Fuel Delivery issue…

jmpacella17

Joined
Apr 8, 2019
Messages
1
Age
49
Location
Gap, PA
Bike
1991 ST1100
Not sure what’s going on with my 91 ST. It bogs down and cuts out after running for a short period of time, like it’s starving for fuel.

It has an aftermarket fuel pump on it with a regulator in line after the inline filter. When I turn the ignition key, there’s no longer the hum of the fuel pump. And when I disconnect the fuel line going to the carbs and turn the key, I no longer get a short stream of fuel, as it usually does. There’s 12V across the leads going to the pump with the key on. And when I connect a line from the battery directly to the hot lead going to the pump (top of the tank), I get a flow of fuel. So, the pump is working, I guess? I even tried a back up pump (same brand as the after market one in it…quantum), to no avail.

I’m a little stumped here…could it be a relay? Any other hints/suggestions welcomed…

Also, It has a new battery and plugs and seems to be getting good spark, as well….
 
If it is hooked to the original fuel pump circuit, there is a fuel pump relay buried up on the left side under the upper fairing (a royal pain to get to). If you don't want to replace it, just set up a keyed on fused hot to the hot side of the pump and ride merrily on. I have a fuseblock on all of my ST1100s and I have a hotwire with proper terminals I carry along just in case the relay dies. If the pump works when hot, chances are it could be the relay. 'Hotwire' it and see if runs that way it would eliminate a possibility of a regulator problem.
 
jmpacella17 said:
Not sure what’s going on with my 91 ST. It bogs down and cuts out after running for a short period of time, like it’s starving for fuel.

It has an aftermarket fuel pump on it with a regulator in line after the inline filter. When I turn the ignition key, there’s no longer the hum of the fuel pump. And when I disconnect the fuel line going to the carbs and turn the key, I no longer get a short stream of fuel, as it usually does. There’s 12V across the leads going to the pump with the key on. And when I connect a line from the battery directly to the hot lead going to the pump (top of the tank), I get a flow of fuel. So, the pump is working, I guess? I even tried a back up pump (same brand as the after market one in it…quantum), to no avail.

I’m a little stumped here…could it be a relay? Any other hints/suggestions welcomed…

Also, It has a new battery and plugs and seems to be getting good spark, as well….
Click to expand...
Bank angle sensor does shut the fuel pump off and there was a recall. The recall has most likely expired but it still can fail even if it was replaced under the recall. Thats all I can remember .
http://www.st-riders.net/index.php?topic=1027.0
 
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