Mechanics, need help understanding Toyota fuel pump problem

lendaddy · 04:14 PM

I got my Tundra back from the dealer (they replaced the frame on a recall) and as you might expect there was a problem within the first 20 miles.

The truck died while accelerating from a stop, acted like fuel starvation with a little bucking and kicking. I managed to get it into a parking lot and started to diagnose.

I checked all the fuses- Check, no problems.

I checked the EFI, fuel pump and another involved relay(C/OPN) in the path of power to the fuel pump - All checked out fine.

I then checked for power at the sockets to the relays and found some issues.

With the key in the run position there is no power to the fuel pump relay. Power to this relay comes from another relay labeled C/OPN (not sure what this stands for) and power to the C/OPN relay comes from the EFI relay. Now that I've cornfused ya

[with the key in the run position]

I have power to the EFI relay in both the main and the "switch" sockets.-all good, you can feel the click when you plug it in.

With the EFI relay in I get power to both the main and the switch sockets for the C/OPN relay but you don't get a click when plugging it in(doesn't energize). If you ground the other side of the switch circuit you get the click and all is good. WTF?

With the ground jumped on the C/OPN relay you get the exact same situation on the Fuel pump relay (you have power at the main and the switch but it doesn't energize till you jump a ground to the other side of the switch circuit).

All of this lead me to believe that there was some kind of ground issue with the fuse box or some ECM issue where this ground is switched. Either way, no power to the fuel pump...but why?

At this point I called the dealer who towed the truck in this morning. They just called and said "yea it looks like the fuel pump needs to be replaced. They supply fuel at the filter and it starts right up." Yea I would imagine so..

I'm not sure what to say about this, the service manager is an old friends wife and she has been great to this point so hardball is difficult from my end. That being said I think the tech is just throwing parts at it quick and dirty style. There was no friggen power to the pump... I admit electrical isn't my best area so maybe I'm missing something. Is it possible that a failed pump would somehow trigger the ECM or some other circuit to cut the ground supply to those relays and a new pump would actually solve this? Any other advice is greatly appreciated. [here is the schematic]

lendaddy · 12-22-2011, 04:20 PM

I should add that after I "jumped" the ground at the fuel pump and C/OPN relays the truck still did not start. I assumed there must be other issues once that didn't work and that's where I gave up.

pete3799 · pete3799's Garage

Highly doubtful that the pump quit . I'd sooner think they didn't get something plugged in good or else, like you said, a bad ground somewhere.

lendaddy · 12-22-2011, 05:51 PM

Thanks,

The great Tim Hancock gave me some tips and I should be able to diagnose it tomorrow. Thanks guys.

TimT · 12-22-2011, 06:23 PM

I'm wondering why you did not get on the phone and call the dealer that just did warranty work..

Tell the service manager you made it a whopping 20 miles from his shop......

Why are you trying to fix things that should have been fixed and checked before the truck was ever released to you...

Chocaholic · 12-22-2011, 07:00 PM

Exactly what I was thinking. You eff with it first, your odds of dealer support begin swirling down the bowl.

lendaddy · 12-22-2011, 07:02 PM

Quote:

Originally Posted by TimT

I'm wondering why you did not get on the phone and call the dealer that just did warranty work..

Tell the service manager you made it a whopping 20 miles from his shop......

Why are you trying to fix things that should have been fixed and checked before the truck was ever released to you...

What should have been checked?

fintstone · fintstone's Garage

C/OPN is circuit opening relay. I believe it works with your fuel pump relay to shut off fuel when the engine is not running. You need a signal from your ECU to start and a signal from your AFM to run. In conjunction with the fuel pump relay, it probably acts as electro-mechanical switching if either condition is present.

lendaddy · 12-22-2011, 10:04 PM

Quote:

Originally Posted by fintstone

C/OPN is circuit opening relay. I believe it works with your fuel pump relay to shut off fuel when the engine is not running. You need a signal from your ECU to start and a signal from your AFM to run. In conjunction with the fuel pump relay, it probably acts as electro-mechanical switching if either condition is present.

Yep, turns out I should have been checking with the engine cranking as the ECU requires a signal(s) from the crank and cam sensors to energize those relays. It probably is just the pump.

That being said, not sure how I can blame the dealership for this. One one hand it's almost certainly occurred because the tank was removed during the frame swap and some debris got lodged in there and locked it up or whatnot. But then again, what could they have done to prevent it really? If they work with me on splitting some of these costs I'll probably be happy.

Mrmerlin · 12-23-2011, 05:56 AM

at this point it might be a good idea to drain the tank and see if it has rust or other debris in it.
Your new pump may get damaged the same way if the tank has internal issues.
fit a new fuel filter as well, inspect the old one for clogging

lendaddy · 12-26-2011, 02:12 PM

Update-

In the immortal words of Dalton: "I want you to be nice until it's time to not be nice."

It has been about a week they have had it. They stood by the idea that it was the pump and I told them if they were convinced then I trust them, but maybe I'll get lucky and it's just a connection or something.

They call today and tell me it's done (my buddies wife is on vacation this week so a new service manager called me).

"Yea, the techs replaced the pump and some connections"

"Connections??? Hmm, any idea what that was about?"

"No, they didn't say but they had an issue with a connection or something."

"Oh, ok good deal...I'll be right down. And can you make sure the old pump is there for me please?"

A slight delay-- "uh, oh sure".

I get there and pay, service manager is very sweet and polite. She apologizes for the whole thing and even goes and gets the pump for me (the techs have gone home for the day). I pay the bill and leave, truck starts and drives fine.

I immediately go to the garage and and jump the pump which of course whirrs right up like a champ, no weird noises, sounds great. Now I'm pissed.

I call the service manager back and politely inform her of the whole situation and let her know I'm not pleased but understand things happen and just want this made right. She totally agrees, says they won't cash the check and will let my buddies wife deal with it when she gets back. She couldn't have been more professional and/or apologetic.

She did ask me how I tested it, which I told her and I offered to bring it right back in the event they wanted to see it. She said that wasn't necessary at all and apologized some more.

The bill as only $465 but still...

It is only $465 so I'm not gonna go crazy and cancel checks or other weirdness, I trust this was a tech covering his ass or just being lazy. The service managers could only work with the info they were given, I don't blame them at all. But seriously, what kind of tech doesn't test the pump?

Now, on a longshot..is there any chance this thing is still bad even though it spun up nice and sharply? I highly doubt it, but thought I would ask. Maybe spins but doesn't build pressure? I'll run the factory tests on it tomorrow (I have the factory service manual) to be sure but thought I would throw the question out there. Thanks guys and forgive the ramble, I'm still a bit pissed.

pete3799 · pete3799's Garage

Sounds to me like they owe you $465.00
Troubles with a connection?

Joe Bob · Joe Bob's Garage

Stop the check or dispute the credit card. By the time you need another Toyota the whole crew will be gone and no one will remember you.

Personally, I woulda wired the damn pump up right there and no way in hell I woulda paid dick.....

Zeke · 12-27-2011, 06:43 AM

Stops under pressure? I'm sure you will find out.

rick-l · 12-27-2011, 11:15 AM

Quote:

Originally Posted by lendaddy

Now, on a long shot..is there any chance this thing is still bad even though it spun up nice and sharply? .

DC motors will sometime have a bad contact or open winding on the rotor that it will not start in that position. They will run and start if you move the rotor to where it makeds contact and will run if it wears off the corrosion or never lands in that spot. The only way to tell for sure is to monitor the current waveform and see it has nice even peaks.

It is a long shot however.