Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - What would cause a car to not start when it's humid ?

Cd · 12-03-2011, 08:57 PM

[QUOTE=Old Mechanic;272979]

You are not reading any voltage with the relay installed versus bypassed?

Correct.

When i install the probes in the plug going to the fuel pump ( the red wire going to the yellow wire and the black wire to the black ) Nothing happens when i have the main relay installed, but i get juice when i have the main relay off and the circuit tripped.

I'll try again tomorrow just in case i did something stupid.

If so then the car should not start with the relay installed but start with it bypassed?

The car does not start with the main relay off ( circuit tripped ) and the fuel pump running. I have tried this several times.

That would be either the relay or the power source to swtch the relay.

With the testing that i just did that showed that the main relay is fine, im guessing it's the power source to the relay.

The relay is probably energized by the ignition switch.

So it indeed could be the ignition switch causing my problems. I used to have a wad of keys hanging on my ignition key and a guy warned me that this might be what the problem stemmed from, since it stresses the inside of the locking mechanism.

Anyway, if I understand your post it seems like the relay is not doing the job. What you need to do is check to make sure the relay is getting good voltage, enough to make it work properly. If you find it has good voltage then the relay is your prime suspect. You can even install a bypass and a switch to power the pump in an emergency, as long as you use the same circuit you have fuse protection. If you make a completely new connection then use an in line fuse for protection. If you have replaced the realy and nothing changed, the odds are you have an issue with the power getting to the relay to activate the coil inside of the relay.

regards
Mech
.

12-03-2011, 08:57 PM	#16 (permalink)
Cd Ultimate Fail Join Date: Feb 2008 Location: Austin,Texas Posts: 3,585 Thanks: 2,872 Thanked 1,121 Times in 679 Posts	[QUOTE=Old Mechanic;272979] You are not reading any voltage with the relay installed versus bypassed? Correct. When i install the probes in the plug going to the fuel pump ( the red wire going to the yellow wire and the black wire to the black ) Nothing happens when i have the main relay installed, but i get juice when i have the main relay off and the circuit tripped. I'll try again tomorrow just in case i did something stupid. If so then the car should not start with the relay installed but start with it bypassed? The car does not start with the main relay off ( circuit tripped ) and the fuel pump running. I have tried this several times. That would be either the relay or the power source to swtch the relay. With the testing that i just did that showed that the main relay is fine, im guessing it's the power source to the relay. The relay is probably energized by the ignition switch. So it indeed could be the ignition switch causing my problems. I used to have a wad of keys hanging on my ignition key and a guy warned me that this might be what the problem stemmed from, since it stresses the inside of the locking mechanism. Anyway, if I understand your post it seems like the relay is not doing the job. What you need to do is check to make sure the relay is getting good voltage, enough to make it work properly. If you find it has good voltage then the relay is your prime suspect. You can even install a bypass and a switch to power the pump in an emergency, as long as you use the same circuit you have fuse protection. If you make a completely new connection then use an in line fuse for protection. If you have replaced the realy and nothing changed, the odds are you have an issue with the power getting to the relay to activate the coil inside of the relay. regards Mech .