Fuel Pressure
 

Guys -

Starting about two months ago.
Car is stalling, showing signs of fuel starvation, initially randomly, now more often, but not exclusively under WOT. (Low fuel pressure, dry/low fuel level in filter.)

The fuel gauge at the carb inlet (Holley 850 DP), starts around 6 psi and gradually drops to near zero, after about 10 - 15 minutes at idle.

The tank and fuel line appear to be clear (tested with air blow through) and the mechanical fuel pump has been replaced. (Both the old and new pumps yielded the same results, but after all the work, the problem seems worse with the new pump.)

Carb appears to be functioning properly (floats, A/F mixture set correctly and jets, PV, and needle/seat checked/replaced.

When not starving, the engine is running annoyingly well.

Possible carb issue, false negative with fuel line check?

Any similar experiences?

Thanks,

Archer

Sure the hoses are good out at the fuel tank?

Another bad fuel pump it sounds like to me....

Might try a Carter or a Holley Pump... 3/8 hose...

:)

Bob -

Thanks,
The hoses are all flexible and patent (as best as we can see).
Even removed the tank sock - got worse.
All 3/8".
The original pump (6 years old) was a Holley High Flow
The new one is an Edelbrock High Perf.

Sure seems like the pumps, but the odds of two different ones doing the same thing, while possible, not too likely.

Archer

Tank vent?

Iowan -

The tank vent is capped.
It's been capped for at least 6 years, possibly 30 years.
This is a new occurrence.

The only thing that changed was the fuel line was modified with a 12" piece of hose near it's midsection, but there's good air and fuel flow through it.

Archer

Run it with the fuel cap off and see if that helps ???

:)

Bob -

Already tried that, no difference.

However, after doing all the checks again, had to start thinking fuel pump - again. Pulled the new pump and a manual test showed it to be working. What wasn't working was the cam excentric that activated the pump. Apparently, it had gone pretty flat. (30 year old cam.)

After labor day, going to install an electric fuel pump and regulator.

Over the winter, we'll think about a new cam and possibly heads. Never ends, does it?

Archer

Sounds like a plan....

So the eccentric part of the cam went Bad?? ... Or did the rod just wear down?

ether way... Looks like you got your money out of that good old cam... :)

And boy do I know the " Never ending Story".....Hahahahahahahahaha

:)

Bob -

The push rod for the pump was perfect. I bought a new one just in case, and the two were the same size. The eccentric must have flattened over time. So there's a block off plate where the mechanical used to be, and hopefully the new electric pump will be in soon.

Just seems odd that the pump eccentric would wear before the valve lobes, since they are under higher tension.

Funny you mentioned the push rod length, that recently happened to another club member. That's why I bought the new rod with the pump.

Well, now I have two good mechanical pumps ...

Archer

This is going in your 74 Charger??? Rite >>>

Have you decided what pump and reg. you going to stuff in it?

Flat lobe, time to look at the rods and mains.

Bob -

Not yet, I have about a week to think about it.
Open to suggestions.

Thanks again,

Archer

I have had good luck with these pump.... Not too bad on noise if you also rubber mount the bracket.... Good For Mild Strip and mostly Street. Just watch the restriction with the fittings you use... :)

http://www.jegs.com/i/Carter/180/P46...oductId=748050


Just My 2 cents.....

Bob -

Thanks, I'd be a little nervous about running a rear mounted pump without a regulator.
Do you use one with that pump, and if not what's the psi at the carb? The mechanical pumps always give me about 6#.

Archer

That unit is 6-8 psi and is self regulating.... Archer

If you don't think the Motor demand is that high. Maybe your looking at something a little smaller and easier to use just for the mean time...

http://www.oreillyauto.com/site/c/de...0515&ppt=C0128

Not sure if this one requires a regulator or not,, on this unit...

Just food for thought.

Bob -

Thanks, I'd tgo the the stronger unit + secondary regulator, since there might be some engine mods in the near future.

Archer

Bob -

After checking and temporarily replacing everything from the sending unit to the (mechanical) pump, it seems that the fuel filter had shifted and the inlet ports became blocked. That's what caused the fuel starvation issue - at least for the time being...

Auto mechanics 101...

Archer

Some Times it can be the Darndest little things that get you.....
Glad your back up to speed before the winters nap !!!!!!
Thanks For the update Archer.....:)