Fuel Pressure Regulator Question...

[engine24355]

Well, I have ruled out the filter possibility now as I am still getting the same pressure with just a straight line. So, at this point, it has to be the pump or the wiring. I have ordered a new pump etc. so we will see when the new pump comes in. Until then, it is time for a break...LOL.

 

[Lee_in_KC]

You can owe me that beer.

Well bud, I'll still buy you a brewskie or three, but I don't owe you one. Hollley actually recommends a filter between the tank and pump. They don't specify what type though, so maybe I owe you a root beer. Tell you what. Meet me at the ice cream shoppe in Calico Rock and I'll but you a root beer float. Oh wait... you won't be in Calico Rock this weekend like the rest of us... too bad, so sad.

(Sorry Milke, I know you would be there if you could. We'll hoist one or seven* in your honor.)

*...this is real beers, not root beers. Who can drink seven root beers?

 

[Screaming Metal]

Hey Lee....did you get your fuel situation straightened out??????? Been a 1/4 milin'..........ya'll know how it is.............

 

[engine24355]

Well, I have changed fuel pumps, filters, lines, and I am still getting only 4 lbs of pressure. I am going to try a different gauge tomorrow, but it still seems like the engine is not getting enough fuel as it keeps wanting to die on me. One of these days I will get this figured out, but for now, I am still "stalled out".

 

[GT63]

What size fuel line runs from the tank to the pump and from the pump to the carbs?

 

[Screaming Metal]

OK Engine.....first.....pull your pump and regulator out of the system........now you got gas lines over the car minus these parts. Yes.....drain your tank first......look at it so you can determine if its clean.

Now, blow out from the engine side to the tank side, listening......you should have good flow, if not.....look at your fittings......after these things are machined and put together......sometimes you got a ton of restriction. Now do the same thing from the carb toward the pump and regulator. You should have good flow, remember.....the fuel isn't gonna flow as well as the air.

Keep the line as straight as possible with as little as far as bends......but before you start assemblying things together on your car.......go to your workbench, plumb up a small tank of somefind......a extra lawnmower fuel tank works great for this...............a short piece of line.............plumb up your pump, regulator and gauge and a plug there the carb goes........this way you can check your setup before you install it all.

Now, you should have good pressure at the workbench, check and make sure the regulator works, run it up and down...........watch your guage. I always keep extra guages.....sometimes they will go south on ya.........

With everything set at the workbench to 6 PSI......start transfering it back to your freshly cleaned out fuel lines.......put a fuel filter ahead of your pump. Get a good quality canister type.....like a holley or fram. I run Fram personally on my own stuff.
Always remember this....if a pump will get to 20 or 30 PSI on the pressure side.....its gotta suck that hard to get the pressure there......it won't and can't pump in a vaccuum..............

Now....you know you were pumping 6 PSI at the bench........with everything working.......transfering it to the car.........you'll NOW have to crank your regular UP because of the restriction in the elbows and bends.........crank her up, let her idle for about 10 to 15 minutes, checking for leaks..............take her for a spin and hop on it hard a few times.......you should never get below 5 PSI.................

Last but not least......pay attention to your flow arrows.....these can mess you up if you put a regulator on backwards, or a filter.....but keep an eye on your fitting openings......sometimes a 3/8 fitting will get below 5/16 of a inch in a 90 degree elbow.......the cheap ones will almost go down to 1/4 inch!!!!!!!

I have several workbench systems setup for testing fuelpumps.....blowers..... and valve seats, etc....

Hope this helps.....just take your time and pay attention to your details......you should get it worked out in a afternoon.....................................happy cruzin'!

 

[Wild Mango]

If you put a filter upstream of the pump make it a low restriction one. Majority of fuel pumps blow a lot better than they suck - a small restriction on the input can have a large effect on the delivery.
Screamin' has good advice. I would add a flow test to make sure the pump is actually delivering the goods - all you need is a stopwatch and a graduated container. As I said earlier, pressure and flow are not necessarily related - if your system is restrictive you will get pressure but not flow, which is why doing a flow test is a good idea.
Say your carb is rated for 6psi, valve the delivery until it just manages 6psi and then measure the flow. That tells the whole story.

