Low Fuel Pressure

New member here, long-time DIY mechanic, and lurker of forums who isn't afraid to Google things, and use the Advanced Search options. I've read thru many threads on here including your FAQ and general rules of engagement, so here we go.

2016 Tacoma Sport 4X, manual transmission. I'm second owner and the truck has 7K miles on it. No open recalls on my VIN. I was driving this last week on the highway at 65 MPH or so and suddenly the engine lost power and started bucking, there was no throttle response. I end up on the side of the road w the engine still running, but stumbling badly if I tried to press the gas pedal. After a few minutes, I am able to drive off gradually accelerating and there are no check engine lights. I get to my destination a mile later and park it. An hour later I start it back up and now the CEL pops, and the TRAC off light is on. OBD II tells me P0087 fuel rail pressure too low, as well as the P0171 and P0174 which tells me bank one and bank two too lean. So this confirms my initial impression of fuel starvation, and I have 3/8 of a tank of gas in it.

Currently on the forum there isn't a lot of P0087 postings, one with this code following installation of a camper cap, etc.

I am able to drive back home 7 mi w the TRAC off light going on and off variably, and the CEL light on, and did not experience any loss of power issues. So how would I work thru this? Well, normally I'd check the fuel filter, but there is none on our Gen IIIs, only filter is in the tank on the fuel pickup. So now I'd put a pressure gauge on the Schrader valve fitting on the fuel rail, but good Lord, I don't find one. I know there is a cam driven high pressure pump on the passenger-rear valve cover for the direct injection, and I suppose the port injection is pressurized by the in-tank fuel pump or something like that (?). It's raining and wet so I don't want to crawl under and trace out fuel lines to look for a pinch, etc but will do that later on.

When I picked up the truck for the first time, it was on dead empty. It started but would barely run, so I put a few fresh gallons in it from a fuel can and drove to the closest gas station and filled up. Is it possible that PO letting it run down that low had burned out the in-tank fuel pump? Honestly, this was 1200 miles ago and there have been no problems until just now.

Since I got low pressure/lean condition in both banks, I feel this tells me the issue is proximal (upstream) of the high pressure pump, and stuff like injectors etc, downstream of this are okay. Since now it is running fine and I have cleared the codes, I think driving it a bit is okay, but I have some apprehension about taking it on a road where I couldn't get to the margins if it starved down again.

So, if anyone has some insight on the fuel delivery system on this truck, or experience in working thru this, like where to check fuel pressure etc, I'd welcome the info. Really didn't think I'd be breaking down so soon in a new truck.

 

Looks like CPS issue

 

I'm not a mechanic but the theory you proposed seems like a real possibility.
There are people that run vehicles on e all the time

 

This sounds alot like the problems people were having with their Crank Shaft Position sensors. I would start there. Also isnt it under warranty? just call the nearest dealer and have them pick it up and fix it.

 

I have read on the forum about CPS, issues w it getting too hot or something. But don't we have a separate, independent code for a CPS issue? Isn't that a P0018?

 

Generally I shy away from any work at the Stealerships. Warranty? I doubt they'd honor any warranty here, I bought my Tacoma at auction for left front corner suspension damage/insurance total. It is a salvage title. Toyota would likely tell me to go pound sand.

I am now reading up on the GEN III CPS threads....thank you for your suggestion. I would figure that CPS failure would be a hard failure rather than an intermittent, but I still need to read more.

 

Okay, have been reading non-stop on CPS threads. I haven't pulled mine to look for hash-mark representing new/updated version, just figure that I'll go get a new one and install, keep the old one as a spare. I'm not partial to blindly replacing parts without evidence of guilt, but these are tricky vehicles. Rather surprised that there is no TSB or recall on this, but I suppose Toyota is gathering data and figuring out (their) cost-vs-benefit of doing this. Maybe it needs a heat shield mod.
At any rate, trip tomorrow to get this part as well as the modified detent for the transmission since I also happen to be having the sticky shifter issue as well. Build date 6/2016. Hopefully have not trashed my Cats.

 

Does sound like maybe a CPS issue....at $100.00, I'd change it out like you plan..... Hopefully the CATS are good.... You do not want to be replacing those on your dime..!

 

I won't be able to order parts at the local Dealership until Tuesday. Until then I will not drive it, and just remove the original/existing CPS to see if it is the "bad" part number, or if it is the newer version, "good" part number. Revised CPS part number I understand to be 90919-05098. I have other vehicles I can get around with in the meantime. Thanks for inputs thus far.

Of course, I'll post up any outcomes and updates because I don't leave my threads unresolved/open ended, and of course, I like to use searchable titles, etc.

 

My money's on CPS.

 

I pulled out my CPS, easy to get to for me from under the truck. Looking at it ex vivo I can tell it is the New version CPS, having the identifying hash mark on it. I figure I'll replace it anyway, and this one will stay in the glovebox as a spare.

What I don't really understand is that I got codes for a low pressure at fuel rail, and too lean on both cylinder banks, and no code for a bad CPS. Maybe someone can explain that for me. The nagging concern is that there really is an issue in the fuel delivery somewhere, I find no pinched lines under the truck anywhere on first inspection.

 

I think you may be wrong on the warranty.

Call corporate, give them vin, mileage and ask how much warranty is left.

At the very least, it's a free call.

 

So both my trucks have known Cps issues lol. The one in my 7.3 has been blamed for everything from crank no start to low tire pressure.

 

If it was my truck I'd hook up a fuel pressure gauge and monitor the fuel pressure of the pump and hopefully there is a PID for the high pressure fuel rail and monitor that and see what the readings do when the truck starts acting up.

 

Well, as mentioned before, I think checking the fuel rail pressure would be one of the first things I'd do, however, any Schrader valve fitting anywhere seems to be quite elusive. If you have insight on where I can hook the pressure gauge, I'd be interested in hearing it.
The fuel rails just don't seem to be laying out there in the open as I am accustomed to on many other vehicles, nor any valve fittings.

 

With a good fuel pressure test kit comes several adapters for hooking into the quick disconnects on fuel systems.

 

Interesting interactions w Toyota this morning, they would not sell me the part even with an S account/preferred customer. I was told it was a service part only, but they did have the part in stock. After some persistence I was told that I needed to call the service manager and was offered his direct line. I have exercised other Ninja options and I am going now to pick this part up and will let you know the outcome. Honestly, I don't know how long it will take once installed for me to feel confident that I have remedied the issue. Of course I realize I could buy this part from an online source as others have done, but it could take a long time to get here to this small rock in the middle of the Pacific, and I'd rather not wait. Wondering why Toyota has yet to issue a TSB on the known CPS problem, though it seems they have abundant awareness of the problem if their distributors/stealerships are parts hoarding. Maybe it's just an Island thing.
Also today, I am picking up the parts for TSB 0088-16 as I have the sticky shifter issue as well, but those parts had to be brought in from the warehouse and won't be there til later this afternoon. Maybe I'll just get them tomorrow.

Edit: In case you're interested, and not to derail this thread, HERE's my transmission mod write-up.

 

Yeah, I thought the CPS was actually a Recall so it would be covered free of charge.

 

With the right OBDII tool, you can read the high and low pressure fuel pump pressures. (My ScanGuage II works.)

 

Only on a certain range of vin's though.