Old fuel pump - New question

[Phishhead61]

I know there's lots of threads about fuel pumps...I've read most of them. I have a question that I haven't seen asked:

 

When you take the points off to replace them, should you be able to push/pull the plunger stem that sticks out of the body of the pump?

 

I have a '98 Royal Star Boulevard with 50K miles and had the usual symptoms of a bad fuel pump. I assumed it was the points and ordered a set. I changed them today, and when I opened up the cap/top of the pump, the points were fine. When I put the two sets of points next to each other, the new ones were silver in color, and the old ones were a coppery kind of color...that was the only difference. No corrosion...nothing. They may have been changed already by a PO. I went ahead and changed the points, but now I get no clackety-clack when I turn on the "run" switch, and it won't start (it tries to, but just can't quite "catch").

 

I did notice the plunger going into the body of the pump would not move. I didn't know if this is an issue or not. If it's not, I guess I will start trouble shooting the electrical going to the pump.

 

Thanks for any and all input,

 

Rich

PhishHead

[djh3]

I dont know for sure. But I would think the plunger should have some movement, to move fuel.

[Condor]

The plunger doesn't actually pump the fuel, but it's a separator that opens the points when the line pressure builds to max. It may be stuck and not letting the points close. You may also have a power supply issue?? If it is an internal problem with the pump buy another used one and swap out the points if the power checks out. 99 times out of a 'hundred it's generally the points... but there's always that 1%...??

[Phishhead61]

I spent some time today doing some trouble shooting.

 

I'm testing this with the pump still on the bike.

 

I took the points off and was comparing them to the first set and found a very thin paper gasket on the back side of the original points, so I transfered it over to the new points and put them back on.

 

While doing so I made sure I caught the "grove" in the plunger with the point set.

 

I tested the wires from the bike at the connector to see if there was electricity coming through. This was difficult as you only have 5 seconds after turning on the "run" switch. After several unsuccessful attempts, I got my daughter to flip the switch for me and I didn't seem to have any electricity coming through the black/blue wire. I tried using the ground side of the connector and grounding it to the bike.

 

I checked (and tested) the fuses in the fuse box and they were fine.

 

I then tried a jumper at the connector to the pump. This would activate the plunger and pull it out. When I disconnected the electricity, the plunger went in.

 

I plugged the connectors back together and when I hit the "run" button, the plunger pulls out and about 5 seconds later the plunger goes back in (although sometimes it only took 2 - 3 seconds, but most of the time it was 5 seconds), so apparently I am getting electricity through the connector on the blue/black wire and the points work.

 

My understanding is the electricity to the pump should be a constant on (yes, 5 seconds until the bike is running, but constant after that). The pumping action is controlled by the points and the electromagnetic field going on and off, and not by the electricity to the pump going on and off (why would you need the points if that was the case?).

 

So now I'm stumped.

 

 

Rich

PhishHead

Edited August 5, 2018 by Phishhead61

[Condor]

 

So now I'm stumped.

 

 

Rich

PhishHead

 

Nope, you're right on... Now go pull the outlet fuel line off the pump and see if you're getting fuel out of the pump when the pump is in that 5 sec cycle. IF nothing you probably have a clogged filter?? Basically the fuel flow goes from the tank petcock, to the filter, to the pump, and then to the carbs... MOF if you're not getting anything out of the tank you might have the Petcock stand filters inside the tank all plugged up?? Again these are all suggestions???

[Karaboo]

Also, remember the pump will not run if there is back pressure.

 

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