Fuel Pump Serviceability Testing

[GTR_JOEY]

Hi all

long story short, the car has been off the road for quite some time now so I want to test the serviceability of the fuel pumps. I want to do this as it will save time at the tuners as they are very busy.

Basic run down of the system.

Nismo pump as the lift pump to the surge tank

twin Walbro 400lph's in the surge tank

those 2 pumps supply fuel to a twin entry rail after running through individual in line filters

then off to a sard fuel reg and through back to the surge tank

There is also a return line from the surge tank to the main tank

I need to check the serviceability of all 3 pumps so im just chasing a simple procedure so correct me if im wrong here

The nismo intake that feeds the surge tank is under minimal pressure so i should just be able to give it 12-13 volts see how long it takes to pump out a litre of fuel. The pump is rated to 275lph though im assuming that is at a base pressure of 30 or 40psi, so in that case under no restriction it should pump even more then 275.

Now for the 2 walbros,

Originally what i wanted to do was place a pressure gauge between each feed line and the reg then measure the amount of flow per pump relative to the pressure. BUT the engine doesn't run so i cant apply a consistent amount of boost or vacuum to the reg so that wont work.

This chart suggests that the Walbro 400 will flow 413 litres per hour @ 12 volts with no restriction but Surely to test the Walbro pumps properly i need some sort of restriction?

If this is the case will the -6 lines with the inline filters give me the restriction i need to create pressure?

cheers in advance

[GTR_JOEY]

Also forgot to mention that the fittings on the gauge I'm using are stepped down so that would create some sort of restriction

[89CAL]

You will probably just need to stick some gauges in. Its hard to say what restriction the -6 lines will create, but you have a graph there which tells you what L/hr at 'x' psi so you should be able to use the fuel reg to set that and check the flow of the pump (s)

Sounds like you are on the right track anyway, the intank pump is easy for me if it has no real restriction, as long as it can keep up to demand it doesnt really matter, so test it as it would work in the car (I assume this is done easy enough by just making it run till it completely fills the surge tank, then work it out on size of fuel tank and time taken)

As for the 2 external pumps, if they are run constantly and the return fuel measured over time it should give you combined flow of the pumps, im not 100% sure but deviding this number by 2 might give you individual pump flow (avg)

As an experiment it would be good to do this then test both pumps indivudually and see if the numbers match up. Testing them individually is probably a better idea anyway so you can pinpoint the weak pump (if one of them is). Assuming that you have a decent enough fuel setup i assume you have an adjustable reg, so just set the pressure at whatever value you want to test as per graph. The only thing that might be an issue is keeping a constant 12v to the pump for accurate testing. Maybe might be easier to test it will connected to another running car and doing the test at 13.5v

[scotty nm35]

It would cost less to buy a new Walbro than get it accurately tested with shipping both ways I suspect. The flow won't change much anyway, the only part that would fail is the DC motor, as it corrodes in moisture.

If anyone is running a 30 amp relay with these, you may want to upgrade to a larger 70 to100a+ relay. I have seen so many 30 amp relays flog out on 460L Walbro's, usually they take other components with them.

[GTR_JOEY]

Cheers for the replies lads,

Cal for the lift pump im just gonna see how long it takes to fill a 2L coke bottle. Like stated before, no restriction should imitate how it will work in the car.

For the Walbros i think its best to test them individually. I have a good battery that should be able to maintain enough current to test each pump, also have a multimeter so ill be able to double check anyway. Regardless, its a very good point!

Also, the FPR i have is a Sard but i cant manually adjust it from memory, just runs off vacuum/boost. That's why i was thinking the smaller fittings on the gauge will work as a restriction.

Scotty, the pumps are 400's, have you heard about any dramas with these? Also ill have to double check but im pretty sure the pumps are fused with 30 amp fuses though im not sure what relays are being used. They've done over 10,000km so far, but I will double check what they are.

cheers

[89CAL]

Sard fuel regs are adjustable i think where the van line goes on. Its a weird setup but if im thinking of the same reg it is adjustable

Your battery will drag down a little bit initially so should be fine once the pump gets up and going

[GTR_JOEY]

Probs easier to use a running car

Will have a good look at the reg on Monday

[scotty nm35]

Is it the sealed connector E85 Walbro you linked above?

The non sealed petrol version is what most call the 400L, these have major issues with e85, hence the need for an e85 tolerant version not long after.

[GTR_JOEY]

That's just a link to a table I found when I searched "walbro 400 lph chart"

To be honest I can't remember what's in the surge tank, it was done in mid 2012 so ill have to pull that apart as well

[GTR_JOEY]

Dunno if you can tell from that, I cant

[scotty nm35]

I have never sold the non sealed connector version, but the e85 pump is all anodised internally with a plastic impeller. The only problem I have seen with one was corrosion on the magnets from testing it with water, it was seized solid.

I can't imagine there would be any issues with yours, and a quick test it still runs would be enough to run it up on the dyno safely imo.

[scotty nm35]

Dunno if you can tell from that, I cant

No, sorry Would need the part number or just check the connector end.

[GTR_JOEY]

I drained the tanks completely once I blew the engine, everything ran fine before but I am worried about any residue from the Ethenol wrecking the pumps. In hindsight I should have flushed them with petrol.

I will hook them up and see how they flow without restriction first and see how they go from there.

Will report back

Cheers

[scotty nm35]

Probably better to spray some WD40 up into the turbine pickup, just to coat the metal parts.

[GTR_JOEY]

No worries man,

Thanks

[GTR_JOEY]

Here Scotty,

Looks like the non e85 ones man

[GTR_JOEY]

Is it the sealed connector E85 Walbro you linked above?

The non sealed petrol version is what most call the 400L, these have major issues with e85, hence the need for an e85 tolerant version not long after.

The only difference I can see from the 400 to the e85 compatible pump is the plug. As you can see from my pic the plug isn't even used In my set up.

Correct?

[scotty nm35]

Not sure what the internals of those are like, very similar in the motor i am sure. I will ask my wholesaler tomorrow if they know the differences other than the sealed connector.

[GTR_JOEY]

Well it's confirmed..

My nismo has survived but my 400s are absolutely cactus!

Going to look at alternatives

[KiwiRS4T]

I don't know why you think your fuel lines will be an adequate restriction on their own. If they are they are not suitable for the job of supplying fuel to the engine. . And your Sard fpr should have a base setting of 2 bar or whatever so should be a sufficient test for the pumps.