Mechanical pump pressure regulator

[spanky55amg]

Ok. The more and more I think about it, I'm pretty sure my problems have to be from high fuel pressure. So that said, what have you ran for a regulator and liked? I'd like to get one with a gauge if possible, especially if it's adjustable, but I'm also not looking to spend an arm and a leg.

 

[chengny]

Ok. The more and more I think about it, I'm pretty sure my problems have to be from high fuel pressure. So that said, I'd like to get one with a gauge if possible, especially if it's adjustable, but I'm also not looking to spend an arm and a leg.

1. What, specifically, are your "problems"?

2. Can you explain what this means? "what have talk ran for a regulator and liked?"

3. What leads you to believe that your fuel pump discharge pressure is too high? Have you measured it?

Here is the procedure for testing the discharge pressure of a mechanical fuel pump:


FUEL PUMP PRESSURE TEST

1. Disconnect the fuel line at the carburetor.
2. Install a low pressure gage onto the line.
3. Start the engine.
4. Fuel pump pressure should be (4 to 6.5 psi) .
5. If pressure is less, check for restrictions in fuel tank sender filter, lines or hoses.
6. Reconnect the fuel line.

Conduct that test and report back with the results.

 

[spanky55amg]

1. What, specifically, are your "problems"?

2. Can you explain what this means? "what have talk ran for a regulator and liked?"

3. What leads you to believe that your fuel pump discharge pressure is too high? Have you measured it?

Here is the procedure for testing the discharge pressure of a mechanical fuel pump:


FUEL PUMP PRESSURE TEST

1. Disconnect the fuel line at the carburetor.
2. Install a low pressure gage onto the line.
3. Start the engine.
4. Fuel pump pressure should be (4 to 6.5 psi) .
5. If pressure is less, check for restrictions in fuel tank sender filter, lines or hoses.
6. Reconnect the fuel line.

Conduct that test and report back with the results.

FIXED: talk was supposed to be you. I cant type on my phone.

I have a qjet that was rebuilt professionally. Thought there was a problem with it being too rich and the float. I pulled off the hat and went through it myself and the float is set correctly. The metering rods are 51's and the secondaries, when activated which is almost never, are DR's. Even adjusting the idle mixture screws, its running rich. Just not burning. I'm getting 8 mpg with 75-80% of my driving being at highway speeds with a 700r4. My timing on this 305 is set to 9-10 degrees. I've replaced the pump with a Delph unit from Auto Zone very recently because I had issues with it: A. running rich, but then B. after driving it 45 minutes, would die like it had no fuel. Replacing the pump helped B, but not A. Lots of research on the infowebz sounds like these pumps put out around 10+ psi.

I could test it, I'm not against it. And I probably will before buying one, but I can tell you that it got 12-15 mpg with a Holley 650, this qjet should get at least that, especially since im never in the secondaries.

 

[Honky Kong jr]

FIXED: talk was supposed to be you. I cant type on my phone.

I have a qjet that was rebuilt professionally. Thought there was a problem with it being too rich and the float. I pulled off the hat and went through it myself and the float is set correctly. The metering rods are 51's and the secondaries, when activated which is almost never, are DR's. Even adjusting the idle mixture screws, its running rich. Just not burning. I'm getting 8 mpg with 75-80% of my driving being at highway speeds with a 700r4. My timing on this 305 is set to 9-10 degrees. I've replaced the pump with a Delph unit from Auto Zone very recently because I had issues with it: A. running rich, but then B. after driving it 45 minutes, would die like it had no fuel. Replacing the pump helped B, but not A. Lots of research on the infowebz sounds like these pumps put out around 10+ psi.

I could test it, I'm not against it. And I probably will before buying one, but I can tell you that it got 12-15 mpg with a Holley 650, this qjet should get at least that, especially since im never in the secondaries.

My thought on that was the slobberjet has such tiny primarys and you gotta open them further to do the same work as that Holley......

 

[spanky55amg]

Should be that much of a difference. Especially since I got the 22s off the thing. And I should be able to break the tires loose.

 

[1987 GMC Jimmy]

Hmm... my car has the exact same pump and motor albeit a more complex carburetor, and I’ve never suspected a problem with too much discharge pressure. Not saying it can’t happen, but I’d exhaust other options first like weak spark. And phew, my 305 can’t handle that kind of timing. I have a bad TCC that I manage to keep going with Dr. Tranny, which makes it much better, although not a 100% fix (more like 90%) Anyways, I have it at like seven degrees and I’m using premium gas because I don’t have the time to adjust it for the next few days. It needs more like three or four. I don’t want to suggest that it can’t run that way and/or your harmonic balancer is off, but 305s are kinda sensitive to advanced timing.

 

[spanky55amg]

Yep. Delphi pump from autozone for a pre-emissions truck, and its putting out 10 psi. Which, searching on the net is common.

So do I:
1. Keep going back to Autozone and keep trying pumps till its correct
2. Just put a pressure regulator on since this is a common issue

 

[spanky55amg]

Hmm... my car has the exact same pump and motor albeit a more complex carburetor, and I’ve never suspected a problem with too much discharge pressure. Not saying it can’t happen, but I’d exhaust other options first like weak spark. And phew, my 305 can’t handle that kind of timing. I have a bad TCC that I manage to keep going with Dr. Tranny, which makes it much better, although not a 100% fix (more like 90%) Anyways, I have it at like seven degrees and I’m using premium gas because I don’t have the time to adjust it for the next few days. It needs more like three or four. I don’t want to suggest that it can’t run that way and/or your harmonic balancer is off, but 305s are kinda sensitive to advanced timing.

So far, it doesnt mind the timing. i dont think, its hard to tell when the carb is getting too much pressure. This is the issue I have been fighting with the Qjet and the Holley.

 

[1987 GMC Jimmy]

I think we have the same pump (Delphi MF0049), and I've not had an issue with it. I've never tested the pressure (maybe I should), but my economy is good, and the car doesn't smell bad for one not running a cat. I would exchange it and try again before I invested money in something else. If it does it again, I'd consider the regulator.

 

[Rusty Nail]

Needs more timing.

 

[spanky55amg]

I think we have the same pump (Delphi MF0049), and I've not had an issue with it. I've never tested the pressure (maybe I should), but my economy is good, and the car doesn't smell bad for one not running a cat. I would exchange it and try again before I invested money in something else. If it does it again, I'd consider the regulator.

Yeah, there are many many posts on the infowebs about these things putting out high pressure... sadly.

 

[spanky55amg]

Needs more timing.

Haha, Im not going to push it anymore.

 

[spanky55amg]

Just an FYI, I live about an bour, with good traffic, from Summit in Arlington Tx. I ordered a part last night. It was $10 for S&H but $0 for ground. I ordered it right before 9 pm and tracking shows it at my door at 318 pm today. All of the sudden, I don't feel bad for basically $10 over night shipping.

 

[spanky55amg]

n’t run that way and/or your harmonic balancer is off, but 305s are kinda sensitive to advanced timing.

Now that it is kind purring like a kitten, looks like Im pulling timing. I fattened the idle back up a little bit and took it for a drive, and when getting above 2k rpms, it doesnt like it. But its 1222 am. So Ill just stay out of the throttle till Im back in town.

 

[1987 GMC Jimmy]

So did you just end up swapping to another pump?