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Discussion Starter · #1 ·
Hi Folks,

My 07 Sentra cranks but does not fire. I suspect it could be the fuel pump / relay. I'm having trouble finding the relay, and how to go about testing it. Can I test at the pump to see if it is receiving power .

Cheers,
 

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Hi Folks,

My 07 Sentra cranks but does not fire. I suspect it could be the fuel pump / relay. I'm having trouble finding the relay, and how to go about testing it. Can I test at the pump to see if it is receiving power .

Cheers,
Because your car "Does not fire" indicates a electrical problem as in a coil, wiring etc -- not lack of fuel. If you mean that you actually have no fuel than yes you may have a fuel pump or pump relay problem. A fuel pressure test would determine - but I agree, replacing a relay is a easy start and very well could be a problem.

I cant help with the location of the fuel pump relay. As a owner of a later model Altima I know that Nissan is not very helpful with fuse / relay info. Example: Using a digital search, the owners manual of my 2013 Altima does not mention the word "Relay" even one time. There is also zero info concerning what fuse does what (No fuse layout diagram). You have to go to the Nissan Service manual for this info - and it is very convoluting to search and determine anything. Info is on the fuse box covers but not always as helpful as it should be.

BACK TO YOUR REAL QUESTION.

If / when you do locate your relay, the best and ONLY sure and practical way to test it --- is to REPLACE it with ANOTHER known working relay. A relay may test ok with a ohm meter -- but fail when put in use under electrical load. When found, check if you have another of the same type relay in use elsewhere (Exact same number ID) where you can switch. If not, consider buying a new one to replace old one - cost anywhere from $10 to $25+. Or as I do with any of my older cars, I go to a junk (recycle yard) with a ID list of numbers of my relays and buy several of at least the main ones -- A/C, Eng, Fans, Pump, etc. With luck they may be $2 or so each. If I have several than I likely have good ones. The same ID relays are used in various models and years but it is easier to find in your own model and year of course. When first obtained I check them against my working systems to determine they are good, so later if needed I have some idea that the junk yard ones are good.

Even if you have to buy a new one from a parts store - and it was not the problem - "This time" - It will be handy insurance in the future, because relays do fail. I cant count how may times I have had to replace A/C, fan and YES a fuel pump relay in the past. Hard working relays do not last forever

Good luck - Please post the solution to your problem when actually determined so we all can learn..
 

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09 Altima 3.5SE 6MT Sedan
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You can also just jumper the sucker if you know the pinout. For instance, these are pretty common labels for automotive relays:



You can easily and cheaply build one of these 'relay test rigs' to say jump contacts 30 and 87 (which should simulate what the relay does when activated)

 

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Discussion Starter · #4 ·
BC2046, thanks for the details. I checked the fuse and it was good. I ended up taking the car to mechanic, and he confirmed it was the fuel pump. Being an older car the fix is as much as the cars value, so I did not go with the repair. But I did go to see my car in the mechanics lot after hours. I reconnected the electrical connection to the fuel pump, and banged the fuel tank with a mallet, that's suppose to be a mechanic trick to potentially get the pump to go again. Tried starting it again, and it fired of. Took the car of the lot, and I let him know what happened. It was a convoluted experience, and the mechanic never said the car fired up when I spoke to him on the phone, don't know if he was saying the truth. Saw him the next day and he claimed he fixed it, after our conersaion, huh? Anyway,he claims there was a loose electrical connection on the fuel pump. The pump has a few wires around it.

This may be the real issue, as my car has some vibrations I need to address. For example the gas latch has trouble closing, as it appears the hinge readjusted itself due to the vibrations. I assume these vibrations are causing my fuel pump to loose electrical continuity with is possible I guess. My car has a broken engine mount, and an exhaust which is rubbing a support bracket on the frame of the body right next to the Catalytic converter. The exhaust touching the support bracket causes vibrations throughout the car, I think these are the causes of my problems. And I need to address both these issues.
 
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