not sure where to ask this but here goes,

"purchased a 1982 280zx that had been parked in a garage for 14 years, great shape and after putting a new battery in it it started right up. After replacing a few fuel lines that were brittle and popped. the fuel pump stopped working. I dropped the tank had it cleaned and was able to clean and unstick the fuel pump. after putting everything back together the pump comes on and spins when the power is on but it wont pump? Is the pump bad or is there something in the system that is telling it not to pump? Any help would be greatly appreciated.

Did you fill the tank, or just put in a gallon or two? Also, the pumps will spin backward if wired backward.

I put 5 gallons in. The wiring only lets me hook it up one way. When i tested off the car i found if the wires were backwards it would pump backwards. But on the car it must be correct. Out of the car it pumped, thats why i thought maybe there was something electronic telling it not to pump?? Should i put more gas in, i have a great flow going into the pump but not even a drop coming out. I even sucked on the exit side and got gas but no pressure?

Most appreciate the advise.

Larry

When you say no fuel pumps, do you mean at the filter or rail area, or where you were able to get fuel to come out? Are you testing flow with the pump spinning at the same spot you're testing flow with suction? There's a damper in between the pump and filter, back where the pump mounts. Maybe that's the real problem. Or a clogged fuel line.

If you pulled fuel through the pump with vacuum, but nothing comes out when the pump spins, it sounds like the pumping mechanism is restuck. Did you take the pump apart to fix it or fix it from the outside? If the pump motor runs, fuel should pump. There are no externally-controlled valves inside.

There's a small cone shaped filter in the "IN" port of the Bosch pumps. It could be clogged.

I disconnected the line from the pump to the damper so the pumps exit nipple is showing, when the pump is spinning no fuel is coming out of the pump, the pump even seems to pressureize and stop spinning, i turn the key off and back on the pump starts spinning again then stops as if it is pressurized, but nothing ever comes out of the other side of the pump? When I disconnect the intake side of the pump from the tank i get fuel all over the place, there is plenty of gas going into the pump, just nothning coming out?? I checked the outgoing backflow presssure spring on the pump and it takes very little pressure to open so the pump isnt pumping???

I think i need a new pump???

and i did take it apart as far as I could from the inside.

larry

Edited April 8, 201410 yr by lascolarry

when you say cone shapped filter, I did not see that?

Things aren't fitting. You said that out of the car it pumps. Do you mean that you had a hose to the intake in a tank of fuel and a hose from the outlet returning it, and you saw fuel flowing out of the return hose?

And, how much gas did you get when " I even sucked on the exit side and got gas"? A big mouthful or just a taste?

There is a check valve in the outlet side of the pump. Maybe it's stuck or something broke inside the pump and is jamming the outlet. Also, is it possible that you connected hoses backward? And is this a factory stock pump or aftermarket? How far apart is as far as you can? I took an aftermarket pump apart down to the steel rollers that do the pumping.

Hard to tell what's really going on. How about a picture so we can see what you're working with.

Im pretty sure its a stock pump I will take a picture and post it later, I did have the pump out of the car and it pumped from the gas can out the other side of the pump. when I sucked on it on the car i got a taste nothing powerful, the outlet valve seems to be working fine like i said it takes very little pressure to open it, I dont think it can be backwards the wiring hook up is a T fitting and only goes in one way, I only got the pump apart to where I would have to uncrimp the casing to get inside, wasnt sure if that was a good idea or not, I did take off the intake cover that holds the four pins and spinner, that was stuck at first but is now spinning fine after cleaning. This is so frustrating because like I said the car started right up before the pump locked up from the debri out of the tank.

If you didn't take it completely apart then whatever clogged it in the first place might have floated back to where it was.

Start a new thread title "Rebuilding stock 280Zx pump" or something like that. Or PM Captain Obvious. He just created a whole thread about rebuilding pumps. Eurodat has rebuilt his pump also. Post a link to your thread in the thread linked below. We love to talk about fuel pumps.

http://www.classiczcars.com/forums/fuel-injection-s30/51862-fuel-pump-check-valve-alternatives.html

thank you, much appreciated!