92 FJ1200 Fuel Pump Problem

[coloradoparadise]

My OEM pump died at 97,000 miles, replaced by the dealer ($550...that hurt).  New pump died 5,000 miles later, replaced by the dealer at no charge.  Now 22,000 miles later the third pump has failed.  What the heck?!

I'm the original owner and the bike is stock original with no modifications to the electrical or fuel system.

Question #1: can this pump be repaired by replacing the point set?  Zero ohm resistance on all contacts till the points are separated.
If it can't be repaired, is there a direct OEM replacement that anyone has had good luck with?

#2: Voltage to the pump relay is only 10.6V, book calls for 12V.  I've checked the wiring connections from the battery (14.4V), fuse block, ignition switch, and kill switch and haven't found any resistance.  The pump voltage reads 10.6 until the rpm is above 2,000.  I'm guessing the low voltage when starting and idling is burning out these pumps.  Any ideas what might be causing the voltage drop?

Thanks for the help...this is driving me nuts!

[Pat Conlon]

Good for you Rich, Kudos in checking the pump's operating voltage.  good2

I think you are on to something here....10.6V low rpm voltage sounds (to me) to be too low.
Ohmn's law tells us (with motors) as the operating voltage drops, the amperage draw increases. Motors run hotter.

We know the distinct advantages of wiring in spst relays with a dedicated circuit for the headlamp and coils.

Perhaps the same should be considered for the fuel pump?
Dunno, but I suspect as our bikes get older, voltage drop on our harness will only get worse....never better.

Should you invest $33 in a points set from RPM?
http://www.rpmracingca.com/search.asp?pg=1&stext=points&sprice=&stype=&scat=&sman=

Or should you invest in new a aftermarket fuel pump? The new pumps (like Facet) don't use mechanical points.
http://www.fjowners.com/index.php?topic=9724.msg92954#msg92954

I'll let George (movenon) chime in here, he has good experiences with the Facet pumps to share.

All good questions.....

What I would do is...check the Mfgr's specs for operating voltage of the Facet pumps and if ok, then go with that aftermarket pump which has a superior design (and FAA certified for aircraft)
If 10.6V is too low for the Facet pump, put in a relay and a dedicated circuit and call it a day.

I know what I would definitely not do is to buy a new oem pump...you've already tried that solution and it has shown not to work. Would replacing the points help? If it does (I don't know) I suspect the solution would be only temporary.
Do the relay mod and new points?  That's a option, unless you can identify where the voltage drop occurs

Hope this helps you....thanks again for checking your voltage before posting...it really helps narrow down the problem.

Pat

[The General]

Good for you Rich, Kudos in checking the pump's operating voltage.  good2

I think you are on to something here....10.6V low rpm voltage sounds (to me) to be too low.
Ohmn's law tells us (with motors) as the operating voltage drops, the amperage draw increases. Motors run hotter.

mmmm.....so if tha operating voltage drops to 1v or (imajining) maybe even zero, the amperage draw would be even more or really high. 

[FJ_Hooligan]

A little electrical engineering:

Volts = Current * Resistance

Given a constant Resistance, a drop in Volts will give a corresponding drop in Current (amps)

If Resistance drops (a short), Current will rise proportionally to keep the Volts constant.

The typical constant in the automotive world is the 12 volts coming from the battery.  If the voltage is less due to increased resistance in the wiring, the load will have less amps available to turn into work.

Class dismissed.

[TexasDave]

I would check the connections and the wires feeding the pump. Electric motors are not affected by low voltage as much as low current. I have seen voltage get through bad connections and broken wires but the current does not. The worst thing you can do to an electric motor is starve it of current(amps). Starved for amps they run very hot and burn up. Just the two cents worth from an old electrician.  Dave

[The General]

A little electrical engineering:

Volts = Current * Resistance

Given a constant Resistance, a drop in Volts will give a corresponding drop in Current (amps)

If Resistance drops (a short), Current will rise proportionally to keep the Volts constant.

The typical constant in the automotive world is the 12 volts coming from the battery.  If the voltage is less due to increased resistance in the wiring, the load will have less amps available to turn into work.

Class dismissed.

Got it, thanks mate. Constant voltage is good. No resistance is bad. 

[movenon]

 Randy at RPM has a direct replacement. I adapted a Facet 40171 and it is working just fine. So far no complaints, but it is adapted. You have to do some minor work to adapt it. Not hard to do but some would rather not go through the effort. Read through the threat Pat sent.



George

[FJ_Hooligan]

Read through the threat Pat sent.

Yeah!  And make sure the money is all small denomination bills.  No consecutive serial numbers or you'll NEVER get the answer you seek!....

