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In or out of tank fuel pumps

Although I understand the value of having the fuel system pressurized prior to cranking, I'm kinda surprised that it's a requirement. I'm able to start from zero fuel pressure and be firing in less than a second (with a mechanical pump). Why is this harder for gasoline rigs? :dunno:

Is it just that the stock gasoline mechanical pumps don't develop suitable pressure?

Or is this just another idea that nobody has tried yet? :dunno:
 
The diesel fuel injection system is closed so the fuel is there in the lines so little cranking and pump builds pressure and fires injectors, the two are just different systems that don't operate the same
 
campfire said:
Although I understand the value of having the fuel system pressurized prior to cranking, I'm kinda surprised that it's a requirement. I'm able to start from zero fuel pressure and be firing in less than a second (with a mechanical pump). Why is this harder for gasoline rigs? :dunno:

Is it just that the stock gasoline mechanical pumps don't develop suitable pressure?
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It would work fine.

A normal customer is not going to pay thousands of dollars for a brand new vehicle that doesn't start when they turn the key.

Martin
 
fastazz81 said:
The diesel fuel injection system is closed so the fuel is there in the lines so little cranking and pump builds pressure and fires injectors, the two are just different systems that don't operate the same
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I'll agree that they're different, but they're not *that* different. They are both closed loops with recirculation lines. And lower line pressure doesn't mean it fails to fire. It just means that you get smaller injections until the pressure ramps up.

Back a few years, my folks had a 1985 cavalier (1.8L TBI 4-banger). It developed a problem where the ECM would not run the fuel pump for its 2-second pre-cranking burst. Our method of starting it was to crank until the oil pressure built up, at which time the fuel pump would turn on and the car would start. The car ran this way for several years (many thousands of miles), and the car was exceptionally reliable in all other regards (though the old battery did run down on a couple of cold, frozen days). The delay between the oil lamp extinguishing and the engine firing off (and running) was quite small. Much less than one second. It did not need the priming burst to get the system running, nor did it require full pressure to start firing. It fired off right away when the pump came on.

82355 said:
It would work fine.

A normal customer is not going to pay thousands of dollars for a brand new vehicle that doesn't start when they turn the key.

Martin
Click to expand...

I understand that normal customers would not enjoy a 1/2-second delay in starting time. But tinkerers like me (and you, I presume) really don't care about such minuscule delays. I'd gladly live with a slightly slower starting procedure if it meant I didn't have to redo my fuel tank & wire in an electric pump.
 
MTBLAZER89 said:
My rig is TBI so the plumbing and wiring are already there.

So basically buy an aluminum fuel cell, cut a hole, build a sump bracket deal for the pump and the return, install new pump, and hook up wires and plumbing?
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Yep. Just make sure your return dumps into your sump, isolate your hot wire real good and you'll be golden. When you buy a pump go with a good name brand.
 
I run tbi with no baffle , I actually had to remove my baffle . The dang thing came loose and kept screwing with my fuel level float knocked the filter sock off etc. I huffed gas fumes for a couple hrs trying to figure out a way to reinstall it. Gas fumes and cold beer clouded my thinking . I grabbed a pair of needle nose and a razor knife and peeled that sucker out like a apple lol. I am one of the ones who have fought the fuel pump battle. I've tried every brand same results. This last go around I replaced the entire module and wiring harness. It's not a good club to be in. My next time I'll put in a new tank , so far without the baffle I've had zero issues but I don't run it lower than a quarter tank .
 
prolinews said:
I run tbi with no baffle , I actually had to remove my baffle . The dang thing came loose and kept screwing with my fuel level float knocked the filter sock off etc. I huffed gas fumes for a couple hrs trying to figure out a way to reinstall it. Gas fumes and cold beer clouded my thinking . I grabbed a pair of needle nose and a razor knife and peeled that sucker out like a apple lol. I am one of the ones who have fought the fuel pump battle. I've tried every brand same results. This last go around I replaced the entire module and wiring harness. It's not a good club to be in. My next time I'll put in a new tank , so far without the baffle I've had zero issues but I don't run it lower than a quarter tank .
Click to expand...

Steel tank + a few spot welds to solve that issue.
 
The baffle that was in was plastic looked almost like a battery box.
 
prolinews said:
The baffle that was in was plastic looked almost like a battery box.
Click to expand...



my 89 saddle tank in Mutt has that...


I come at this subject from a different perspective as a marine mechanic.. Mercruiser has been battling this issue for yr's... keeping smaller, compact electric pumps cool, so they survive.. many a "cool fuel" system has been engineered, and used by Merc... some with better results than others.... Crusader has a killer setup out with their MPFI...

I'm building the gas version of Mutt's 70 gallon cell with a setup similar to what Vinnie is running.. in tank custom pickup/quality pump till I swap it to dizzle....

that said, if you're willing to spend the money, you can buy externals that dog internals... but we're not talking a couple hundy here...
 
Ive looked into the fuel cell thing a bit. I think its just too much important room to give up in the truck. That said I think maybe I could raise the tank up after I do the 1 inch body lift... maybe im better off bringing it halfway into the bed? Then again ive never hit it on the trail...
 
depends on how much fuel you need, etc, etc.. I ran one 1/2 in, 1/2 out of the trunk of my Pro Street Chevelle... Mutt's is gonna be a giant middle custom towrig one.. IIRC, Zim has a custom fuel cell 1/2 in, 1/2 out of the Maiden... his multi-point pickups and such can be very helpful offroad...

if expedition, large quantities aren't needed, some beefy protection and a quality in-tank pump are probably the best solution for most in a wheelin rig... it's all I plan on for my K5 pretty much...
 
AC Delco pump for a 90 blazer, plus tank, plus pick up. Run a post pump filter along the frame rail that has AN fittings. Carry an external pump in the tool box with the same fittings. Carry a 20ft extention cord, 2 wire style, cut the ends off and terminate for the battery and pump. That should get you home unless you are using a "returnless style" fuel system where a ECM regulates the pump.

Or install the pump next to the filter and don't wire it. But the next question is, will the external pump pull gas through the internal pump?
 
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