Dimensions of fuel pump motor

[Matthew Jeschke]

I have a brand new fuel pump assembly and sending unit. Pump motor is garbage. I've decided I'll swap in a good aftermarket pump from AEM, Holley or another reputable brand. However, I don't have the dimensions of the basket or pump itself to know which motor will fit. I called AEM and they hadn't a clue. I don't want to pull the tank off just to measure the size of the pump motor / dimensions for fitment. Anybody know where I can find pump dimensions and or have them? 2001 Tahoe

 

[rockola1971]

You can buy just the fuel pump itself and stick it in your OEM module. All you have to do is go by application year/make/model then. Yours is either a 1 3/4" pump or a 52mm (4 door model note) per rockauto for a 2001 Tahoe 5.3L. Of course just about any other supplier offers mutliple pumps brands for your ride. Unless you have some ridiculous fuel needs, I would stick with the OEM AC Delco! They will last well over 100k.

 

[Matthew Jeschke]

Delphi gave me a phone number to call after a couple emails with tech support but I really don't think they know what's going on. I'm on pump #2 and both have same symptoms. The OEM replacement pump is low on fuel pressure. I have another post here where my Key On Ignition Off pressure is approx. 20% low... The pump doesn't keep up very well with demand either (revving engine) ~ Not exactly sure what is typical been over 20 years since I last fiddled with fuel pumps and regulators... However, it drops pressure quickly when I just blip throttle blades (DFCO disabled in tune for test). I'd not expect it to fall so quickly. I find no issue outside the pump; electrical, line set, regulator, or otherwise maybe a leak evap line-set but purge valve works perfectly. Long story short, I think they're not building the pumps as well as they used to and or they changed the spec but not the marketing.

My fuel economy SUCKS too (evap leak??). I've been troubleshooting it for a year or longer. Truck runs great but I'm getting like 13 MPG highway driving like grandma. Found lots of minor faults chasing the fuel economy. I think the fuel pressure maybe aggravating it. Long story short; I'm looking for a quality, made in USA if possible, pump. Done fiddling with OEM on that part. They must have started sourcing pumps from China or something but seems they don't have the answer.

I'm not for sure how to find the basket size though for fitment of an aftermarket pump. I'm not too concerned about over spec'ing the pump so long as it's quality. AEM had no clue what size the fuel pump basket is for our trucks though. Called Summit and they weren't sure outside of if they're catalog didn't cross reference a pump motor.

FYI ~ I'm dumb, I replaced original pump for truck at around 250k miles. It was working perfectly but I figured would be a good idea cause I didn't want it going bad / stranding me. I should have kept it. Seems everybody I have spoke with who tested their original pumps had no issues w/ pressure. They got 55+PSI per spec. I can tested on my C5 corvette as well and is the correct pressure. Just this new Delphi pump (warranty replacement replaced for same low pressure issue) is wrong pressure.

 

[exp500]

Just to mention in case you have not looked- Try Rockauto and look at pump specs for 2001 suburban . You might find a big difference.At least it may provide a direction forward.

More Information for TYC 150045

More Information for AIRTEX E3509M

More Information for US MOTOR WORKS USEP3509

 

[Matthew Jeschke]

Just to mention in case you have not looked- Try Rockauto and look at pump specs for 2001 suburban . You might find a big difference.At least it may provide a direction forward.

More Information for TYC 150045

More Information for AIRTEX E3509M

More Information for US MOTOR WORKS USEP3509

Hey thanks man. That's a good idea. Thanks for the links. Some of them spec the fuel pump flow! Very helpful. It appears I may need around 127 LPH for 400 HP which my engine should be give or take a bit...

Gallons Per Hour = (maxHP x BSFC) / 6
BSFC is Brake Specific Fuel Consumption ~ 0.4 to 0.5 for NA gas.
3.8L/gallon

Video is quite helpful.

Not sure what size the fuel line set is for the truck though. It says 6AN fittings, 3/8" ID, would flow enough for 550HP. I don't know what size the factory line set is. However, I seldom if ever go WOT so not sure this is even my trouble.

Looks as though this next tank may break into the single digits, under 10 MPG I've checked in process of troubleshooting...

- Injectors are not leaking (leak tested).
- Line set is not leaking or clogged.
- New fuel filter
- No vacuum leaks
- No miss fires
- Engine is not knocking (nothing on scan tool / HPT VCM Scanner)
- New fuel pressure regulator
- No brake rub, wheels spin fine
- Transmission temps are good
- Transfer case fluid also looks good (quick and dirty check for excess rubbing in AWD clutches).
- No leaks on tank; filler & vent hose good, pump seal good, tank evap ports good.
- Small leak in evap system. I hooked mighty vac up to test port and it didn't hold pressure. Maybe inconsequential?
- Evap canister is shot. It flows but carbon is used up. Can see & smell fumes coming out vent when it's open.
- Small leak in input pipe to muffler (my crappy chicken welds didn't hold up when I installed exhaust).

 

[exp500]

I don't really want to mention it but feel as if I should.... The chance of a computer failure, mechanical, or possibly in one of the earlier flashes so every later one somewhat corrupt. Is that a possibility with your equipment?

 

[Matthew Jeschke]

I have a second computer. I could plug it in and see if it will work better. Might be worth a try. Thanks!

This latest tank of gas is dropping fast, like I suspect a leak but cannot find one. I need to double check AFR with the wideband.

Backstory, my most resent saga is... I had dialled in VE table (fuel calibration) about a year ago. Somehow my closed loop fuel suddenly got lean! Like 25%+ lean as in nearly 20:1 AFR. Engine BARELY ran. I kept adding fuel, as much as 50% more, to the VE table but mixture wouldn't enrich.

I decided to load a LQ9 baseline to the PCM and mixture was much better... Oddly the LQ9 baseline VE table is much leaner the table I was working on which wouldn't richen. So I copied the VE table into my tune and started recalibrating fuel. Got it running great open loop.

However, in that mess I realized the new drop in OEM pump I bought not quite a year ago had wrong pressure. 45 to 48 PSI KOEO. I got a brand new pump under warranty warranty replacement pump and same story! I put in a new pressure regulator, same story. I tore EVERYTHING apart, evap (again), fuel lines, rail, injectors, wiring harness, etc and it all works perfectly (minus small leak on evap). Only the pump is out of spec.

Another thing I noticed about the pump was I could cycle the ignition and it wasn't consistent pressure. I'm going to try my backup PCM as you suggested and see what happens.

 

[Donal]

I would be tempted to put the occillisope on the pump leads and see what the volts and amps are doing during operation.

 

[Matthew Jeschke]

Done.. I don't recall the readings but voltage was correct... However current wes not for advertised load. If memory serves me correctly it was lower than spec'd and also lower than diagnostic procedure from delphi.

 

[Donal]

If the amps were lower than published expected value, I would suspect a restriction in the line between the pump and the access point on the fuel rail. Remember that a centrifugal pump does the most work when pumping full flow and the amps should be high. When the volume being pumped decreases the amps decrease because the pump is not moving as much volume. If the pump is deadheaded, the amp will be very low.