Fuel pump issues

shelby racer · #1 (**permalink**) 04-06-2009, 05:24 PM

Hey gang,
I need more advice / guidance. I have always had problems with the fuel pumps with csx4788. I run them all the time because no one told me that one of the fuel lines was for a mechanical fuel pump (which made it very interesting the first time I turned the fuel pumps on and had 1 psi) and had to re-ground the front one because it would not run all the time with the ground that it had. Months ago (maybe even last fall) I was running the car and the fuel pump fuse blew. I replaced the fuse and the car fired right up but I think I had shorted one of the pumps because I discovered later that it did not work anymore. I replaced it (the front pump that had been re-grounded) with a new Facet pump and everything was happy. Last Thursday night I blew the fuel pump fuse again (which is why I wrote the forum last week) but this time, as soon as I replaced the fuse , it blew again. I have been doing diagnostics today and I get 12 - 14 v at the fuse box and at the power connections at the pumps. When I give power to only the new pump, it is happy. When I give power to the old pump (or both pumps) the fuse immediately blows. Should I just replace the old pump? Are the pumps not meant to be run all the time (even though they are sold as race pumps to be used as the sole source of fuel)? Are there any other tests to try and determine why the pump went bad / is shorting the circuit? Any help or insight is appreciated. Thanks.
John(;-)

Tim Brewer · #2 (**permalink**) 04-06-2009, 06:49 PM

I don't know what you're talking about having two pumps. You only need one pump period. Assuming you're using the correct fuse, make sure you are also using a relay, you must use a relay.

FWB · #3 (**permalink**) 04-07-2009, 07:17 AM

a fuel pump will at times draw more than 10 amps, if you have two wired into the same circuit, do the math. what amp circuit are they on? as i have no idea what kind of pumps you are running and their amperage draw or their gph rating. but to run two fuel pumps why? is it the first fuel pump is underated for the application? get a good fuel pump 140gph and that should be the only pump you need to feed most motors under 700 hp. if your lines are small then putting two pumps trying to push fuel thru small lines you could have 10 pumps but you will only get as much fuel thru a small line as the line can hold. maybe the addition of the second pump just fights the small volumn of a small line and the pump self destructs like there is an obstruction.

shelby racer · #4 (**permalink**) 04-07-2009, 08:30 AM

I am used to running a single holly hi volume pump on my other cars. Shelby (SAI) designed the system with two pumps running in series / paralel (?) on a single circuit with a 15amp fuse. To the best of my knowledge all the 4000 / 4700 were built this way.
John(;-)

Tim Brewer · #5 (**permalink**) 04-07-2009, 08:51 AM

Well I'd pull off the smaller of the two, and did you check for a relay?

shelby racer · #6 (**permalink**) 04-07-2009, 09:13 AM

They are exactly the same and are supposed to only draw 1 amp each.

CJ428CJ · #7 (**permalink**) 04-07-2009, 09:40 AM

Sounds to me like the old pump either has a short circuit or is encountering a locked rotor condition. Either one will cause the fuse to blow. You need to either replace the bad fuel pump or figure out if you can use only one pump and permanently remove the second one.

Chris

shelby racer · #8 (**permalink**) 04-07-2009, 09:43 AM

Luckily Pegasus has the right pump for about $50 less than racer parts wholesale so I will be ordering another one.

Power Surge · #9 (**permalink**) 04-07-2009, 07:51 PM

The 1 amp draw rating is not right. Should be more like 10 amps draw each.

Those Facet pumps are junk IMO. I had one in my CSX and when it started giving me trouble, Facet's customer tech help was horrible and they just wanted me to buy a new one.

As for the wiring, you should definitely have them on a relay. A standard Bosch 4/5 pin relay should be plenty for both pumps. Those pumps shouldn't draw more than 12-13 amps each. You should try to have the relay in the back of the car somewhere. Grab the main hot lead right off the battery, and use the wire from the car's harness as the trigger.

bret a ewing · #10 (**permalink**) 04-08-2009, 06:34 AM

John,

The fuel supply system on the CSX4XXX is quite similar to the original cars.

Utilizing a fuel cell with 2 pickup tubes and 2 separate fuel supply lines, one from each pickup. One pickup in the fuel cell is higher in the tank than the other.
The primary pickup is the higher of the two and is fed to the carb via the engines' mechanical fuel pump.
The secondary fuel supply is the lower pickup in the fuel cell and feeds the carb. via dual electric fuel pumps. They were Stewart Warners if I recall correctly.
The reasoning was, since there was no fuel guage on the S/C cars, you would run the car on the mechanical pump until the driver noticed the fuel pressure drop on the guage. At that time the driver would flip on the electric pumps giving him a reserve of about 3-5 gallons and head for the pits or gas station.

shelby racer · #11 (**permalink**) 04-08-2009, 08:41 AM

Quote:

Originally Posted by Power Surge

The 1 amp draw rating is not right. Should be more like 10 amps draw each.

