The V8 Owners Forum -

I bought a brand new Carter pump last week, to replace my old one, that has been starting to fail.
Its the slightly better model that should give 6-7 psi at full flow.
The reason I changed it was because the pressure on the old one was becoming erratic, and, although I have a new petrol tank, I had noticed muck in the filter. I checked the old pump and it was quite scored in the chamber. So, new pump, new filter on the inlet and I fired it up. At first it didnt want to start, so I thought Air?
Purged the line ok and she fired, but running rough and chugging. A few revs and she cleared, but my AFR meters were showing very rich at idle. Then she faded and stopped. Took ages to get her going again and after a few mins at tickover she died again. Then my mate noticed fuel dripping fron the secondary spindle and we shut her down. The carb was making gurgling noises and the inlet manifold was soaked with fuel.
I decided to fit the pressure gauge and found that the pump is developing 13psi !!!

Now, should I just fit a regulator, or should I take it back and change it?
I think I'd feel safer with a regulator, but the RS book says 6-7 psi. The Weber 500 only wants 4.5 to 6psi. I assumed an extra 1 psi wouldnt matter that much, but an extra 7psi has obviously upset the carb.

Anyone else use a Carter pump?

Hi. Thanks for the help on the rear axle problem.
I have a Red top Facet that for various reasons increased the pressure on.
The car ran fine for about 50 miles then I thought the engine was about to disintergrate. She would not run at all. After a few mins she ran OK again and got me to where we were going.
I remembered that I was recently told above 6psi the valves can get lifted on the Webber so I checked and yep it was running at 7psi. I dropped the pressure down to 5 and all was OK. I have done about 300 miles since then.
Dave

pressure is dependant on the flow, and restriction to that flow.

Its really best to use a fuel pressure regulator, that way you can be sure of what fuel pressure you are running, rather than guessing.

Cheers Stevie
It took me by surprise as the old Carter pump has been running pretty much spot on 5 psi with no reg for 3 years.
But talking to Simon at RS today, he informed me that on occasion, Carter send out the odd hi performance 12psi pump in the wrong box. It didnt seem to surprise them that this had happened. So I'll keep the pump and have just bought a reg to fit tonight.

Hows that monster of yours going mate?

mgbv8 wrote: Hows that monster of yours going mate?

Driving fine at the minute. Havent really been anywhere to race it recently.


Roll on Saturday

AARRGGHHH!!!!!

I gave up after two hours of trying to get the Holley regulator to give me stable pressure. The unit is supposed to give 4.5 to 9 psi.
No reg = 13psi
With reg, at any setting gives 5 psi max, but its not stable. I'll swap with the other reg tomorrow night and see if that works any better.

At leat my new AfR meters are working!!!

I currently don't have any regulator in my fuel supply but I want to make sure that I am getting the correct pressure to my newly fitted Edelbrock 500 - could anyone offer any advice about what make/type of regulator is most suitable?

Thanks in advance.

I swapped this one with the new one for my other fuel system and its fine.
5psi and stable.
I fitted the twitchy one to the Nos fuel system on the Holley pump and it settled down straight away to 6 psi.
They are Holley regulators from Real Steel at around 20 quid and they seem ok to me.
If you are going to fit a regulator, you should think about a gauge as well, just to know whats itsa doing.
The holley ones seem to be set to 6-7 psi out of the box.

I have a Filter King running from a Red Top Facet pump.
The pressure is adjustable but not very linear. No adjustment then suddenly it drops 2-3 psi.
I have had trouble with over pressure (7psi) so I am running at about 4psi at the moment.
I would definitely agree that a gauge is needed, you can see if the pressure drops with load etc.
Dave

Gauges should only really be used for setting up, and then removed, A friend of mine left a gauge inn his regulator for a year or so, Stopped at a set of traffic lights, someone pointed out he was leaking water, pulled over to have a look, It turned out to be fuel, coming out of the gauge,
Gauge mechanisms generally work by pressure [fuel in this case] expanding a wound copper tube that offhand operates a small lever or rack to move the needle in the gauge, the tube is only a few thou thick, and this is what split, dumping fuel over his engine, it was never determined if it was vibration or work fatigue that split the tube, but speaking to a old retired instrument maker I know, he was surprised that the gauge had been left in situ, the suggestion I have is if you want to leave a pressure gauge in position, get a Glycerine or oil filled gauge, they are less prone to failure due to the damping effects of the fluid around the coil, I seem to remember in the bumph with a regulator I fitted for someone, it stated quite clearly the gauge should be used for setting up only and then removed, [filter king, I think]

Ian

Your quite correct Ian.
Filter King recommend the gauge is only used for setting up.
Dave

Thanks guys, that's very helpful.

I'll hae a browse around the usual suspects & see what I can find!

ian.stewart wrote:Gauges should only really be used for setting up, and then removed, A friend of mine left a gauge inn his regulator for a year or so, Stopped at a set of traffic lights, someone pointed out he was leaking water, pulled over to have a look, It turned out to be fuel, coming out of the gauge,
Gauge mechanisms generally work by pressure [fuel in this case] expanding a wound copper tube that offhand operates a small lever or rack to move the needle in the gauge, the tube is only a few thou thick, and this is what split, dumping fuel over his engine, it was never determined if it was vibration or work fatigue that split the tube, but speaking to a old retired instrument maker I know, he was surprised that the gauge had been left in situ, the suggestion I have is if you want to leave a pressure gauge in position, get a Glycerine or oil filled gauge, they are less prone to failure due to the damping effects of the fluid around the coil, I seem to remember in the bumph with a regulator I fitted for someone, it stated quite clearly the gauge should be used for setting up only and then removed, [filter king, I think]

Ian

I bought a cheapie Ebay gauge to check my fuel pressure, but it flickered constantly in time with the pump pulses, so I guessed it would disintegrate in time and removed it.

The copper tube is called the Bourdon tube, and as you say it is pretty skinny and will fail through metal fatigue in time. We have gauges at work that read to 15,000 psi, with a realy heavy stainless Bourdon tube.

Most decent quality gauges can be filled with glycerine to stop then flickering, which gives a kore accurate reading.

You can also get a 'remote gauge' device that transfers the fuel pressure into a non flammable medium so you can out the fuel pressure gauge inside the car without the risk of torching yourself if it does crack up. I'd guess that is only for the serious racer types though.