Bypass fuel pump relay (Nissan Altima)

[Martik]

My relay failed and I want to bypass it to ensure the pump is working. Will
this cause any problems? Why is there BOTH a fuse and relay in this circuit?

Thanks

 

[carneyke]

You must not be very experienced. The fuse is there for an obvious
reason. Find the contacts for the relay and place a wire in the socket.
When you know it's the relay (cause the car starts), remove the jumper
and get a new relay. The relay is activated by something (it turns the
pump on as needed) and never stays "on" all the time. Why don't you
test the relay or spend $20 and get a relay ?

 

[[email protected]]

You must not be very experienced. The fuse is there for an obvious
reason. Find the contacts for the relay and place a wire in the socket.
When you know it's the relay (cause the car starts), remove the jumper
and get a new relay. The relay is activated by something (it turns the
pump on as needed) and never stays "on" all the time. Why don't you
test the relay or spend $20 and get a relay ?

I suppose you know about this car. My one car's fuel pump is always ON.
First there is a sort of smoothing regulator then it feeds into another
bypass regulator. Over the years I have become intimately familiar with
my Nissan Datsun 280Z

gs

 

[Jim Yanik]

My relay failed and I want to bypass it to ensure the pump is working.
Will this cause any problems? Why is there BOTH a fuse and relay in
this circuit?

Thanks

If the relay is the same as the "main relay" used in Honda products,it
probably has a bad solder joint,and can be taken apart and resoldered.
I've done it and had no problems since.

See http://www.tegger.com/hondafaq/startproblems.html#mainrelay

 

[bloggybob]

the relay is used as a switch to carry battery current to the pump from the
battery which is controlled by the ignition switch through the relay trigger
wire ... you dont have to use a factory relay ... just get a standard SPST
relay at 30 amps will do fine .... and use a 20 amp fuse on the B+ constant
12 volt lead ....

as far as wanting to bypass to test it ? find the two biggest wires going to
the relay and connect them together .....

regards ....

 

[Jamie]

My relay failed and I want to bypass it to ensure the pump is working. Will
this cause any problems? Why is there BOTH a fuse and relay in this circuit?

Thanks

yes it will cause a problem.
the pump is very capable of generating
more pressure than is needed and should blow the fuse.
you have fuel regulators that operate the
relay, fuses are in line in the event that
for lets say the regulator does not shut off it
then should cause the pump to bind up enough to
blow the fuse.
never put in a fuse larger than what belongs in
the fuel pump line.
the question is, is it your relay that failed?
was it burnt contacts,open coil or maybe the
fuel regulator failed which is also a set of contacts
which can cause erratic operation of your engine
when you need the HP!.
you can for a moment jump the relay just to
listen for the pump on action but do not leave it
that way.

 

[Martik]

yes it will cause a problem.
the pump is very capable of generating
more pressure than is needed and should blow the fuse.
you have fuel regulators that operate the
relay, fuses are in line in the event that
for lets say the regulator does not shut off it
then should cause the pump to bind up enough to
blow the fuse.
never put in a fuse larger than what belongs in
the fuel pump line.
the question is, is it your relay that failed?
was it burnt contacts,open coil or maybe the
fuel regulator failed which is also a set of contacts
which can cause erratic operation of your engine
when you need the HP!.
you can for a moment jump the relay just to
listen for the pump on action but do not leave it
that way.

The relay was ok, I was not testing the right terminals.

Turns out the problem is oil leaking into the distributor and contaminating
the optics

 

[Art]

Yupper: Comtaminated optics in the distributor will kill the fuel pump
always. Datsun found that out long ago, then changed their name. LOL BTW
Cheers on actually finding the actual problem.

 

[James Sweet]

yes it will cause a problem.
the pump is very capable of generating
more pressure than is needed and should blow the fuse.
you have fuel regulators that operate the
relay, fuses are in line in the event that
for lets say the regulator does not shut off it
then should cause the pump to bind up enough to
blow the fuse.
never put in a fuse larger than what belongs in
the fuel pump line.
the question is, is it your relay that failed?
was it burnt contacts,open coil or maybe the
fuel regulator failed which is also a set of contacts
which can cause erratic operation of your engine
when you need the HP!.
you can for a moment jump the relay just to
listen for the pump on action but do not leave it
that way.

Turning on the pump won't cause any problem, there's a pressure
regulator on the fuel rail that will bypass any excess fuel back to the
tank, and the pump itself will also contain a pressure release valve.

 

[Martik]

It wasn't easy, but with a little reading in some Nissan forums problem
solved. What a dumb design, rubber seals that wear out and allow oil to
contaminate. Hopefully some RV sealant will permanently stop future leaks.
It's a $900 distributor!!!

 

[Jamie]

The relay was ok, I was not testing the right terminals.

Turns out the problem is oil leaking into the distributor and contaminating
the optics

ha, valve cover problems?

 

[GregS]

It wasn't easy, but with a little reading in some Nissan forums problem
solved. What a dumb design, rubber seals that wear out and allow oil to
contaminate. Hopefully some RV sealant will permanently stop future leaks.
It's a $900 distributor!!!

Good reason not to use optics. Use Permatex No-Leak rtv gasket maker.

greg