Symptoms of a bad fuel pump

[dirk22]

I am looking for some help on fuel pump symptoms vs relay.
When the truck does not start I bang on the tank with a rubber mallet after a few times it starts. It is very intermittent problem sometime it fires right up then other times it does not.

 

[77'911]

Just do a pressure check, but it sounds like it's time for a fuel system rebuild. The ethanol is doing a number on the fuel systems in these old trucks. I've had to do the following to our 1990:
1) clean and reseal injectors/housings
2) replace pump, regulator, and relay
3) replaced gas tank cap, twice (ethanol killed the first cap seal in 14 months, aftermarket)
4) more frequent filter replacement (ie every 2-3 years)
As pumps go bad, you might experience:
1) MPG goes down
2) longer or increased cranking to start
3) fouled plugs
4) fry the relay and EFI relay due to increase circuit resistance (and age)
You might consider, due to age(and miles/kms) alone, might be worth replacing the EFI relay ($12) as an insurance policy. Is the truck cranking when it does not start? It might be worth checking the contacts in the starter(if the fuel pressure is up to factory Toyota specifications). In the colder weather, this gremlin can rear it's ugly head. Best of luck with it.
regards

 

[KidVermicious]

It sounds like it could be a bad pump, but let's be sure before you yank the old one. A pressure check is pretty easy - next time it doesn't start, leave it cranking a few seconds longer then crack the fuel line at the fuel damper on the rail (22mm wrench). If fuel sprays out, you've got pressure through the fuel filter and can rule out the pump and filter as your trouble. If you don't get a spray, then you're looking at a possible bad pump or filter.

 

[dirk22]

Thanks for the info.. the truck cranks fine I know it is fuel because the fist time it did not start I sprayed starting fluid in the filter and it started.

 

[dirk22]

I replaced the fuel pump today it ran fine and starts fine. it sat for 15 minutes then same thing will not start. I let it sit for an hour then it started fine. I guess relay next??

 

[SV_Dude]

Download a fsm and go through the trouble shooting. Throwing parts at it and hoping for the best gets expensive.

It could be something in the old wiring causing an intermittent signal to the pump or relay. The fsm can help narrow that down by testing each component.

Good luck.

 

[RiFF RaFF]

I am looking for some help on fuel pump symptoms vs relay.
When the truck does not start I bang on the tank with a rubber mallet after a few times it starts. It is very intermittent problem sometime it fires right up then other times it does not.

What year is your 4Runner?

 

[dirk22]

89 with 3.0

 

[KidVermicious]

I replaced the fuel pump today it ran fine and starts fine. it sat for 15 minutes then same thing will not start. I let it sit for an hour then it started fine. I guess relay next??

Did you test the pump you had, first? When the truck fails to start, do you have fuel pressure?

 

[dirk22]

Latest testing
loosened fuel rail definitely have fuel pressure.
with fuel pump jumper in I can hear the pump running.
checked spark from coil this is good.
all of a sudden I am having starter issues.
just clicks then I hear nothing. this goes back and forth
then I started tapping on the black box the holds the relays and fuses and checking the wires then it fired up.
when I fire it up again there is a delay from when the key is on to when it decides to turn over.

I read there were some issues with the wires that come out of the fuse box?
any other tips would be great

 

[dirk22]

Replaced wire from fuse box to battery.
still same issue.
will not start after driving if I let it sit foe a wile it will start fine.

 

[dirk22]

I replaced the wire from battery to fuse box and effective relay still having the same issue.

 

[Trip_84]

Ever figure out what the problem was?

 

[acebadass]

im haveing the same issue

I can tell you this tho its getting spendy