1970s 40, 350/TH350 on Megasquirt 1 PCB3.0 (1 Viewer)

[toyotaspeed90]

Long time since an update..... that's how the priority of the 40 stands, though.

With weather changing I plan to get more work in on it.

Most of the wiring is now done. Wiring that's left at this point is:
Injector positive from relay
Fuel pump (pump itself, relay is otherwise wired)
Connect injector wires to TBI, plug in TBI items.

All carb stuff was removed. Mechanical pump was removed and blocked off. Mechanical pump feed line (not OE, was a nylon braided line with hydraulic ends) was pulled from the frame.

TBI adapter plate was installed, TBI mounted

Fuel pump is next on the agenda. Kept going back and forth with how to run the feed line. The mech line ran under the body to the passenger frame, up to the front where the mech pump was. The TBI has the inlet facing the firewall, and I hated the idea of running the line anywhere near the headers (over frame) and didn't like the idea of running 10 extra feet of line using the mech line.

Next option was to run under the tub, but could be exposed off road. With all of this was "where will the pump and filter land?".

Decided that I'll just build some SS braided AN lines, mount the pump and filter next to the tank under the passenger seat, and run a short line over the doghouse, through the firewall, right to the TBI. With a 1500 psi rating on the hose for a 20psi pump, I'm comfortable with that option


I'll be working on the fuel lines, mounting everything, and wiring the pump on Thursday.

Soon after I will update MS with the proper injectors and do a test start.

Nothing is loomed yet...

 

[srgould41]

What will you use for a pump?

 

[toyotaspeed90]

It's a universal TBI Carter P5001, I found a "Dewhale" or something like that, fuel filter that came with AN fittings and is serviceable/cleanable and 100 micron filter.

 

[srgould41]

I need to double check, but I believe that is the pump I run. Only problem, besides being so loud, is it my inline pressure gauge shows only 10psi, not the listed 20. Maybe I need to cap off the return to actually see the 20, but while running I see 10.

 

[toyotaspeed90]

The stock regulator is built into the TBI unit - I believe it's factory settings to 13psi. However if it's damaged it's possible to be lower. I don't know if it's a factory rising rate regulator or not.

I had a 1990 Bayliner Capri that I swapped motors in, and the new didn't have provisions for a mechanical pump. I had massive issues with the electric pumps providing fuel, and being overly noisy. First was a cheap pump and the 2nd was a carter.

The first problem was the pump was too high... it was physically too far above the tank. The flow of gas was limited.

The 2nd problem was using cheap, and too long, of hose from the tank to the pump, and the hose was collapsing.

Both of those contributed to performance and noise issues. Once the Carter was lower with the shortest possible hose, no more problems and no more noise.

Unless you buy a pump that's specifically meant to be a puller, fuel pumps are designed to push fuel through the system.

I have some concerns that putting the pump under the seat may not be physically low enough for the gravity/venturi feed and could cause problems and/or be noisy.... it will, however, technically be lower than the outlet from the tank with a short hose feed (about 1 foot).

The P5001 is a pusher pump.

I recall you mentioning running warmer than you like... it's possible your running a bit lean and the noisy pump and/or its setup could be contributing...

 

[SuperBuickGuy]

I run the same pump, it's noisy. If I hadn't done the Holley sock (hydramat), I'd have gone with the $400, in-tank aeromotive... and I still might if I find another tank or I built a new, larger-volume tank.

 

[srgould41]

I mounted my pump underneath behind the tank. It was a perfect spot but close to the body which may lead to some of the noise. My engine does run warmer than with a carb. I believe it is a leaner fuel mixture as part of it. I programmed the computer to run a little rich at low RPM to help with cooling on the trail. Using an electric fan has made a huge difference in temps. I rarely go over 205 now. I did use 18psi in my calcs for fuel flow so I am a bit off. I modded the regulator for manual adjustment and cranked it up. To get more pressure from it would require a different spring. I do wonder what that would do to the line pressure. I don't know if it would really increase or not.

