I fitted a 455 walboro, they have check valves built in.

 

^ did you decide on the walbro to complement the largers injectors and has that been a difference you can feel? or is difficult to isolate as all mods are cumulative, i realize. i ask since injectors may well be in my future and everyone that upgrades has been walbro with SRM stuff quickly coming up from behind given its recent introduction. to hear it told.

 

Popping the old pump out was cake! For the next person trying this https://www.6speedonline.com/forums/...-pictures.html that thread is helpful.

Pull lines off pressing indented tabs, unplug electric, unscrew big nut. Mark location of top plate, maybe snap a picture. Pull up fuel level indicator and top plate, disconnect lines and wires gently. Wiggle out sender float. Reach into tank and disconnect side feed line that has an indentation on right side. Press button on side feed connector and disconnect it. Unplug large black hose that goes towards back of car - is about a half inch around. disconnect left side feeder by pressing button, don't recall having to do a separate hose here. Turn pump assembly left a quarter turn and it's ready to pop out! Easy peasy!

Basket disassembles by lightly lifting tabs around the sides, be gentle as it could be brittle. Separate halves. Pump is removed by lifting tabs on the body too. Mine has zero markings on it but I can tell someone had been in the tank before I have some pics if anyone cares but the linked thread is pretty clear overall.

Ah, just found this thread from Tim! Even better and he's got some good assembly tips in it. Much thanks to Tim!

Will source a pump and get it rolling ASAP, pretty darned sure this was the culprit and really happy it was this easy to get access to. Not sure I want to do a 455 E85 pump only because it'll only be in there for a month or so before the car goes to Garth lol

 

I fitted one walboro to start with as we thought we had a pump issue and we needed more fueling for the hybrid K24's I was running so went 455 and 5 bar reg, I now have 2 455's and 2 -6 feed lines and a -6 return, with 1100cc injectors and Alpha 28's I think we are 45% duty cycle.

 

i wonder if anyone has quantified the gains/drawbacks of running dual 044's vs the dual walbros. i would imagine esp at the power levels you're at, the difference(s) if they exist would be mostly academic. either way, i think one's enough for me. thx for the info.

 

You don't want too little pump (duh), you don't want too much pump. You also don't want sky high pressure past what the injector manufacturer may have desired.

With too much pump you churn the fuel constantly bypassing it back to the tank and you can even overrun your return and see whacky fuel pressure issue - which may not show up until the pump has some mileage! (been there, done that)

With multiple pumps I'd always stage them both for voltage draw reasons and for volume\churn reasons. I prefer not to run pumps in parallel. Multiple pumps can draw big power, especially under high pressure. On my Supra I staged pumps after overrunning the return when broken in and I ran a higher amperage alternator to support it. The voltage draw curves for some pumps are crazy so pay attention to the electrical feeds and the draws. Even if you have massive fuel flow and volume you still have to sweat things like rail volume and pressure fluctuations if you run big injectors. I'd prefer injectors sized to see higher than 50% duty on my chosen fuel. Since I'll run E85 occasionally mine are larger than what I'd normally do for just gas so on gas the duty will be lower than I'd normally want - it's a compromise.

I'll be running dual pumps on my car from SRM soon. I'll stage them and may be able to easily make my goals on a single pump honestly but with E85 I'll want the volume available and hope that more stations here begin to carry it soon. For now I just need a single pump to get the car back to running and to make the trip to get the big fuel system installed

 

I might have missed it in the thread but with all your trouble shooting did you check your fuel filter? Was your pressure gauge before or after the filter? And now that you have the pump out, can you bench test it to make sure that it is the culprit?

 

No, I didn't check the fuel filter and I'll admit I considered that it might be clogged. However the groaning sound the car makes priming, the fact that it only seems to have issues when hot, and the fact that it had no fuel from just a prime but had fuel after cranking makes me think it's the pump. I'll admit I could be wrong but I think this is a good bet! All of it is due to be replaced soon with shiny SRM parts.

Gauge was fitted to the test port in back which I suspect is post filter. Fingers crossed I've not made a poor assumption on the filter.

 

My friend runs twin 044's and suffers massive fuel overheating.

 

As im going to be running 3582's I think 1100cc inj may be way too small on E85

 

When I built my MKIV Supra...I used 2 brand new in-tank Supra pumps. They pump as much or more than any aftermarket fuel pump, and draw less power. (Poor pictures, but they were taken with the first flip phone with a camera)

 

If anyone is interested in just fitting a walboro into the stock pump location I can get a fitting machined up so it is literally a drop in, one of my customers has just done this and is happy to make more

 

Okay, I'm stumped and could use a little help!

I've got a pump to use, a 455lph Walbro - thank you Garth! I've managed to mount it in the can and I wired it but before installing into the tank I wanted to test prime it as it's a used pump.

Plugged in harnesses, turn key, NO noise from the pump. I'm not cranking mind you just turning it forward. Every EFI car I've worked on will prime the system when you do this - I get nothing here. This is what I was doing when I tested system pressure too BTW.

Confused, I plug in the old pump. Same behavior. I bench run both pumps, old pump runs and spins, Walbro pump spins then whines after a second or three. This is dry so I'm not too freaked out by this but both pumps work for sure.

Lastly, the groan I'd been hearing under the hood previous is still there. ABS pump or something else must be doing this. Is the fuel pump on these cars supposed to prime when the key is turned? Up until now I've assumed the rumbles I've heard turning the key forward was the fuel pump.

So - previously it would run and start fine cold. Once warmed it wouldn't restart without sitting a bit and it stumbled once and shut off at hot idle but only once. I think the MAF is fine. I need the car reliable so I can drive it 3+ hours to Garth's shop for EMS and fuel system replacement

 

Not sure if you checked it yet, but bad intermittent fuel pump relay? Pull relay and just jump it out temporarily?

 

I'm starting to wonder about that honestly, no I've not checked it and I'm going to have to figure out where it lives. I'm pretty frustrated!

Swapped in Garth's pump, no start, no fuel pressure. Pulled out pump and checked it by jumpering power out of the car and away from vapors - it spins. Swapped in old pump, turn key, fires right up! Warm it up and shut it off - fires right up!

Going to drive it tonight. I'll take the pressure gauge and a flashlight with me and hope like hell it doesn't strand me!