Fuel Pump help...

[jmihalchik]

Im fixing a buddies 86 gn. he has had shops do all this upgrades... Lots of them. It ran out of gas yesterday then after getting some it ran about 2 miles and died. Fuel pressure builds when car has been left alone to bout 50 psi then when cranked shoots to 0, all cranks after that are 0. I'm almost certain it is the pump? also he is running bout 500whp (60lb injectors, afpr) What in tank pump should we go with im sure its upgraded as is but he has no idea what lph/gph , would like to order one prior to dropping tank and all its 12 gallons lol. Thanks for helping a gn noob.

 

[Topjimmy]

I'd replace the fuel filter just to be sure since the lines may have picked up debris when the pump went dry...I'll assume the current pump is already hot-wired so here's a link to the Walbro in-tank pump that supports up to 600 hp ;
FULL THROTTLE SPEED - BUICK TURBO HP FUEL PUMP KIT
Be sure to buy your pump from a reputable dealer as there are lots of off-shore knock-off pumps flooding the market just now.

Good Luck - Jimmy

 

[jmihalchik]

I'd replace the fuel filter just to be sure since the lines may have picked up debris when the pump went dry...I'll assume the current pump is already hot-wired so here's a link to the Walbro in-tank pump that supports up to 600 hp ;

Be sure to buy your pump from a reputable dealer as there are lots of off-shore knock-off pumps flooding the market just now.

Good Luck - Jimmy

i did replace the inline filter forgot to add that. thanks for the link.

 

[Black Car]

Make sure that the pump is getting electrical power before replacing.

Gary

 

[RUQWKNF]

Typically, when ever a Walbro 340 pump is installed, most people do away with the Pulsator Dampner that is on top of the factory pump. Inside this pulsator dampner is a check valve which helps keep fuel pressure built up. The factory wiring setup kicks the pump on for the fuel line prime, then gives power to the pump after the engine has started, or after oil pressure has reached a certain point.

If you remove this pulsator dampner and install the straight piece of FI hose that connects the pump to the hanger, you effectively removed that check valve. The result is, you will see this condition. If the car won't start on the first couple of spins, the fuel pressure will drain back down to zero. My personal car does this exact same thing. Most people have never even seen this pulsator dampner, but it is a small black rectangular piece with a goldish metal top that simply pushes onto the factory feed line on the fuel sending unit, and the fuel pump pushes into the other side of it. Most people remove it for a little bit of extra volume, as well as hack off the feed line tube step down on the sending unit. This does make it hard to start the car when the fuel system looses prime, or if starting a car for the first time after a rebuild and or trying to set your cam sensor correctly after a rebuild. You have to cycle the key a few times to get the pump to reprime. But for it to die going down the road, I would suspect a dead pump, or clogged line/lines.

Hope this helps.


Patrick

 

[jmihalchik]

thanks for all your help, seems like a great community. I did plan on testing the power feed prior to dropping tank. any wierd quirks on dropping these tanks or is it simply straps , drop, disconnect lines / harness?

 

[jmihalchik]

nm i found a link
Fuel Pump Remove and Install

 

["Turbo-T"]

Typically, when ever a Walbro 340 pump is installed, most people do away with the Pulsator Dampner that is on top of the factory pump. Inside this pulsator dampner is a check valve which helps keep fuel pressure built up. The factory wiring setup kicks the pump on for the fuel line prime, then gives power to the pump after the engine has started, or after oil pressure has reached a certain point.

If you remove this pulsator dampner and install the straight piece of FI hose that connects the pump to the hanger, you effectively removed that check valve. The result is, you will see this condition. If the car won't start on the first couple of spins, the fuel pressure will drain back down to zero. My personal car does this exact same thing. Most people have never even seen this pulsator dampner, but it is a small black rectangular piece with a goldish metal top that simply pushes onto the factory feed line on the fuel sending unit, and the fuel pump pushes into the other side of it. Most people remove it for a little bit of extra volume, as well as hack off the feed line tube step down on the sending unit. This does make it hard to start the car when the fuel system looses prime, or if starting a car for the first time after a rebuild and or trying to set your cam sensor correctly after a rebuild. You have to cycle the key a few times to get the pump to reprime.

Interesting Patrick. Most people I have talked to have told me the fuel pump pulsator is worthless. Heck I even have one sitting around no one seems to want.