Fuel pump issue - I think...

[laseron]

So I've got my 89 FJ rebuild all put back together, and hooked up an auxiliary fuel tank. I pulled the choke, switched on the ignition, but didn't hear the familiar fuel pump sound. The starter turns the engine over fine, just won't fire, though there are slight hints that it's trying. With empty carb bowls, I expected the fuel pump to run until the bowls filled (or overfilled). I tried starting with the reserve switch off, and then on. I also checked that the fuel supply is feeding into the correct inlet on the fuel pump (according to the manual). I'm probably missing something simple here. I rebuilt the carbs during this project, so settings could be wildly off. Any suggestions?

[freakhousecustoms]

I've experienced a similar issue, also running an auxiliary tank, I wonder if there is something in the fuel gauge wiring that needs to be hooked up to complete the circuit?

What I do is just jump the wire for the fuel pump to "prime" the carbs and fill the bowls.  Oddly enough, once they're filled and my bike is running, I don't have to run that jumper wire and the pump makes that "familiar fuel pump sound" again and the bike runs, as normal.  It's also a quick & easy way to test if the pump is still working.

Blue wire off the fuel pump, I go on the side with the yellow tape, because it's easier to get to the metal inside the plug.



Then just hold the other side against the positive battery terminal until the bowls are full.



Now, of course, you have to remember that you can/will experience sparking, so make sure you don't have any fuel leaks and/or you are not COVERED in gasoline.

[laseron]

Thanks! Sounds good! I'll give it a try. And this time, I won't soak my clothes in gasoline before hand. Bad habit.

[aviationfred]

You are correct with the clicking noise. As soon as you turn on the ignition, the fuel pump should start clicking to build fuel pressure in the carbs. I would check 2 things.

1. The fuel pump relay is located next to the fuel pump. Hold it with your fingers and turn on the ignition. You should feel a single click. If you don't than you have a bad fuel pump relay.

2. If you feel the click on the fuel pump relay, but the fuel pump does not click repeatedly. Your fuel pump failed.


Also, both of the checks can be done with neither fuel lines connected to the fuel pump. For trouble shooting, this is my preferred method.

Once you get the fuel pump working, with no fuel lines connected. It is very easy to figure which port to put the fuel lines on. With the fuel pump running, put a finger on one of the ports. One will blow and the other will suck. The fuel line from the fuel tank goes to the port that sucks and the fuel line that goes to carbs goes to the port that blows.

Hopefully this helps and is not covering ground that you have already covered.


Fred

[freakhousecustoms]

Also, since you're using an auxiliary tank, and it sounds like you just want to hear the engine run, you can just bypass the fuel pump completely.

When I got my Black bike, which hadn't run in forever and the tank was all rusty, I pulled a spare tank off the shelf and plugged it directly into the carbs.  Obviously, keep the aux tank higher than the carbs and once the bowls are full, gravity will provide all the fuel pressure you need to get the bike to fire.  I also like to shoot some carb cleaner down into each individual carburetor before hitting the button, just to get things moving.

[ribbert]

I would check 2 things.....

1. The fuel pump relay is located next to the fuel pump. Hold it with your fingers and turn on the ignition. You should feel a single click. If you don't than you have a bad fuel pump relay.

2. If you feel the click on the fuel pump relay, but the fuel pump does not click repeatedly. Your fuel pump failed.


Fred

Fred has offered good advice there, to which I would add, check for power to the relay, and from the relay (to the pump).

Fuel pump failure is usually progressive, so, if it has stopped working because it's faulty, a sharp tap will usually see it spring into life. This is not to say it has become serviceable again, but merely a diagnostic test that identifies the pump beyond any doubt as the culprit.

If you don't have an instrument for checking for the presence of power, you should! A test light or multi meter cost less than $10. My preference for voltage tracing is a test light, they're waaaay better for that.

No electrical diagnostics can be done without at least some basic tools, a multi meter and test light can be bought for less than the cost of a tank of fuel, in fact, probably for less than the cost of a mid ride lunch.

As has been mentioned, for the purpose of just firing it up, gravity feed will do the trick.

Noel