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Fuel pump for TBI conversion

bp71k5

bp71k5

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So I'm getting very close to finishing this swap and am at a place to make a decision on fuel pump choices. Here's what I've read, been told, etc.

I've got two choices:
1. An external fuel pump is ok, but needs to be mounted below the level of the fuel in the tank. Given the way the 71 frame and tank sit, mounting the fuel pump in the frame rail would *at best* put the fuel pump at the mid point of the tank. It's probably closer to the top of the tank.

2. Internal pump might work if I can get the pump to fit in the smaller hole of the early tank. I've got a mockup of a sender that looks like it'll fit, but the other issue is that there's no baffles in the tank to keep the pump from running dry on steep inclines or hard corners.

I'm leaning towards the external option, but I want to make sure the pump will be reliable in the location I have for it. Any expert opinions on external pumps to run? I've heard the Carter p5001 is good.

Also, would a gerotor style or a rotary vane work best in this case?
 
Nothing wrong with the external pump but an internal one will usually outlast the external one. The external pump will be a little more noisy over an internal pump.

I'm not sure which style is better.

As long as the external pump is mounted as close as possible to the tank you'll be ok. The lower you can get it the better but it will still work. I like to install it in the C of the frame rail to keep it safe but that definately wouldn't be convienent to change if it were to fail. I also woldn't worry too much about the tank not being baffled. I would however make sure you install the return line through the sender and bring the return line tube all the way down to the pick-up sock so that will help with fuel starvation when the tank is low on fuel.
 
I would however make sure you install the return line through the sender and bring the return line tube all the way down to the pick-up sock so that will help with fuel starvation when the tank is low on fuel.
Click to expand...

That part I can do. I test soldered a return line on an old sender I had. It seemed to work pretty well. I was even able to mount a stock fuel pump on the feed line and get the whole thing through the hole in the tank. My only problem with that setup is that the pump isn't secured very well. The last thing I need is the pump breaking loose inside the tank. :eek1:

I've heard the gerotor style pumps are a little quieter, but the rotary vane style is better at sucking the fuel up the line.

Is the external one louder than a set of flowmasters?
 
bp71k5 said:
That part I can do. I test soldered a return line on an old sender I had. It seemed to work pretty well. I was even able to mount a stock fuel pump on the feed line and get the whole thing through the hole in the tank. My only problem with that setup is that the pump isn't secured very well. The last thing I need is the pump breaking loose inside the tank. :eek1:

I've heard the gerotor style pumps are a little quieter, but the rotary vane style is better at sucking the fuel up the line.

Is the external one louder than a set of flowmasters?
Click to expand...

No way, you probably wouldn't even notice it anyways since it will be at the back of the rig. Have you tried to get a later model sender from a TBI rig and used some of the plumbing for the pump to adapt to your sender? That's a thought that i'm sure you could easily make work. Also if you're smart you would make a large enough access hole in the rear floor so you never had to drop the tank to change the pump should it fail on you.

I haven't been that smart twice now. Once for the original pump when it failed and the second time when i changed the pump to a higher pressure pump for my new engine. :doah: I really didn't want to spend alot of time making an access door that would still seal out the elements.
 
u can get a gas tank from a later blazer 87 and the sending unit and such, it will bolt right in and u will have the plastic reserve tray in it, the only thing that maybe a problem is the filler neck
 
chevyuser74 said:
u can get a gas tank from a later blazer 87 and the sending unit and such, it will bolt right in and u will have the plastic reserve tray in it, the only thing that maybe a problem is the filler neck
Click to expand...

I don't think a 2nd gen tank will fit a 1st gen blazer.
 
good point i missed that, but checking the strap part number should tell u that, but i doubt it would fit.
 
I have a Napa External pump on mine, mounted in the C channel of the frame, it came with insulation type wrap and clamps and it is within a couple feet of the tank on the passenger side frame rail.

Only time I hear it is when I turn the key on and wait the second or two for the pump to stop, then flip the switch and Voila'.

Also its the stock tank for the rig with a skid under it.
 
I did look at the later style tanks and those wouldn't fit. I'll go with an external pump.

Anybody got part numbers for one that works well?
 
Brian, if you want to make an intank pump work i have the old one i removed from my tank you can have. It is a replacement pump that i put in about 5 years ago. Nothing wrong with it, i just needed a higher pressure pump for my BBC injectors.

EDIT: I may have lied, i might have thrown it away already. I'll double check though.
 
Thanks for the offer. If I did go with the intank style, I'd just get a new one since they're less than $50. I'd want to make sure I didn't have to drop the tank for a long time. I couldn't bear to cut a hole in the bed to access it.
 
I'm curious to hear if anyone knows whether the earlier sending units mount to the tanks the same way (same size hole, o-ring) as the later ones.

Would certainly make using an in-tank setup easier. Cut/weld the pickup to the right height and be done with it. Of course, the fill hose fitting is probably different, at least the angle of outlet...
 
The sending unit hole is much smaller on the earlier tanks. I got some wrecking yard parts and the hole for the later model tanks is almost twice as big. The hole for the 71 is just slightly bigger than the diameter of the intank fuel pump.

I can actually get the intank pump mounted on my old sending unit, but the fuel sock has to get squeezed pretty tight as it's going through. I probably couldn't get it back out without damaging it.
 
The socks are pretty cheap apparently, so probably not a big concern. Shouldn't have to replace a Delco pump but once in 100,000 miles or so. :)

Be pretty cool if you could meld various stock parts together to get it to work! :)
 
bp71k5 said:
I did look at the later style tanks and those wouldn't fit. I'll go with an external pump.

Anybody got part numbers for one that works well?
Click to expand...
You already mentioned the P5001 from NAPA. Read the directions and it will say "mount no higher than 2 feet above tank" I have used this pump in many places and all worked well. Need a filter before the pump.
 
The p5001 is a good pump. It will work fine.
You can also use any Walbro inline pump for TBI. 115 LPH is the recomended pump for TBI.
But
If you have a performance build and want more flow. You can go with a pump of 190 LPH or more. The return line must be larger than the fuel line to run at the reduced pressures that TBI requires.
As said above you need a filter before the pump if you dont have a sock in the fuel tank. Dirt is the reason most inline pumps fail.
 
Thunder said:
The p5001 is a good pump. It will work fine.
You can also use any Walbro inline pump for TBI. 115 LPH is the recomended pump for TBI.
But
If you have a performance build and want more flow. You can go with a pump of 190 LPH or more. The return line must be larger than the fuel line to run at the reduced pressures that TBI requires.
As said above you need a filter before the pump if you dont have a sock in the fuel tank. Dirt is the reason most inline pumps fail.
Click to expand...

I'm running a 255 LPH pump with the stock fuel and return lines with no problems. I am running 18 PSI of pressure on my BBC injectors.
 
So is the fuel sock inside my tank an adequate filter for an external pump? What about a pressure regulator? I'm hoping to keep the stock regulator in the tbi since everything is stock (for the most part)
 
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