Topic: No longer thinking about a Phanotm Fuel Line Obstruction:

[SOHC4ever]

I was riding my 76 cb750F the other day, when I felt the familiar power loss that goes comes with the fuel level dropping to reserve - but it was early. Switching to reserve did not improve performance.

I was running an in-line fuel filter before this happened, but have since removed it and am running a new, clean, transparent primary fuel line. I've also removed the T connector, other two fuel lines and petcock and confirmed that they are clear (Naturally, I had already filled the tank up, so I had every discarded milk jug in my neighborhood full of gas to get that petcock off.)

SO: If I'm reading this right, my fuel obstruction is either:

1. in the T's that run between 1&2, 3&4 carbs (unlikely, because of the in-line fuel filter)
or
2. not a fuel obstruction at all - in which case I have no idea and need your help, 4ums!

[mgbgt89]

Plugged fuel cap vent?

[SOHC4ever]

Plugged fuel cap vent?

I checked that, too. flow rate doesn't change with the cap off, and a skewer slides through the vent without snags.

[BobbyR]

Low floatbowl levels?

[camelman]

Blockage in the carbs?  When is the last time they were cleaned?  Some of the junk that is in the tank is small enough to bypass the filter, but will still block up your jets.

Did you run any fuel additives lately?

Could something have fallen into the tank?

Camelman

[SOHC4ever]

Blockage in the carbs?  When is the last time they were cleaned?  Some of the junk that is in the tank is small enough to bypass the filter, but will still block up your jets.

Did you run any fuel additives lately?

Could something have fallen into the tank?

Those carbs were off and cleaned by me last spring. All jets were crystal clean. I added fuel stabilizer to the 1/2 tank that it sat with over the winter, but that was 4 or so tanks ago. No way anything fell in the tank.

Low floatbowl levels?

I'll check them, but those carbs were running beautifully before all of a sudden not getting gas.

I'm going to pop those bowls next, though.

Could this be electrical? A short somewhere interrupting my spark? Is there a way to check, or am I barking up the wrong tree. This feels so much like out of gas... but I don't want tunnel vision over this.

[OldSchool_IsCool]

Water in the tank/bowls?  Drain the bowls into a glass jar and take a look for water/crud.

[mgbgt89]

Blockage in the carbs?  When is the last time they were cleaned?  Some of the junk that is in the tank is small enough to bypass the filter, but will still block up your jets.

Did you run any fuel additives lately?

Could something have fallen into the tank?

Those carbs were off and cleaned by me last spring. All jets were crystal clean. I added fuel stabilizer to the 1/2 tank that it sat with over the winter, but that was 4 or so tanks ago. No way anything fell in the tank.

Low floatbowl levels?

I'll check them, but those carbs were running beautifully before all of a sudden not getting gas.

I'm going to pop those bowls next, though.

Could this be electrical? A short somewhere interrupting my spark? Is there a way to check, or am I barking up the wrong tree. This feels so much like out of gas... but I don't want tunnel vision over this.

Check your points recently? On my 350, I felt like i was running out of gas, Turns out one of the contacts decided to start to fall off the breaker arm.

[SOHC4ever]

After a re-check to make absolutely sure that there was free flowing gas from the tank through to the venturi, I was thoroughly high on gas.

mgbg mentioned points, so I popped off the points cover to notice that the ring connector for the ground on my Hondaman ignition wasn't really crimped on all that great, so I re-crimped that, put it all back together... and the bike still ran like sh*t. But that got me thinking.

I unplugged the Hondaman unit, set the points up stock, and Va ROOM! Stock Honda Power!

It didn't make any sense to me that the well respected Hondaman transistor ignition would just up and stop working after less than a dozen hours of use, so I re-checked my connections. Lo and behold: I am not a wirer of things.
The leads that go from the box to the coil weren't long enough to reach, so my inner McGyver kludged together a couple of extension leads out of some spare wire and the bullet connectors that came with the unit. I have no crimping tool, so I just mashed the connectors onto the wire with a set of pliers.
I suppose that as the connections loosened the juice wasn't making its way down the circuit, causing in a loss of spark that felt a whole lot like a fuel obstruction.

SO: anyone digging up this thread because they think they have a fuel obstruction might want to consider having a close look at their ignition wiring - especially if it's been monkeyed with.