Those Facet pumps are junk IMO. I had one in my CSX and when it started giving me trouble, Facet's customer tech help was horrible and they just wanted me to buy a new one.

As for the wiring, you should definitely have them on a relay. A standard Bosch 4/5 pin relay should be plenty for both pumps. Those pumps shouldn't draw more than 12-13 amps each. You should try to have the relay in the back of the car somewhere. Grab the main hot lead right off the battery, and use the wire from the car's harness as the trigger.

All right - sounds like a plan.

shelby racer · #12 (**permalink**) 04-08-2009, 08:45 AM

Quote:

Originally Posted by bret a ewing

John,

The fuel supply system on the CSX4XXX is quite similar to the original cars.

Utilizing a fuel cell with 2 pickup tubes and 2 separate fuel supply lines, one from each pickup. One pickup in the fuel cell is higher in the tank than the other.
The primary pickup is the higher of the two and is fed to the carb via the engines' mechanical fuel pump.
The secondary fuel supply is the lower pickup in the fuel cell and feeds the carb. via dual electric fuel pumps. They were Stewart Warners if I recall correctly.
The reasoning was, since there was no fuel guage on the S/C cars, you would run the car on the mechanical pump until the driver noticed the fuel pressure drop on the guage. At that time the driver would flip on the electric pumps giving him a reserve of about 3-5 gallons and head for the pits or gas station.

I got some tech support (NOT from SAI , but from a nor Cal SAAC member) regarding how to plumb the fuel system after the motor was in the car. I probably will put a relay in run the facets for now, but I am investigating either adding a mechanical (there is no eccentric on the cam shaft right now) or just re-plumbing the whole system with a hi volume holly

rokndad · #13 (**permalink**) 04-08-2009, 11:08 AM

Quote:

John,

The fuel supply system on the CSX4XXX is quite similar to the original cars.

Utilizing a fuel cell with 2 pickup tubes and 2 separate fuel supply lines, one from each pickup. One pickup in the fuel cell is higher in the tank than the other.
The primary pickup is the higher of the two and is fed to the carb via the engines' mechanical fuel pump.
The secondary fuel supply is the lower pickup in the fuel cell and feeds the carb. via dual electric fuel pumps. They were Stewart Warners if I recall correctly.
The reasoning was, since there was no fuel guage on the S/C cars, you would run the car on the mechanical pump until the driver noticed the fuel pressure drop on the guage. At that time the driver would flip on the electric pumps giving him a reserve of about 3-5 gallons and head for the pits or gas station.
__________________
B. Ewing

This is exactly how my car is plumbed and it works exactly as Bret described. I have an Aeromotive one-way inline valve on the "out" side of the mechanical pump with a Tee so it doesn't pressurize fuel back to the electric pumps. The "high" pickup is connected to the input on the mechanical pump and the "low" is connected to the aeromotive one way valve on the Tee at the mechanical "out" so I get the reserve effect. Never run them unless I want to pre-charge the fuel system if it has sat for a few weeks. Then turn them off and fire up with the mechanical.

Simple, reliable and it works. You must have some kind of short or a burned out pump. Sorry you seem to be having a bad time with this car.

PANAVIA · #14 (**permalink**) 04-08-2009, 11:50 PM

Ok, here is a loaded question; anyone have a wiring diagram for a CSX 4000 car >? so we could see the pumps relays etc...

--and how much alike are CSX 4000-to 4999>?

--Steve

shelby racer · #15 (**permalink**) 04-10-2009, 08:04 AM

The original 4000s were like kit cars - you got the pieces and made them fit - or had some one else do it, but they came from Las Vegas. Still not great build quality, but better than the original 4700 series built in South Africa. They were all supposed to be plumbed like the 3000 series.

A fact I have come accross in my fuel pump searches was that the older facet interupter pumps had issues with short life spam (that they supposedly - hopefully have fixed with the newer ones). I am wondering if SAI got a "great buy" on a bunch of the older ones (since my car was ordered in 11/2003 and delivered 11/2005) and I just happened to get two bad pumps??? Do I really care if they gave me a couple of bad pumps - in the short run - yes, in the long run, I really just want my car to drive and go Vroom Vroom - maybe I should have kept my miata