[movenon]

Read through the threat Pat sent.

Yeah!  And make sure the money is all small denomination bills.  No consecutive serial numbers or you'll NEVER get the answer you seek!....

Oops Bouncing to fast through the spell check 
George

PS  I always carry a 2 foot section of fuel line and barbs coiled up with me just in case of a pump malfunction on the road.

[ribbert]

One thing no one mentions is simply giving the points a clean. A couple of passes with a bit of emery is all it takes. The points in the pump are no different to the ones in the distributor of your old coil ignition car except no one here ever mentions freshening up the contacts. Like distributor points they technically deteriorate every time it clicks and they should be cleaned periodically.

A couple of years ago mine had occasionally needed a light tap to get it going first start of the day. I cleaned the points and have had no trouble since.
I wonder how many serviceable pumps get chucked because of dirty points.

You can do this in situ just by removing the end cap.  Even if this is not your specific problem, it should be a regular service item and literally only takes a couple of minutes.

As far as replacement pumps go, any low pressure, 12v pump you can cram into the space will do (or even relocate it) I use a $30 Facet type eBay knock off on my other bike and carry one with me on trips in the tool kit.

Noel

[coloradoparadise]

Thanks for all of the really quick replies and suggestions!  I've checked the points and no obvious issues.  So instead of throwing money at an old pump I think the best choice is a new pump with current design.

Pat, I'll check with Facet on Monday to see if 10.6V will be an issue.  If it is, would you put the relay before the pump relay, using the red/white wire (red/green on my bike but the schematic shows red/white) as the actuator or after the pump relay using the blue/black wire as the actuator?  Then I'll need to find a relay that will work with just 10.6V.

George, can you walk me through the adaptation of the Facet 40171?

Thanks for everyone's input, this forum rocks!!!

Rich

[Pat Conlon]

Definitely after the oem pump relay.

There is a safety circuit that runs the fuel pump only a set amount time (5 seconds?) after the engine stops (based on the tach signal) In the unfortunate case of a accident (engine off but your key on) this prevents the fuel pump from continuous running...feeding fuel into a potentially bad situation.

If you wire in your spst relay in front of the oem pump relay, you will bypass this safety feature.

[movenon]

Thanks for all of the really quick replies and suggestions!  I've checked the points and no obvious issues.  So instead of throwing money at an old pump I think the best choice is a new pump with current design.

Pat, I'll check with Facet on Monday to see if 10.6V will be an issue.  If it is, would you put the relay before the pump relay, using the red/white wire (red/green on my bike but the schematic shows red/white) as the actuator or after the pump relay using the blue/black wire as the actuator?  Then I'll need to find a relay that will work with just 10.6V.

George, can you walk me through the adaptation of the Facet 40171?

Thanks for everyone's input, this forum rocks!!!

Rich

As you can see from the picture it mounts differently,  I use a different rear shock with the stock adjuster removed and no stock air box so I have a lot of room to play with.  Here is a thread that might be of interest. http://www.fjowners.com/index.php?topic=9724.msg92533#msg92533
As far as the fittings I have a straight barb on the front and a 90 degree on the rear. I would have preferred hose fittings but barbed was all I could locate at the time

Here is an R6 pump on Marshs FJ  http://www.fjowners.com/index.php?topic=1147.0

Also check out http://www.rpmracingca.com/proddetail.asp?prod=fuelsystem%3AFP.

I am still wondering why you only have 10.6 volts.. Tempted to go measure mine.  I will see what tomorrow brings...
George

[moparman70]

 

[movenon]

Just information from my voltage reading.

1990 FJ - 2 year old gel cell battery - been sitting for 2 days and probably didn't go to full charge last time I ran it.

Battery voltage before start (cold):  13.27 volts

Voltage at the fuel pump connector with ignition on and not running (until the CDI shuts it off) 10.57 volts

Voltage at battery with engine running, just after cold start @ 1100 RPM 13.40 volts.  It will climb up to 14.4 volts at high RPM until the battery is charged back up. I didn't run it long enough to see where it settled, that would take 10- 20 min of riding. Best guess.

Voltage at fuel pump connector with pump disconnected (measuring on the spade terminal / blue,black wire). The engine will run fine with the connector unhooked for a few minutes anyhow. The ground leg of the meter is attached to B- on the battery.  I noticed that I got a lower reading trying to read from the back of the connector, probably not getting a solid connection on the probe.

@ 1100 RPM 12.6 volts
@ 2500 RPM 13.4 volts  voltage stabilized there.

A question, is your regulator/generator putting out a good charging voltage at idle ?
George