 

[srgould41]

I kind of like this option.
2L Litre Billet High Flow Swirl Fuel Surge Tank AN6 + 044 External Fuel Pump SL | eBay

Use the mechanical fuel pump to fill it if you can find a spot for it under the hood or else a low pressure electric pump if you mount it in the bed somewhere.

 

[srgould41]

Have you ever checked your line pressure? I am curious how it would compare to mine.

I run the same pump, it's noisy. If I hadn't done the Holley sock (hydramat), I'd have gone with the $400, in-tank aeromotive... and I still might if I find another tank or I built a new, larger-volume tank.

 

[toyotaspeed90]

I mounted my pump underneath behind the tank. It was a perfect spot but close to the body which may lead to some of the noise. My engine does run warmer than with a carb. I believe it is a leaner fuel mixture as part of it. I programmed the computer to run a little rich at low RPM to help with cooling on the trail. Using an electric fan has made a huge difference in temps. I rarely go over 205 now. I did use 18psi in my calcs for fuel flow so I am a bit off. I modded the regulator for manual adjustment and cranked it up. To get more pressure from it would require a different spring. I do wonder what that would do to the line pressure. I don't know if it would really increase or not.

Are you sure you didn't use a carb regulator? An efi external regulator should easily go upwards of 50-80psi... your regulator is fitted on the return line, correct?

18psi for the tune but getting 10? That's gotta be way lean unless you have really long (ms) acceleration enrichments....

 

[srgould41]

I meant the TBI pressure regulator. I performed the modification to make it adjustable. I ran the adjuster nearly all the way up. I left about an 1/8" gap in the screw travel slot.

Adjustable Fuel Pressure Regulator for TBI equipped F-bodies - ThirdGen.Org

This should have netted me about 15psi.

Because I didn't have the pressure I wanted I had to mess a lot with the original fuel tables. It took me about 20 burns to get the AFR's right.

Are you sure you didn't use a carb regulator? An efi external regulator should easily go upwards of 50-80psi... your regulator is fitted on the return line, correct?

18psi for the tune but getting 10? That's gotta be way lean unless you have really long (ms) acceleration enrichments....

 

[toyotaspeed90]

I see the mod - and it would be completely dependent on the spring... age/worn or if it was an aftermarket spring with a tad less tension than stock.

If I ever decide on a non stock FPR then I would go external with a rising rate unit.

Where are you reading the pressure?

 

[srgould41]

I agree about the spring. There is a different spring advertised for this purpose. I was using an inline gauge just in front of the fuel inlet port on the TBI. I have since removed it, but can easily put it back.

 

[SuperBuickGuy]

Have you ever checked your line pressure? I am curious how it would compare to mine.

11

 

[srgould41]

So maybe it is not the pump but the FPR limiting the upstream pressure.

11

 

[SuperBuickGuy]

The FPR is on the outlet from the TBI - it'd be quite possible to mix up those two lines, but the regulator needs to be on the return line not the supply line otherwise you'd have no pressure to the injectors.

for the record, mine is adjustable too - the entire unit isn't GM-built but Holley built.

 

[toyotaspeed90]

The outlet line is smaller.

The pumps ability and the regulator are what create the pressure.

Although it seems more of a North America thing (I've bought JDM motors with and without them) Toyota added dampers on their feed lines as well at the fuel rail. I'm not sure what "emissions" would have to do with that, but it seems to me like it would be a better way to even the pressure peaks/drops in the rail from injector firing. Both the TBI and batch fire MPI really aren't that precise to need them, but food for thought.

I still like the idea of a rising rate FPR..... again, another stock Toyota setup I like.

 

[toyotaspeed90]

Granted pump is new and not under load - it has a humming noise and the return line I have is more noisy than the pump.

My standards may be different - since a low pressure pump thats struggling to pull fuel, attached to a fiberglass hull that's reverberating the constant pumps clicking is my definition of a 'noisy pump'. This is nothing, probably won't hear it over the exhaust.

 

[SuperBuickGuy]

mine gets louder the longer I drive - almost to the high-pitch-dentist-drill level.

 

[srgould41]

Mine gets better with speed. If I drive fast enough I don't hear it