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Settle a debate. Fuel pump edition

Wisconsinite

Wisconsinite

Red Skull Member
Joined
May 19, 2020
Member Number
132
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1,017
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Milwaukee, WI
A buddy is building an ultra4 stock class jeep TJ with a bone stock 4.0l. He is using a fuel safe fuel cell, and an aeromotive fuel pump system.

They are trying to set him up with a Aeromotive 340LPH pump FOR A STOCK TJ. We are currently disagreeing whether or not having a pump that large is going to be an issue or not. I don't think a 340LPH pump will be beneficial due to the extra heat that will be put into the fuel due to overworking it, and returning 90 percent of it back to the tank via the return line from the regulator.

Flow chart for the pump they selected below, keep in mind his system will need to provide 40 PSI to the rail. I don't know why he needs anything bigger than a stock pump for his stock engine, stock rails, stock injectors. I have been wrong in the past, and could very well be wrong on this too.

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What says IBB?
 
Regulated with return or stock fuel system/regulator.

50 lbs/hr = 100 hp
so 550 lbs/hr = 1100 hp??
 
CarterKraft said:
Seems excessive?
No idea on how much return is ideal.
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I would assume that you would want enough flow out of the pump that you have whatever your ideal fuel pressure is when the engine is running full out with the injectors flowing as much as they're going to.
Anything more than that is wasted energy and money.
If everything is stock and there are no plans to "go faster" with anything, it would seem that anything much over stock would be overkill.

Aaron Z
 
I have been through 3 automotive 340 pumps on my dd with only 430 whp. I wouldn't oversize the pump that much on a jeep, especially not an automotive 340.
 
went trough couple of those pumps. swapped to dual Bosch 044 system 56 psi base and its been trouble free every sense. second pump comes only in when needed. flex fuel system in bbc
 
I’ve started typing this 10 different ways and don’t know how to proceed. Would you be interested in taking advice from an old timer who learned a bunch of hard lessons in 4.0 based fuel delivery in Ultra4? That’s an unobtanium aluminum head 5.0 stroker fwiw.

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For a bone stock 4.0 race car(they never stay stock) why would you want something complicated? Surge tank and cooler? Return line from engine with cooler? Duel stock pumps in tank? Best filters you can get, plus hydromat and baffles or foam.

If OPs friend wants a winning combination then do what JR4X says.
 
What’s wrong with factory fuel pump & housing assembly? Especially for a stock 4.0.

There are fuel cell kits to reuse the factory set up. You get to have functioning gauge if retaining the factory instrument cluster and they’re known to work well with low fuel level at steep angles.

The simpler it is, the easier it is to be reliable and troubleshoot.

I’d be worried about sucking air at low fuel level with a high flow rate pump due to so much fuel get returned to tank or sucking a corner of tank dry quickly.
 
TrailTamer said:
What’s wrong with factory fuel pump & housing assembly? Especially for a stock 4.0.

There are fuel cell kits to reuse the factory set up. You get to have functioning gauge if retaining the factory instrument cluster and they’re known to work well with low fuel level at steep angles.
Click to expand...

Because it’s going to get hotter under the hood than non racers have ever ever had to deal with. Ultra4… rules that are counter intuitive to longevity when it’s an endurance race. Must retain the complete inner fender well. Cannot cut holes in the hood to let heat out. No louvers no hood scoops.

If you run the factory dead headed fuel rail you are setting yourself up for pure trouble. The 4.0 has two major engineering fails that cause the #6 cylinder to get murdered.

And what U4 legal fuel cell will accept the factory Jeep fuel sender?
 
JR4X said:
Because it’s going to get hotter under the hood than non racers have ever ever had to deal with. Ultra4… rules that are counter intuitive to longevity when it’s an endurance race. Must retain the complete inner fender well. Cannot cut holes in the hood to let heat out. No louvers no hood scoops.

If you run the factory dead headed fuel rail you are setting yourself up for pure trouble.
Click to expand...
It'll be best to have the regulator AT the fuel rail? Otherwise fuel vapor remain a problem with aftermarket fuel pump if the regulator is mounted to frame rail or somewhere else far away from engine...

Pretty sure all TJs came with return-less fuel system. I think 97-04 are regulated at 49 psi, 05-06 at 60 psi. I'll want to run the 05-06 fuel pump as vapor lock is less likely when operating at higher pressure.

JR4X said:
The 4.0 has two major engineering fails that cause the #6 cylinder to get murdered.
Click to expand...
what 2 things? fuel vapor locking and lean out the #6 cylinder? insufficient cooling?

JR4X said:
And what U4 legal fuel cell will accept the factory Jeep fuel sender?
Click to expand...
I can't find one a "bolt-in" for a TJ on my quick search but I found this.

1679495004273.png


I think a bolt-on ring (as how the rule book says, "mechanically sealed by a ring and counter-ring system by either flat joint or an O-ring") for the fuel sender and somehow add a "nest" in bottom for the sender to sit in (like factory tanks) to keep bottom end secured is acceptable?
 
TrailTamer said:
It'll be best to have the regulator AT the fuel rail? Otherwise fuel vapor remain a problem with aftermarket fuel pump if the regulator is mounted to frame rail or somewhere else far away from engine...

Pretty sure all TJs came with return-less fuel system. I think 97-04 are regulated at 49 psi, 05-06 at 60 psi. I'll want to run the 05-06 fuel pump as vapor lock is less likely when operating at higher pressure.
Click to expand...

