Fuel Pumps?

[peach_]

Rite heres one for you, After looking at some photos of engine and there bays (Sarge  ) Iv noticed some ppl out there are still running standard fuel pumps and I just wanted to get a general opinnion of what ppl thought and what ppl are running? i.e Has anyone found the running big carbs and a Standard fuel pump can cause fuel starvation?, If you running a standard fuel pump what carbs are you running?, basically anything to do with what fuel pump your running and if you have any advice for me as i was about to run a aftermarket one until i saw the photos 

Cheers

[Jason Foster]

  I ran my car on stock pump with IDA's low 13's no problem. My float bowels are enlarged and I never had fuel starvation. I now run a Holley HP125 because I went to steel braided hoses. For street use I think there is no problem at all with stock line and pump.

Here's a shot of my engine in it's first incarnation. Nice and old school I often miss this look.


This is how it looks now since electric pump and braided lines have been added.

[Rennsurfer]

Peach, you can run any fuel pump that you prefer. Personally, the factory ones have never let me down. Gene B. told me that one thirty years ago. He's still correct. Unless you're building a full-on race car... there's really no need for anything else. The factory one won't starve the carb(s) on anything less.

By the way, Jason... your car looks great as always.

[glenn]

2180, dual IDAs, Steve Tims Stage 2 heads and FK-8 with mechanical fuel pump.

I've not run my car at the track but I do live at the end of a 3 lane highway and have done a number of 0-100mph runs.

I can take off in first, shift 2nd @ 7600rpm, shift 3rd @ 7600rpm, shift 4th @ 7600rpm with not problem. But if I hold 4th to 7600rpm and then shift into 5th (Berg 5) I do run the float bowls dry. If I back off for a second and then put my foot into it again the car continues to pull.

BTW... I shift 5th gear @ 105mph and the car is still pulling hard.

[Rennsurfer]

BTW... I shift 5th gear @ 105mph and the car is still pulling hard.

Scenic! That sentence, right there, is what's all about. You, sir, are doing it right.

[neil68]

2332 cc, IDA's with enlarged float bowls by Jaycee, 7,000+ rpm, 12.9 seconds @ 104 MPH, stock fuel lines, stock pump

[Shubee2 (DSK)]

I am Using A Stock  Pump on my 2332 with IDA's but did have to enlarge the float bowls due to them being empty on a Hard Run also use 7mm type 3 fuel lines no Problems now

[Bruce]

Four years ago I screwed together an oval window that ran a stock pump.  12.9s with stock gears.

[Sarge]

I think a lot of what goes on here has to do with copying what others are doing, rather then actual trial and error.  There's no glamor with a stock fuel pump, so something that LOOKS GOOD has GOT to be better.  Truth be told, there are certainly a few folks here that actually need a big electric fuel pump but the majority could easily stick with a stock pump.  My $.02

[louisb]

Too bad you cant use one of the nice looking older style fuel pumps with an alt though.

--louis

[glenn]

I like the looks of the mechanical fuel pump.

During one of the "Biker Build Off" show they had Indian Larry building a custom chopper and he always talked about how a bike was a machine and needed 'mechanical" stuff and moving parts. He did not the newer ultra modern and sleek bikes where everything was hidden and they had billet wheels. Larry was "Old School" and used spoke wheels and chains and had exposed cables.

While I like the engines where the linkage, hoses,wires, fuel pump and even distributor are all hidden I really enjoy the "old school" look.

My 2180


John Plow's 2110

[Rasser]

Now I´m not saying that mechanical fuel pumps aren´t up for the job, because I have never tested or heard of any tests.

But A few weeks ago I helped a friend out when he had his 2366ccm dynoed. I was standing behind the car, and could see both the fuelpressure gauge (mounted on the firewall) and the LM2 AFR gauge (mounted inside car, looking through rear wiindow).  He had a electrical german fuel pump mounted (can´t remember the brand), but anyway brand doesn´t matter because the pump wasn´t up for the job, and we went through 2 other pumps before finding one that was up for the job.

We could clearly see that when the engine reached 4500rpm, the fuelpressure went down to 1 psi and not many rpms later 0psi. The AFR gauge showed that the engine was running lean above 5000rpm (chassisdyno - 4. gear). No matter what size mains we put in the carbs, then the afr would not get better. After talking about it, we finally decided to try some other fuelpumps, and we finally found one that was able to hold at least hold 1-2psi through out the rpm range. He had 51,3mm Ida´s with 3.0 needle inlets, and fuelbowls was enlarged.