 

[engine24355]

Thanks for the advice guys, I really apprecate it. I do not have to tell you that I am really frustrated and baffled by this, but trying not to let it get to me. Since I was having no luck with the regulator I took that setup off and have replaced it with just a fuel line from the carb to a gauge port, then to the filter (after pump), then to the hard line that runs along the frame to the pump (new carter 8 lb). Before the pump, I replaced the filter with an Earls mesh 85 microns filter. After all of this I am still getting the same pressure. So, my plan of attack now is to get another pressure gauge and see if I get anything different. Then, based on what that does, I will start checking all lines and fittings (again) for ristrictions. Stay tuned...

 

[GrumpyOldMan]

The Holley 670 CFM Four Barrel has a Built-in inlet fuel filter,
So maybe when you have everything hooked up without the regulator it
might have enough pressure but the screen type filters in the carb are plugged.

Or you can try these sites from Carter.

Correctly Diagnosing a Low Pressure,Low Volume or No-Fuel Problem:

Carter Fuel Delivery

Carter Installation Instructionsfor both in tank and universal pumps)

http://www.carterfueldelivery.com/fuelpumps/_pdfs/training/InTank_Elec_FP_Inst.pdf

I hope this helps you.

 

[Screaming Metal]

If you put a filter upstream of the pump make it a low restriction one. Majority of fuel pumps blow a lot better than they suck - a small restriction on the input can have a large effect on the delivery.
Screamin' has good advice. I would add a flow test to make sure the pump is actually delivering the goods - all you need is a stopwatch and a graduated container. As I said earlier, pressure and flow are not necessarily related - if your system is restrictive you will get pressure but not flow, which is why doing a flow test is a good idea.
Say your carb is rated for 6psi, valve the delivery until it just manages 6psi and then measure the flow. That tells the whole story.

Mango.....YOU DA MAN!!!!!!..........what he said..................let me say this.....sucking or blowing the wrong way with 11+ psi of fuel pressure will shred a cheap paper fuel filter.......keep your eyes on the details....................

 

[engine24355]

Thanks again for all of the help and advice guys. At this point, I have addressed every part of the fuel delivery system with the exception of wiring (checked all wires and connections, but not voltage). I put a different pressure gauge on the system and I am still getting 4.5 lbs (same as before). Last night I took everything out down to the new pump and ran a pressure check coming straight out of the pump...4.5 lbs. So that tells me the issue must be somewhere between the tank and pump. As Screamin suggested I looked over the fittings and the ones on the pump seem a little small. There is a 45 on the inlet side of the pump and a straight on the outlet side. Both pump fittings are 11/16 #6 fittings. However, the actual opening does look small. So, my plan now is to replace the fittings on the pump with the hose barb ones that came with the pump to see if that frees up anything. However, even if it does, can you get a less restrictive #6 fitting? If this does not work I am not sure what I am going to do. Should I try bigger lines...running 3/8 now with small section of hard line on the frame. Another thought is that the fuel tank fitting (bottom 90 fitting). I may need to go to a 45 or straight. I have always read that you should never use more than a 45 angle throughout the whole fuel line system. Sorry guys, I am just reaching at this point as I am running out of things to try quick. It would be my luck that it would come down to a few fittings after all the new parts I have bought recently. We will see. Stay tuned...may have a slightly used parts sale soon...LOL.

Thanks!

 

[Screaming Metal]

Hey Engine.....try this.....bleeding air from the line andsee if your pressure comes up.......yes.......go with less restrictive fittings. Usually when you mix types of lines.....you usually get into this.....whateve I start with at the tank is what I finish with at the carb.........whether its braided with AN fittings or solid hard line.

If you bleed the air and still under 5 PSI.....return it or try another pump from Carter....they used to have great pumps///I'd hate to stop using them, too!!!!! Try a known hi pressure pump in its place, borrow one from a friend or a club member......and see what your pressure is at the carb......this will give you a baseline to shoot for.

