Thread: Electric to Mechanical fuel Pump????

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Ok ..... heres what I have:

87 GM Crew Cab dually
454 TBI (tbi has issues)
Electric in tank factory fuel pump

What I want or am going to do:

replace COMPLETE TBI injection unit with:

Carb
Intake
MSD
HEI
Mechanical fuel pump (like the old days!!)

I want to know if anyone has done this without removing the electric pump in the tank.

Will the mechanical pump draw fuel trough the de-energized electric pump (I'll pull the fuse) and what can I expect from what I'm doing.

PLEASE don't ask me why I don't want the tbi ..... I'll sell the complete unit to you if your interested.

Thanks.

Ratty 46

First check you block to see if it machined for a mechanical pump .
The easest way to do this is to use the electric pump with a pressure
regulator

Yes ....... the block has a fuel block off plate already so I figured ..... they put that on it due to the fact that those blocks are similar, if not the same, as the earlier blocks. My engine is actually a GM crate engine that replaced the original .....

My question is will the mechanical pump draw fuel through the electric unit in the gas tank?

I think it will ....... but who am I.

Ratty 46

Never have done it, Regs---but it would seem that leaving the in-tank pump in the system might create a few unwanted restrictions in the fuel supply??????

Use the tank pump with a bypass line back to the tank and a regulator. Done that, works great.
Some fuel will move through the inoperative pump, but I would think it will not be enough for a big block.

The couple of times that I have tried to get fuel thru an inactive factory intake pump it would not work.

Chances are you will either need to remove it or as suggested use it and run a regulator and by pass line (chances are the by-pass line is already in place).

Hate to be the bearer of bad news, but the factory camshaft does not have a cam lobe on it for a mechanical pump.... you will have to change cams. The swap will work fine with a regulator and the existing electric pump ( if the pump is good ).

Why don't you want the tbi?

Sorry, you made me ask .

Thanks for the info guys ....... Maybe a cam change will be in order ....too.

As for you moparjack44 ..... I do not have enough space here to go through the issues the factory tbi is having/has ...... the unit is on my '87 & is now 23 years old & is in need. I do not have the time nor the skillset to fool with a computerized TBI unit.

I was even trying to eliminate the elec. fuel pump.

REGS

LOL, I know, time is short, and should not be wasted on something you don't like to begin with.

MERRY CHRISTMAS

Not to be a jerk or anything, but a TBI is easier to fix than a carb switch is to do, just go buy a use TBI and replace it if you can't fix it. Other than that there is only the ecu & wiring, which you will need to deal with any ways.

I have been running TBI & TPI, and they are better than a carb setup, and they don't gas wash your cyl's.

Pat

Hey Pat ..... I don't consider your thoughts to be "jerkey" but ..... like I tell people when I do aluminum welding work ...... Aluminum is easy to weld - easier than steel.... for me. Why?? Because I've been doing it for a long time & I've become very good at it. Although I offer to teach them most don't have the time, skill set or ability topurchase the equipment after I get finished.

I have the same view on this new fangled tbi/tpi stuff. You'd be better off telling me to go to a mechanical fuel injection unit - I understand the mechanics of it. I do not understand, nor do I want to expand my skill set, on electronic injection - anything.

With that said - it is actually easier for me to replace it with a carb, intake, HEI & msd box than to purchase, borrow or steal the diagnostic equipment & learn how to utilize it.

So in a nutshell ..... I'm "old school", narrow minded & don't have the ability to learn & am not going to change out tbi stuff unless it will be replacing it. Of course if someone wants to come by & figure it out & address it ..... by all means don't let me stand in your way - pm me & I'll get you my address ....

Paul/aka Ratty 46

well i can say if you have a TBI they will not take a big cam the map will go nuts and run rich at idle. if any thing like the sbc need to idle a round 650 or less. i just went thru this on a sbc that the customer wanted a roller Hyd cam and with a set of v tec heads had ERSON grind a very very small hyd roller cam so every thing works. i knew this they before i ever put the cam in the block were i get my master kits did not know this they wanted to sell me a cam that wound of never worked. so if your going to cam it you may be better with a carb in this case .i like the TBI to they work great on stock stuff . you said the block has the pump hole block off plate ? i know the latter mark 6 block s did have the fule pump mount put back on the block .but may not have lobe on the cam .alot of the cams i get for the mark 6 rollers cams do not have the pump lobe

I'll be checking the cam for a lobe prior to purchasing any mechanical pump .... but I will be changing the tbi stuff out.

Thanks all for the info - it has been inlightening.

Ratty 46

Ok,
Then use the fuel pump thats in your tank. It has a return line, so put your carb on and get a pressure regulator that uses a return line! and your done! No need to remove it!

You will need to reroute the exciter wire going to the relay under the hood. because the ecu controls it, but not if you are replacing everything. Plus you'll always have a check engine light, unless you know how to change that.


Pat