Pump reservoir
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Pump reservoir There's been lots written about what kind of in-tank pump people are using but I haven't found much about the "container" that the in-tank pump goes into. I'm about to build one for a Walbro pump using a GM top flange with standard GM Quick disconnects. The tank is a poly TANKS unit with baffle. Does the pump NEED a reservoir? Show us pictures of your pump.
Unless you're willing to deal with occasional, sudden and intermittent shortages of fuel at the injectors or carb while the engine's trying to run -- you need some way of assuring that the pump pickup stays submerged as fuel moves around in the tank when fore/aft/lateral g-forces are present. Usually handled by vented or baffled reservoir inside the tank or a small sump that's part of the tank. Just like an oil pump pickup is handled.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Pump reservoir You mentioned "small sump" and that's what I'm really wanting to know. The cup or sump on a factory pump is small, just big enough to fit thru the hole. The one I have is about 3 1/2" in diameter and about 4 1/2" deep. Of course the pump is in the sump which takes up some of the area for gas but I think there is a little over a cup of fuel in that sump. Is that enough to smooth out the waves?
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Pump reservior This is going into my '39 street rod that has a stock 5.3. I'm plagued with high long term fuel trims right now. I have a stock Trailblazer pump in the tank, converted the fuel rails to non-return and a 'Vette filter/regulator. Fuel pressure is about 55 lbs at the rail. Not sure if it's pump, regulator or gauge is the problem.
TECH Enthusiast
Joined: Feb 2007
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From: Raleigh, NC
Does the engine ever stumble during braking, cornering, or acceleration?
If no, not likely to be a fuel bucket problem.
edit - If I were having this problem I would figure out how to retrofit an OEM bucket assembly. It's easier to leverage the OEM engineering on the fluid system, and figure out how to fabricate a tank opening and mount, than vise versa.
If no, not likely to be a fuel bucket problem.
edit - If I were having this problem I would figure out how to retrofit an OEM bucket assembly. It's easier to leverage the OEM engineering on the fluid system, and figure out how to fabricate a tank opening and mount, than vise versa.
My questions similar to Holden - are you able to monitor fuel pressure while driving? If so, does it falter? If not, I'd expect high long term trims are a tune or component incompatibility issue. Are you getting a check engine light - any other relevant codes?
Pickup going dry most associated with drivability/stumbling issues in long duration turns while trying to accelerate or stumbling when accelerating hard over a long period, all exacerbated (or only occurring) when the tank is low on fuel.
Pickup going dry most associated with drivability/stumbling issues in long duration turns while trying to accelerate or stumbling when accelerating hard over a long period, all exacerbated (or only occurring) when the tank is low on fuel.
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Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Fuel reservoir Can't monitor the fuel pressure while on the road but I can watch the LTFT bounce around which is, I think, connected to the throttle pedal and not fuel starve. Not sure where the weak link is and I like to carry a spare pump while on trips that's why I decided to build a pump with sump and hopefully rule out low pump output. I assume that the filter/regulators are tested for correct settings but not sure of that. Cleaned the MAF as well as hunted for a vacuum leak. As soon as I get the new Walbro pump I'll post pics of the build.
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Verdad Gallardo Lots complain of Walbro noise -- if you're open to another approach, I use a DW300 (Deatschwerks). More capacity than W255 and as quiet as a church mouse. I can't even hear it prime inside the car. 5-6 years of flawless performance in mine.
Appears there may be some good tank info here -- https://ls1tech.com/forums/conversio...brication.html
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Got in touch with PSI who did the programming and did my harness. He suggested I put new fuel in, dump a bottle of injector cleaner in and go for a long ride. I did. After driving about 40 miles I noticed the trims were down to just above 10. Great...this is working. Stopped at a guys shop for a while and when I left the trims were back to 25% but dropped over the next 10 miles. Stopped again and the trims went high as I left. Got home and put the gauge on and it read 55 lbs as usual.
Got my Walbro pump yesterday and try as I might I could not get it in the stock GM bucket. Built a tray 1 1/2" high and 7" long to put the sock in. Question is: how big should I make holes for fuel to get in the tray? Wish I could use the GM bucket check valve but it's all plastic and my new tray is steel.
Got my Walbro pump yesterday and try as I might I could not get it in the stock GM bucket. Built a tray 1 1/2" high and 7" long to put the sock in. Question is: how big should I make holes for fuel to get in the tray? Wish I could use the GM bucket check valve but it's all plastic and my new tray is steel.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Forgot to ask a question. Does altitude impact the fuel trims? The standard fuel rails on a 5.3 has a regulator with a vacuum hose but the 'Vette filter/regulator could care less about engine vacuum. I'm at 4500 feet.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Well, that didn't work! Installed a Walbro pump in my homemade container and everything worked exactly the same. Pressure was at 55lbs just like my other pump and fuel trims maxed out. Beginning to think the problem is actually in the program. Is it possible to have the wrong data in the ECU such as wrong injector info that will cause this problem?
FYI the Walbro pump was not noisy at all. I could hear it prime but could not hear it run and after I shut the engine off it held pressure better than my other two GM replacement pumps. I will carry it as a spare.
FYI the Walbro pump was not noisy at all. I could hear it prime but could not hear it run and after I shut the engine off it held pressure better than my other two GM replacement pumps. I will carry it as a spare.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Pump reservoir Yes, PSI were the one's who told me I should go to the 'Vette style non-return system. Just wondering if they got the injector poundage wrong in the program. That's about the last thing I haven't changed.
Last edited by 33willys; Jun 10, 2017 at 02:38 PM.
I'd expand your dialogue with them....I think they'll help you find the issue. Hardly any of us thought it was a pump issue. They were quite helpful with me working a couple of start up bugs out.
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
Come Monday I'll do that. Gone as far as I can go here. My injectors are 22 lb/hr and I wonder if the ECU thinks they are bigger? Would that cause the problem?
Depends on how big the mismatch is. The ECU with feedback from O2's has the potential to "learn" and adjust so that it's injecting the appropriate amount of fuel through the smaller injector. However, if you're heavy on the throttle a lot of the time and the injectors just won't flow enough, I'd think you'd be showing some "lean" codes too.
If you can access a/f ratios real time through an app or data log (or maybe you have a gauge) -- see if it's consistently going lean under heavy extended throttle. Did they ask you to supply your injector size?
If you can access a/f ratios real time through an app or data log (or maybe you have a gauge) -- see if it's consistently going lean under heavy extended throttle. Did they ask you to supply your injector size?
Thread Starter
Joined: Mar 2014
Posts: 699
Likes: 59
From: Alamogordo, NM
I was just laying on the couch thinking about what is driving the lean condition and of course it comes down to the O2 sensors. I'll see if I can watch the voltage on them to see if they indicate something else going on. When I took my extended drive lots of it was at 65 MPH and the LTFT actually dropped to 10-12 range. After running a while (20 minutes) the trims seem to drop to mid teens but if I stop and shut off the engine for, say 15 minutes, the trims will max at 25% for a while after restarting.