Can a fuel pump be bench tested?

[84_t-type]

I have my tank pulled and replacing the fuel lines and was wondering if I can bench test my fuel pump? If so what is the best way to do so? The only thing I know is that the fuel lubes the pump and should not be run with out fuel or fluid. I have searched around the inter web and have not found too much on bench testing. I would like to ensure that the pump is good before reinstalling it in the tank.

Thanks

 

[turbo nasty]

How old is it?

 

[84_t-type]

Well it is a new one bought 5 years ago with no miles. When I rescued my ttype I replaced the original one with this it ran fine then would not start. I can't remember if there was any pressure at the rail ( this was 5 years ago the last time I worked on it). I am just trying to get it running before I start to make performance mods. I don't want to but stuff that is just going to get upgraded soon. Side note can I test the pressure regulator? I have plans to up grade both later one when more funds become available.

 

[earlbrown]

It would probable be less trouble to install everything to test it than to gather up all the hoses, fittings, clamps, wiring, etc... to build a bench.


That being said, about a month ago I bought a blazer with a questionable fuel pump. I just happend to have a 100PSI gauge and a brass barbed fitting that would fit. I cut the top off a milk jug, poured gas in it and powered the pump with a cordless drill motor battery. All that told me had adequate deadhead pressure. I had to install it to check for any extended heating problems, regulator problems, etc...

 

[84_t-type]

Ok well I am a pro at dropping this tank. So worst case I have to drop it agin and swap it. I am still a few weeks away from installing the new tank so I was just wondering.

 

[belsie]

Take a pretzel jar with large open top place pump on hanger assembly and set in jar. Fill jar 1/2 way and run a hose from output to return side, create power (splice a matching connector or ?) and pump will run as if in the tank. Did this last year and ran pump for app. 4 hours to test. Keep bucket of water or extinguisher handy just in case!!

 

[Nick Micale]

I have my tank pulled and replacing the fuel lines and was wondering if I can bench test my fuel pump? If so what is the best way to do so? ........Thanks

It is very simple if your tank is out of the car.

Leave the pump in the tank and just put power and ground to the pump.

Since pumps are rated at liters or gallons per hour, pump out gallon a or more into a container and time it.

You can then calculate to determine if your pump is up to spec or not.

 

[turbo89]

It is very simple if your tank is out of the car.

Leave the pump in the tank and just put power and ground to the pump.

Since pumps are rated at liters or gallons per hour, pump out gallon a or more into a container and time it.

You can then calculate to determine if your pump is up to spec or not.

Nick... will this really tell you If your pump Is upto spec ??

A 255 lph pump may hit that spec with Zero pressure against it.. but will it produce 255 lph @ 45 psi is another matter...

If you want to really test the pump you have to check it with the pressure it will be working with..

Also another point is the power your putting to the pump ... whats the power source ? 11.5 V ... 12 V .. are you powering it with what the actual wiring of the car is providing ?
you will see a big difference between a 10 V power source and a 14 V power source

to the OP ... if your going to lean on the car .. don't skimp in the fuel pump dept. ... they aren't much money and are key to making power ...

 

[turbo89]

Ok well I am a pro at dropping this tank. So worst case I have to drop it agin and swap it. I am still a few weeks away from installing the new tank so I was just wondering.

its easy to create a bench setup to test this.. but if you don't want to go through the hassle let me know I can test the pump for you

 

[Nick Micale]

Nick... will this really tell you If your pump Is upto spec ??

A 255 lph pump may hit that spec with Zero pressure against it.. but will it produce 255 lph @ 45 psi is another matter...

If you want to really test the pump you have to check it with the pressure it will be working with..

Also another point is the power your putting to the pump ... whats the power source ? 11.5 V ... 12 V .. are you powering it with what the actual wiring of the car is providing ?
you will see a big difference between a 10 V power source and a 14 V power source ...

I do not know if you are just "bustin' my balls", or you have a better method to test a pump like the OP asked?

One thing I do KNOW after pumping out hundreds of GN fuel tanks, you can see the difference and measure the difference by volume vs. time.

I usually time a given quantity of fuel of an old pump when I am replacing it and time the quantity with the new pump. Since the battery voltage is almost the same before and after, I consider this a valid test.

So with your experience on actual cars, you have a test method that makes mine not valid?

The better test for fuel delivery is to read a fuel pressure gauge when driving from idle to WOT, but OP has a Hot Air street street-driven car that he would like to be reliable, and will upgrade it later.

 

[Marty Fairchild]

Exercise extreme caution here.
Gasoline and an electrical arc in close proximity would not be good!
Do NOT use water,CO2 and a dry chem. fire extinguisher should be close at hand.
Just an old firefighters 2 cents!

 

[84_t-type]

its easy to create a bench setup to test this.. but if you don't want to go through the hassle let me know I can test the pump for you

Where do you live I might take you up on that?

 

[Raeban]

I do not know if you are just "bustin' my balls", or you have a better method to test a pump like the OP asked?

