What I think is a pump issue - '89 1200

[arthurdent510]

I've got an '89 1200 that I'm trying to track a problem down on...  best I can track it down to at this point is that it centers around the fuel pump.  I've had the bike since around the start of summer but haven't been riding much due to the heat.  It was actually fairly cool (only a high of 100 :p) last week, so I had the bike out a couple times.  I noticed that the pump, which up till now ticked very rapidly when you turned the bike on, started ticking very slowly.  I also have been having problems getting the bike to start.  I've had to play with the throttle to get it in a sweet spot, then it will start up.  First couple times it did this, it ran ok.  However, middle of last week I was pulling out of my subdivision and the motor suddenly cut out on me.  It picked back up right away though and kept going.  I had to get gas anyways, so I pulled over a mile up the road at the station.  It was fine up till then.  Gassed it up and as I was pulling out of the station it cut out on me again.  Similar situation both times - choke all the way off, accelerating, and it cut out on me right about 5k rpm.  Would only cut out for maybe half a second and it'd keep going.  I turned around and got it home while trying to reproduce the issue but no luck.

Later that night I went through the usual checks... 12.6 volts at the batter, getting good voltage at the pump, fuel filter looked good.  I pulled the fuel lines going in and out of the pump and I had good fuel flow coming from the tank through the filter.  I turned the bike on again with the fuel lines off the pump and it promptly spit the fuel out and started ticking like it should.  Hooked it all back up, worked good for a day, then went back to its old habits.

It is an aftermarket pump...  it has a mitsubishi logo on the back end of it.  The inside of my tank is fairly clean, but is the #1 culprit junk getting past the filter and clogging the pump?  Is there anything else I should check out?  Or am I completely off the mark and need to go down a different route?  Thanks!

[Pat Conlon]

Look at the venting on your gas tank. The next time this happens, open your gas cap and see if problem goes away. You will tell immediately when the cap is opened, if a vacuum is present in your tank.
Your gas cap has some salmon colored flapper valves which can be trimmed or removed to assure that the tank stays equalized at atmospheric pressure. If the tank is not vented, it will develop a vacuum which will impede fuel flow to the pump.

Hope this helps. Report back your findings.... Oh, yea, welcome to the forum. Shall we call you Art?

[rktmanfj]

It is an aftermarket pump...  it has a mitsubishi logo on the back end of it.

The OEM FJ pumps are from Mitsubishi...

[arthurdent510]

Ah, didn't know that about the stock pumps being mitsibushi....  I forgot to mention that I've already taken the flapper valves out of the filler cap.  So I don't think that's affecting things now...

[Pat Conlon]

Ok, then the pump it is......

[fj11.5]

could it be the vent itself and not the cap

[movenon]

As a test can you just bypass the pump and gravity feed with a 1/4 inch fuel line (or splice) ? For a temp splice you could use a small engine in-line fuel filter ( male ends on both sides). Buy them at any parts store. I know it probably will not deliver full power under extended full throttle but.... Just a thought from a poor retired guy. I have no experience doing this but it is what I would try if my pump failed on the road. Maybe I should make a fuel pump bypass kit to have in my tool kit.... Things to ponder next winter .

[Yamifj1200]

Well after replacing the stock pump with aftermarket pumps twice in 30,000 miles, I replaced the aftermarket pump with a working stock pump and keep a spare stock pump under the seat.. No need to be stranded when ebay has working pumps from time to time. The last one I bought was brand new stock unit for 95 dollars. I figure its cheap insurance...

Eric M

[Rich Pleines]

Well after replacing the stock pump with aftermarket pumps twice in 30,000 miles, I replaced the aftermarket pump with a working stock pump and keep a spare stock pump under the seat.. No need to be stranded when ebay has working pumps from time to time. The last one I bought was brand new stock unit for 95 dollars. I figure its cheap insurance...

Eric M

Totally agree. Started carrying a spare pump several tears ago and this week my pump failed without warning on a trip 275 miles from home. Changed the pump and was back on the road in 15 minutes. The folks I was riding with are still in shock and can't believe I had a spare pump with me. Ordered another. Life is good.

[movenon]

Sounds like a good idea. I will put one on order . To old to push ........