How do I test mechanical fuel pump

[Eighty5ov]

I’m in a situation where I took off my quadrajet, without checking my fuel pump. Can I just crank it over a couple times without a carb on it ?

Now I’m looking at carbs and the Edelbrock setup calls for a fuel pump change to regulate the pressure and if mine is toast then I might as well go that way with it.

Any help is appreciated

 

[fast 99]

yes, but to be safe disable spark. Stock pressure should work around 5-7 psi.

 

[nvrenuf]

Put some sort of catch can on the fuel line or it’ll spit fuel everywhere.

 

[PrairieDrifter]

Just shove a bottle over the line, will only take 3-4 pumps for most of the bottle to fill.

 

[Ricko1966]

Gentleman I believe he is talking about a pressure test. Put your pressure gauge in the hose and crank. If it were me I'd clamp the pressure gauge into the hose,set the old carb back on the manifold dribble a tablespoon of fuel down each primary throat and start it.If you have more than 6lbs of pressure Edelbrock recommends a pressure regulator or fuel pump making 6lbs or less.

 

[fnny6770]

I have a 1978 454 it's in a 1980 GMC k3500, I may need to change the fuel pump so I'm asking who makes a good mechanical fuel pump for this engine? It has a fuel return on it

 

[Sad Sack]

I have a 1978 454 it's in a 1980 GMC k3500, I may need to change the fuel pump so I'm asking who makes a good mechanical fuel pump for this engine? It has a fuel return on it

Depends on what ya want to spend. What's the budget?

Always good things about Carter and inexpensive.

1978 CHEVROLET C30 Carter M6628 Carter Mechanical Fuel Pumps | Summit Racing

Free Shipping - Carter Mechanical Fuel Pumps with qualifying orders of $109. Shop Fuel Pumps at Summit Racing.

www.summitracing.com

 

[Grit dog]

You don’t need a regulator for an Edelbrock or really any carb with a mechanical pump.
To test, just crank the engine. If it squirts a lot of fuel it’s good.

 

[fnny6770]

Most of time it hardly puts fuel in the fuel filter

 

[fnny6770]

When I go to start the engine it'll crank and crank and crank and I have to add fuel to the carburetor and then once it's running then it'll stay running but I haven't tried driving it that way because the fuel filter remains practically empty

 

[Sad Sack]

Edit

 

[Ricko1966]

When I go to start the engine it'll crank and crank and crank and I have to add fuel to the carburetor and then once it's running then it'll stay running but I haven't tried driving it that way because the fuel filter remains practically empty

Empty fuel filter means very little.if the fuel filter is mostly full is more of a bad sign. Unless the filter is mounted vertical,it's going to trap air.Like a doctors syringe The more plugged the filter paper becomes, the higher the fuel has to climb to find a clear spot to come through. To test a fuel pump put the carbureator fuel linen in a bottle and crank you should get 8 ounces in 30-45 seconds. Check fuel pump vacuum on the inlet side and fuel pump pressure on the outlet side 3lbs or more. If you aren't having drivabilty problems,I don't think you need to test the duel pump.

 

[Ricko1966]

I was looking for vacuum spec. Look what I found. Way better than what I can write for you..https://www.kemsoracing.com/blogs/news/fuel-pump-vacuum-tester-your-essential-guide-to-diagnosing-mechanical-fuel-pumps-accurately?srsltid=AfmBOoqsbxKTCDAaOwfS2dGLpz-LLIoaLHgzmO6jEzUwCabuFKTWREmD

 

[fast 99]

I was looking for vacuum spec. Look what I found. What better than what I can write for you..https://www.kemsoracing.com/blogs/news/fuel-pump-vacuum-tester-your-essential-guide-to-diagnosing-mechanical-fuel-pumps-accurately?srsltid=AfmBOoqsbxKTCDAaOwfS2dGLpz-LLIoaLHgzmO6jEzUwCabuFKTWREmD

Interesting 10-15 hg. Checking the vacuum side, don't think I have ever done that except by hand with a finger over the inlet. That is one reason I recommend checking volume. no sucky. no volume.

FYI, went through several defective pumps on a 350 before I wised up and bought an AC unit. Not sure if the same issue crops up on big blocks. However, I think you'll have better luck with AC, Delphi, or GM parts.

Am not a fan of Carter. We will only use Carter in-tank pumps if nothing else is available. We have had warranty/replace too many. The mechanical pumps might be fine don't know. Personally wouldn't take a chance.

 

[Sad Sack]

I was looking for vacuum spec. Look what I found. What better than what I can write for you..https://www.kemsoracing.com/blogs/news/fuel-pump-vacuum-tester-your-essential-guide-to-diagnosing-mechanical-fuel-pumps-accurately?srsltid=AfmBOoqsbxKTCDAaOwfS2dGLpz-LLIoaLHgzmO6jEzUwCabuFKTWREmD

Now that is a write-up!