PapaSmurf Posted May 28, 2010 Share Posted May 28, 2010 Hey guys, I just got my f54 block installed in my 78. I discovered a show stopping issue with my e88 head so I had to refresh the p79 and use it. The problem is the p79 has no place for the mechanical fuel pump I've been using all these years with my SUs. So I purchased a cheapo Mr.Gasket 4-7psi fuel pump knowing that these carbs really don't need much pressure. The problem with the pump is that the left/front carb overflows out the float chamber outlet at less than 1100rpms. The right/rear carb does not exhibit this problem, my guess is that the front carb gets the fuel first or there is an imbalance somewhere to that effect. So my thoughts are there must be too much fuel pressure. I went down to shucks looking for an oem fuel pressure regulator and the only one they had regulated it down between 1-5psi and had no bypass, it was also plastic and drastically low quality. So I'm doing research and trying to find the fuel pressure regulator I need. I was thinking something like the holley 12-803bp Any suggestions? I want to know what you guys are using for this application. One further question, should the ports on top of the float chambers be connected to the vent line? It doesn't seem right to leave them open. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 28, 2010 Share Posted May 28, 2010 The floats are being overwhelmed by the pressure above 3 psi which is why they are spitting out the vents. They need to be open to atmospheric pressure so don't connect them to the vent line. They were plumbed to the air filter by the factory in order to capture the vapors and have the engine burn them. I went through the same issue of trying to regulate to 3 psi when I was running SUs. The problem I found with this regulator is that it really wants a larger input pressure. It did not maintain a consistent pressure with a relatively low input pressure. I hate to say it, but I think you should be looking for a 2-3 psi electric fuel pump. I'm afraid I don't have any part numbers to suggest, although I know there are many who like the early RX7 carb'd pumps which don't need any regulator and are supposed to be very quiet too (in case that matters to you). I know that Facet (or is it Faucet?) makes a cheap pump with 2-3 psi output, but it's pretty noisy. That's what I ran until I switched to Megasquirt. It was shaped like a cube I think, about 2" x 2" x 2"? I'll bet you could find one of these at Autozone or O'Reilly's for about $25 as generic replacement. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 28, 2010 Share Posted May 28, 2010 The Facet pump I had was one of these two but I don't remember which one: http://www.pegasusautoracing.com/productdetails.asp?RecID=82 http://www.pegasusautoracing.com/productdetails.asp?RecID=83 Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 aww, I just spent an hour under the car getting this mr.gasket pump installed, I don't have the packaging anymore and I doubt they would take it back anyways. It was sitting for a while so there are spiders and I am not good with spiders in tight quarters. So the holley regulator I was thinking about is not going to work well enough with this lower pressure pump? What would the symptoms be? I'd like to go megasquirt too one of these days but with a custom intake manifold - too much money and time for now though. I do have an early rx-7 sitting in the field so I could use it's pump. The problem is my wife would be mad at me because I'm supposed to be fixing that car up for her. I hate that thing, it needs new apex seals, the wiring has been eaten by mice I'm sure and the interior is red with leopard trim - seriously. I just don't want to battle the 8 legged menace when I already have a new fuel pump plumbed and wired in. I'd rather get a regulator, that way when I go to replace this pump eventually for more demanding mods I can just adjust the pressure. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 28, 2010 Share Posted May 28, 2010 I can relate to your frustration - been there (and likely will be again too). The issue I had was that the output pressure wasn't consistent from minute to minute. I figured there was a reason why there are $300 adjustable regulators. Or maybe I just had a bad unit? Perhaps someone else can chime in with another suggestion. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 Thanks zmanco, hopefully I can get a few more suggestions. I'd like to know all my options before I commit to anything in particular. I got my Z running well enough to take it around the block. It's amazing how much more juice this engine has over my previous one. I found myself accidentally peeling out between shifts! It's running very rich and still leaking fuel at low rpms but I solved some of the overheating issues. Amazingly no leaks of any kind are showing up. So now this fuel pressure issue is the only thing keeping me from driving it Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 zmanco with that holley fuel regulator what pump were you using? Were you using the stock pump? I wonder if this pumps relatively lower pressure might negate the inconsistencies you were having. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 (edited) I've been reading around the interwebs and I've come across many examples of these Holley regulators giving inconsistent pressure. So it would seem like it's not just you. I still wonder how they would behave with a lower pressure pump, Does anyone have any suggestions for an alternative fuel pressure regulator? Maybe I should just buy an inline fuel pressure gauge and solder up a potentiometer to the mr.gasket fuel pump and just dial down the voltage a bit until the pressure is where I want it. Any opinions there? Edited May 28, 2010 by PapaSmurf Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 28, 2010 Share Posted May 28, 2010 The Holley regulator came as part of a package deal with a Holley Blue fuel pump IIRC. I just looked at the spec on the link you posted and it's only rated to go as low as 4 psi. The issue as I remember it is that the regulator adjusts by loosening a screw that applies pressure to a spring that in turn applies pressure to the regulator mechanism. The lower the spring pressure the lower the fuel pressure. The problem was that the screw was about to fall out at its lowest pressure setting and I suspect the poor machining of the parts resulting in stiction and other inconsistent movements. In any event, as I said earlier, I suspect that's why there are $300 regulators. Of course you can try it with the mr. gasket pump and see, but I'm doubtful it will work well. I really think you need to find a low pressure high volume pump like the Facet or RX7. It's an interesting idea to drop the voltage to the mr. gasket pump, but I doubt you have a potentiometer that can handle the current required. You could try some wirewound resistors, but unless you already have them, I wonder if you wouldn't be better off just getting another pump. BTW, you might try looking for a low cost generic that's spec'd for the early RX7. Perhaps something else will show up? Good luck! Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 (edited) I'm going to try the potentiometer today, the current demands are actually very low. According to the information that comes with it the mr.gasket pump only pulls 1 amp at load which means 12-14 watts depending on if the alternator is running or not. amps x voltage = wattage, that is a fairly low requirement I'm pretty sure I can find something to suit it. Just so long as my flow remains good enough this might work. *edit* Sorry a rheostat is what I'll be using. With the resistance I'm looking at and the wattage requirements it will be dissipating up to 1.5 watts as heat fully restricted which is more than most pots can handle. I don't want the device controlling my fuel pump melting and catching fire in the hatch. Edited May 28, 2010 by PapaSmurf Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 Interesting, my local radioshack took out their components section. It used to be radioshack carried every tidbit in their catalog, then a few years ago they just switched to having a few drawers full of stuff, now they have nothing. I purchased the made in china Mr.gasket 1-5psi cheapo regulator for 30 freakin bucks because there are no other options in town. I still want to find a decent regulator though because I don't like the idea of leaving this thing installed more than a few months. If it goes out it will leak fuel all over my alternator and probably kill my fuel pump. Since I don't like the idea of an engine fire I would still love some recommendations for a decent fuel pressure regulator. On the mr.gasket regulator: The car is running great now! It idles at 700rpms with no issues, no fuel leaking out the float chambers anymore. Now I can get the carbs tuned and hit it with the timing light. I also have to give the valve clearance one more pass and maybe add a push fan to keep her from getting too warm. I had to shave a little bit off my clutch fan for it to clear the 3 belt crank pulley that came on this f54 block. I tried getting the pulley off and replacing it with my 2 belt pulley but I broke two pullers trying to get it off! The fan is not vibrating, I actually think I did a rather good job evenly trimming the blades, but I know it's not pulling as much air now so I have to watch the temps. I'm still looking for recommendations on a permanent fix to the fuel pressure regulation. The Mr.Gasket regulator was an expensive bandaid that will allow me to do some tuning and wheel it around a few miles. I just don't trust it. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 I had another thought that might allow the continued use of this mr.gasket regulator. What about a blow off valve in front of the regulator that dumps into the return line when pressure exceeds a certain level? I've never seen such a thing but I'm sure one exists, somewhere. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 28, 2010 Share Posted May 28, 2010 Glad you got it up and running. I'm not home this week so can't look under the car to be sure, but I searched for a fuel pump for an '80 RX-7 at O'Reilly and got this: http://www.oreillyauto.com/site/c/detail/ATN0/E8016S.oap?year=1980&make=Mazda&model=RX-7&vi=1192238&keyword=fuel+pump&pt=C0401&ppt=C0025 I'm pretty sure that's what I have on my car now feeding the surge tank. It's quiet, been bullet proof reliable for a few years now, and can feed enough fuel to keep the engine happy, even now that I have the turbo. I ran this pump without a regulator feeding SUs as well as triple webers and never had a pressure problem. I'm sure you're not looking forward to changing the pump again, but... Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 Glad you got it up and running. I'm not home this week so can't look under the car to be sure, but I searched for a fuel pump for an '80 RX-7 at O'Reilly and got this: http://www.oreillyauto.com/site/c/detail/ATN0/E8016S.oap?year=1980&make=Mazda&model=RX-7&vi=1192238&keyword=fuel+pump&pt=C0401&ppt=C0025 I'm pretty sure that's what I have on my car now feeding the surge tank. It's quiet, been bullet proof reliable for a few years now, and can feed enough fuel to keep the engine happy, even now that I have the turbo. I ran this pump without a regulator feeding SUs as well as triple webers and never had a pressure problem. I'm sure you're not looking forward to changing the pump again, but... Not bad for $66.99 Figuring the cost of the pump around $50 and the cost of the regulator at $31 I'm in this $81. So next time I get some pocket money I'll pick one up. For now I can take her down the freeway (after I get some tabs) and blow the spiders off. Thanks zmanco! One last question: I have an 85 rx-7 is it the same pump? I'm thinking of taking it from that. Then I can just stick the mr.gasket mess on the rx-7 and let it deal with the pain. I don't care if THAT car catches fire! Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted May 28, 2010 Author Share Posted May 28, 2010 (edited) I'm trying to tidy up some of the loose connections, On the alternator one of the sense connections goes to the positive and the other is just hanging, near it the only wire in the harness that is homeless is a blue one and when I connect it to sense all of a sudden my charge light comes on with power on (It didn't before) and the fuel pump turns on only for a second and then off again until cranking which is what it's supposed to do - I wasn't sure if it would behave this way because I have a push button set up. So it seems that wire is where it goes however I'm getting 15-16v with it plugged in and 13-14 with it not plugged in. Seems like it's not doing a good job of sensing... Oh well that's what fuses are for - I'm excited the pump is now behaving properly priming and shutting off with power on. *edit now it's not priming and shutting off properly. It runs constant with the power on. I need a new wiring harness. I got my headlights to work on dim for the first time ever, then they stopped working too. Ghosts in the machine... Edited May 29, 2010 by PapaSmurf Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 4, 2013 Author Share Posted July 4, 2013 I'm ressurecting this topic again to report on the longevity of the mr.Gasket fuel regulator I used. Shortly after my last post on this thread I started having head sealing issues and I tore the engine out and started a rebuild. Well now it's been 3 years and the car went on her first drive with the newly rebuilt engine the other night and once again I have a fuel problem. Fuel is spitting out the float bowl on the rear carb and out of the filter. So it seems the Mr.Gasket regulator did some rotting while it sat and now my fuel pressure is too high. I've got a new float valve on the way too just in case this one was blown out as it seems to have been. The moral of the story is cheap parts should not be in charge of protecting expensive parts it just doesn't work out. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 13, 2013 Author Share Posted July 13, 2013 (edited) Well fark I'm losing this battle. With the holley regulator holding a steady 3psi and a brand new float valve the carb is still leaking out the float chamber. The float is not sinking and is adjusted. I'm at a loss. I blew through the return line to check for blockage and it was not easy and it seemed to just pressurize the tank as though its not venting. After blowing fuel spewed out so I guess its not clogged. I popped off the gas cap and It didn't make any difference. Edited July 13, 2013 by PapaSmurf Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 13, 2013 Author Share Posted July 13, 2013 I think it isn't venting properly or the system was just designed for the return pressure from fuel injection and the carbs flow before the return line does... It doesn't leak when the engine is running at least but it makes me nervous. With the ignition on the fuel pump runs constantly and does not shut off like it should I think I need to deal with electrical gremlins soon Quote Link to comment Share on other sites More sharing options...
xtreme_240z Posted July 13, 2013 Share Posted July 13, 2013 I had issue with fuel coming out the bowl after i turned the car off, maybe 5-10 min after. I also run and inline fuel pump and im regulated to about 3psi when the car is warm but im using a by pass regulator. Now to fix the problem im still getting i seen someone on here post to put a kill switch and turn off the fuel pump beafor you get to your desired location. i have not had any issue with fuel coming out of bowls since i put the switch. Quote Link to comment Share on other sites More sharing options...
PapaSmurf Posted July 13, 2013 Author Share Posted July 13, 2013 Makes me want to swap heads and use a mechanical pump or get off my ass and get started with megasquirt and a return to efi but that would mean a new fuel tank. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.