Fuel Pump(s) Reliability

Moderators: 330GT, abrent

J.Barta
Posts: 2
Joined: Mon Mar 05, 2012 1:16 am

Fuel Pump(s) Reliability

Post by J.Barta »

I had a most unpleasant experience on the freeway this past Saturday which makes me question if I can ever rely on my 330GTC fuel pumps to reliably perform. The long and short of it is both fuel pumps stopped working and I had to be towed home. This is after I had both the mechanical pump and electric pump diagnosed, rebuilt and tested last year (18.5 hrs. labor) by an experienced shop. After the rebuild the mechanical pump worked ok until the
engine oil was approx.90 degrees then it would cut out, especially below 3,000 rpm. The electric pump fortunately would kick in when needed. I was told I could leave the electric pump on continuously without a problem...of course until there is a problem! I've read on this forum over the past couple a years about problems with mechanical pump replacement parts so I'm wondering what the collective experience has been to improve the reliability of these pumps and/or alternatively replacing one or both with something else like a solid state Facet pump. I've owned this car for four years and never had any
concerns like this that would prevent me from enjoying it. Perplexed. Any input would be appreciated.
Joe
'67 330GTC
User avatar
tyang
Posts: 4060
Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
Contact:

Re: Fuel Pump(s) Reliability

Post by tyang »

Hi Joe,

Sorry to hear about your problems. As these units age, parts could wear beyond the ability of a rebuild. The electric pump has a winding inside that could have intermittent conductivity, the points could be worn too far for service, or the plunger could be sticking inside the pump. The mechanical pump has a whole bunch of wear areas, and a worn out pump body may not allow the rebuild seals to work properly. It could be anything.

How much fuel did you have in the tank when the mechanical pump couldn't keep up? Sometimes a little more head pressure on the mechanical pump intake side will help the pump work a little better. This is certainly not a solution, but just a question.

A lot of owners have given up on relying on these pumps, and have installed a solid state pump like the facet you mentioned. The trick is whether you want to remove the original pump and put in an aftermarket pump. Some owners have installed the facet pump in tandem with the electric pump, so you'll still get the "CLICK CLICK CLICK" of the old pump, with the tick,tick,tick reliability of the Facet.

Tom
'63 330 America #5053
J.Barta
Posts: 2
Joined: Mon Mar 05, 2012 1:16 am

Re: Fuel Pump(s) Reliability

Post by J.Barta »

Hi Tom,

The mechanical pump first cut out with about a quarter of a tank. I ran on the electric pump for another 10 miles, filled up and ran another 10 miles until the electric pump stopped running. I think the mechanical pump output continued to be inadequate after it first cut out.
One theory, I've been told, about my rebuilt mechanical pump is that the metal center in the replacement diaphragm is slightly bigger than the original one which reduces the pump stroke and results in inadequate fuel delivery, especially when warm/hot. Don't know if this is true or not. If shaving this diaphragm disc fixes that so be it. I am in agreement that the facet pump in conjunction with the electric pump is probably the best way to go. Coach
built Ferrari's are not meant to be disabled on the side of the road!

Joe
Joe
'67 330GTC
User avatar
tyang
Posts: 4060
Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
Contact:

Re: Fuel Pump(s) Reliability

Post by tyang »

Hi Joe,

Agreed. At least with a Vintage Ferrari, you'd be less likely to have people experiencing schadenfreude as they pass by a broken down New Ferrari!

I'm sure your shop checked the length of the pushrod stroke coming out of the timing case? The bakelite spacer may need to be shaved down to give the pushrod a little more travel.

Bob Smith of Coachworks shared a really cool trick I want to try someday soon on how to add a secondary electrical fuel pump without cutting the original plumbing. Most modifications I've seen cut the rigid pipe from the fuel filter and add soft rubber hoses to make the new connections. The problem with this is returning it back to original requires new rigid pipes and some soldering. Bob has simply made longer banjo bolts and stacked another banjo fitting on top of the inlet and outlet banjos at the original fuel pump. The second set of banjo fittings can go to the modern pump. I wonder if there would be sealing issues with so many sealing surfaces, but it's worth a try.