You can then go to the parts store and say.....I did this and that.....now give me a pump that works!!!!! Ha! :evil:

 

[engine24355]

Well, I have ruled out the restrictive fitting theory as I am still getting the same result. I currently have the Carter 8 lb pump which should be enough, but maybe not. I guess I will pick up a holley blue and see if that gives me any different result. If so, then I can keep the holley (remount etc) or return and try a bigger Carter (already have wiring and mount for Carter). The other thought is voltage (as has been suggested). I have ruled this out before, but I guess I need to check with a meter to be sure as I just cannot imagine why an 8 lb pump would not give at lease 5 lbs of pressure. This has really been a learning experience...LOL. Thanks for all of your patience with my stupidity.

 

[Screaming Metal]

Well, I have ruled out the restrictive fitting theory as I am still getting the same result. I currently have the Carter 8 lb pump which should be enough, but maybe not. I guess I will pick up a holley blue and see if that gives me any different result. If so, then I can keep the holley (remount etc) or return and try a bigger Carter (already have wiring and mount for Carter). The other thought is voltage (as has been suggested). I have ruled this out before, but I guess I need to check with a meter to be sure as I just cannot imagine why an 8 lb pump would not give at lease 5 lbs of pressure. This has really been a learning experience...LOL. Thanks for all of your patience with my stupidity.

Hey Engine.....you are by no means stupid.......alot of the time....its just a area outside your expertise......yes....there's a learning curve.....but you've got a lot of backup here..............keep shooting us info.....we'll get it eventually.........

Alot of the time we could possible arrive at a quicker diagnosis if we were there in person, seeing what was happening........hey.....but thats the way you learn though.............

The 8lb. pump SHOULD put out more pressure..........but even with a 8 to 10 lb pump......it still needed to be regulated......cause more than about 4 to 6 psi......you seats are made just to shout off fuel flow.....not to hold any kind of pressure.
And you need that pressure to feed a healthy engine.......or you suck your fuel lines dry.

Try feeding a 600 cu.in. blown motor with fuel injectors and the smallest opening inside yourfittings is gotta be 3/8 of a inch.......or you risk starvation on all out launches....but we use pumps driven drirectley off the engine in the old days.....now we have electric ones that can be controlled by computers.................

Hang in there......it'll get better.......:razz:

 

[GT63]

I don't know if this has been asked or not , but is your tank vented? Is it possible that the pump can't draw the fuel from tank due a vacuum condition going on in the tank?

 

[engine24355]

I don't know if this has been asked or not , but is your tank vented? Is it possible that the pump can't draw the fuel from tank due a vacuum condition going on in the tank?

GT63 -

The tank is a fuel cell type with the aircraft style filler (see below). I thought of putting a vent in at one point, but was advised that it was not needed with this filler. Should I try to leave the cap off and see what pressure I get?

 

[Screaming Metal]

Hey.....GT might be onto something......see if it is......it might be but maybe its still capped off.............

If your engine is making 350 horses or less...............you should be OK with 4 to 6 PSI at the carb........BUT a 8 PSI pump ought to hit 7PSI with 12 volts feeding the motor and no blockage in the pump or the inlet feed.

Have you had the feed lines on the car while fab'ing up???????? Look to be sure you might not have smaked a line and pinched it off..........on the pressure side you'd just build pressure to the blockage......but on the suction side.....would cause low pressure...........if you put the Holley blue pump on and got low pressure................we'll have to call for a exorcism!!!!!!!!

 

[engine24355]

I have taken all lines off and either replaced or cleaned out (hard line). I have a multimeter now so I will run some voltage tests this evening. Also, I will try it with the fuel filler cap off. Stay tuned...

 

[Screaming Metal]

Hey Engine.....have you had any luck yet??????????????????????

 

[engine24355]

[quote name='Screamin' Metal']Hey Engine.....have you had any luck yet??????????????????????[/quote]


Thanks for asking Screamin. I just got in from another bout with the pressure gremlin and it is still beating me...UGH. I checked the voltage to the pump and it shows to be almost 12 volts. I checked the battery and then the pump and the volts look good. What other way should I check the voltage? I have checked through the wiring and cannot find anything that would cause an issue so it seems like something mechanical. I have ordered some new fittings to try and also a pump relay as I need to make these improvements anyway so we will see if these make a difference. I need to try the bench top set up still.