Tacoma Troubles

I have a 99 toyota tacoma with fuel system problems. What should I look for as the cause of my fuel pump relay to go bad?

Relays are mechanical/electrical. They simply just wear out.

That’s understandable… Let me be more specific. This is the third relay in 4 months. Started with the fuel pump, it went out, so I changed that out, and in the process of the fuel pump giving out, the relay went bad the first time. The relay has gone bad twice since then, and I have no clue as to why.

Are you sure it’s the relay? Have you checked for power to the relay coil when it’s “out?”.

Have you opened a failed relay to see (a) if its contacts are fried, (b) if it’s coil will operate with voltage applied (its voltage requirement should be stamped on the side of the canister)?

Have you double-checked the relay parts number? Are you using the number from the first relay as a reference for the replacements? An error in the first could carry through. My thinking is that if the OEM unit is rated for 12 VDC and you’re replacing it with one rated for 5 VDC the coil could be overheating. Or, if the OEM is rated for 5 VDC and the voltage drop at the relay is now 12 VDC you have a problem elsewhere in the circuitry, the voltage is not being “dropped” or “stepped down” as it should be.

The new relays are coming straight from the dealer, I have taken one apart, and actually reinstalled it in the truck. When I turn the key, it moves, but that’s all I can tell you. I’ve replaced the fuel pump twice also. What kind of electrical problem could have come out of nowhere like this? All other fuses and relays are operating correctly. It seems to me that there’s something bigger that I’m missing somewhere. All my wiring “seems” to be in tact, and I see no cuts or breaks. Volt meter says all circuits are good as well.

Are you certain that your problem isn’t something else, the fuel pressure regulator perhaps? Are you certain that these parts you’re changing are actually bad?

If you took a relay apart and then reassembled and reinstalled it and the truck worked after, it makes me wonder what level of diagnosis went into the problem. Did you verify that the pumps were actually bad?

Perhaps a clogged fuel filter is causing the pump and relay to work too hard and resulting in premature failure?

Changed the fuel filter out, it’s brand new. Also took the line loose on the front half, and had gas pour out. Took the line off on the back half, and got fuel pour out as well, but no flow when I tried to crank the engine. As for the relay, I took the shell off, and installed the relay without the shell. That’s how I saw the relay click over. So the relay is brand new, the pump is brand new (warranty swap) and the fuel filter is brand new. I’m getting electricity to everything, but no pressure. What else can I possibly do here? And yes, I varified the pumps were bad.

You’re getting power to the relay coil, as verified by it clicking over, but are you getting power at the pump? The pump circuit goes through the relay contacts rather than the coil.

It’s starting to sound like an intermittant short to ground in the pump circuit.