FUEL FLOW

[RHO]

'55 President we have been restoring for over 4 years now. Total engine rebuild and all components inlcuding carburetor, fuel pump, fuel lines, filters, and cleaned gas tank. Car last run in November and December but just around the drive. Car would not start so I primed the carburetor and it started but died; two or three iterations of this. Then I checked the transparent fuel filter and no fuel was coming from the tank (tank is over 3/4 full). Primed a couple more times and the car made it up and down the block. ON return I noticed the fuel was bubbling in the filter but the car still cold, not warmed up and no fuel lins near manifolds. No restart next day. No fuel coming from the tank. Today I pulled the line off from the pump and ran it into a gas can and eventually the car did start and idled well although for only a 3-foot piece of hose it took awhile to pump to the carburetor and the fuel filter was not filling up and the flow did not seem correct. Pulled the fuel line to the tank and blew it out both directions with 120 psi air. Car restarted and again the fuel flow didn;t fill the filter and intermittently there was a sloshing of fuel into the fuel filter, like a surging. Car seemed to idle ok. Did not try to venture out up the driveway hill. Additionally this time and two previous occassions a loud bump was heard and felt under the center of the car and it's origin is unknown. Any ideas? I'm leaning towards it being a deficient fuel pump although it is new. The loud bump noise I'm clueless on as that has never happend previously since the car has been driven short distances off and on for almost a year now.

'55 Commander
'55 President

[buddymander]

I wonder if you have two problems. One being no gas tank ventilation; causing the loud bump when the tank indents, and the other being a clogged filter on the inlet of the pickup tube in the gas tank. For some reason I suspect a loose clamp or a crack on the inlet fuel line.

[Studeman]

Things to check:
1) You need a vented fuel cap on the filler neck (try it with yours off)
2) Your fuel pump has a piece of "trash" under ONE on the one-way check valves. This is not unusual- even for NEW pumps
3) You have an air-leak somewhere before the fuel pump

Loud Bump
1) How are your rear springs? Check under the car for signs of the driveshaft hitting the floorboard.
2) Check your exhaust hangers... you may have a muffler bumping somewhere.

Ray


Specializing in Studebaker Restoration

[RHO]

OK thanks. Haven't changed the gas cap out but certainly the first thing I'll do is remove the cap and see what happens. And I'll check the other items out also. The new fuel line has couplers so can check those for tightness. The pickup tube has no filter screen on it, the first filter being the add-on I installed just before pump.

'55 Commander
'55 President

[RHO]

Well, you guys were right on about the gas cap. I guess the rubber seal portion of this old gas cap just isn't flexible anymore. I removed the gas cap and the car started right up twice about half hour apart. The fuel flow seems normal now. The question I have is would this failure of the gas cap to vent keep the fuel from being pulled forward by the pump? Could that also be the starting problem?
Thanks for this help!

'55 Commander
'55 President

[N8N]

just get a new, correct gas cap and then worry about it if you still have a problem. No sense worrying about issues you're not sure you have yet

nate

--
55 Commander Starlight
http://members.cox.net/njnagel

[RHO]

Yes, Nate, you are exactly right. I just sent out the order for one.

'55 Commander
'55 President

[buddymander]

Air has to replace the fuel used out of the tank or a vacuum forms above the fuel, causing the pump to have to draw against the vacuum. The vacuum causes the tank to collapse, making a bumping sound and then again when a leak allows air to return to the tank.

[RHO]

OK, maybe I should start a new subject title but this is kind of a continuation of the fuel saga on the '55 President. I am getting the loud thumping noises from the right side of the car even with the gas tank out of the equation, running from a bucket. And it does it even after warmed up a bit, just once in a while upon depressing the accelerator pedal to the floor. I wonder about the heat riser valve. It is new and the outside spring easily turns by hand so I am assuming the valve in the exhaust is turning. But after running for 10-15 minutes the rear exhaust never gets warm like the left side. I just cannot discern exactly where the thuming sound is coming from still. The exhaust is well below the floor and away from anything else.

'55 Commander
'55 President

[StudeRich]

The closest point is the "dip" in the Body Mount Crossmember, that is where the exhaust pipe usually rattles or on the hand brake cable.

You should be able to rotate the counterweight on the Heat Riser Valve. And if it is original or NOS, it should point straight forward when warm, and straight up when closed and cold, if aftermarket the weight is round, but still works the same way, this type requires grinding the butterfly (flapper) to clear the Manifold opening and exhaust pipe flange, or it will jam.


StudeRich at Studebakers Northwest -Ferndale,WA

[RHO]

Thanks, I'll check that out.

'55 Commander
'55 President