What I really wanted to say is, that you have to run an AFR gauge in order to know whether or not your engine is getting sufficient fuel. Even with the first fuelpump (the one that wasn´t up for the job), we could still run the car high up in the rpm range, but after 4500rpm the AFR would lean out. But it didn´t lean out enough to misfire, but it was lean - not healthy for the engine. You couldn´t feel or hear that the engine was running lean, but if you had a quick look at the AFR gauge, you just knew it was WRONG. Changing the pump to a more efficient one made it possible to jet the carbs.
We also guess that the engine must have used almost all the fuel in the bowls at 4-5000rpm, and after that the engine was dependent on the fuel it could get from the pump. But this is only our guess, based on fuelpressure and AFR readings.
If you don´t use a proper chassis dyno that can put good load on the car/engine, the you may not be sure that your fuel supply is up for the task.
The cool thing about using the LM2, is that it has a "record" function and a rpm input (rpm input is not std.), so after running a 1/4mile race or high speed autobahn testing, then you can look back at the recordings and see what you AFR is at different rpms - this is very very handy!


Remember to check with your AFR gauge - you may very well be running your engine lean at high speeds with high rpm.

[danny gabbard]

One thing nice about stock pumps, There quite.

[lawrence]

How many PSI does a stock fuel pump produce? Is it dependent on the length of the pushrod and the thickness of the bakelite base? My friend has a 2110 with IDAs and in order for him to use a stock fuel pump he had to stack multiple gaskets under the bakelite so that the fuel pressure would come down. Has anyone experienced this?

[Rasser]

I think it´s mentioned how to adjust pressure in the original volkswagen service manual.

[glenn]

How many PSI does a stock fuel pump produce? Is it dependent on the length of the pushrod and the thickness of the bakelite base? My friend has a 2110 with IDAs and in order for him to use a stock fuel pump he had to stack multiple gaskets under the bakelite so that the fuel pressure would come down. Has anyone experienced this?

I'd used multiple gaskets many times to reduce PSI. It's better than grinding down the rod as i've seen done.

[Bruce]

How many PSI does a stock fuel pump produce? Is it dependent on the length of the pushrod and the thickness of the bakelite base? My friend has a 2110 with IDAs and in order for him to use a stock fuel pump he had to stack multiple gaskets under the bakelite so that the fuel pressure would come down. Has anyone experienced this?

When I first tried running the car I mentioned above, the fuel pressure was 11psi with a stock pump.  Gaskets were needed to get it down below 3psi.

One problem with an electric pump is that it has one speed, on or off.  The stock pump is variable.  As the rpms increase, so does the delivery.

[Jason Foster]

I think a lot of what goes on here has to do with copying what others are doing, rather then actual trial and error.  There's no glamor with a stock fuel pump, so something that LOOKS GOOD has GOT to be better.  Truth be told, there are certainly a few folks here that actually need a big electric fuel pump but the majority could easily stick with a stock pump.  My $.02

 
   I agree completely with this statement. In my endeavor I was running my car more and more and the tracks frown on more than 12" of rubber hose. I decided it was time to switch to braided hoses as well an MSD ignition and came up with a new "look" for my engine in my head and carried it out. I've gone 12.50's at 106 with this delivery system probably could of done the exact same with the stock pump as well. If it weren't for the tech inspection hassles I'd of stayed with the stock pump. 

[glenn]

I'm probably under 12" of hose.



Stainless, seamless .250(od)/.196(id) hardline.

[Jason Foster]

  If you had a dollar for everytime that shots been used Glenn you'd be set huh... Yeah I get you there but done is done ya know.

Peach, run the stock pump bud.

[glenn]

  If you had a dollar for everytime that shots been used Glenn you'd be set huh.

True... but i've received many inquiries on what I used and have seen a number people start using more hardline in the fuel system.

I'm not saying I was the first, but that picture does get seen and gets the "juices flowing" in many people's minds.

That's the beauty of the internet... you can find what others use and pick what works best for you and your situation.

[ACSwede/DBR]

...I now run a Holley HP125 because I went to steel braided hoses. For street use I think there is no problem at all with stock line and pump.

