[Crevatsch]

Hi folks!

My 1995 corolla has developed a starting problem and i suspect the fuel pump. It starts very good most of the time. When it doesn't i have to keep starting for approx 10 seconds and then it starts, running on 2 or 3 cilinders. After 30 seconds it runs normal and drives fine. I've checked:

• All the fuses under the hood and behind the kick panel on the drives side.
• Relais under the hood.
• The relais under the radio. (Can't remember the name)

I've noticed the relais under the radio is only energised, and the fuel pump in the tank is only running when starting the engine. Because there's no priming the fuel system before starting. That's why i suspect the one-way valve in the fuel pump of leaking.

What do you guys think could be the problem?

 

[Pete Suhman]

Are you sure it's a fuel problem? My immediate suspicion is the cap and rotor and wires and spark plugs, or perhaps the distributor guts. Definitely do some more diagnosis before spending any cash...

The fuel pumps in these cars seem to be super reliable, and I don't recall ever hearing of one fail in these forums.

 

[DrZ]

It could also be the fuel pressure regulator IF it's a fuel pressure related problem.

My 90 Corolla takes a long time to start when it's been sitting and cold, and usually if I crank it for several seconds then stop then crank again it will start right up, so I was thinking it might be a fuel pressure problem. On the 6th gen you can jump Fp and +B to manually turn on the fuel pump, so I did this to build up the pressure before cranking and it didn't help it start any faster, so I guess it's not a fuel pressure problem in my case.

I guess I'm saying in your case it may not be a fuel problem either. It could be cranking too slow, then the cylinders get flooded and that's causing it to run on 2 or 3 for 30 seconds.

 

[Crevatsch]

Thanks for the comments! I've been reading up on circuit opening relais (source at the bottom) and it seems the fuel pump should be running when turning the key to 'contact'. This way the system can build pressure before cranking. Can anyone confirm this? Because the fuel pump on my corolla is only running when cranking the engine, not sooner.

wilbo666 / Circuit Opening Relay

wilbo666.pbworks.com

 

[Pete Suhman]

I don't think I've ever been able to hear the fuel pumps in any of the Toyotas I've owned.

 

[75aces]

Try bumping the starter to see if that helps. If it does run, then the starter is weak.

See if there is a fuse for ignition and verify its not blown.

Confirm your battery terminals are in good order and tight.

 

[DrZ]

The fuel pump will only run when cranking the starter or the engine is running. The ECU determines the engine is running by either receiving the signal back from the igniter that the coil is firing or by the crank/cam position sensors. (I can't remember, and it might say in the repair manual.)

I don't think it will even prime for a second or 2 just by turning the key to the ON position. I seem to remember on an old Honda that the fuel pump would "prime" for a second with key in the ON position, but on our cars this isn't the case.

And when the fuel pump runs in the START position it is because the fuel opening circuit (relay) gets voltage from the ignition switch. That is, you can remove the starter relay, then when you turn the key to START the engine doesn't turn at all, but you can here the fuel pump turn on.

 

[Crevatsch]

The fuel pump will only run when cranking the starter or the engine is running. The ECU determines the engine is running by either receiving the signal back from the igniter that the coil is firing or by the crank/cam position sensors. (I can't remember, and it might say in the repair manual.)

I don't think it will even prime for a second or 2 just by turning the key to the ON position. I seem to remember on an old Honda that the fuel pump would "prime" for a second with key in the ON position, but on our cars this isn't the case.

And when the fuel pump runs in the START position it is because the fuel opening circuit (relay) gets voltage from the ignition switch. That is, you can remove the starter relay, then when you turn the key to START the engine doesn't turn at all, but you can here the fuel pump turn on.

This sounds correct and would mean the fuel relais is working as intended. Also means the starting trouble is caused elsewhere.

I checked the following things: I did the blinking engine light diagnose procedure and the light was blinking fast which i think means there are no error codes in the system. The plugs are pretty new, i think i replaced them 6 months back, so now i'm suspecting the spark plug wires.

 

[Haloruler64]

Welcome to Toyota Nation! Did you notice any correlation with weather? AKA temp and humidity.

 

[Crevatsch]

Welcome to Toyota Nation! Did you notice any correlation with weather? AKA temp and humidity.

Thanks for the welcome! It's hard to say if there is any correlation. I could say: it's worse when its cold and damp but it's hard to know for sure. The corolla has only done it 10 times in 2 years so its hard to really pinpoint. Last couple of weeks it has been getting more frequent so i thought i would be time to take a look at it.

 

[94RollaDad]

@Crevatsch any updates? I recently posted a similar thread - so wanted to check on whether you got any resolution.

 

[Crevatsch]

Sorry for the late reply! For the past couple of months i havent had this problem anymore, and i can't really say what ''solved'' it.

The last thing i changed was messing about with the fuel shutoff relay that is located behind the radio. I took the relay out of it's enclosure, but everything looked fine so i put it back in and installed it back into the car. My corolla used to have a moisture issue so maybe the contacts of the relais were corroded slightly and the messing about make the contact better or something?

If the problem comes back i will make a new reply but for now i guess it's solved. Good luck with your repair!

 

[94RollaDad]

Thanks for the update!