Fuel Pump

davem · Post by **davem** » Sat Feb 05, 2011 9:26 am

Hi I am new to this forum so if this question has been asked too many times before i'm sorry. I am in the middle of a 1999 v8 swap. I am installing a 1989 5.0 HO with forged pistons, comp cam and a elderbrock 625 carb. My question is The truck was originally a fuel injected 2.5. Is it best to remove the pump in the tank and install an electric downstream or use a pressure regulator. Can a downstream electric pump suck thru the intank pump? What have you done and what kind of success.

Thanks Dave

cgrey8 · Post by **cgrey8** » Sat Feb 05, 2011 11:49 am

I don't think you can pull through the stock pump. Looking at the mechanism of how those pumps work, I wouldn't expect that to work very well. So I'd plan to pull the bed off so you can get to the pump, remove it, and worst case, just let the hose dangle in the bottom of the tank. Although I'm sure they make some kind of device that will let you pull from the tank without just having a dangling hose. But since I'm EFI, I wouldn't know much about that.

v8ranger · Post by **v8ranger** » Sun Feb 06, 2011 3:20 am

The pump is still in gas tank on my 86 and I dont have any problems being able to pull gas threw it. I am using an inline pump and its mounted in the engine bay. So, yes, you can leave it in there. Just unhook the power wire to it. Or pull the fuse or relay...

carvinmark · Post by **carvinmark** » Sun Feb 06, 2011 4:48 am

My dad has a inline that is pulling thru the OE pump(in tank) in his old Chevy plow truck, been that way for a couple years and seems fine

davem · Post by **davem** » Sun Feb 06, 2011 7:52 am

Thanks for the info saves a lot of hassle not having to pull the tank. I have found some regulators available but i don't trust them to regulate that much pressure. I have a lot of work left to do, this is a show truck and it is getting all new suspension parts and the frame cleaned and painted prior to the new engine going in. It going to be a 5.0 HO 350 hp with a TCI C4 trans. Any ideas or suggestions would be greatly appreciated. I have taken pics during the whole process to help somebody else do this Swap.

Thanks Dave

cgrey8 · Post by **cgrey8** » Sun Feb 06, 2011 8:19 am

Impressive. I never would've guessed you could pull-thru a high pressure pump. Nice to know.

Dave · Post by **Dave** » Sun Feb 06, 2011 3:43 pm

Well like V8Ranger said, disable the power to the pump, use an exteral low psi pump close to the tank and use just about any good regulator. Think the early Rangers had an external pump mounted back there on the frame rail. Pictures are coming?
Dave

Grumpy · Post by **Grumpy** » Sun Feb 06, 2011 4:40 pm

my 87 had a low pressure pump in the tank and a high pressure pump on the frame rail... right under the drivers seat .... i had to replace that one once and the intank one twice .....

plowboy34 · Post by **plowboy34** » Sun Feb 06, 2011 8:55 pm

My son's 85 was just like Grumpy's, we actually use the in tank pump running it directly to the carb. It only put's out 6 psi and we have had no problems with it.

MalcolmV8 · Post by **MalcolmV8** » Sun Feb 06, 2011 9:36 pm

davem wrote:I have a lot of work left to do, this is a show truck and it is getting all new suspension parts and the frame cleaned and painted prior to the new engine going in.

Sounds like you are stripping it down to a bare frame anyways. Swapping out the in tank pump shouldn't be to bad at that point.

carvinmark · Post by **carvinmark** » Mon Feb 07, 2011 4:05 am

plowboy34 wrote:My son's 85 was just like Grumpy's, we actually use the in tank pump running it directly to the carb. It only put's out 6 psi and we have had no problems with it.

That worked out as good as it could!

v8ranger · Post by **v8ranger** » Mon Feb 07, 2011 5:47 am

plowboy34 wrote:My son's 85 was just like Grumpy's, we actually use the in tank pump running it directly to the carb. It only put's out 6 psi and we have had no problems with it.

Yes, you are right, I forgot that the pump in the tank was a low pressure pump in the early years...

jzwartster · Post by **jzwartster** » Mon Feb 07, 2011 1:38 pm

My dad than I have had a lot of problems with fuel pumps. You must eliminate just the pump in the tank but leave the pick up. (pulling through will eventually cause the electric pump to fail.) I have a 91 and it too had one in the tank and on the frame rail. bypass the one on the frame rail and usually the lines are way small for the stock engine. Replace all the lines I used 5/16 inside diameter. Also use the fuel pump required for your engine not the truck. My case I have one for a 93 mustang and its mounted just before the tank. The little $50 after market electric pump are junk, my truck as gone through about 10 of them in about 50k miles. Best bet to run a fuel pressure gauge so you know you have at least a constant 7lbs at all times if not you know something is not right. They recommend using a taugo swith to turn off your pump in a hurry in case of a collision the gas dont continue pumping. I havent done this yet but will one day. Take my advise and save you a lot of head ache, time and money as it did me.

Soul · Post by **Soul** » Wed Feb 09, 2011 9:42 am

I just did a v8 swap (carbed but still applies) I swapped in a high volume 255lph walbro fuel pump (just replaces stock one) and ran new fuel line with a regulaor, Holly doesn't seem to mind at all. Easy Peasy.

jzwartster · Post by **jzwartster** » Wed Feb 09, 2011 10:07 pm

what ever works i tried the Holly fuel pump with the regulator it didnt work and later found they discontinued that unit.

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