Yearly Safety Anouncement

[FJmonkey]

For those of you that have been paying attention to my Help In Chino post and the one before with my New member ride with Frank on his GTS, my 86' petcock was failing (I did not know at the time). But I could restart and run like stink with no issues. This problem drove me Nucking Futs, it took a few more rides to get more information on when the failure happened and what worked to restart my bike. Then I felt I had enough information to rule out many possible causes and BLAME the  petcock. With the new and old petcock side by side I could test them and realize that the original 86' was toast and was the cause of shitty Kookalooo. In truth I went with an 84/85 petcock to get the Prime option and ditch the electronic reserve (Thanks Pat). Untested the bike was loaded in my truck and 400 miles later it ran with zero issues (mostly, but not petcock related) during the Napa Renegade rally. We covered almost 400 miles of the best roads any FJ could ask for. The gravity feed 86' ran faster than I can ride her.... Thank you Randy for getting the replacement to me ASAP.

[Derek Young]

All this talk about the petcock and the possibility of fire, I just want to make sure everyone is aware.

All three versions of the FJ petcock to the inventory at www.RPMracingCa.com quite some time ago, just search petcock and you will see all three versions, plus the aftermarket Pingle unit. The early, 84-85 version can be used on the 86-90 model bikes if you want to eliminate the electronic reserve function.

I also have on order the 84-90 gravity feed formed 10mm fuel hoses that should be here next week for those looking for them as well.

The two early version petcocks with the infamous "L" fitting that I offer for sale at RPM are safety wired with S/S wire to prevent corrosion of mild steel wire on the aluminum as well. This can also be done without any modification of grinding of the petcock housing.

The early gravity feed version tanks/petcocks will not interchange with the late model fuel pump version.

There has been talk of adding the fuel pump to the gravity feed bikes, and I have to ask the obvious question; WHY?

There are several thing that one must take into consideration if you are thinking of converting the gravity feed bike to a fuel pump supplied.

#1 - The CDI has a fuel pump timer for a prime circuit of the fuel pump. The fuel pump will run for 2-5 seconds and then it shuts off the electrical power if it does not see any ignition P/U coil signal. This timer works as well if the bike shuts down, losing ignition signal to not keep pumping fuel.

#2 - The fuel pump does act as a "check valve" or "petcock" to stop the flow of fuel to the carbs when shut off since the petcock is not an automatic petcock. But, there still is a small trickle that comes from the pump, but the flow is so slight the N&S can handle the pressure.

#3 - Pre 1989 dual gravity feed carbs will have an issue hooking up the fuel line as the difference in since is 10mm Vs. 6mm ID hose. The increased supply diameter as well as the dual feed will allow a pump, if it is on the high side of the pump range to lift the needles from the seats and cause flooding issues. We used to see this all the time with people trying to use the dual feed carbs on the race cars. Once you convert the carbs back to the small single inlet the problem is resolved.

#4 - The fuel pump only "truly" shuts off and stops pumping when the electrical supply is stopped. I have seen mentioned several times over the years that the pump shuts off when the pressure builds to the max pressure. In actuality the pump is a magnetic pulse style supply pump, thus the reason the click/rattle/pulse and you can hear them. What happens when the pressure builds to a high enough point, the plunger can no longer move a full stroke and pump more fuel past that set pressure point, and it becomes quiet. If you touch the pump at this point, you can still feel the plunger action working, but since the pressure has reached maximum, the plunger cannot stroke to supply more fuel, only maintain the pressure. Once the pressure drops and the pump can again begin to stroke, then you will hear it and it will supply more fuel. It is trying to pump more fuel, but until the pressure drops it cannot.

While many people have problems with the gravity feed system, it is usually operator error; running the fuel line routing incorrectly, adding fuel filters or a mechanical failure of the petcock itself. But, if everything is routed properly, no modification have been made to the system by adding fuel filters or other type(s) of fuel hose and the petcock is operating properly the system will function properly for years.

Maybe as part of this annual safety reminder, is the fact these petcocks are now sometimes 28 years old and should be replaced with a new one. There seems to be no issue recommending the replacement of the O.E. brake hoses to every new member that comes along, maybe the petcock should be added to the list as well. I mean, no issue spending money on braided brake hoses, so why not spend less than $200.00 bucks for a new petcock as a form of insurance against ever being the victim of a fire due to the petcock failure.

Finally, don't be fooled to think the late model petcock is not prone to failure. The have rubber o-rings and plastic components inside of them that fail as well due to time & heat. I have personally had two of them leak on customers bikes, and they leak the whole tank out every time...

Randy - RPM

Well written Randy.  That is very informative.  I had considered converting my 86 to a fuel pump on more than one occasion.  I have seen alot of posts on here that make it seem an easy task.  It is very frustrating being the guy pulled over on the side of the road holding up a group ride.  I have been that guy on more than one occasion.  It makes you strongly consider buying a newer motorcycle.  But, as you say, replace the old petcock and fuel hose and route your fuel hose properly and the gravity feed system functions just fine.  They are just a little more finicky than the fuel pump versions.  Removing the vent flapper in the cap also helps for sure.

Thanks for clearing up some misinformation that many of us had about the fuel pumps.

Derek