KaiNalu

First I have installed a Mallory Pro Comp 140 Fuel Pump with regulator. When the car is running for an extended period of time where it gets to normal operating temp I start loosing pressure in the regulator. Also at high revs it goes down to almost 0psi from 4psi. It is a single line setup with only the main fuel line connected, return line plugged and vaccum line open. I think that the vaccum line may need to be connected in order to pressurize the tank and fix the problem but I wanted opinions from others with after market pumps. Is the vaccum line required for this setup or not? If not why am I loosing pressure?

trochoid

iTrader: (6)

The Comp 140 needs a minumum of a 3/8" return line, I know I ran one and replaced both my supply and return lines with 3/8". Are you also running the 4309 fpr? You would be better off with the Comp 70, it is more than sufficient for a 12A.

KaiNalu

The main line is 3/8 i have no return. The reg is a 4207 i think. I have this setup as I am running a streetport soon to be turbo setup. Wanted to make sure I had plenty of fuel. Also I have a weber 45 dcoe carb that I am running that doesn't have a return on it.

trochoid

iTrader: (6)

Then I suggest you run a return and an FI pump, along with the 4309 fpr. Add up the psi the carb needs and the boost you plan on running, you stand a good chance of exceeding the psi capacity of the pump.

KaiNalu

What is a FI pump (Fuel Injection)? What are the benefits of the 4309 to the 4207 fpr as they both do the same thing? 140gph with 12psi capacity is not good enough for a turbo setup I find that hard to believe. Other opinions would be great.

dj55b

iTrader: (2)

FI means fuel injected ... he might of thought that you were running that route if you're going turbo. I would assume that would also be fine if you will be running a boost prepped carb. Ya you better use that return line on the Mallory. You'll blow the thing up if you don't. (I speak from experience ... i ran mine for about a 3 weeks without return, and it went out on me yesterday. So now i'm bidding on another one.) Had to pay 85$ towing to get it back to my house too.

trochoid

iTrader: (6)

Nope, no mistake. If you run 4psi of fuel pressure, and 9 psi of boost, you lose. That's why I suggested the 4309 fpr, it will handle a Fuel Injection pump and bring the pressures down for carb use. Not familiar with the 4207, is it a rrfpr?

I had similiar plans as you, running the Comp 140, which puts out more volume than an upgraded TII pump btw. I'm now going with an FI pump, when that's sorted out, I will be looking into a turbo set up.

cdrad51

Running a return line would lower, not raise the psi, AFAIK. So why are we talking about running a return line as a fix if the problem is low pressure? Just curious. Maybe I'm missing something.

trochoid

iTrader: (6)

The Comp 140 requires a return line of 3/8", at a minumum, otherwise the pump burns up. The 4309 is a rrfpr, with return, and will hold the fuel pressure it is set at. for those looking at the Comp 140, buy the 70 instead. For blow through an FI pump is the best option. I argured the same issue and lost to better experience.

KaiNalu, if you are looking for a more experienced answer, contact Robert at Rotaryshack. Turbo carbs is one of his specialties.

KaiNalu

So from what I gather even with the regulator the pump is pushing too much gas to the carb even with the pressure dropping? Because of this I require a return line to put the extra gas back to the tank. Correct? This will then allow the pressure to remain stable I guess. Though cdrad51 makes a point about the pressure dropping when adding a return. I am totally confused.

DJ55b, I don't understand why Mallory would give you a diag with the pump stating that you can run it without a return knowing that the pump would blow out. Did you have any symptoms prior to it going out on you? My pump is making strange noises like its sucking in air along with gas from the tank. What makes our cars different aside from being a rotary that requires a return where others do not?

Trochoid, I'm getting a bunch of mixed information about the regulator. According to Mallory documentation I can hook it up with a return. According to Summit the comp 140 comes with a non-return reg. Well my reg came with the 140 so wtf?? I have not heard of this measure before either about the 4psi of fuel pressure + the boost psi can't exceed the psi capabilities of the pump itself? Do you have noted documentation from an accredited source? I have dealt with RotaryShack before and would prefer not to again thanks for the recommendation though.

trochoid

iTrader: (6)

When I bought my 140, it came with the 4309. The reason for running an FI pump is you do not want to exceed the pumps psi capacity when you add the base pressure the carb requires and the boost level you plan on running. i.e. if base carb psi is 4, you add say 9 psi of boost and the pump only puts out 12 psi, you will run lean at full boost and stand a good chance of detonation, and losing the engine.

By running an FI pump, you will not have to worry about lean spikes.

When I bought my pump, no where in the specs did it say that a return line was needed on the website. When the pump came, it did state that in the installation paper work that came with the pump. I was not a happy camper. I have had nothing but trouble with the pump and have finally given up on it. So I now have an fpr that cost me over 300 bucks.

The funny noise you hear coming from the pump may be cavitation, as the pump has reached max flow and the preset 12 psi bypass has kicked in. Mine never sounded right and I removed the bypass, yet still had problems with it.

dj55b

iTrader: (2)

The syptoms that i had before that happened are when the car is just turned on and then idles ... you can hear the pump noise go higher due to the higher restriction. You can hear the pump when it has to work harder. With the return line not only does it help with reducing the wear on the pump (extending the life of your pump like that too) and the other one that i've been told by a few people is that if there's no return the fuel doe tend to warm up a little bit in the lines, so having a return line will provide cooler fuel which would be better for performance.

