I had the same FPR, and I had the same issue with it. I went through two mallory fuel pumps in less than a year (im assuming this pulsing caused them to fail)

The problem seem would go away if a adjusted it for over 6PSI, but then the carb would spew gas.

I never did find a fix for it, as I started swapping out everything for an EFI setup after the 2nd fuel pump failed.

 

Did you ever call and ask them about it?

I have a feeling my return line isn't big enough. :/

 

stock lines are fine but i noticed a slight difference when i instaleed -8 and -6 aluminum lines on my other rx-3. Btw, i found the rb throttle cable bracket for a dellorto. You want it?

 

I don't think the stock RB unit is going to work with my carb's throttle lever. The angle would be too high, and I doubt I would have any leverage on the arm nearing full throttle (basically perpendicular to the arm's position at WOT) My solution mounts the throttle cable in a location better suited to my application. Thanks though.

Back to fuel pressure pulsation:

I was led to believe, by the RB instructions, that the fuel return line is the line closest to the centerline of the car. This is correct, correct? I can see how it would cause pulsing if I reversed the two.

I'm thinking that perhaps my return line might be partially clogged. Should I pour some seafoam down it and let it sit overnight? Then again, if it was clogged, it would have made the same pulsing noise before I began the swap, right?

When I started the car in the video, I had taken the adjustment screw completely out of the regulator. It's obviously not a orifice that can leak fuel, but perhaps it allowed the spring inside to bounce around? I didn't think to look.

 

with an -SE your fuel feed and return lines should be large enough. Do you have your fuel pump hooked directly up to 12v or is it hooked up with stock wiring? You could have a hidden issue with stock wiring??

Not sure how many amps the -SE alternator is but I had an issue with the stock 55a alternator producing enough juice to run constant voltage to the mallory pump. When I switched to the 80a I got much more constant draw.

In watching your video and looking at the fuel in your filter it does seem like there is a block or sucking lots of air from somewhere. If working right fuel should really be flowing through that filter and out the return line.

 

In the RB instructions it said to install a jumper wire on a certain plug so that the pump runs continuously when the key is in the ignition position, which it does.

 

Just a thought,.have you tried running an independent 12v to the fuel pump? Straight from alternator with a 30amp relay of course. That simple mod helped alot on all of my first gens and RX-3s

 

Isn't that what I recommended....

 

Can you explain what this would do?

 

move the gauge down line from the regulator closer to the carb and needle will not bounce. when mounted in the regulator port it is reading the pulse from the diaphram and will bounce causing gauge failure and improper readings

 

Gives your fuel pump a direct power source rather than one that is feeding everything else in the car. An easy way to test if it solves issue before doing the wiring would be to hook a battery directly to the fuel pump.

 

This is also true however I can hear your fuel pump surging in your video.

One of three things: blocked line, air leak, bad electrical connection

 

I really don't think it's electrical. Before I lowered the pressure, it ran without surging at 6-10psi. No pulsation. It was only when I lowered it down below 3 that it happened.

What could cause an air leak?

And again, is the SE's return line the one closest to the centerline of the car? (at the firewall)

 

Disconnect both fuel lines and turn-on or start the car. The line where gas shoots out is your mqin

 

Sorry bro, i didnt see your post.

 

So I did some more experimentation today. When I turn the ignition key to the accessory position, the regulator regulates the pressure down to 3 or lower psi and will stay their without moving. When I try and move the adjustment screw in (to increase pressure at the outlet) it will start pulsing around 4psi and then stop pulsing again at like 5psi. I let it run at 3psi and it held steady for as long as I watched it (over a minute). As soon as I tried to start the car, however, the pulsing returned.

If it was a clog, it would pulse no matter what. If it was electrical, it would also pulse all of the time, no? I just don't understand it.

The only thing I can think of is either a screwed up regulator diaphram (brand new, very unlikely) or air in the lines somehow.

 

Good news! I played with the FPR some more and the pulsing seems to have gone away. I also rigged up a (temporary) throttle linkage so I could use the throttle pedal and observe rpm and stuff like that.

Not so good news: I think she is running very lean. The engine bay feels very warm and there is actually smoking coming off of the header wrap, something that never has happened before. Wish I had a carb expert to help out on this one. I think I'm gonna get an A/F ratio gauge + wideband, see if I can tune it a little better.

For starters though, should I play with the idle mixture and see if I can richen it up a little, or is it going to require more than that? All the jets and e-tubes are correct for a stock 13b. I'm gonna check the float level, and see if it's within spec. My perception is that it is running fine when it first starts but the longer it runs, the leaner the mixture gets, until it finally shuts off. Does this sound like a float level issue?

 

If you want to play with the carb, start with idle jets and such but do not touch the main jets until such time that you feel acceleration/launch is fine. Either buy more idle jets or buy a set of index drill bit.

 

To be honest, I think the mixture is fine, but it's running out of fuel is my guess. Float level is probably wrong. I'm going to check it tomorrow when I have light again.

 

Running out of fuel at what level or rpm?

 

At idle.

I just noticed that fuel seems to be seeping out of the carb where the top plate bolts to the carb body. Time to rebuild it.

 

the A/F gauge is a good idea, but at idle/low speeds there is no harm trying different mixtures. give it more fuel and see if it likes it. then give it less fuel and see if it likes it, let the engine tell you what the happy spot is. i have a little notebook, so i know what i tried.

at first you should make one change at a time, so you learn what does what.

 

If this is happening your floats are either set WAY too high (unlikely) or your needle is not seating and shutting off fuel (much more likely)

Fuel should never rise so much that it comes out of top plate. Take the brass circular piece off when the car is running, you should not see fuel. When you take the top cover off fuel should only fill the bowl like half way.

 

Ok thanks. I think the issue is probably the needle then, probably gunked up, I will take a look next time I am able to work on the car...which is sadly not often

Which brass circular piece are you talking about, by the way? Here is my setup for reference:

 

I forgot you are running a dell and not a weber. Hard to see under your fuel filter but what ever color your jet cover is, open it up with the fuel pump running; fuel should not overflow.

I notice your adjustment skrew is not in your regulator. My pressure bounces all over when there is not any pressure on the internal diaphram as well. You need to have the adjustment skrew in and tightened down a bit. If you can't dial your pressure down enough your return line is not large enough. I can easily maintain a constant 2.5 PSI with the same setup as you.

Also I would not have my filter after the regulator. You don't want crud to plug up your regulator. I would recommend placing it before.