Mikelly Posted April 20, 2000 Share Posted April 20, 2000 .....Took the afternoon off yesterday and spent $75 on some aluminum line, fittings, braded line, more fittings... and decided to modify the Mallory Comp140 pump per their instructions, and re-plumb my return style regulator with 1/2inch return line. I got everything nice and tidy and it all looks real professional. Now the pump will not prime. I let the thing run, over a period of 4 hours, cycling it off when it got warm to the touch... moved the lines around, raised and lowered the car... I have no idea why the pump was working before, and now isn't... any ideas or suggestions? I'm real close to replacing the pump... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 20, 2000 Share Posted April 20, 2000 Are you sure the return line is OK? I'm not really familier with your components but if you didn't screw around with the pickup line and just messed with the return you could have a kink or something that is causing a pressure buildup on the return not allowing the fuel to go into the pickup. I really have no idea what I'm talking about and I'm sure you have already considered this... SpencZ Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 20, 2000 Share Posted April 20, 2000 I also have no idea what your plumbing looks like , but from a physical standpoint it sounds like you have an "airlock" situation on the outlet side of your pump or regulator. Have you tested your filler cap? Faulty cap could explain your pressure inconsistency. Just kickin ideas around, but I know you must be getting frustraited by now. Hope you get her back soon. Tony P.S. It aint got no gas in it...I reckon. Carl(slingblade)Childers ummm hummm!!! ------------------ 74 260, early 350,K.B.pistons,edelbrock manifold,carb,and cam,202 cast iron heads.Let the transformation begin. [This message has been edited by takman57 (edited April 20, 2000).] Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 20, 2000 Author Share Posted April 20, 2000 I have no sharp bends, all nice transitions, and no cheesy T fittings. ALL AN and braded line. I double checked all the lines to make sure... even ran compressed air back through the lines after disconnecting them form the regulator and the pump.... I'm gonna unbolt the pump and lower it to below the tank this evening and see if that helps. Then I'll have to suspect the pump is bad. Something is strang and I'm clueless... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 21, 2000 Author Share Posted April 21, 2000 I FINALLY fixed the problem with the fuel... Seems that the pump won't prime unless you loosen the outlet fitting to let the pump cavetate... crazy. I also simplified the system going to the rear of the tank, losing the cool cut-off valve, but getting the pump back to an exhaust friendly location. I also only used two 90 degree fittings this time, as I also believe they contributed to fluxuation in pressure. I now have a pressure gauge at the regulator and the fuel log.... Had both, might as well use them, right? Now I can send the BG regulator and Autometer pressure gauge back to Jegs....$150 back in my pocket... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
MYRON Posted April 21, 2000 Share Posted April 21, 2000 Mike, I have a Holly Blue and regulator they come as a set for 84.99 out of Summit. I have all 1/2 line from the tank to the regulator then #6 an to the carb. See pics in members rides. I have a hp4150 custom carb 750body/850base. I am running 7.5psi and the pump works like a champ. I had a mallory gp40 that would not suck fuel out of a coffee can from 6 inches away! I have a budy that has ONE these holly's running a 603 hp and a 150 shot of the gas and he doesnt have any problems... Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted April 21, 2000 Share Posted April 21, 2000 Is your pump mounted low and near the tank? Electric fuel pumps push fuel well, but do not pull. Pressure losses between the pump and tank should be minimumized for the pump to work properly. Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted April 21, 2000 Share Posted April 21, 2000 I just realized you have a fuel log.Is it the style that your return runs off the log?If so your problem may be in your log.Aren,t they adjustable?Also have you tryed the new pump with the new regulator,or did you already send it back?I don,t know for sure,but I don,t think you need a return line with a holley blue pump. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 22, 2000 Author Share Posted April 22, 2000 Well I spoke way to soon. Took the day off today and drove the car to my local hot rod shop... Between my house and the shop I lost 4PSI of presure. I went ahead and bought the Holly Blue pump and installed it and changed my plugs (What plug are you guys running??? I'm running accel 416s and the are pricey!). After changing the pump out I figured I would let her run up to temp and then adjust the regulator... Same problem... System gradually drops off. I went from 7.5 down to 5.5 in 3 minutes. Why in gods name won't this system hold presure???? I'm beat. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
MYRON Posted April 22, 2000 Share Posted April 22, 2000 I cant remember what your set up is like.. Do you have a fuel cell or a stock tank? If it is stock, maybe you have some blockage in the tank. you are not trying to get fuel for the v8 throught the factory lines are you? Maybe you are experiencing vapor lock. You dont have your lines too close to any exhaust? where is your pump located. What about your floats sticking open? Is the pump sucking air from somewhere? Did your fuel line get damaged from driving or maybe a floorjack slipping and crushing the line? Last i can think of is the pump sucking your fuel line closed on the inlet side?...I have seen this happen on a cooling system but never on a fuel system but you never know... just a few ideas Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 22, 2000 Author Share Posted April 22, 2000 Here is the setup...RCI fuel cell, #8AN and 1/2 inch line all the way up from the cell to the engine bay and then back to the return. The pump is only about 8 inches from the sump the cell. The log I have is just the BG long style fuel ports to #8AN fittings and line that run just in a line. no adjuster. The return is on the fuel presure regulator. I haven't sent the BG regulator back yet, as I'm still troubleshooting. I have a Vent rollover valve in the cell, so I don't think I have a vaporlock issue. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted April 23, 2000 Share Posted April 23, 2000 I allways thought that a return is needed if your runing a fuel pump that requires one?I,d try the new pump(I don,t think it requires a return)with the new regulator,and no return. Quote Link to comment Share on other sites More sharing options...
