Quality, reliable mechanical fuel pumps

[Cadman-iac]

  Well I got it installed on the firewall to the passenger side of the distributor, and i got the original fuel lines reinstalled and modified to fit the carb and the regulator.
 I kept trying to find a way to keep the mechanical pump as a backup for the inevitable failure of this magnificent Chinese electric pump in the tank, but the logistics were too difficult.
 I did however keep the electric pump on the frame rail. I tested the tank pump and it pumps right through the rail pump without any issues, and I tested the rail pump to see how well it would draw through the tank pump and it works great. The two work perfectly and will put out enough pressure to keep the carburetor happy.

 As for the cutoff, I wired through the oil pressure switch, and instead of buying that Revolution Electronics fuel pump controller 12003 to prime it when you turn on the key, i found out that I can use the original pump priming module, GM calls it a "Hot Fuel Handling Module ", which does not need to go through the ECM. It's just got 3 wires, a ground, a hot from the ignition switch, and the output to the pump which is tied into the same wire coming from the original fuel pump relay. Turn the key on and i get  20 seconds of power to prime the system.
 I did a little research on these because I have 2 square body Suburbans, a half ton and a 3/4 ton. The heavier vehicles were outfitted with the longer running module, the light duty ones got a 3 to 4 second module, which i confirmed on mine.

 I just got the wire harness back into the truck last night and did some preliminary tests to make sure I got everything wired correctly. I'll take it out today and make sure there's no problem on the road. So far though I'm very happy with it.
 One thing that I've noticed since installing the regulator is the AFR is more steady at an idle. The fluctuations are very minimal now.

[Cadman-iac]

  Here's a couple of pictures of how I plumbed the fuel lines and regulator.  I finally figured out how to post pictures.
 The original fuel lines reinstalled and modified to fit the carb and the regulator is mounted on the firewall above the supply and return lines.

 I made a "manifold" or i guess it's more like a "fuel rail" out of a "tee" fitting and 3 pipe to inverted flare 90° fittings.
 Now the only portion of the line that doesn't have constantly circulating fuel in it is just the short section between the tee and the carb. This will prevent any issues with heat soaking and vapor lock.

 With the factory "Hot Fuel Handling Module " running the pump for 20 seconds each time the key is turned on, I should always have a full carburetor bowl.

 

[quadrajam]

That looks really good. Now you will have plenty of fuel all the way to the end
of the 1320.
  A few months from now you will be going "mechanical WHAT " .

QJ

[Cadman-iac]

That looks really good. Now you will have plenty of fuel all the way to the end
of the 1320.
  A few months from now you will be going "mechanical WHAT " .

QJ

   If I try getting to the end of a1320 foot run in a timely manner, I'll need stock in an oil company, lol! This is a HEAVY truck.

 That said, I made a run to Tucson and back today and checked the mileage, it got 11.73 miles per gallon at speed with the a/c on during the return, which is the uphill run.

 I think I have more work to do to fine tune it, but watching the AFR gage on the run, at 70mph and at 3000 rpm with a vacuum reading of 10", the AFR was fluctuating between 14.0:1 to 15.3:1.

 I noticed the AFR at idle was running around 11.2:1, so I leaned the idle mixture slightly and brought it up to around 12.9:1. Doing this seems to have an effect on the AFR at higher RPM's, is that normal?

 At what point does the idle circuit cease to have an effect on the main circuit?

[tayto]

11:1 to 12:1 is WOT mixture territory. should be in the 13.5:1 to 14:1 for idle.

[Cadman-iac]

11:1 to 12:1 is WOT mixture territory. should be in the 13.5:1 to 14:1 for idle.

 That's what I thought, and I've adjusted the mixture to bring it up, but it seems to run better with a richer idle mixture.
  Leaning it out at idle seems to have an effect on the cruise mixture from what I've noticed on my last long run.
 I need to do some more tests to see if this is really the case, or if it was just my throttle position at the time.

 That's why I asked about when the idle circuit stops affecting the main circuit, or does it continue to flow even with higher RPM's?

 Do you want the idle circuit to work after the main circuit takes over?
 I know they work simultaneously during the transition from idle to mains, but is there a point at which the idle circuit drops out?

 I ask because if it is normal for the idle circuit to work well into the main circuit, then I know i need to compensate for it.
 If it's not supposed to be working at say 2k RPM's, then I need to figure out why it is still flowing.
 Does that make sense?

[77cruiser]

11 to 12 is rich unless you are using gas with ethanol in it. Straight gas would be in the 12.5-13 range.

[Cadman-iac]

11 to 12 is rich unless you are using gas with ethanol in it. Straight gas would be in the 12.5-13 range.

 Yes, this is my daily driver, so I just run the ethanol fuel through it. At 10 to 12 mpg, ethanol free fuel is a bit pricey.

[Cadman-iac]

In my square body I actually have the TBI running everything but the injection. sure is nice to change timing with a couple key strokes and then flash it to the ECM.

  So are you using the original distributor and coil and the ECM?  How did you make it work without setting off codes for TBI faults?

[tayto]

  So are you using the original distributor and coil and the ECM?  How did you make it work without setting off codes for TBI faults?

i can turn off the codes that would trigger a check engine light in the calibration

[Cadman-iac]

i can turn off the codes that would trigger a check engine light in the calibration

 So you're using the original distributor for the TBI system, and the knock sensor?
 What year is your truck?

[tayto]

So you're using the original distributor for the TBI system, and the knock sensor?
 What year is your truck?

My truck is 1986, but I added a TBI harness out of 1990 suburban. Yes I am running TBI distributor & knock sensor. I originally did this to controlling my 700R4 but have plans to go with a 4L60E or 4L80E without having to buy an expensive transmission controller. controlling timing and fuel pump was a bonus. would work better if I had a theottle position sensor.

[Cadman-iac]

My truck is 1986, but I added a TBI harness out of 1990 suburban. Yes I am running TBI distributor & knock sensor. I originally did this to controlling my 700R4 but have plans to go with a 4L60E or 4L80E without having to buy an expensive transmission controller. controlling timing and fuel pump was a bonus. would work better if I had a theottle position sensor.

That's interesting, I didn't think that any of the ECM would work if you didn't have the whole system.
 I've been worried that I might have detonation that I can't hear because of my poor hearing, and I've been trying to figure out how to use a knock sensor without the ECM.
 Very interesting indeed.