Mechanical or electric fuel pump for carb??

[RangRayy]

I was unsure where to post this. Feel free to move accordingly.

Which fuel pump to use? Mechanical or the stock electric ones inside the tanks?

I am converting an '87 350 to carb and ditching the tbi. I have another thread on that so no changing my mind on this conversion.

The block has the provisions for the pushrod already so no going to the machine shop.

My truck has dual tanks and currently only the right side tank functions. I hit the switch inside the cab to go to the left tank and nothing happens. I already know the pump in that tank needs replaced.

Can I pull through the elcctric pump in the one that doesn't work with a manual fuel pump still? I have read mixed reviews on pulling through an electric pump.

My logic is why try and wire up the relay to kick on with the ignition to run fuel from the tanks to a regulator then to the carb, when I could use a mechanical pump and pull the fuse for the tanks.

Planned on using the existing fuel lines for the tbi. Running a line down to the pump,then from the pump up to a regulator with a return, to the carb and to the return line.

Thoughts or experience with such?

 

[87scotty]

I plan on doing the same gonna keep the electrics both mine work still and all you need to do is buy a regulator make sure you get one with the return have to since the fuel pressure is being cut down so much

 

[RangRayy]

I might still keep the electrics just because but it could change. Well keep an eye for my write up I should be done with it soon. Once I figure this fuel issue and get the heads back from the machine shop I'll be putting everything back together and on the truck.

 

[87scotty]

Will do!

 

[HotRodPC]

IF it's a carbed model truck, then it only has a manual pump on the passenger side of the engine block. I'd keep it. Though if you want, you can add a low pressure electric too. Get a 4-6lb electric external pump and wire it to a toggle switch with a fuse. In the event you have a vapor lock issue, or your manual pump goes bad, then you can flip the switch and not be stranded. The external low pressure pumps are also flow through so no worries there.

 

[RangRayy]

IF it's a carbed model truck, then it only has a manual pump on the passenger side of the engine block. I'd keep it. Though if you want, you can add a low pressure electric too. Get a 4-6lb electric external pump and wire it to a toggle switch with a fuse. In the event you have a vapor lock issue, or your manual pump goes bad, then you can flip the switch and not be stranded. The external low pressure pumps are also flow through so no worries there.

The truck is an '87 so it's factory electric pumps on both tanks with a selector valve and switch inside the cab. The block just had a plate over the pump spot. I pulled the plate off and saw oil and thought what the heck? But by my surprise I had a hole for a pushrod for a mechanical pump.

Are the electric pumps for tbi flow through?

 

[chengny]

Are the electric pumps for tbi flow through?

Per the 1987 Driveability & Emissions Manual, they are classified as turbine type pumps (i.e. not positive displacement) - so it should be possible to pump through them.

But whether or not the internal clearances are great enough to allow the mechanical pump to produce sufficient flow - for proper operation - remains to be seen.

Just bolt on a mechanical pump and do the standard flow test - 15 seconds of engine cranking should produce a volume of at least 8 ounces at the pump outlet.

 

[RangRayy]

Are the electric pumps for tbi flow through?


Just bolt on a mechanical pump and do the standard flow test - 15 seconds of engine cranking should produce a volume of at least 8 ounces at the pump outlet.

I should've thought about that. But I am uneasy of purchasing a mechanical pump if in lou of things it doesn't produce enough suction.

I've read on other forums especially the guys on the camaro sites have had no issues with a mechanical pump. I just was curious since this is on a truck application it might be different.

 

[87scotty]

Trucks tend to burn more fuel than cars lol I'd play it safe and keep the electrics

 

[RangRayy]

Trucks tend to burn more fuel than cars lol I'd play it safe and keep the electrics

That's what I am thinking. Since I already have it set up just need to snip and solder a few wires. I do not feel like spending the $40-60 on a mechanical pump. Not to mention save some $$$ on extra fuel lines to run to the pump.

 

[87scotty]

You will need a regulator that feeds excess into return line