started flowing to the pump again all would be ok. No such luck.

Cycle the kill switch a bunch of times and no fuel pump run. Then on a random whim I heard it start clicking like usual again and it ran fine for the rest of my 30 mile errand trip. I didn't have my voltmeter with me. Maybe that relay is suspect afterall. So far the count is one warm and two cold snuffouts.

[dingy]

Attached is a link to a thread showing a fuel pump dissected.

 

http://www.venturerider.org/forum/showthread.php?t=63062

 

Gary

[Keemez]

Well, it did it again. This time after several hundred miles of riding with no apparent issue. The only thing that seems to be common in each of these instances is that the fuel level in the tank was below 25% or so, and I'm ruling that out as being an issue because I know I thoroughly blew out the vent lines.

 

I received the spare fuel pump relay (thank you, Dingy) and it is currently installed but haven't tested it yet. I will be embarking on a multi thousand mile journey to put it through its paces. One oddity I noticed before I installed it- it does not seem to be the same size as the one I pulled off my 93. I'm wondering if the one I had in there (I got this scoot used with 60557 miles on it, so I don't intimately know its service history) was nonstock, although it looks just like several of the other ones up under the dash there. If anybody else has their dash apart, take a look at that relay and see if it matches the spare that I got from Dingy (on the left side of the pics I will attach) or the one I pulled outta there (right side in the pics). I gotta say- I'm a bit confused about this.