I echo above - In my experience the the HP125 is a great choice if not going stock - It's quiet, reliable and sure looks great 
(make sure you have GOOD ground when running this pump - I had some weird issues driving me nuts before isolating it to bad ground  )

[Jeff68]

My engine- 2110, dual IDA's, K10 cam, stock mechanical "crimp top" alternator fuel pump, stock fuel lines from tank to pump to carbs, 26mm oil pump, full flow oiling, all german cooling tin and in shroud oil cooler etc. Engine has 500 miles on it.  Car is a full weight (not lightened) 1968 Beetle 4 speed car with stock 4th gear.
Experience : This past weekend, myself and a friend was driving back from a car show in Florida - 85 mile trip one way.  Air temperature was 74 F, and there was a pretty good cross wind 10 to 15 mph wind. The roads and highways are very flat here as on this trip.  For most of the trip I was driving 65 mph on the highway.  Half way through trip I decided to step it up.  Took a blast up to around 90 mph  and held it here for several minutes.  The oil light began to flicker (very dim flickering) after about 5 minutes.  I slowed back down to 65 oil light stopped flickering.  When I got off the highway either going to the show and going home the engine was cool, Berg dipstick contact tab only rotated half way around.  I don't have termperature gages installed in my car. In city, stop and go, stop light grand prix, or regular city driving the oil light never flickered and Berg dipstick tab never got close to the contact to turn the oil light on even in the HOT summer months of Florida.
I think from my experience it shows that for longer sustained rpm operation a standard fuel system may not be able to deliver enough fuel.  I have not run my car at the drag strip yet but I'm interested to see if i have any fuel delivery problem(s).

[Jason Foster]

Sounds great Jeff but how are you figuring oil light ficker relates to fuel delivery? You said you ran 90 or so mph for a few minutes wheres the problem with that?

[Jeff68]

Jason - Actually, I was at 90 mph for at least five minutes or a bit more.  I'm just assuming that the engine may have been running lean which could have caused it to start to overheat or run hot.  I'm just thinking that the engine's fuel requirements during constant, sustained higher rpm periods may exceed what the stock fuel pumpp can deliver.  Since I have no gage to show me what the fuel pressure or volume of fuel was being delivered to the engine I can only assume this.  If I had an air fuel mixture monitoring device (LM-1) in place while I was driving the car I would have data that could further support my assumption.
As I was saying, the engine had never showed any evidence of overheating previous to this and since this was the first time I held the engine at a higher rpm for 5 minutes I thought this might be due to a fuel delivery problem.
I welcome any suggestions or thoughts as to if my assumptions are correct or not.  Everything else with the engine seems to be in order as I've had no problems with it.

[javabug]

I lost the bolts for my pump.   

[Rennsurfer]

I lost the bolts for my pump.   

(coughFUELINJECTIONCASEcough)

Pardon me... must be that cough that's goin' around.

[Bruce]

...., the engine had never showed any evidence of overheating previous to this and since this was the first time I held the engine at a higher rpm for 5 minutes I thought this might be due to a fuel delivery problem.

More likely is that it was the first time you made 90mph worth of hp for that long at constant high rpm, and that at that rpm, your oil cooler was being bypassed.  Lots of heat + bypassing the cooler makes things hot.
If it was an air fuel ratio problem, the engine would have started bucking.

[kingsburgphil]

Ok! regarding enough fuel pump pressure.   PRESSURE IS MEASURED AS RESISTANCE TO THE FLOW!   If you need to ck f/p pressure, then dead-head the the pump, Otherwise ck the flow rate, Gal/Ltrs per min. Under load the floats are down and the needles and seats are open, the pressure should be low. In other words forget PSI and concentrate on flow rates (GPM) when working with a NA carb motor. Either the pump can maintain
a minimum fuel level or it can't. EX. a stock engine with pump failure just quits under high load (Hills) and resumes when the pump can catch up.
That is assuming fuel supply to the pump is adequate, and unimpeded.
A fuel injected or turbo motor has different parameters that are best explained on other threads.


Thanks for letting an old tech vent some "pressure".

[vwtaiwan]

I have couple questions about stock fuel pump:
Does it pump more fuel when engine rev more RPM?
When you spend 10000+USD on the engine, why still use stock fuel pump, any advantage?