All 4.0’s came with a returnless fuel rail. If you want to keep one alive you need to make it a flow through fuel rail and regulate it after the fuel rail.

TrailTamer said:
what 2 things? fuel vapor locking and lean out the #6 cylinder? insufficient cooling?
Click to expand...
Yes those are both the problems. A 4.0 doesn’t get adequate coolant circulation to the back of the engine so cylinder 6 runs hotter than the rest. The fuel rail dead end is under the cowl and gets vapor issues on just cylinder 6. Between the hotter cylinder temp and lean fuel it detonates the top off the #6 piston. Not much you can do about coolant circulation but making cool fuel flow all the way through the fuel rail and return some to the tank will save that back cylinder.


TrailTamer said:
I can't find one a "bolt-in" for a TJ on my quick search but I found this.

1679495004273.png


I think a bolt-on ring (as how the rule book says, "mechanically sealed by a ring and counter-ring system by either flat joint or an O-ring") for the fuel sender and somehow add a "nest" in bottom for the sender to sit in (like factory tanks) to keep bottom end secured is acceptable?
Click to expand...
That was the point of my pointed question. There isn’t one, and that’s fine, I’m suggesting NOT using the Jeep sender in a raced rig. A Bosch 044 or Ford E2000 external inline pump will more than supply reliable fuel to a stock or even stroked 4.0 and keep from suffering lean conditions and detonation the 4.0 is famous for.
 
mobil1syn said:
sounds like the cowl needs to breath
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Suggestions? Firewall has to remain sealed from the occupants area.

Our bronco breathes out the cowl but I don’t think the Jeep tub is built the same way
 
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Wisconsinite said:
They want him to run an external regulator set @40psi, and then run a return from the reg to the tank.
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If the regulator is external and is essentially running over a relief path, it's going to add a ton of heat to the fuel if the engine isn't using most of it. If the engine is stock, the stock pump should be more than enough and retain factory longevity.

Hydraulic systems run over a relief are on/off use type systems, if they're left on they can get hot enough to boil the oil in the tank from relief resistance. That would be hazardous in a fuel system.
 
thank for your reply. I don't race so I don't know those kind of problems.

The 4.0 otherwise been a great engine for me across all jeeps I had. I had one with 375k miles, the jeep fell apart around it and it keep on purring....

JR4X said:
Yes those are both the problems. A 4.0 doesn’t get adequate coolant circulation to the back of the engine so cylinder 6 runs hotter than the rest. The fuel rail dead end is under the cowl and gets vapor issues on just cylinder 6. Between the hotter cylinder temp and lean fuel it detonates the top off the #6 piston. Not much you can do about coolant circulation but making cool fuel flow all the way through the fuel rail and return some to the tank will save that back cylinder.
Click to expand...

The 5.9/6.7 Cummins sorta have this problem, uncommon, but there are bypass kits to alleviate this. I wonder will something like this be beneficial to a Jeep 4.0 in racing applications?

Cummins hot rodders install rear bypass primarily for 2 reasons; 1) help keep cylinder #5 and #6 from running hot and 2) to prevent damaging pressure (pushing out freeze plugs at high RPM).

www.fleeceperformance.com

Fleece 03-05 Dodge Cummins Coolant Bypass Kit (Auto Trans)

Optimize cooling in your 2003-2005 Auto Trans Cummins with our Coolant Bypass Kit. Improves coolant flow and helps prevent overheating issues.
www.fleeceperformance.com www.fleeceperformance.com
 
So the Renix 4.0 has a flow through fuel rail with regulator at front of rail. It was only offered on the XJ so it's easily forgotten about
 
JR4X said:
Suggestions? Firewall has to remain sealed from the occupants area.

Our bronco breathes out the cowl but I don’t think the Jeep tub is built the same way
Click to expand...

nevermind, was thinking galvanized beer can.

unless hes a podium contenders id push the rules and dgaf.

also stock mod is going to be more enjoyable racing experience. stock class racing is in the words of dave cole “fundentally retarded”
 
SMI17 said:
So the Renix 4.0 has a flow through fuel rail with regulator at front of rail. It was only offered on the XJ so it's easily forgotten about
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Pretty sure both my HO XJ's (91-96) and my YJ and my current 92 MJ i know for surehad the same flow through, but all the TJ's and 97+ xj got the returnless.

Not sure what a 98 ZJ would have had.
 
Thats right I keep forgetting the YJ got fuel injection its last handful of years. MJ><XJ

Pretty sure just the renix had real flow through the others had feed and return at the same end. Making me 2nd guess my memories, haha.

98 ZJ would have the regulator in the tank with that bs corrugated plastic tube that like to crack or come loose
 
rockdog57 said:
E2000 can be picked up almost anywhere too.
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That’s an excellent reason to run one. Every parts store chain stocks E2000’s. We ran stroker engines with big injectors and live monitor 02 with a wide band in the dash. E2000’s kept it Fed no problem. The Aeromotive fuel regulator costs more than the fuel pump but the regulators last forever. Change the pump once a year for maintenance sake.

I don’t see the point in the big pump being recommended. I think that’s the pump we’re using to support the 7.4L stroker in dads 4500 car.
 
SMI17 said:
So the Renix 4.0 has a flow through fuel rail with regulator at front of rail. It was only offered on the XJ so it's easily forgotten about
Click to expand...
Said plastic regulator loves to break in pieces and start a fire under the hood.
Buddy lost a car to this.
 
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