Why Did my Jackal Lose Power at 70 MPH?

[Pasta Hog]

I took the Jackal for a ride today. After about 40 miles, I got 3 1/2 gallons of gas. Maybe 20 miles later, at around 70 mph, the engine lost steam. It was fine at low revs, but when I rolled on the throttle, it sputtered and threatened to quit. I slowed down to about 40 to get home. When I was near the house I ran the bike up to 50 in second to see if I could reproduce the problem, but nothing happened.

I don't know what's happening. I rode as I always do, except I tried to stay above 80 instead of the usual 70.

Help!

[oldbike54]

 Hmm , may be a fuel delivery issue . Check the tank vent , and the filter and electric petcock .

  Dusty

[Pasta Hog]

I was thinking it acted like a tank vent problem, but I have no idea where the tank vent is on this thing. I guess I need to figure that out.

[rocker59]

I was thinking it acted like a tank vent problem, but I have no idea where the tank vent is on this thing. I guess I need to figure that out.

In the tunnel.  Pull the tank, and you will see.

[rodekyll]

Ummm. .  .  what gear were you in?     :BEER:




Seriously -- look for critters in the airbox.

[Pasta Hog]

When it started farting, I was probably in 5th. I had been riding at 80, and I was slowing down for congestion on an exit.

A messed up vent would explain a number of things I have noticed.

[oldbike54]

 PH , Rodekyll was being silly re the "gear" thing  ;D Pretty funny David  ;-T

  Dusty

[Pasta Hog]

I don't really understand the fuel system on this thing. I always thought the fuel in the tank was under pressure. If that's the case, how does an air vent figure into it?

[Wayne Orwig]

Dirty TPS.
Bouncing sidestand switch.
Bad relay contact.
Electric fuel tap not opening.

In other words, I would suspect electrical first.

Dirty/plugged fuel tap.Tank vent (easily identified by a high suction when you pull the gas cap).
And of course air intake as mentioned.

[Wayne Orwig]

I don't really understand the fuel system on this thing. I always thought the fuel in the tank was under pressure. If that's the case, how does an air vent figure into it?

The one way vent valve does tend to slightly pressurize the system from what I've seen.

[Pasta Hog]

The sidestand switch is long gone, so I don't think that's it.

[fotoguzzi]

sounds like tank suck to me.. no the tank should not be under pressure.. when you open the cap is there a whoosh of air? do you still have all the evap crap connected?

[rodekyll]

PH , Rodekyll was being silly re the "gear" thing  ;D Pretty funny David  ;-T

  Dusty

I thought the beer meant I was being silly.  But if he was in second, that would explain it.

Do look at your air filter.  It's spring.  Someone may have moved in for the winter, or the element may have collapsed.

[Kent in Upstate NY]

Clogged petcock filter. easy to check.

[Vagrant]

if it ran fine until you put in new gas odds are you got a load of junk. dump it and refill with new from a different location. you might get lucky and not have to replace the fuel filter.

[oldbike54]

if it ran fine until you put in new gas odds are you got a load of junk. dump it and refill with new from a different location. you might get lucky and not have to replace the fuel filter.

 I haven't been aware of bad gas in the U.S. in years . YMMV (literally ;D)

   Dusty

[Kent in Upstate NY]

I haven't been aware of bad gas in the U.S. in years . YMMV (literally ;D)

   Dusty

I got a tank of bad gas i n Wyoming back in '92. There was a 60 Minutes episode that exposed the bad gas scandal in the state. No regulations led to poor quality. Thank you, Dick Cheney.

[oldbike54]

I got a tank of bad gas i n Wyoming back in '92. There was a 60 Minutes episode that exposed the bad gas scandal in the state. No regulations led to poor quality. Thank you, Dick Cheney.

 Yeah , have read about that , but that was at least 22 years ago  ;D Damn , how can that be ? :o

  Dusty

[Kiwi_Roy]

RUST

It happened to the 98 EV I bought in Denver.
First of all it started loosing power on the hills but gradually got to a point where it would barely run.
I took the filter (under tank) of at the KOA in Ourway, flushed it backwards and it ran like a top all the way back to BC.

Another symptom of a plugged filter is an extra noisy fuel pump.

A few months later I decided to flush the filter properly, ran a little gas in the outlet, shook it up then let it run out the inlet.


It blinded off the shop cloth as you can see with the finest rust you can imagine, took about half hour to run through.


EVs and Jackals share the same fuel tank with a recessed filler cap. This has a little drain at the back to run off any water (rain or washing) but it rusts up so the water collects below the cap until you go to fill up, then it runs into the tank. You don't see this happen because it's gone by the time you get the tank open. Patrick Hayes alerted me to it and explained how to fix it.
Open the cap and drip a bit of fine oil or gas into the drain, chances are it won't run away.

I don't think it blocks off the petcock filter to the same degree, every time you stop the rust drops off but in the main filter it has nowhere to go.

You could just replace the filter but it's easy enough to flush.
Do it outside because you are going to spill some gas.

[Zoom Zoom]

If it is a vent not working, you will hear air rush into the tank when you remove the cap. It will feel "stuck" when you go to open it. Thing is, you need to try it when it is acting up to find out. Eventually the internal pressure will likely equalize after the bike has set for a while. 

If the fuel filter is clogged, it is possible to "run out of fuel" when the filter is unable to pass enough to supply demand. I ran into this a few times when GM used to put the little filter stone in their carbs. They would plug up enough to partially restrict flow.

If course, as others mentioned, the filter screen on the petcock, and electric fuel tap are also suspect. You can check both of those simply by connecting a hose to the fuel tap pointed into a can, and turn on the bike. (Not start.) If no fuel, either the tap is not opening or the screen is clogged. You may also be able to hear of feel the petcock clunk when energized as the magnetic valve opens.

My money is on the fuel filter.

John Henry

[Kiwi_Roy]

My money is on the fuel filter.

John Henry

That reminds me, if you remove the return line at the front of the tank and put it into a bottle when you turn the key on
you should get a full pipe flow, with a blocked filter you will just get a dribble.

[MotoGoosy]

Exact same thing happened to me on the Hugger yesterday.  Runs up to 50, then further twist of the throttle and it goes flat.  Garbage in the fuel system.  Clean it out.  Only takes a few specks of sediment to do it.