Tom
'63 330 America #5053
John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: Fuel Pump(s) Reliability

Post by John Vardanian »

Cool trick... longer banjo bolts. I love it.

john
PF Coupe
kare
Posts: 547
Joined: Sun Sep 22, 2002 11:34 am
Location: Helsinki, Finland, Europe

Re: Fuel Pump(s) Reliability

Post by kare »

Why should sealing a double banjo bolt be any different from a single one? Search Ebay for double banjo bolts and you'll see it is not a very exotic solution!
250 GT 2+2 3197/GT
DWR46
Posts: 621
Joined: Tue Sep 22, 2009 8:23 pm

Re: Fuel Pump(s) Reliability

Post by DWR46 »

You will find double banjos on a number of Ferrari's drum brake applications and they seal brakeline pressure, so fuel presure is not an issue.
User avatar
tyang
Posts: 4060
Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
Contact:

Re: Fuel Pump(s) Reliability

Post by tyang »

Thanks guys. When mating surfaces are nice, flat, and square, I wouldn't imagine a problem. It's all the factors that get thrown in that cause the problems. The id of the sealing washers sometimes aren't exactly the same as the original ones, so they can shift when tightened, or the face of one of the banjo fittings could have an imperfection, ...these are the issues I'm considering.

It's still worth pursuing this mod one day.

Tom
'63 330 America #5053
User avatar
330GT
Posts: 1640
Joined: Wed Sep 04, 2002 9:30 am
Location: Seattle, WA
Contact:

Re: Fuel Pump(s) Reliability

Post by 330GT »

tyang wrote:...A lot of owners have given up on relying on these pumps, and have installed a solid state pump like the facet you mentioned. The trick is whether you want to remove the original pump and put in an aftermarket pump. Some owners have installed the facet pump in tandem with the electric pump, so you'll still get the "CLICK CLICK CLICK" of the old pump, with the tick,tick,tick reliability of the Facet.

Tom
The GTC parts book lists the electric fuel pump with both FISPA (click type) and Bendix (tick type) part numbers. Late 330 GTs came with the Bendix pump, so it is likely that late GTCs would have changed over at the same time.
Regards, Kerry
http://www.330gt.com 330 GT Registry
http://www.parrotbyte.com/kbc/ferrari 250 PF Coupe 1643GT, 330 GT 2+2 8755GT, 308 GTS 23605
User avatar
hgraham
Posts: 45
Joined: Tue Jul 05, 2011 12:36 pm
Location: Petaluma, CA

Re: Fuel Pump(s) Reliability

Post by hgraham »

Now that I have my car back and the Summer heat has returned, I'm remembering the fun of my old vapor lock problems. I think my mechanical pump is nearly dead, and while the rebuilt electric pump seems to be working fine, I'm tired of having to worry about fuel supply problems. I'm intrigued by the inline Facet installation with double banjo bolts. Has anyone tried this out, or have a diagram of the setup? How would it be wired so that it operates independently from the electric pump?
1966 330GT #8553
User avatar
tyang
Posts: 4060
Joined: Wed Nov 27, 2002 10:28 pm
Location: New York
Contact:

Re: Fuel Pump(s) Reliability

Post by tyang »

I'm working on a different approach. I'm thinking of having the banjo bolt machined to have a nipple coming out of the face of the bolt for a 1/4 inch fuel line instead of a double banjo bolt. Despite the opinions of others on this list, I still think there will be leaks from sandwiching two banjos together. It may have worked well when these parts were new, but things wear and leak.

In the interim, I found another solution for my car. There is a short yellow line between the fuel filter assembly and the hard line heading towards the mechanical pump. This line is located near the electric fuel pump. You can unbolt this line, remove the yellow hose, and clamp a 3/8 inch fuel line to either end and put a facet pump in line. The pump will pull fuel out of the tank and push it forward to the mechanical pump. The check valves in the mechanical pump will allow this flow to reach the carburetors. I wired mine into the electric pump circuit disabling the old electric pump. I now run it all the time. Eventually, I'll make these new banjo fittings, and perhaps sell it as a kit for every one else, but for now, I can drive my car without the worry of my electric pump failing.

