i recently converted my 1989 firebird formula from tpi to carb and ever since i cant get it running right i have a electric fuel pump to a mallory 4309 regulator how do u ajust this regulator ? im really thinking about putting a mechanical fuel pump on the block has any one done this yet? how big of a job is it ? i see theres some type of coolant lines in the way it seems like im getting way to much fuel right now gas sometimes comes out the carb and once its running for awhile i shut it off and it wont start again ??? what could be my problem

 

Sounds like you need to adjust that fuel pressure and retune your carb. Did your regulator come with instructions? Fuel injected motors require higher fuel pressure than carbed motors. That's where the regulator comes in. Get yourself a gauge to place on your fuel line so you know what you're working with.

 

Do you have a fuel pressure guage installed after the regulator? You need one - set fuel pressure to 5-7 psi max. - a guage is only $10 - cut it inline between the regulator and the carb. Adjustment on the 4309 is simple by loosening the large nut on the top and adjusting the inner portion with an allen wrench. DO NOT attach a vacuum line to the 4309 - that's for blowers or something, not needed in your case. You have the feed line going in the side, and the return line coming out the bottom right?

 

What carb are you using? That info may also help set floats & idle//vacuum issues.

 

I agree, sounds like a carb tuning issue.

I always start by adjusting the air fuel mixture screws all the way in. Then un screw them 1 1/2 turns start the car. Adjust from there. If you have fuel site glasses, use them to see how much gas you have in each site glass.

 

yes i do have the fuel on the side and the return on the bottom of the regulator .. i have the in line on one side of the regulator and the out going to the carb itself. i am running a edelbrock 600 4 barrel carb and no i do not have a fuel pressure guage on i will put one on this weekend ! is there anything else i should try?

 

Grab a vacuum guage as well. Install your fuel pressure guage after the regulator and before the carb, turn on key and see what kinda pressure you get, and adjust the fuel pressure reg to about 5psi.

Then like mentioned, turn the two screws on the carb all the way in, then unscrew them both about 1.5 turns and see if you can get the car to start with them set there. The vacuum ports that are not connected anywhere should be capped off. Once started and running, check timing, and adjust if needed - try a base timing of 8*BTDC to start with - unplug and cap the timing vacuum port while checking timing.

Then, put the vacuum guage on the small left vacuum port, and adjust the left screw slowly until you reach the most vacuum you can get, then cap that port and do the same with the right port and the right screw. Now, leave the vacuum guage on the right port, and adjust the left screw more both directions and see if you can squeeze any more vacuum out, then cap the right port and go back to the left port again, adjusting the right screw to see if there's any more vacuum that can be squeezed out.

Make sense? left port - left screw, then right port - right screw, then criss cross.

The entire time, you may need to adjust the idle set screw as well to keep your idle at about 800 or so.

Then, check timing again, and advance it a tad or retard it a tad and see if car runs better or worse. Then, check vacuum at the rear port where the brakes get attached - you want the most vacuum possible there - I think I'm getting 12 hg/in on mine which makes the brakes work well. You can sometimes adjust timing up a degree, and lower the idle screw down a tad, and get better vacuum for brakes. Once you get good brake vacuum, take a short test deive and test the brakes - if they seem to not be "powered" enough, try increasing timing a tad more and reducing idle screw a tad again.

Once brakes are good, lock timing at best position, and redo the carb adjustments again testing for the highest vacuum on each port (the left, then right, then criss cross thing). Then lastly, take another spin and see what happens when you floor it - you may need to adjust up or down the position of the little arm and where it attaches to the accelerator pump.

Once all that is done, connect your vacuum lines and you should be good. Left vacuum port to dizzy, right port capped (unless you have something I don't), center large port to your PCV valve or capped.

Hope that helps.

 

does a 1989 firebird formula 350 tpi have a lobe on the cam shaft to run a mechanic fuel pump????

 

I can't say for sure how it works with a Chevy small block vehicle. BUT on the Plymouth Satellite and the Olds Cutlass I used to have, there was a fuel pump eccentric bolted to the front of the camshaft sprocket. http://www.dustyengineering.com/cord...s/IM001591.JPG

 

I don't think it does - I think this cam was designed for the TPI system in mind, and therefore no cam lobe

 

89 TPI cam is a crap-shoot. From personal experience..... 87 definitely had one, 91 definitely didn't. Sometime around 1990 (some say 1989) they stopped putting the fuel pump eccentric lobe on the cam.

Wish I could say more definitively, but I'd definitely check in this case. Don't take the word of us internet jockeys for it. You don't want to be wrong about this.

The Mallory 4309 is adjusted the same way most regulators are- by the set screw in the middle (takes an allen key to turn it). The nut around the outside is to lock the setting in place once you have it where you want it. Straight out of the box they allow about 4 PSI of fuel pressure (assuming your return line is of adequate size and not restricted for some reason). Turning CW on the set screw raises pressure, CCW reduces it. Right out of the box, before you touch anything, it's well down on the low end of it's adjustment range. Which, like I said, is about 4 PSI.

 

so i put the mechanical fuel pump on the block and timed it to 14 degrees advanced it runs so much better. thanks guy one question i put it under a load by putting it in drive and it popped out of the carburator and stalled out.. i then tried starting it again and flames came out of the carburator and ideas what would case this ? bad ignition ? unburned gas?

 

That would indicate a timing issue - double check firing order, double check that #1 piston tdc on compression stroke, test all spark plug wires for continuity, and make sure they are all securely on the distributor and on the plugs. If non of that yields anything, reset the timing elsewhere - try 10*btdc.

 

ok thankyou ! im gonna try that when i get back home next weekend .. the car runs awesome in park and feels like it has full power right now i have it timed at 12 degrees advanced and the idle is 800 rpm motor doesnt shake or anything and when i rev it it seems to have full power ..

 

what kind of distributor are you running? anything done to the motor?
i would try throwing more timing into it, with the vac advance disconnected. get it up around 16* initial.
If its an HEI you can add screws to the weights to get it to stop at what ever mechanical advance you want it to.
if its a points style or MSD you can just get bushings to limit the travel. IIRC they have them for the HEI also.
i would shoot for around 36-38* total and bring it all in around 3000rpms.
it will run much better.
90% of the time when people have an issue its timing related.

my SB loves 20* initial with 18* mechanical advance. for 38* total in at 3000 rpms, i also have the vac advanced hooked up for 52* total.

it will rev just fine in park/neutral, but under a load is when you will have your issues.

i also use a vac gauge to help set the timing and the idle. the idle will increase when you increase the timing so you will need to back it down until you get desired timing and idle. something i learned was if you keep cranking the timing up and watching a vacuum gauge, when the gauge stops gaining vacuum that’s when you know how much total timing the engine wants.

good luck.

aaron

 

k thanks ... my fans dont work after i did the carb swap ? any ideas what to do i jumped the relay for now

 

You swapped from TPI ... dual fans ...
As I understand it, the TPI system uses the ECM to run the driver side fan, and the pass side fan is engaged by the A/C. If you've swapped to carb, and removed the ECM, then the driver side fan may not work. You may need to run a seperate fan controller to operate the fans - I would anyway - I never liked the fan switches in the pass head, never got them to work well. I installed a Flex-a-lite controller that probes the radiator, and it works much much better - well worth the $90 I paid for it.

 

make sure your rotor is pointing at the #1 spark plug tower (or real close) at tdc on the compression stroke. your distributor may be a tooth off.