Hi all,
I have a clear plastic fuel filter on my '70 b20 with the stock (probably origional) fuel pump going to a Weber DGEV (whose choke I finaly got figured out. Thanks to all who provided info).
The fuel hosed are routed in a way that the filter is vertical, with the hose the the carb on the top.
Lately I've noticed about 1/4" of air at the top of the filter, and bubbles occasionally coming up from the bottom.
Do they alwayse do this and I never noticed?
Can this be a cause of the engine stumbling when accelerating?
Would this tell me that the fuel pump is due for a replacement/rebuild or that I have a break in the fuel line upstream from the pump where air is getting sucked in?

Although I don't like to disagree with Magnetic Matt, all the plastic fuel filters I have had have had air bubbles in them. I don't think you can get
all the air out of them without going to fairly extreme measures.
BTW if you have an air conditioning compressor installed it is indeed more
difficult to change a fuel pump. I have also found the Pierburg pumps (OEM) to be far superior to other kinds, both in performance (accuracy of pressure delivery) and also durability. Typically they have lasted 10 years or more.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

I agree entirely. Air at the top of the fuel filters, even when mounted vertically, seems to be a fact of life. I don't know how the fuel gets around it to the carbs, but it sure seems to. One day I'll work it out, but in the meantime I won't lose any sleep pver it.

I've read about the fuel pumps (pierburg vs the rest) but I've never had a fuel pump fail on me since I stopped owning British cars. The dreaded SU electric pumps were less than reliable!

John H

That is how mine is too, and always has been. The stumbling has nothing to do with the air in the filter. I would suggest fumbling with the idle speed, timing, and idle mixture. Did wonders for my 74 b20 DGV equipped 68 142.
Later,
Kyle

I had bubbles in mine recently, and it ran fine... but would occasionaly stumble. Then get worse.... then die.

If I were you, I'd get a new fuel pump and try it. Might solve both your problems. Keep the the old pump and a 1/2" wrench and a screwdriver in back. Only takes 5 minutes to swap pumps, and a new pump costs less than a tow truck ride.

I believe that no carburetted Volvo should be without a spare pump. Seems I have about as many fuel pumps go bad as I do tires going flat... and a spare tire costs more and is harder to change than a fuel pump....

-Matt

Centric -

The orientation of the fuel filter sounds fine - they don't care if they're vertical or horizontal or what - as long as the fuel is flowing in the right direction. Should be an arrow pointing away from the pump, toward the carb on the filter itself.

The airspace you mention is really not a problem. I have SUs in one 122 (with a larger air space than you mention), a DGV in a 544 (same air space), SUs in another 122 (with a big ol' airspace), recently removed a pair of DCOE side drafts from another 122 that had a 21300cc big bore (and always had an air space) and am now running a single DCOE with a V-Performance supercharger.. and even that has the air space.

None of these fuel setups has ever provided a completely full fuel filter. All of them leave a visible air pocket in the filter. No big.

If you're stumbling on acceleration, I'd bet your acceleration pump jet is too small... or the idle jet might need to be larger (and then the idle mix screw leaned out a bit). The float bowl in the carb more than accommodates the amount of fuel used on acceleration, regardless of air pockets in the filter or line.

Depending on your timing - ya might try a hair more advance (not more than about 22 degrees at idle though), then readjust the idle speed back down and see what that does...

Viva Italia! Or l'Espagne, depending on the Weber...

Best,

Cameron
Rose City

"21300cc big bore"

Wow - that IS big bore!!! And with a supercharger too! >:0)

The filter on my PV looks practically empty. I'd think something was seriously wrong if the car didn't run perfectly.

If there is a hole in the line the pump will draw nothing but air and the car won't run. unless its a very small hole, in which case you should see small bubbles bubbling into the filter as the car runs. Although at idle the car hardly runs any fuel through the pump.

I would be interested to see the installation and ask questions about preformance and drivability in reguards to the SC kit from V-preformance. Will you have the car at the Garage sale?

Sorry to butt in, but I think the iPd guys are going into the annual OMG The Garage Sale Is Upon Us scramble instead of hanging out on the board, so I'll answer for Cam...

Yes.

Phil nailed it: OMG the garage sale is upon us! Yow!

I love the garage sale. It's a BLAST! (to be honest, though, it was more fun to be a customer and hang around all day than to be stuck inside being accountable and stuff).

I'm now driving the s/c daily and using the old beater wagon only for errands that... well, require a wagon. Now that the teething seems to be over with, the s/c requires a whole lot LESS attention than I expected. I have yet to give it full throttle and I'm still using the lowest boost pulley available (4lbs). At small throttle openings/moderate driving, it feels like a very well balanced B20 (it should: it is). Very smooth, pulls well from 1000rpms and up, doesn't ever feel like it's 'on cam' or 'off cam.' No problem driving it like a 'regular' car in 'regular' traffic (just don't use more than about 1/4 throttle).

If you push the gas pedal further, though, HOLY CRAP! I took a friend for a ride last week... using a whole half throttle we ran through the gears and were doing well over 100 before we realized it. I haven't had a car that gave me butterflies for some time (not from acceleration anyway - sliding sideways unexpectedly does the same but isn't nearly as cool). Sounded good. Felt good. Addictive.

Couple things to work out still - throttle doesn't open fully (don't need it to, so it's not a priority yet), having to top up the (liquid) intercooler reservior on a fairly regular basis, need to experiment with carb jetting some more, want a brace for the header (it does bottom out sometimes and changing a manifold gasket is no longer a 45 minute job - it's a 5 hour pain in the butt), and I'm not used to (nor graceful with) the 4 puck "not for street use" clutch yet either.

I have ZERO complaints with this. Way, way beyond my expectations already - and I'm running 'only' 4lbs boost (approx 150-155 rear wheel hp). One of the other test cars is running something around 240...

Wicked fun.

Cameron
Rose City

*breaks out tape measure under hood of PV*

Hmmm!

It fits in a PV no problem.

8^)