Tom
'63 330 America #5053
jroswell
Posts: 13
Joined: Fri Aug 21, 2009 4:58 pm

Re: Fuel Pump(s) Reliability

Post by jroswell »

Tom:

I still think the double banjo is the more elegant solution, and certainly easier than machining a special outlet. If leakage is a problem, I would try the same type of copper gasket/washers that are used for similar sealing in many other locations. An '84 Mercedes I once owned had those washers on both sides of the banjo at the fuel pump and filter.

When you first mentioned (many years ago) hearing about people adding a modern electric pump to replace both pumps , you said "with a pressure regulator to provice approx. 5 psi to the carbs." This was probably because a pump used for a modern fuel injected engine has a very high output pressure that would force fuel past the needle valves flooding the carb. The Facet pump however, is available in 4 pressure ranges, all below 9 psi. (Does anyone have any experience selecting one - I would assume the 4.4 to 6 psi is most compatible.)

You also mentioned the check valve in the mechanical pump. I don't know how this check valve is supposed to work, but I always thought that the the whole point of running the electric pump until the clicking slowed down before starting the engine was to fill the float bowls, because they drained back to the tank while the engine was off. If the check valve functioned, this wouldn't occur, would it?

BTW - all this is nothing new. Back in the early 50's hot rodders were regularly bypassing mechanical fuel pumps with electric ones.
250GT
Posts: 968
Joined: Wed Oct 15, 2008 7:41 am
Location: germany/holland

Re: Fuel Pump(s) Reliability

Post by 250GT »

Used on drum brake pre1960 Ferraris too.
C.
Attachments
double banjo
double banjo
Ohne.jpeg (57.07 KiB) Viewed 11507 times
250GT
Posts: 968
Joined: Wed Oct 15, 2008 7:41 am
Location: germany/holland

Re: Fuel Pump(s) Reliability

Post by 250GT »

Maybe interesting this text found on Ferraricraft side.
the new overhaul mechanicapump 150 sup kits used this one-layer thick black diaphragm now.

C.

The camshaft that operates the fuel pump on V-12 Ferrari’s has very little lift, so the first thing I do is replace the rocker shaft pin and make sure there is no play on the mechanism. The solution to this problem is very simple but is a trade secret. Next I clean all the parts and send off the top cover and the hardware to be re-plated. I have tested the original check valves against ones sourced from a tractor parts supplier as well as the aluminum ones that come in many of the current rebuild kits for the FISPA pump and have found all to work well. To my knowledge, the original check valves no longer exist so I am happy to find that other styles work just fine. The issue I have found is that the replacement diaphragms are the source of the headache. The diaphragm material is a black single thick layer rather than the 3 thin layers on the red original equipment stuff and in some instances it does not seem sealed properly at the head of the operating rod. Also, they seem to make too much pressure. I realize that the regulator should reduce an over-pressure situation but the red material consistently makes less than 5 psi where I have experienced the black material making as much as 12psi! With testing the black material for leaks at pressure, I alter the return spring to get the pressure where it belongs which gives me the confidence to ship it!
DWR46
Posts: 621
Joined: Tue Sep 22, 2009 8:23 pm

Re: Fuel Pump(s) Reliability

Post by DWR46 »

Both the mechanical and electric pumps have one-way valves that keep fuel from draining back to the tank. They also keep fuel from just circulating in a circle between the mechanical and electic pumps and not filling the carbs. Usually when these cars have a fuel delivery problem, one of the valves has malfunctioned.

As to fuel pressure, Weber carbs like 3-3.5 psi. Anything over 4.5 psi is on the verge of trouble as the needle and seat design will not consistently hold against that much pressure. In our racing Ferraris, we never run over 4-4.5 psi and we use the Grose-Jet needles and seats which are much more stable under higher pressurres. Unfortunatly, the Grose-jet "ball" design tends to stick closed with today's ethanol fuels if the car sits very long and then you have to take the top cover off the carb to "free" them up to start the car. So after 25 years of running Grose-Jets in our street engines we have switched them all back to standard needles and seats.
Post Reply