S5 13bt blowthrough with a 45dcoe.
So. I can't get my FPR to drop below 7psi. I'm running a holley blue fuel pump. 110gph @ 14psi. ANd I'm using a Mallory 4309 It seems as though the fuel return is clogged, but I spraied brake cleaner and mmo down the return then ran the feul pump to bypass the FPR and Carb and run straight down the return hoping all 14psi would clear it out. I let it run for about 15 minutes, and still nothing. I hooked the carb and FPR back up and the second I turn the key 7psi and its pooring fuel out of the main jets. What the fawk is going on. I'm beyone frustrated with this. I just want it running, or gone forever. Also the car is a 83GSL if that matters as far as return size or tank size go. I figure tomarrow I'm going to try and run it with the fpr return dumping into a bucket and see if that lowers the fue pressure. Mind you these results are with the pressure control bolt turned all the way out.

 

Did you take the factory fpr out of the return line, the little silver barrel thing? Probably did, just covering bases.

If you hit the carb with 7-14 psi, the needle/seats/floats may be sticking. Not that familiar with the Webers. It's also possible you need a bigger return line. I know when I put my Mallory comp 140 on, it requires a 3/8" return line, minumum. The stock 12A return line handles less than 1/2 the volume of a 3/8" line.

I'm running the 4309 also and have no problem getting the psi down to under 3 if I need too.

 

I'm pretty sure the factory return line is 5/16s isn't it? Where is the factory FPR under the hoos or by the tank? If its under the hood it's gone. If its by the tank it might not be.

 

Oem fpr is a barrel shaped insert spliced in between the carb and hard return line. Stock hard line return line is barely over 1/4".

Doing the bucket test will tell you if the return is too small, which I think it is for the 110 gph pump.

 

Yea 4/16's is a 1/4 inch, so yea 5/16ths is just over a quarter inch. and 3/8th's or 6/16ths is regular fuel line. I think I might need a new return line... FAWWWKKK!!! I know the stock GSL-SE pump is like 60psi, but it's only about 35gph.

 

I was worried about the same with my Mallory fpr, that's why I ran all 3/8 stainless. If you plan on changing the line let me know cause I have lots of 3/8 line left if that's what you want to do. Free to you cause you helped me out so much, just pay to ship, plus stainless 3/8 fittings.

 

I had similar problem before with a 4309 (ask doluck). Accoding to Robert @ Rotaryshack, Mallory built 2 types of 4309. I bet you got the same one I have. You may need to get a different set.

 

Wha do you mean??? Two types. Is there anything I can do to fix it? What causes the problem? I might be getting a different fuel pump later. Is the Holley just too much flow for it? Makes no sence to me cause they sell them as a package deal with the Mallory 110, and thats 110gph @ 14psi. I don't know...

 

I haven't heard about the differing 4309s, but a Mallory comp 70 is more than enough of a pump for you. I went overkill with the 140, but it was the same price packaged as the comp 70 and 4309 would have been seperately.

When I redid my fuel lines, I went to the local speed shop and bought a 25' roll of 3/8" aluminum tubing for less than 20 bucks. Took out the old lines, used them as a pattern to pre-bend the new, then bubble flared the ends for the hose clamps. The aluminum is soft and can be easily bent using thumbs.

 

top...

 

I'm back so results are as so. FPR dumping into a bucket: Fuel ressure at 2.5 psi! PERFECT! soooo good news is I found the problem. either the return ine is just too small, which makes no sence cause 12at guys have no porblems with the fuel return, or it's claugged. Which I need an air compressor to unclogg it with. FAWK, I don't have one or know anyone with one!!! So I could get a bigger line and run a new line back to the tank and that'd be perfect. Problem with that is I'm allreaddy $150 over drawn on my acct. What to do, what to do...

 

Well, at least replacing the line is cheaper than the fpr.

 

IIRC something like the older models came with stiffer springs (cant have lower than 9 PSI) while the newer ones are softer. Due to my tight work schedule, I just modded a regular holley fuel pressure regulator for a return and it worked fine using a MSD F/I in my IDA.

 

Well the reguator works when dumping into a bucket, so the FPR is fine. When it was N/a I was running a holey FPR w/o a return, so I think the Holley is just too much flow for the return. Your MSD pump is like 85psi, but it's only like 43gph, so the 5/16ths line should flow enough. I did mod my holley FPR for boost reference, but it would leak boost pressure above 8psi. so I couldn't boost more than that. BOOOOO!! LOL! Time to ***** myself out.

 

told you....

 

LOL!!! ****! I'm going to buy 3/8th's copper tubing since it's cheaper than steel braded lines. Hope it works!

 

Stay away from the copper, it will corrode out too quckily. Aluminum is cheaper anyway.

 

I've never heard that! Where can I get aluminum? I work with lowes as a manufacturers rep and I've never seen it there.

 

Stainless steel, only way to go.


I got mine to follow the stock lines with a tubing bender, so they fit under there perfect and was able to use the stock holders. Where they come out in the engine bay I polished them with some mothers and steel wool and now they shine

 

I agree, ss would be the best long lasting option. I found the aluminum at the local speed shop that caters to the dirt trackers and 4wd guys. Jegs or Summit should carry it too. Mine came out to 80 cents a foot.

 

Well I got to get running this weekend My mom is demanding her car back!!! So I might just do rubber crap for right now! LOL!! Thanks for the tips If I can afford, and find it, that's the way I'm going.

 

Like I said before, if you ever want to do the ss lines, let me know. I got tons of it and will be tossing it in the garbage cause I keep tripping on it. LOL

 

So I ran new fuel return and pressure is where i want it, but the bitch still won't start. I'm about done. If someone wants to give me $2500 you can have the car and all my parts. I'm done...

 

fawk so I've got spark. when I crank it with the plugs out and on the shock tower they spark like a mother! I've got fuel cause it mists out the plug holes when I crank it. I know I have way better compression than before. So why won't it start? timming. I put the pulley at tdc and lined up the dizzy and dropped it in. I'm utterly lost. I don't know where to go from here... this is it if it doesn't start tomarrow I'm going to unload 2 boxes of amo on the pos and have it hualled away...

 

Pour a capful of oil down each carb barrel, kill the pump and crank it over. Take the plugs out, clean them with brake cleaner and compressed air. If it won't start, then try pull starting it.