New fuel pump,no fuel pressure


#1

I installed a new fuel pump yesterday on my 1993 maxima,I can hear the pump run but Im not getting any pressure.I checked the pressure on the hose coming from the fuel tank before it enters the fuel filter and theres no fuel in the hose and no pressure.
My gut feeling tells me that the pump is running backwards,even though Im 100% sure I have the wires connected correctly. Is it possible that an aftermarket pump could be running backwards even if the wires are connected correctly? (positive to positive negative to negative) Its real loud when its running could that be because its running backwards?

Im going to pull the pump out tomorrow,how can tell if its running in the right direction? While I have the pump out what else should I look for that might be causing it not to pump?


#2

Is this a fuel pump assembly? Or just the fuel pump motor?

Tester


#3

Its just the motor, Im sure the wires are connected correctly because the positive terminal on the new pump is larger than the negative terminal so I had to cut the original connector off the positive wire and replace it with a larger connector so that it would fit the new pump.

I think Im going to remove the pump from the pump assembly and put it in a coffee can half full of gas and turn the key,if gas shoots out the top of the pump Ill know its turning in the right direction,if gas doesnt come out I`ll switch the wires.

I was very careful to make sure I connected the wires correctly so I`ll be very disappointed if I have to take it all apart again to connect the wires “wrong” so that the put will work correctly.
I guess I should have got an OEM pump huh?


#4

Most of these in the tank pumps are one unit, pump and motor. It makes sense to replace them both…But yes, give it the coffee can test. Outdoors…Be careful about sparks from temporary wiring…


#5

Thats what this one is, the pump and motor all in one unit, its a metal cylinder with the intake on the bottom where the strainer connects and the output on the top where a hose connects and 2 terminals one positive one negative.

Im kind of hoping it is just a case of reversing the wires otherwise it means the fuel line from the tank to the engine is kinked or clogged,and Im not really anxious in having to replace that.


#6

I will just add a story about wire connectors. Over 20 years ago I owned a SAAB 900 that would overheat a bit when the A/C was on. It wasn’t bad enough to panic over but it was abnormal.
Everything checked out fine but the problem continued. This car had 2 radiator fans; one operating off of engine temperature and both operating with the A/C on.

One day while checking it again I walked in front of the car and felt a faint blast of warm air. A closer inspection showed that the right side fan (operable only when A/C on) was running BUT it was pushing air out through the front of the radiator instead of pulling it through as the left side fan was doing. Unplugging the fan a few times I saw the fan blade winding down and noted the blade was spinning backwards.

Inspection showed that the male spade connectors on that fan were reversed and was apparently a factory screwup that had never been caught. Unlocking the spades and swapping places in the connector solved that problem.


#7

Best to do that experiment outside and away from anything that might catch fire, and keep a fire extinguisher handy. In fact it’s probably best not to do that experiment at all. It sounds like you’ve given it the old college try and the aftermarket pump just isn’t working for some reason. If I had this problem the first thing I’d probably do is return the pump to the parts store. The parts stores deal with these issues all the time and often have test fixtures that will test electrical items like fuel pumps, alternators, starter motors. I had a faulty replacement starter motor right out of the box a couple years ago for my Corolla, and that’s how the parts store determined it was faulty.


#8

I suggest you try reversing the wires on the outside of the tank to make it easier to test it. Even if you have to run seperate leads from the battery.


#9

Mystery solved, Today I removed the pump and the first thing I noticed was that some dumba$$ connected the wires backwards,the pump was running backwards. lesson learned, even after checking, and double checking, and youre sure you got it right, go back and check it one more time. Maybe Im just getting too old to be fixing my own car and I should start taking it somewhere to get it fixed.


#10

@tardrex, believe me, you are not alone…


#11

What I usually do is write a nasty email to myself telling myself how stupid I am. On the other hand, the labor rates are pretty low and we’re not about to tell anyone what happened. Seems to me though that it is pretty keen analysis to determine the pump was running backwards. So might want to reference that in the email.


#12

Thanks for posting back @tardrex. Nah, keep on truckin’, it’s just one of those things. If it is true that misery loves company, listen to this one. I was driving along I80 from Reno Nevada to Salt Lake City, high rambling desert all the way, miles and miles between small towns. I pulled in to one of these small one-horse towns for some gas and got to talking w/a local there; he was a potato farmer and I’ve always thought the Winnemucca, Nevada potatoes are particularly tasty, so he was explaining why. He had a big dog with him in the back of his pickup truck and while chatting away I was petting the dog, so I put my keys down to free up my petting hand. On the bumper of his truck!!! So as he drives away , there goes my keys. Oh Oh!! Alls well that ends well, there’s a lot of bumps and potholes on those small town dirt side roads, and so I found the keys where they fell off, about a block down the road. But while I was running after that truck I was sure complaining about myself … lol …