Fuel pump volume test

[Merle Coggins]

Hello. I’ll be helping a friend to diagnose a potential fuel pump issue this coming weekend. I have what I need to check the fuel pressure, and I have that spec (4-5 psi). However, I can’t find a spec for the pump volume. I’m aware of volume tests where you disconnect the line going to the carb and direct the flow into a container, then crank the engine for a certain amount of time and measure the volume. Does anyone know that spec for our trucks? 

[greg g]

Don't think it's different but 12 pulses should be 6 to 8 ounces for p15s.  The service manual covers it in the test written procedure not on any spec chart. I may misremember stuff these days.  So please consider a second source.  Your results may vary.

[Robert Harrison]

I took a look at this and the attachment is what I came up with.  I could not find volume in the Dodge truck shop manual.  Comments are welcome.  Bob Harrison

Fuel pump volume.doc

[Young Ed]

My 46-54 Plymouth manual says to disconnect at the carb and connect a short piece of hose to the line and place it into a container. Crank engine for 2 revolutions to prime pump and fill lines. Dump out the container and then crank engine for 15 pump strokes. You should get 5-6 ounces. 

[Merle Coggins]

Thanks guys. This gives me a target to shoot for. As Robert said, this is not stated in the truck shop manual. It only references the pressure. And, in the test procedure it states 3-1/2 - 5-1/2 psi, but if you look in the Specs pages it shows 4-5 psi. (Gotta love inconsistency in service literature 🤔)  It’s good that the Plymouth manuals state it. I might do a test on my truck one evening this week for comparison/baseline. 

[Merle Coggins]

I just performed the test on my truck. I got 4 oz. After 15 pump pulses. It would be a little low based on Ed’s spec., but it’ll hold 4.5 psi on a pressure test. So I’ll use this as a guideline too. 

[Young Ed]

14 minutes ago, Merle Coggins said:

I just performed the test on my truck. I got 4 oz. After 15 pump pulses. It would be a little low based on Ed’s spec., but it’ll hold 4.5 psi on a pressure test. So I’ll use this as a guideline too. 

I would think you're close enough there. When my truck's pump died I got about a tablespoon 

[Plymouthy Adams]

1 hour ago, Merle Coggins said:

I just performed the test on my truck. I got 4 oz. After 15 pump pulses. It would be a little low based on Ed’s spec., but it’ll hold 4.5 psi on a pressure test. So I’ll use this as a guideline too. 

if it is as hot there as it is here, I would suspect it is evaporating faster than you can pump it....🌞

[Merle Coggins]

2 hours ago, Young Ed said:

I would think you're close enough there. When my truck's pump died I got about a tablespoon 

Yes, close enough. Especially since my truck runs just fine with it. 
 

59 minutes ago, Plymouthy Adams said:

if it is as hot there as it is here, I would suspect it is evaporating faster than you can pump it....🌞

LOL… it’s actually nice here today. Low to mid 80’s with a nice breeze. 

[Plymouthy Adams]

low to mid 80's sound closer to cost to fill my gas tank...

[rustyzman]

1/2 gallon per minute running is the basic standard for any stock gasoline engine.  Assuming you can get it running of course.  Carb or EFI is the same, just operating at different pressures.  The old SUN fuel pump gauges had a spring clamp on a bypass hose to check it.  Later EFI gauges also had a bypass button for it.

This is the standard we used in the shops and whatever service data we could find from different manufacturers generally agreed.