John Scott Posted April 23, 2000 Share Posted April 23, 2000 Could it be your cell isn't venting? If it starts out at a good pressure than falls, maybe its creating a vacuum in the tank. If you were to open the filler and it came back up... Just throwing ideas out here. Good luck. John Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 23, 2000 Share Posted April 23, 2000 At this posint I would agree with the non-venting tank scenario. Is that rollover valve in your tank an inline unit? If it is could it be installed backwards? I'm trying to think how a valve like that would work because you really need flow both in and out of the tank. Have you already pressurized your tank to see how if vents? Hang in there dude....it is just a matter of time before everything that can go wrong does..then you are home free!! SpencZ Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 23, 2000 Author Share Posted April 23, 2000 The last three posts are excellent ideas... I'll give them all a try later today, or maybe later this week. I'm gonna resolve the starter issue 1st. Taking it back to the guys I bought it off of... Gonna exchange it just 'cuz... it got hot enough to smoke.. It still cranks, but over half the life is gone I'm sure. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted April 23, 2000 Share Posted April 23, 2000 Glad to hear that there wasn,t any damage done to any wireing. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 24, 2000 Author Share Posted April 24, 2000 Well I checked the venting of the roll over valve, and it was blocked by insulation under the rear deck. I had bolted the fuel cell up as close to the deck as possible. Thankfully I left enough threadall to lower the cell 1/2 inch. However, after wiring in the new pump, new regulator, and lower the cell to allow the cell to vent properly, the presure is still dropping rapidly. Within 10 minutes of warmup the psi drops from 7 down to 5.5! I guess I'm gonna have to drop all the lines from the tank forward and runs some compressed air through them all. I must have an obstruction in the line somewhere. Starter is still dragging, even with the Hotshot out of the system. I'm gonna exchange this starter since it got so hot. Thankfully I have a 1year replacement on it. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 24, 2000 Author Share Posted April 24, 2000 Well I now have another area to check on the fuel pump presure drop issue.... Voltage and amperage... I have a 14 guage wire running the pump thru the 30 amp switch on the roll cage... Might be dropping voltage at the pump over time... Now for the kicker.. If this is the case, I am not gonna be able to return the blue fuel pump and regulator I just bought at my local speed shop. People ask why I shop mail order... Jegs and Summit have 100% return policies.. I'm whining I know, but it would have been nice to recoup the $100 spent on a part I now probably won't need... Anyway, I'll be checking voltage readings tonight at the pump and the switch... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
pparaska Posted April 24, 2000 Share Posted April 24, 2000 Mike, I was going to use the stock fuel pump wiring, but after talking to Jim Biondo and hearing about his problems with high speed power loss, I'm convinced I'll wire it separately, using a direct type connection (fused of course) from the relocated battery, using JTR's method of an oil pressure safety switch and a key "on" powered circuit, in parallel with a "start" powered circuit to run a relay back near the pump. The power for the fuel pump will go through the contacts on the relay from the rear mount battery, with a good sized groung back to the battery. That stock wiring is long, and I think, 16 gage at best. FYI, here is a table of resistances per length (ohms/meter) for different AWG gage wires: 14 gage: 0.0083 ohms/meter 12 gage: 0.0052 10 gage: 0.0033 8 gage: 0.0021 6 gage: 0.0013 4 gage: 0.0008 2 gage: 0.00051 1 gage: 0.00041 0 gage: 0.00032 (I think this is 1/0 gage) 00 gage: 0.00026 (2/0?) 000 gage: 0.00020 (3/0?) 0000 gage:0.00016 (4/0?) V=IR So, for a 1 meter total circuit length with 14 gage, and an assumed 30 amp load (mostly the pump, a bit of the wire resistance), you get a 0.25 volt drop. That's a pretty short length for a circuit. For 3 meters, it would be 3 times the voltage drop (roughly), or .75 volts. Not alot, but what if the pump output decreases greatly for that amount of voltage drop to it? Maybe rewire with #10 gage just to be safe? Oh yeah, Jim talked about his switch possibly having some kind of internal vibration issue and the current carrying capacity going down because of it. He got this info on the advice of some race car builder who had seen the cheaper switches do just that. He hasn't had the car out yet to see if th switch fix did anything for him yet. I think you might be barking up the right tree on the pump voltage issue. How much current does it draw when the car is idling and the pressure is going down? Regards, Pete Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 25, 2000 Author Share Posted April 25, 2000 Pete, Per JTR I'm running the Oil presure switch. But I need to get a relay for the fuel pump. What do you recommend? I'm gonna dig thru the JTR manual tonight, pick up some 10 Guage wire and rewire the whole system after I get the voltage numbers off the switch and pump. Anyone need to buy a pump and regulator ??? Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
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