Dmonhunter

I installed the 50$ aftermarket universal pump (6 psi)from pep boys in my 85 12a. and put on a F.Reg. It just clamps right in, and then had my carb rebuilt. (Just bought the car from a guy who let it sit too long) Then, at the shop (marvel speed in rowlett, texas-specializing in 7's) I craqk it up, run right along down the road, with no problems. Then run out of gas-stupid me, got so excited to finally have the darn thing working, forgot to put gas in. Put gas in, and got on the highway, accelerate to 50 mph, and it dies...
I pull on to the shoulder, let it sit for a minute, adjust the aftermarket in-line feul regulator, (spectre-12$ @ pep boys) and started it up again, decided that the service road is now a better option. Go up the ramp, and it dies halfway. Great. push it up the hill with the help of some passersby. Put it in front of a gas pump. put in 10$ worth of gas, and the problem is fixed. great. take off about 7 mi later it dies again. Feels like it is running out of gas, but i know that i jsut put in 16$ woth of it. SO, now Im pissed. I can start it and it will idle for about 3 min, then dies a slow death. or, I can try to run it, get about 50 ft, and coast to a stop without brakes(hmm) so now, Ive got a car stuck in another town, i jsut put 1500$ into it, and Ive replaced about half the feul lines, none of them are leaking now, New filters(purolator) new pump and feul regulator. Next I've got to get a ride back there and drop the gas tank to see if there is a bunch of crap in it. And probably replace the sock, (does it have one?) and clean out the tank.
****Have you had anyof these probs with your aftermarket? because, I dont have my car here to look at, and I dont think it has a return line, if it does, I jsut wasnt observant enough to notice it. (got a nikki, all stock, but with Grossflow needles and seats)

KaiNalu

After thinking the worst it ends up being that i didn't have the regulator adjusted right. The reg shows 6psi when i started the car. After running for a little while it would drop the psi to about 2 and when reving it would drop. Adjusted it to 4 psi at that point and it stays. The reg was adjusted for cold instead of normal operating temp. So my problem is fixed for now. I haven't driven it down the street yet as I have some other minor things i have to take care of. So dmon to answer your question I haven't experienced that problem as of yet. However its sounds like you may have a filter problem or a leak in one of your lines. I'd check to make sure everything was tight.

dj55b

iTrader: (2)

Most likely clogged up tank as you've guessed. My first tank did that. What would happen is that if I let it sit for a while, the fuel would fill the fuel lines a bit, so when i cranked it it would run on what ever it filled the fuel lines with. SO the longer you let it sit the more your lines are filled the further you could go, but for every 5 minutes of driving you'r have to wait like 20 to get all the line filled up again.

85TIIDEVIL

iTrader: (2)

I have the Mallory 4309 FPR, with a Holley Blue Fuel Pump on a N/A 12A which is completly STOCK.

The FPR has the little vaccum / boost nipple and I havent hooked it up to anything yet.

I have a return line hooked up off the bottom port of the FPR directly back to the tank. I used 3/8 line.

The same problem you speak of above is happening...? My pump sometimes sounds like it is straining...??? So I check my Fuel Pressure Gauge which is under the hood directly off one of the FPR's ports and sometimes it'll be as high as 6psi and other times it'll be as low as 0psi...??? Very odd. I always set it back at 3.5ish since I am running a STOCK NIKKI.

I thought maybe the return was too small causing the inconsistant Fuel Pressure readings... since I am running a 1/2" Feed. So I ran another return using the Nikki's return line directly back to the tank. (this makes two working 3/8 return lines directly back to the tank)... And I am still having the same wacky pressure readings.

Next step which I am in the process of right now is... I ordered fittings to run a isolator into the car so I can watch the Fuel Pressure as I am driving to see what and when is causing the drops and spikes on the pressure.

I've yet to hook up the vacuum / boost nipple to a vaccum source since my set-up is N/A. Any recomendations on where would be the best spot..???

As soon as I sort out the messed up pressure readings I'll post it.

trochoid

iTrader: (6)

The nipple on the 4309 is what makes that fpr a rrfpr. Unless you are adding a turbo, leave the nipple alone.

85TIIDEVIL

iTrader: (2)

Couldn't it be useful even without boost to raise the fuel pressure as the RPM's rise or vacuum decreases also...?

trochoid

iTrader: (6)

No, that's what all of the other jets, emulsion tubes and different circuits, etc., inside the carb are for. By varying the fuel pressure, it would screw up the way that the carb supplies fuel, and driveability. If you want to try it, do so, report back the results.

Dmonhunter

Thank you for reinforcing m y suspicions, I have not dropped the tank yet, because I haven't gotten a ride back to my car yet, and I'm out of money--lmao- bec ause I underestimated how much it would take to get this thing running. Severely. That should be on the newby FAQs!!

*This car is going to cost more than you think...*
I htought i would be okay, I estimated the repairs at about 600$-then had double that on hand- and should have made it triple...

anyway-I am curious-- is it hard to clean the tank on this car-got a 1st gen- or does it have those balasts to keep the sloshing to a min.?

dj55b

iTrader: (2)

Our cars are made as simple as possible nothing really fancy in there. Depending on what year you have, if you look under the tank you might have a drain bolt that comes in really handy. First drain all the fuel out of there, then there's different methods on cleaning it out. Cheapest method you'll hear is probably filling the tank with a few clean rock and shake it around (or roll it around). Other methods you could do it take it in to a shop to have it cleaned out. Most radiator shops will do such a service. After you clean it out somehow from all the big debris, I would take an air compressor with a air spray nosel on there and spray air into all the lines coming the top of the tank just incase anything is stuck in there. After all that, i would recommend using some kind of gas tank sealer. Just because when you have all the rock in there it damages the inside sealer sometimes so like this prevents rust from coming out any time soon.

If you do a search on "Gas tank cleaning" you hsould be able to find a few good threads concerning it. Some are more extreme than others.