One thing I do KNOW after pumping out hundreds of GN fuel tanks, you can see the difference and measure the difference by volume vs. time.

I usually time a given quantity of fuel of an old pump when I am replacing it and time the quantity with the new pump. Since the battery voltage is almost the same before and after, I consider this a valid test.

So with your experience on actual cars, you have a test method that makes mine not valid?

The better test for fuel delivery is to read a fuel pressure gauge when driving from idle to WOT, but OP has a Hot Air street street-driven car that he would like to be reliable, and will upgrade it later.

Nick- the test you are performing is a free flow test and as you have indicated there are measurable differences in pump performance with this type of test. I used to do this test on my carbed race car to watch out for pump deterioration over the course of a season. The trouble is that it becomes hard to compare the pump you are testing without having a good pumps performance to compare it to. If you had some of that information from previous tests it would certainly be a gem indeed.

What turbo89 was referring to was confirming if a pump is performing to factory specs. To accomplish this a pump must have a set voltage and head (PSI) as a pumps performance curve is an inverse function of flow vs head. Flow also tends to increase as supply voltage increases as well.

 

[87GN_70GS]

Very simple to test a pump's output under a load or expected operating conditions. Find a graph/table of pump flow vs pressure. Safety first. Leave it in the tank as mentioned earlier or mount it and submerge it in a suitable container. You will need a suitable power supply - either a battery charger and battery or bench type (lab) supply with adequate current. Plumb a regulator setup (either an external pressure regulator or remove yours from the car and make proper connections) or use the manual method - simple manual valve and pressure gauge - adjust flow to get the desired pressure. Use a stopwatch and record the time required to fill up a measured bucket. Check at a few pressures and collect flow data. Flowrate is fluid amount divided by time with the proper units.

 

[Mike Licht]

even easier, leave everything alone and connect a hose to the schrader apply power and measure time/ output this gives you system volume under pressure which is the only way a pump can be tested properly IMO. (Without a real test stand) even the few Walbro pumps that had the bad bypass valves in them years ago would pass a free flow test.

 

[turbo89]

even easier, leave everything alone and connect a hose to the schrader apply power and measure time/ output this gives you system volume under pressure which is the only way a pump can be tested properly IMO. (Without a real test stand) even the few Walbro pumps that had the bad bypass valves in them years ago would pass a free flow test.

Mike I fully agree .... this was my point .. many pumps can pass a free flow ... ramp them up under load and .. TOILET !

also why I bring up the power applied .. also why I bring up load, also why I bring up heat cycling the pump ...

I have a bench setup that i use.. it takes a while to fully test a pump ... It's really interesting to see a pump work just fine initially but after 15 -20 minutes of run time and under load that the numbers FAIL the specs of the pump.

With these cars you don't skimp or mess with fuel delivery.

 

[GNRick]

Mike I fully agree .... this was my point .. many pumps can pass a free flow ... ramp them up under load and .. TOILET !

also why I bring up the power applied .. also why I bring up load, also why I bring up heat cycling the pump ...

I have a bench setup that i use.. it takes a while to fully test a pump ... It's really interesting to see a pump work just fine initially but after 15 -20 minutes of run time and under load that the numbers FAIL the specs of the pump.

With these cars you don't skimp or mess with fuel delivery.

Any particular brand/pump you would recommend? My Red's XP pump is still running strong after 3 years as far as I can tell.

 

[GNRick]

even easier, leave everything alone and connect a hose to the schrader apply power and measure time/ output this gives you system volume under pressure which is the only way a pump can be tested properly IMO. (Without a real test stand) even the few Walbro pumps that had the bad bypass valves in them years ago would pass a free flow test.

Would you put the rear up on jack stands and floor the gas pedal to simulate load? Then measure the amount of gas pumped out in say 10 seconds? Sounds kind of dangerous but how else do you simulate load?

 

[turbo89]

Any particular brand/pump you would recommend? My Red's XP pump is still running strong after 3 years as far as I can tell.

Funny you should ask.. I just got done replacing a Red's duel setup because 1 of the pumps was weak... I replaced both pumps with DW301's .. now the customer has TOO MUCH FUEL !!

I have had the best results with the DW pumps .. especially on E85 ... put simply they work and out of all the pumps Ive used in years ... I've only seen 1 DW failure .. It was a simple no hassle exchange ..
I am not a fan of the walbro's... too many failures.. warranty replacement is a joke.

 

[turbo89]

Would you put the rear up on jack stands and floor the gas pedal to simulate load? Then measure the amount of gas pumped out in say 10 seconds? Sounds kind of dangerous but how else do you simulate load?

you can use the factory return line to fill a measured container.. but the best scenario is to have a bench setup that you can repeat the tests in succession and have real answers and see actual performance of both injectors and fuel pump with relations to rail pressures @ boost levels .. pump out put as it correlates to boost pressure.. this also would keep voltage fixed and give you actual flows of the pump in real world conditions.